Iain Peat-06012564-main report

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1. Introduction
The motor car as we know it was invented and developed in the late
nineteenth century and for as long as there have been cars on the
roads there have been road accidents. The first recorded road death
in a motor accident in Britain was in London 113 years ago. On 17
August 1896, a South London housewife entered the history books
by being run over. Bridget Driscoll became the first person recorded
to have died in a motor accident in Britain when her visit to a fete in
Crystal Palace ended in tragedy. She apparently froze with fear at
the sight of a Roger-Benz approaching and was knocked down by
motorist Arthur Edsell going at 4mph.
The vast growth in the volume of traffic on our road network over the
last century has been matched by a similar rise in the numbers of
road accident casualties. With 272 people killed on Scotland’s roads
in 2008 with an overall figure of 12,756 people injured in road traffic
accidents in Scotland. (Key 2008 Road Casualty Statistics)
I am currently employed as a Road Safety Engineer within the City of
Edinburgh Council and one of the most common subjects for letters
received from the general public is the reduction of vehicle speeds
and actual or near miss accidents on city streets. These letters all
request immediate action be taken but are usually followed by the
statement “but without that annoying traffic calming or speed
cameras”. It seems that a part of the population of Edinburgh feels
that reductions in vehicle speeds should be possible without being
hindered by road humps or enforced by safety cameras.
This research plans to evaluate the physical effect that the
introduction of a VAS has on vehicle speeds over a determined

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length of carriageway as well as the public perception and
acceptance of VAS as a speed reduction measure.
“Speed limits are set to indicate to drivers the maximum speed
permitted on a particular road. Unfortunately, a number of motorists
drive above the speed limit or at an inappropriate speed for the
conditions. In Scotland in 2006-07 a total of 163,826 speeding
offences were recorded by the police.” (Go Safe on Scotland’s Roads
2009)
Historically, there has always been a perceived link between vehicle
speed and the frequency and severity of road traffic accidents. To try
to quantify this relationship the TRL conducted a study in 2000 into
the correlation between vehicle speeds and the frequency of
accidents (Taylor et al 2000). This research looked into road based
and driver based studies and used modeling and statistical
techniques to investigate the links between vehicle speeds and
accident statistics.
It concluded that:
• “In any given situation, higher speeds are associated with
more accidents.”
• “Reducing the speed of the fastest drivers (relative to the
average speed for the road) is likely to bring greater accident
benefits than reducing the overall average speeds for all
drivers, particularly on urban roads. This demonstrates the
value of engineering and enforcement measures which target
the fastest drivers.”
• “The often quoted broad result that a “5% reduction in
accident frequency results per 1mph in average speed”

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although still a good rule of thumb actually varies according to
road type and is around 6% for urban roads with low average
speeds or 4% for higher speed urban roads.”
• “Targeting “problem” roads would be the most effective
strategy and Priority should be given to roads which combine
high speeds with high accident frequency.”
This study advocates the use of speed reducing measures which are
not specifically targeted at the majority of drivers, just at the higher
percentiles. This would seem to suggest that a system of VAS would
be considered ideal for this purpose as long as it was targeted at
roads with a speeding problem and a higher than expected accident
frequency. This study also did not take into account the simple
relationship between the speed of a collision or impact and the
amount of damage done. Any reduction in this speed can mean the
difference between a fatal accident and a serious or even slight
injury.
Research has also been carried out, again by the TRL, to “identify
relevant psychological theories to provide an insight into how specific
road design measures might reduce driving speeds…” (Elliot et al
2003). This research comprehensively tackles complex theories such
as retinal streaming, perceived danger, and cognitive load to name
but a few, but also simply states that one of the reasons for drivers
not exceeding the speed limit is a better knowledge of the posted
limit and a better knowledge of their own traveling speed. This can be
achieved in a number of ways from in car based systems to VAS.

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In car systems or “Intelligent Speed Adaptation” technologies are
currently the focus of a number of studies into both their
effectiveness and acceptability.
These systems fall into four categories:
• Advisory
• Voluntary
• Mandatory
• Dynamic
Advisory systems – these systems give the driver information on the
current speed limit. Some systems also use camera recognition
systems to display the most recently passed warning signs
graphically onto a dashboard display.
Mandatory systems – these systems have an actual effect in the
control of the vehicle. In built computer systems will not allow the
vehicle to pass the posted speed limit. If the vehicle passes from one
limit into a lower limit the system will gently apply the brakes to slow
the vehicle down to the new speed.
Voluntary systems – these fall into the same category as the
mandatory systems, described above, with the addition of an option
to opt out, which means the driver of the vehicle can choose to
disable the ISA system.
Dynamic systems – can be applied to all three of the above systems.
A dynamic system is constantly updated to take into account variable
speed limits. For example limits that have been temporarily reduced
through sections of road works.

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A recent study in to the effects of ISA was carried out by the
University of Leeds (Carsten et al 2008). This involved fitting this new
technology into a fleet of 20 vehicles which was then driven by a total
of 79 drivers, over a period of 6 months. For the first month the
drivers had the ISA turned off which was proceeded by four months
where they drove with a voluntary system in operation. The last
month of the study was conducted with no ISA in place again to
determine if any of the driving behavior passed over into normal
driving.
The study claimed to achieve a 26% reduction in road traffic
accidents over a 60 year period (2010 to 2070) although this is based
on empirically derived relationships between vehicle speeds and
accidents using previously published studies. This does not seem to
take into account the complexity of different variables which can be
involved in a road traffic accident. The 60 year timescale was used to
calculate a cost benefit ratio in accordance with the WebTAG
guidelines.
Interestingly the results of the study also showed that the drivers, in
the main, reverted back to similar levels of non compliance with the
posted speed limits after the 4 month period, showing that there was
not a significant long term change to driver behavior. This technology
is also being pushed for its ecological benefits with a computer taking
control of the acceleration, speed and braking creating a smoother
more fuel efficient journey.
One of the biggest stumbling blocks for the large scale introduction of
this system lies in the requirement that the whole of the UK speed
limit system would need to be electronically mapped. Transport for

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London (TfL) is currently the only authority to have carried out this
process and have introduced a separate study into this technology.
They have fitted ISA devices to a number of buses, taxis and a fleet
of 20 cars which are being driven by TfL engineers. (Going green - the
'ITS' way)
TfL have also introduced a system where you can download software
onto your personal GPS device which will beep a warning to you if
you are traveling over the posted speed limit within TfL’s boundary.
The new Road Safety Framework for Scotland “Go Safe on
Scotland’s Roads” also has a long term objective to introduce a pilot
study of an advisory ISA system in Scotland. Full details of both the
timescale and location of this future study have yet to be revealed.
ISA may prove to be an effective nationally based system in the
future but in the meantime we could look to VAS systems as a viable
low cost option for short and long term speed reductions at specific
local sites.

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2. A Brief History of VAS
Electronic vehicle activated signs have been in use since the late
70’s with the introduction of automatic signs in Hampshire that
informed drivers to “move apart” if detectors showed them to be
driving too closely together. Studies at the time showed that these
signs were found to have a modest success rate, although at that
time before and after surveys consisted of 100 cars measured by a
hand held speed radar gun, so the results were not particularly
robust.
The results of this study showed a reduction of around 30% in
vehicles travelling within 1 second of the vehicle in front and that
these results were maintained 800m further down the road. (Helliar-
Symons 1983)
These signs were fairly quickly joined by speed detection devices in
the early 80’s which were along more similar and recognisable lines
to the signs we see today. These were first introduced in
Warwickshire and boasted the legends “too fast” or “slow down 30”.
The engineers and public figures of the day where concerned that
saturating drivers with these signs could prove to be detrimental to
their effectiveness so it was decided that the threshold speeds would
be set up between the 75th
and 81st
percentiles so that the signs
would only be triggered by a minority of the vehicles. Another site in
the area had the trigger set between the 20th
and 30th
percentiles
which produced more pronounced results.
(Helliar-Symons et al 1984)

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These initial studies showed that vehicle activated signs could not
only prove effective in the short term but also in the long term with
the results showing no noticeable degradation over a five year
period. However the vast majority of these signs and studies have
been in rural locations with urban locations being more unusual.
Similar trails have carried out in a number of different areas over the
intervening years. A recent TRL study was tasked the job of
reviewing a number of these different trials and reporting on the
general effect these signs have had. (Winnett et al 2002)
This study concluded that VAS in gave an average reduction of 4mph
(a range of 1mph to 7mph) as well as a statistically significant
reduction of a third of all accidents.
2.1. Different types of VAS and their uses.
In the years since the early trials of VAS their use has become more
widespread with a variety of different sign types. These different
types can be described as:-
• Warning Signs
• Speed Signs
o Speed Roundal
o Speed Indicating
The warning sign variation includes a standard triangular warning
sign taken from the Traffic Signs Regulations and General Directions
2002, for example the “bend ahead”, “junction ahead” or “crossroads
ahead” sign faces and are usually paired with a “slow down”
message. These signs are triggered by vehicles approaching the
hazard at an inappropriate speed which is set in advance by the local
roads authority. This speed may be lower than the posted speed limit

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and is usually set at the engineer’s discretion in conjunction with the
Police.
The speed sign variation of these signs can be in one of a couple of
configurations. They can show either the speed limit roundal as
described in the Traffic Signs Regulations and General Regulations,
again usually paired with a “slow down” message or they can show a
digital display of the actual speed at which the approaching vehicle
is travelling (Speed Indicating Device – SID). These can be
reinforced by either a smiley or grumpy face graphic or a simpler
variation of green text if the vehicle is below the speed limit and red
text if the vehicle is above the speed limit. A message of “Slow
Down” if above the limit is shown with positive reinforcement
message of “Thank You” if the speed is at or below the limit. One of
the selling points of these SID’s is that they can be used to record the
traffic speeds at the site which means that constant data on the signs
effectiveness can be retrieved. There is no reason why this speed
recording function could not be introduced to any other type of VAS
but as yet does not seem to be a standard feature.
2.2. VAS Guidelines
In 2003 the Department of Transport issued an advisory leaflet on
the introduction of Vehicle Activated Signs. This leaflet outlined a
general checklist that should be worked through at each site where
VAS is being considered.
This checklist consisted of the following steps.
• Audit existing street furniture, signs and road markings and
assess their standard and condition,
• Determine if the site specific problems can not be remedied by
replacing or increasing fixed plate signs,

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• Undertake an accident investigation of the site and determine
if the erection of a VAS will have an effect on any accident
pattern,
• Monitor traffic speeds to determine if a speeding problem
exists.
The leaflet also states which traffic sign faces can be used without
the need for a specific sign authorization from the Department of
Transport or the Welsh or Scottish Executives.
2.3. Public Opinion of VAS
A road side survey was carried out in 2000 (Winnett et al 2002) where
over 300 drivers in Norfolk were asked to stop and were asked a
number of questions to discover the different factors which influenced
drivers response to vehicle activated signs. This road side survey
was then repeated 1 year later in Wiltshire to see if there was any
regional difference in the responses given.
These road side surveys were carried out on routes that featured a
VAS which was in good working order and had a safe location to pull
vehicles in to. A survey was also carried out at the same time to take
a sample count of the percentage of vehicles they stopped which had
triggered the sign. The questions consisted of showing the driver a
series of photographs of the sign they had passed as well as a
number of different VAS sign face variations, such as the bend
warning, junction warning and safety camera repeater sign. The
drivers were asked if they understood the signs and their use as well
as there opinion of the effectiveness and whether they thought that
the signs were a good idea.
When the survey was broken down it was found that around two
thirds of the drivers were male with around 25% over the age of sixty.

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80% of the drivers stopped traveled the route at least once a month
so would be familiar with the sign and it’s location.
An overwhelming percentage of 92% of all drivers surveyed believed
that the signs were a good idea and that they were a good way to
remind drivers to check and adjust their speed.

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3. Current Road Safety Programmes in Edinburgh
On March 1st
2000 the Government issued a document called
Tomorrows Roads - Safer for Everyone. This document outlined a
set of road safety targets for roads authorities throughout the UK for
the period between 2000 and 2010, set against the baseline average
of 1994 to 1998. These targets were:
• A 40% reduction in the number of people killed or seriously
injured ( KSI) in road accidents;
• A 50% reduction in the number of child KSI; and
• A 10% reduction in the slight casualty rate, expressed as the
number of people slightly injured per 100 million vehicle km.
To this the City of Edinburgh Council added its own targets of:
• A 50% reduction in injury to cyclists; and
• A 40% reduction in injury to pedestrians.
The City of Edinburgh Council’s Road Safety section have been
working to meet the 2010 targets with great success and will
continue to work towards the new 2020 targets. They are responsible
for an average annual budget of £1 million and are working towards
Vision Zero which means achieving a city road system where no one
is killed in a road traffic accident.

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City of Edinburgh Council
Progress towards the casualty reduction targets for the year 2010
1994 - 1998 Average 2008 (Provisional)
2004 - 2008 Average
(Provisional)
Fatal
Fatal &
Serious
All Fatal
Fatal &
Serious
All Fatal
Fatal &
Serious
All
17 267 1,995 13 176 1,299 9 184 1,405
Table 3.1 Data taken from “Key 2008 Road Casualty Statistics” published
by the Scottish Government
On June 15th
2009 the Scottish Government published it new targets
for accident reduction or the period of 2010 to 2020 in a new road
safety framework entitled “Go Safe on Scotland’s Roads – it’s
everyone’s responsibility.” These targets are set against the 2004 to
2008 baseline.
Target
2015 milestone
% reduction
2020 target
% reduction
People killed 30 40
People seriously injured 43 55
Children (aged <16) killed 35 50
Children (aged <16) seriously injured 50 65
Table 3.2 Taken from “Go Safe on Scotland’s Roads – it’s everyone’s
responsibility.” Published by the Scottish Government

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In a bid to meet these objectives the Road Safety Team are
responsible for a number of capital funded accident reduction
programmes which consist of:
• Accident Investigation and Prevention - as an ongoing yearly
programme,
• 20mph Zones – both residential streets and around schools,
• Safety Cameras – as part of the Safety Cameras Partnership,
3.1. Accident Investigation and Prevention (AIP)
Edinburgh streets are currently divided into two types, a main route
network and a system of residential streets. Historically the accidents
on these two different types of road were treated by the council’s AIP
Team. The main road network was divided up into a series of road
links and junctions (nodes) on a geographical information system
(GIS). This system would then, using pre-recorded traffic volumes,
calculate an expected accident number for each node which is then
compared with the actual accident history. The difference is then
calculated which gives us a PAR value (Potential for Accident
Reduction) for each node. This allows the funding allocated to the
AIP team to be targeted at specific locations where it will have the
greatest effect in accident reduction terms. It does, however, by its
very nature require accidents to be already present at locations
before any road safety measures can be introduced.
The PAR system allows for the creation of a list of sites which then
go forward to a preliminary investigation which disregards
approximately half of the locations by discarding any sites which
don’t have an obvious accident pattern. This is then followed by a
detailed investigation of the remaining sites to discover if any pattern

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of accidents present can be treated by low cost engineering
measures.
Out of approximately 100 original sites of concern the AIP team
would expect to work up around 5 or 6 schemes to an onsite
conclusion.
3.2. 20mph Zones
The City of Edinburgh Council also has a policy to reduce the speed
limit on all appropriate residential roads to 20mph and has chosen to
carry this out with a program of self enforcing traffic calming.
There is currently a priority list in place for the introduction of these
20mph zones. This list was created by dividing the City into small
areas which are bounded by the main route network. Accident
statistics for these areas were then retrieved and weighted by criteria
such as the presence of pedestrian generators and the percentage of
accidents involving vulnerable road users, i.e. pedestrians and
cyclists. An estimated cost of the scheme was then used in
combination with this to produce the prioritized list of 182 areas. To
date around 44 of these 20 mph zones have been constructed with
over 3000 traffic calming features used so far.
Running alongside this policy was a similar programme which
undertook the installation of traffic calmed 20mph zones around
every school in Edinburgh. This programme was completed in 2008.
The 20mph zone programme has been a proven success with a
reduction in the recorded average vehicle speed to around 18-19
mph throughout the treated areas. The 20mph zone programme has
an annual budget of around £300,000.

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3.3. Safety Cameras
The City of Edinburgh Council is a member of the Lothian and
Borders Safety Camera Partnership which consists of the Lothian
and Borders Police as well as the Council Authorities which fall
geographically within their boundary. This partnership is responsible
for the installation and maintenance of a network of safety cameras,
both speed and red light, throughout the Lothian and Borders area.
The introduction of a new safety camera depends on the location
meeting several strict criteria. These consist of:
• Minimum number of accidents within a 1 km length. Over the
previous three year period there must have been a minimum
of 3 Killed or Seriously Injured (KSI) accidents.
• The existing speed limit at the location must be inspected and
found to be appropriate.
• 85th
percentile speeds must equal or exceed the Lord
Advocate’s current enforcement threshold for the site speed
limit.
• The Local Roads Authority and the Police must be in
agreement that the proposed intervention is the most
appropriate for the circumstances.
(Scottish Safety Camera Programme Handbook)
As you can see the allocation of funding in Road Safety within
Edinburgh is strictly controlled and heavily based on existing accident
history. If there is no history of accident activity at a site then it is very
unlikely that any engineering measures would be recommended.
This existing system does, however, mean that it is difficult to treat
areas where there is a perceived or actual speeding problem but with
no history of accidents.

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A long term objective of this research is to develop acceptable
criteria for the future introduction of VAS’s throughout Edinburgh.
This phase of the study will be carried out after the signs have been
in place for at least 6 months and due to time constraints will not form
part of this report.

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4. Previous Use of VAS in Edinburgh
VAS’s have been used in different forms throughout Edinburgh over
a number of years with different types of sign being used in different
locations.
In 2005 the AIP team introduced a number of warning VAS’s. These
were mainly used at bends in rural areas with a higher than expected
accident history as well as a loss of control pattern to the accidents.
These signs featured the “Road bends to the left or right” warning
sign along with 4 flashing amber lights and an illuminated “Slow
Down” message.
Vehicle speeds were recorded at the sites in question and suitable
threshold speeds were selected to trigger the signs, which were
determined by the mean and 85%ile speeds.
These signs were also erected as part of a larger overall road safety
scheme. The other measures where made up by improvements to
the road markings as well as the introduction of anti-skid surfacing on
the approaches to the bend.
Around the same time a “side road ahead” warning sign was erected
on Comiston Road after the AIP PAR system highlighted a higher
than anticipated number of vehicle conflicts on Comiston Road at it’s
junction with Pentland View. This VAS was erected in conjunction
with a larger scheme which included narrowing the traffic lanes and
widening a pedestrian refuge island.

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Sign Location Sign Type
Accidents 3
years before
Accidents 3
years after
A70 Boll'o'bere Bend 9 7
Riccarton Mains Road Bend 8 1
Lang Loan Bend 8 0
A71 Addiston Mains Bend 4 1
Comiston Road Side road 5 1
Table 4.1 Accident reduction results from existing Edinburgh VAS
It is evident from the results shown in the above graph that the
introduction of these signs, in conjunction with other road safety
measures, has had a beneficial impact on the accident rate at these
sites. However, regression to the mean has not been factored into
these results so it is unknown how the accident statistics would have
changed at these sites had no engineering interception been carried
out. The sign situated on the A70 at Boll’o’bere outside Balerno did
not achieve the same reduction in accidents as the other locations.
This was due to the length of the original investigation area with the
bend in question only being a small part of the site. It is the Council’s
intention to trial another new technology at this site this year with the
installation of solar power LED road studs which will help to highlight
the geometry of the route in dark and overcast conditions.
Speed warning VAS’s have been also been put in place at all mobile
camera sites throughout Edinburgh. This was in an attempt to reduce
the average speed at these sites on a more permanent basis. The
perception was that the average speeds were only affected when the
mobile camera van was seen to be in position and not at any other
times.

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More recently in 2008, speed warning signs were installed on
Maybury Road. This location lies on the outskirts of West Edinburgh
and could be considered to be semi-rural. It had a 4 lane carriageway
with no central reservation and was covered by a national speed limit
for the full length of the scheme. A history of loss of control accidents
had occurred along its length with the majority involving vehicles
crossing over the double white line and striking oncoming vehicles. It
was decided that the introduction of VAS along the route would be
complemented by the reduction of the number of southbound lanes
from two to one with the creation of a new chevroned lane separating
north and south bound vehicles, the scheme also included the
reduction of the original national speed limit to a posted speed limit of
40mph. This scheme has been in place for just over a year and in
that period the accidents have reduced from a total of 13 personal
injury accidents, including one fatal, in the three years prior to the
schemes construction to 1 personal injury accident in the 1 year post
construction. As yet, although the short term results are promising, it
is too early to reasonably forecast the effectiveness of this scheme.

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5. Aims and Objectives
The aim of this report is to discover the perceived and actual
effectiveness of VAS equipment in Edinburgh, as a stand alone traffic
calming measure. And to ascertain if they are only effective at one
point or if their effects can still be seen further down the route.
The objectives of this research are to:
• Produce a weighted priority list of sites in Edinburgh using
speed survey data as well as accident history and
environmental factors,
• Erect Vehicle Activated Signs at each of the top 6 sites on the
priority list,
• Survey and analyze the before and after speed survey results
at each of these sites, as well as a point approximately 300m
beyond the site,
• Develop and implement an online questionnaire to ask the
general publics opinion on VAS,
• Compare the speed survey data with the questionnaire data
to discover if the number of drivers who say that they slow
down in response to these signs matches the percentage of
drivers who actually do slow down.

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6. Methodology
6.1. Site Selection.
A request was made to various departments within the City of
Edinburgh Council as well as to the Chief Constable to provide a list
of streets which had a history of speeding problems or speed related
correspondence. A number of the sites also came from the yearly
assessment list for new safety camera locations, sites that had met
some but not all of the safety camera criteria. This allowed for the
creation of an initial list of 49 locations (Appendix 2).
Each site was then investigated in some detail. This investigation
involved collecting accident details for the last 5 years as well as
gathering 24hr speed survey data and details about the local area.
6.2. Accident Details
The City of Edinburgh Council keeps an accident database on a
Geographical Information System (GIS). This holds all stats19
information, received from the police, and shows it in a graphical
format. The systems allows for the retrieval of the accident location
details to a 10m by 10m grid, overlaid on an OS map, as well as
details of the accident type, severity and an accident story, which is a
description of the vehicle movements and how the accident occurred.
This system currently holds accident data from 1981 onwards and is
updated on a regular basis by data supplied from Lothians and
Borders Police. (Appendix 6)

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6.3. Speed Surveys.
An initially 24 hr speed survey was carried out at each of the 49 sites.
These surveys were carried out as part of a contract awarded to
Count-on-Us, a company which specialises in traffic surveys. The
surveys were carried out by placing a pair of pneumatic tubes across
the carriageway which are connected to an electronic device. This
device records the time taken for a vehicle wheel to cross between
the first and second tube and calculates the vehicles speed. The
system also allows for the collection of fully classified traffic volumes,
giving information on the volume of cars, motor cycles, light goods
vehicles and heavy goods vehicles.
This speed information is then presented in BINS which collect the
data into predetermined categories, for example the percentage of
vehicles traveling 1-2mph over the limit, 3-5mph over the limit etc.
This system also measures the gaps between the vehicles. If the gap
is less than 4 seconds it can be reasonably deduced that the flow of
vehicles is congested which will bring down the mean and 85
percentile speeds and will give a false result. Therefore the speeds
recorded in free flow conditions (greater than a 4 second gap) are
analysed separately which gives a more accurate picture of the traffic
speeds.

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Photo 6.1 Example of speed survey equipment
Photo 6.2 speed survey tubes in situ
Photos 6.1 & 6.2 Pictures provided by Count On Us

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6.4. Weighting
A weighting process was applied to rank the sites, which took into
consideration a number of factors.
The accident history was broken down by severity with a higher
weighting factor given to Killed or Seriously Injured (KSI) against a
lower factor for slight injury accidents.
The speed survey information was weighted giving the percentage of
vehicles travelling 0ver 20 mph greater than the speed limit a greater
value than the percentage of vehicles travelling 1-2 mph over the
limit.
A copy of the weighting sheets for the top 6 sites, along with their
speed survey data and accident records can be found in the
appendices.
Other environmental factors were included in the weighting process
which included the proximity of pedestrian generators, these
included:
• Schools,
• Nurseries,
• Churches,
• Parks, Leisure Centres,
• Bus routes,
• Pedestrian crossing facilities
• Etc…

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This weighting process produced an overall score which was taken
against the length of the site. This was then worked out as value per
kilometre and the figures were compared to create the prioritised list.
The top 6 sites were chosen to take part in the pilot study. On closer
investigation it was decided that two of these sites would not be
included within the study and the next two sites on the list would be
moved up. The first site to be discounted was Telford Road (West
section). This stretch of road is already covered by a Safety Camera
and it was felt that this would bias any results received from this
location. The second site to be removed from the list was Craigmillar
Park. An order for a part time 20mph zone is currently being
promoted for a part of this length of road which would make it
inappropriate to also erect a VAS.
A further 7 day speed survey was carried out at these sites along
with surveys at two control sites which were chosen for their similarity
to the installation sites. Another 7 day survey has been arranged for
3 and 6 months after the signs erection.
In addition to this the accident records for these sites will be
monitored over the first three years. The results of this final survey
and monitoring were not available in time to meet this dissertations
deadline.

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6.5. Sign Erection.
After this selection process was complete I was able to find suitable
sign locations on site. Consultation letters were then issued to the
residents of any properties affected by these sign locations. This
consultation didn’t generate any disagreement with the need for
these signs but in some cases a small alteration to the signs
locations was agreed.
Sign poles were erected by the City of Edinburgh Council’s direct
labour contractor and a power supply was connected up from the
nearest street lighting column.
The tender for the supply and fitting of these signs was won by
Dambach Ltd who erected the signs on the 6th
and 7th
of August
2009.
Photo 6.3 Speed limit aspect of the VAS

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Photo 6.4 Slow Down message aspect of the VAS
Photos 6.3 & 6.4 taken by author
Due to a power supply problem the signs on Telford Road will not be
operational in time to be included within this study.
6.6. Speed Survey Analysis.
The 7 day speed survey results taken before the signs were erected
have been analyse along side after surveys taken at the same
locations in the week immediately after the erection of the signs.
Where the site conditions allowed, a second 7 day survey was
carried out at a suitable location around 200m beyond the sign
location. This additional survey was undertaken to try to find if the
signs had an effect on the speed of vehicles beyond the immediate
location of the sign. The distance of 200m was chosen because of
the site constraints. It would have been statistically, more useful to

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have speed survey details at a location further away from the sign
but unfortunately, due to the urban nature of the sites a larger
distance would included junctions with other routes and traffic which
had not passed the sign.
According to the TRL study in 2000 (Taylor et al 2000) “Reducing
the speed of the fastest drivers (relative to the average speed for the
road) is likely to bring greater accident benefits than reducing the
overall average speeds for all drivers, particularly on urban roads.
This demonstrates the value of engineering and enforcement
measures which target the fastest drivers.”
Therefore the speed data was divided to show the percentage of
vehicles travelling above the posted speed limit, the speeds were
divided into 1-2mph, 2-5mph, 5-10mph, 10-12mph, 12-15mph, 15-
20mph and 20mph+ bins. This will give us an indication of whether
the signs are having an effect on the faster vehicles. The total
percentage of vehicles travelling over the posted speed limit was also
recorded.
The more traditional speed indicators of the mean and 85%ile
speeds where also recorded and compared.
A full graphical breakdown of the speed statistics can be found site
by site in appendix 3.
Control sites were also selected and subjected to before and after
surveys to provide a comparison between treated and untreated
locations.

30
6.7. Speed Survey Conclusions.
The overall speed survey results show a downward trend with each
site showing a reduction in both mean and 85% speeds.
Before After After + 200m
Live Sites Direction Mean 85%ile Mean 85%ile Mean 85%ile
Eastbound 40.8 46.8 38 42.7 35.3 41.8Hillhouse
Road Westbound 38.7 44.5 37.7 42.9 38.7 44.3
Northbound 31.2 35.1 30.9 34.4Lauriston Farm
Road Southbound 27.9 33.6 27.3 32.2
Northbound 33.1 38.7 30.8 34.9 29 33.6Craigentinny
Avenue Southbound 32.4 36.9 31.7 36.2 30.1 34.7
Northbound 26.5 32.9 26.6 31.8 28.6 32.4Willowbrae
Road Southbound 32.5 36.5 32.1 36 29.9 34.7
Eastbound 33.9 38.5 30.1 33.6 27.1 30.2
Redford Road
Westbound 34.7 39.4 31.8 35.3 30.7 34.4
Before After
Control Sites Direction Mean 85%ile Mean 85%ile
Northbound 30.7 34.9 30.8 35.1
Balgreen Road
Southbound 29.5 33.6 29.7 33.6
Northbound 31.5 35.6 32.3 36.5Craigleith
Crescent Southbound 32 35.8 32.5 36.5
Table 6.1 Mean and 85%ile speeds
Mean Speeds
0
5
10
15
20
25
30
35
40
45
Eastbound
Westbound
Northbound
Southbound
Northbound
Southbound
Northbound
Southbound
Eastbound
Westbound
Hillhouse
Road
Lauriston
Farm Road
Craigentinny
Avenue
Willowbrae
Road
Redford Road
Speed
Before
After
After+200m
Chart 6.1 - Mean Speeds

31
85%ile Speeds
0
5
10
15
20
25
30
35
40
45
50
Eastbound
Westbound
Northbound
Southbound
Northbound
Southbound
Northbound
Southbound
Eastbound
Westbound
Hillhouse
Road
Lauriston
Farm Road
Craigentinny
Avenue
Willowbrae
Road
Redford Road
Speed
Before
After
After+200m
Chart 6.2 - 85%ile Speeds
Table 6.1as well as Charts 6.1 and 6.2 show us a reduction in both
the mean and 85%ile speeds at each treated site. The mean speeds
show an average reduction over all of the sites of 1.5mph within a
range of 3.8mph to in one case an increase of 0.1mph. This
reduction was carried on further down the route with an average
reduction of an additional 1.2 mph.
The 85%ile speeds show an average reduction of 2.3 mph within a
range of 4.9 mph and 0.5mph, with an average reduction of an
additional 1mph.
Willowbrae Road Northbound and Hillhouse Road Westbound have
not shown the same overall decreases in speed as the rest of the
study sites. These signs are partially obscured by foliage which could
possibly reduce their effectiveness. A works request order has been
issued to cut back the foliage at these sites.
The control sites showed an average increase of 0.5mph on both
mean and 85%ile speeds over the same timeframe.

32
Total % of vehicles travelling above the
posted limit.
Live Sites Direction Before After After + 200m
Eastbound 58.1 32.9 25.3
Hillhouse Road
Westbound 40.4 33.8 39.8
Northbound 60.1 58.8Lauriston Farm
Road Southbound 40.8 30.6
Northbound 73.6 56 41.3Craigentinny
Avenue Southbound 70.3 66.3 51.3
Northbound 31.2 29.4 35
Willowbrae Road
Southbound 73.8 70 51.8
Eastbound 80.9 45.9 16.4
Redford Road
Westbound 85 65.8 55.2
Control Sites Direction Before After
Northbound 54.3 55.8
Balgreen Road
Southbound 42.9 44.1
Northbound 63 69.5
Craigleith Crescent
Southbound 68.8 74.5
Table 6.2 Total % of vehicles over posted speed limit.
Live Sites
0
10
20
30
40
50
60
70
80
90
Eastbound
Westbound
Northbound
Southbound
Northbound
Southbound
Northbound
Southbound
Eastbound
Westbound
Hillhouse
Road
Lauriston
Farm Road
Craigentinny
Avenue
Willowbrae
Road
Redford Road
%oftotalvehicles>psl
Before
After
After + 250m
Chart 6.3 % of total vehicles travelling over the posted speed limit – Live
Sites

33
Control Sites
0
10
20
30
40
50
60
70
80
Northbound Southbound Northbound Southbound
Balgreen Road Craigleith Crescent
%oftotalvehicles>psl
Before
After
Chart 6.4 % of total vehicles travelling over the posted speed limit – Control
Sites
Table 6.2 as well as Charts 6.3 and 6.4 shows the reduction in the
number of vehicles which were found to be travelling above the
posted speed limit. These results show an average decrease of
19.3% of vehicles travelling above the speed limit within a range of
43.4% to 2.2%.
The speed survey results for 200m further down the route shows an
reduction of 32.7% within a range of maximum reduction of 79.7%
and in one case an increase of 12%.
Again this increase was at the Willowbrae Road site.
The control sites showed an increase of 3.7% of vehicles travelling
over the posted speed limit over the same timeframe.

34
7. Questionnaire
7.1. Setup
A questionnaire was set up using the Survey Monkey website to find
out the views of the general public and their attitude towards vehicle
activated signs.
The survey was issued to all staff at the City of Edinburgh Council as
well as to all staff and students at Edinburgh Napier University.
The survey received 442 responses.
Concerns regarding subject bias have been raised. This is where the
respondents to the survey give a response that they think the
surveyor wants to hear or one that they think puts them in a better
light. The high response rate and the assurance that the survey
results were 100% anonymous should have countered this effect.
7.2. Analysis
The survey was broken into three sections.
• Personal information
• Opinions
• Comments
The personal information consisted of general information such as
age, gender, annual mileage etc.
The opinions were on the signs effectiveness, where should they be
used, in what speed limits etc.
A final section was used to allow responders to leave any comments
to reinforce their answers or if they wanted to comment on something
more specific.

35
Charts 7.1 to 7.5 below show a general breakdown of the personal
details of the survey respondents.
Chart 7.1 Age distribution
What gender are you?
70%
30%
Male
Female
Chart 7.2 Gender Distribution
How old are you?
7%
27%
22%
22%
22%
17-21
22-30
31-40
41-50
50<

36
Are you a professional driver?
20%
80%
Yes
No
Chart 7.3 Split between Professional and Non professional drivers
How regularly do you drive?
47%
23%
13%
9%
8%
Daily
Two or three times a week
Weekly
Seldom
Never
Chart 7.4 Driving frequency

37
What is your average annual mileage?
31%
26%
24%
10%
9%
Under 4,000
4,000 - 8,000
8,000 - 12,000
12,000 - 15,000
Over 15,000
Chart 7.5 Average annual mileages

38
Charts 7.6 to 7.17 below show the breakdown of the responses to
the “Opinion” questions.
Vehicle Activated Signs are effective in enforcing speed limits.
12%
54%
21%
12%
1%
Strongly agree
Agree
Not sure
Disagree
Strongly disagree
Chart 7.6 Effectiveness of VAS
There is a need for them in Edinburgh.
10%
43%
32%
12%
3%
Strongly agree
Agree
Not sure
Disagree
Strongly disagree
Chart 7.7 Percentage split of opinions of the need of these VAS in
Edinburgh

39
Do you adjust your speed when you approach them?
61%
12%
27%
Yes
No
Sometimes
Chart 7.8 Percentage split of drivers who slow down for these signs.
What speed limit do you think they should be used in? (You can tick
more than one box.)
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
90.0%
20mph 30mph 40mph 50mph National Speed
Limit
Chart 7.9 Percentages of speed limits these signs should be used in.

40
What speed reducing method do you think is most effective?
50%
23%
27%
Traffic Calming
VAS
Safety Cameras
Chart 7.10 Percentage split of what respondents viewed as the most effective
speed reducing measure.
Which do you think is more effective. The flashing speed limit sign or
the sign that tells you what speed you are doing?
33%
67%
Flashing Speed Limit Sign
Speed Indicating Sign
Chart 7.11 Split in the perceived effectiveness of SID against the speed limit
roundal

41
They cause an unwanted, dangerous distraction.
3%
7%
19%
60%
11%
Strongly agree
Agree
Not sure
Disagree
Strongly disagree
Chart 7.12 Percentages of respondents who believe that VAS causes an
unwanted distraction.
They should be more widely used.
13%
50%
24%
10%
3%
Strongly agree
Agree
Not sure
Disagree
Strongly disagree
Chart 7.13 should these signs be more widely used?

42
Should they be used as a stand alone measure or as one part of a
wider scheme?
12%
57%
31%
Stand alone
Part of a larger safety scheme
Both
Chart 7.14 should they be used alone or as part of a larger scheme?
Long term exposure to these signs limits their effectiveness.
9%
35%
30%
23%
3%
Strongly agree
Agree
Not sure
Disagree
Strongly disagree
Chart 7.15 does long term exposure limit the effectiveness of these signs?

43
There is an embarassment factor if other drivers see you triggering
one of these signs.
3%
26%
20%
42%
9%
Strongly agree
Agree
Not sure
Disagree
Strongly disagree
Chart 7.16 is there an embarrassment factor in triggering these signs?
Excessive speed can be an important factor in road traffic accidents.
58%
34%
3%
4% 1%
Strongly agree
Agree
Not sure
Disagree
Strongly disagree
Chart 7.17 is excessive speed an important factor in road accidents?

44
The overall response from the survey indicated that the general
public agree that these signs are an effective means to slow general
traffic with only 13% (Chart 7.6) of respondents in disagreement, a
total of 53% (Chart 7.7) are in favour of these signs being used as a
speed reducing measure in Edinburgh
There is more of a desire to see the installation of VAS on 20 and
30mph routes which would hint at the fact that they would be of some
use as a deterrent to speeding within the urban environment.
The questionnaire also shows us that although not necessarily
popular traffic calming is still seen to be the most effective
engineering measure to reduce the speed of vehicles.
In my experience, one of the arguments made by people who are
against the introduction of this type of technology is that they can
cause driver distraction by causing them to take their eyes off the
road ahead, either by looking at these signs or checking their
speedometers. This chart shows that the majority of respondents did
not agree with this assessment.
The results of the opinion survey give us a good indication that the
general public agree with the principal of using these signs across a
wider area.
The questionnaire was designed with an open comments section at
the end. This section allowed respondents to give fuller answers to
some of the questions or to go into more detail on certain aspects of
speeding and road safety. In some cases it became more of a rant or
a chance to vent frustrations.

45
A number of the comments took exception to the wording of the
question “Is excessive speed an important factor in road accidents.”
It was felt that inappropriate speed is more of a contributory factor to
accidents where the driver does not show an awareness of the road
conditions.
“Excessive speed can be an important factor on the severity of any
injuries resulting from an accident. However, it is far from clear
(despite what some may say) that excessive speed is a primary
causation factor. It is thought that the variance of speeds could be
more important and VAS can help with this.”
The general feeling was that VAS are an effective road safety
measure, however their effectiveness can be undermined by
incorrectly setting the trigger speed or by using them too prolifically.
The signs in this study have been set at trigger speed of 10% above
the speed limit plus 2. Therefore, on a 30mph limit the sign will
trigger at 35mph and on a 40mph limit at 46mph.
“Care should be taken in installation and 'turn-on' speeds as if the
signs appear to be going off under the displayed limit - the signs will
be ignored.”
It was also felt that these signs are more effective if it is thought that
the speed limit for the route is set appropriately and are particularly
effective when used at a change in the speed limit, especially at the
entry point to a village. This is where these signs have been
traditionally used and to good effect.
“The illuminated signs are most effective on the approach to villages
on rural main roads, in the built environment I can see little use
except perhaps for an accident black spot over load of signs needs to
be avoided.”

46
Issues were also raised about improving existing driver training with
the suggestion that the minimum driving age should be increased to
at least eighteen.
“Road traffic accidents occur because of poor driving or a lack of
attention, not due to excessive speed. Improving the poor driving
standards in the UK with a wider ranging and more stringent practical
examination along with time based retests to ensure drivers do not
develop a lax attitude to their own driving.”
“Driver education through hard hitting adverts is more effective than
physical speed restraint measures.”
On the whole the jist of the comments was generally in favour of
using VAS in Edinburgh but overall there was more of a view that
existing speed reducing features, i.e. traffic calming and speed
cameras were more effective and that VAS should be backed up with
regular police enforcement.
” Physical traffic calming is the only way to reduce speeds. I hate
them but it physically stops high speeds. Enforcement works but it
can’t be present all the time.”
Generally the use of SID was thought to be better than simply
displaying the speed limit roundal, although it was thought that a
section of the population may see these speed indicating devices as
a target and a way of showing their peers how fast they are going.
This can be a problem with VAS which show you the speed that you
are travelling and to solve this it is general practice to have an upper
cut off speed, so if the vehicle is travelling at say 15mph or over the

47
limit then the vehicle speed is not displayed and is replaced with a
simple “slow down” message.
“Another type of VAS sign is available, one which measures your
speed and then tells you to slow down if you trigger the sign. Those
which just show a speed tend to encourage boy racers to compete to
get the fastest speed up!”
Finally the last point that came from the comments was a desire to
see speeds reduced by actively changing the road design. By
removing footways, signs and road markings you effectively take the
drivers belief in his right of way from them and promote more of a
feeling of a shared surface, similar to the “naked street” concept.
“Excessive speed in urban areas can be reduced through road
alignment, carriageway widths, surfacing e.g. setts and the nature of
the surrounding environment. Removing excessive signs is
supposed to help. VAS may be suited to particular situations but
should not be viewed as the solution in every case”
A few of my favourite responses to the open comment question in the
survey were.
“Please, NO MORE ruddy signs! There's too many already. Those
grimacing signs are a pain in the arse and are never calibrated
correctly anyhow. Stop wasting money!!”
“I speed up in order to activate the one on a road I travel on daily - I
am usually a fairly careful and sensible driver. This is one that
flashes "slow down". “

48
“Listening to Radio 4 tends to calm your driving down too.”
“VAS’s are a non intrusive way of making you feel like you are being
watched and therefore should watch your speed. Cameras work but
their fines are completely unfair and mean you have to always watch
the side of the road instead of in front, but flashing signs just give you
a reminder in case you missed the speed limit signs.”
“Anyone caught breaking any speed limit should have their car
removed and crushed and forced to re-sit their driving test.”
“I like the ones in north east England used during road works which
flash your speed and also flash up your registration plate. It put the
fear of Barbara Castle up you. The trouble is people who speed
between cameras/signs.”
A list of all quotes can be found in appendix 5.

49
7.3. Statistical Significance of the Opinion Survey
The survey results were cross tabulated to determine if the
differences in opinion between different groups where statistically
significant. This was determined by running the results through a chi
squared test.
The chi squared value was found by using this formula:
Chi squared formula = Sum (Observed – Expected) 2
/ Expected
The observed value was the total number of respondents in that sub
group who gave that response. The expected value was found by
taking the proportion of the overall responses to the total response
count and applying that proportion to the observed value.
For example if the “are they effective” question had a total response
count of 423 with 52 responses in the “strongly agree” box, then if we
know that 299 males responded to the question we can show that
using percentages:
(52/423)*100=12.3%
So 12.3% of the overall population responded with “strongly agree”.
Therefore if you take 12.3% of the overall male responses of 299
then you get a figure of 36.7 rounded up to 37 which is your expected
value.
The chi squared test is not effective if any of the response numbers
are below 5. If this occurs in one cell or more the whole column or
row will be merged with another E.g. merging strongly agrees with
agree or 17-21 with 22-30 year olds.

50
Answer
Options
Strongly
agree
Agree Not sure Disagree
Strongly
disagree
Response
Count
Obs Exp Obs Exp Obs Exp Obs Exp Obs Exp
Male 43 37 150 159 62 63 44 40 - - 299
Female 9 15 75 66 27 26 13 17 - - 124
Overall 52 225 89 57 423
Disagree and Strongly Disagree merged due to low numbers.
Table 7.1 cross tabulation between Gender and the statement “Vehicle Activated
Signs are effective in enforcing speed limits.”
Obs Exp ((obs-exp)^2)/2
43 37 0.97
150 159 0.51
62 63 0.02
44 40 0.40
9 15 2.40
75 66 1.23
27 26 0.04
13 17 0.94
Chi2
= 6.51
Table 7.2 an example of the chi squared calculation using values from the cross
tabulation between gender and the statement “Vehicle Activated Signs are effective in
enforcing speed limits”
These values are then used in the chi squared formula to give a
figure which is then checked against a pre-published table of critical
chi squared values.
To check these figures against these tables we first have to
determine the degrees of freedom the result table has. This allows us
to use the appropriate part of the chi squared table. The degrees of
freedom value is found by using this equation.

51
(Number of Rows-1) * (Number of Columns-1)
This method is used to prove or disprove a hypothesis. In the first
instance I state “There is a difference between the opinions of the
sexes.” If the calculated value of chi squared is lower than the critical
value from the table, using the appropriate degree of freedom and
confidence level, then it can be stated that this statement is false and
there is no difference in the opinions between the sexes. However, if
the calculated value is higher than the value taken from the table
then it can be said that with a confidence level of 95% the opinions
differ between men and women.
This method has also been applied to the statements “There is a
difference of opinion relative to the annual mileage covered,” and
“There is a difference of opinion between different age groups.”
A decision was made not to cross tabulate the results using the
“Professional / Non-professional” and “driving frequency” groups.
This was due to these groups being too similar to the annual mileage
group. The following chi squared tests were all carried out for a
confidence level of 95%.

52
Table 7.3 Results by Gender – Vehicle Activated Signs are effective in
enforcing speed limits
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Male 43 37 150 159 62 63 44 40 - - 299
Female 9 15 75 66 27 26 13 17 - - 124
Overall 52 225 89 57 423
Table 7.3 has 3 degrees of separation. With a chi squared of 6.51
This value is lower than the table which shows us that there is no
difference of opinion between the genders.
Table 7.4 Results by Gender – Is there a need for them in Edinburgh?
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Male 35 31 126 129 91 94 45 43 - - 297
Female 9 13 58 55 42 39 16 18 - - 125
Overall 44 184 133 61 422
Table 7.4 has 3 degrees of separation. With a chi squared of 2.62.
This value is lower than the table which again shows no difference of
opinion between the genders.

53
Table 7.5 Results by Gender - Do you adjust your speed when you approach
them?
Answer
Options
Yes No Sometimes
Response
Count
Obs Exp Obs Exp Obs Exp
Male 178 182 37 35 81 79 296
Female 79 75 12 14 31 33 122
Overall 257 49 112 418
Table 7.5 has 2 degrees of separation. With a chi squared of 0.87.
Table 7.6 Results by Gender – What speed limit do you think they should be
used in?
Answer
Options
20mph 30mph 40mph 50mph
National
Speed
Limit
Response
Count
Male 139 145 228 224 112 113 59 56 65 61 285
Female 67 61 91 95 48 47 21 24 22 26 120
Overall 206 319 160 80 87 405
Table 7.6 has 4 degrees of freedom. With a chi squared of 2.52.

54
Table 7.7 Results by Gender - What speed reducing method do you think is
most effective?
Answer
Options
Traffic
Calming
VAS
Safety
Cameras
Response
Count
Male 147 142 65 66 75 78 287
Female 54 59 29 28 36 33 119
Overall 201 94 111 406
Table 7.8 Results by Gender - Which one do you think is more effective? The
flashing speed limit sign or the sign that tells you what speed you are doing.
Answer
Options
Speed
Limit
Sign
Speed
Indicating
Sign
Response
Count
Obs Exp Obs Exp
Male 103 95 185 193 288
Female 31 39 89 81 120
Overall 134 274 408
Table 7.8 has 1 degree of freedom. With a chi squared of 3.44.

55
Table 7.9 Results by Gender – They cause an unwanted, dangerous
distraction.
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Male - - 31 30 53 55 177 177 35 34 296
Female - - 12 13 25 23 73 73 13 14 123
Overall 43 78 250 48 419
Agree and Strongly agree merged due to low numbers.
Table 7.10 Results by Gender – They should be more widely used.
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Male 38 38 149 148 70 72 31 29 8 9 296
Female 16 16 60 61 32 30 10 12 5 4 123
Overall 54 209 102 41 13 419

56
Table 7.11 Results by Gender – Should they be used as a stand alone
measure or as part of a wider scheme?
Answer
Options
Stand
Alone
Part of
larger
scheme
Both
Response
Count
Male 37 33 155 162 90 87 282
Female 10 14 73 66 32 35 115
Overall 47 228 122 397
Table 7.12 Results by Gender – Long term exposure to these signs limits
their effectiveness.
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Male 26 26 105 103 89 87 66 67 5 8 291
Female 10 10 40 42 34 36 29 28 6 3 119
Overall 36 145 123 95 11 410

57
Table 7.13 Results by Gender – Is there an embarrassment factor if other
drivers see you triggering one of these signs?
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Male 8 9 79 77 64 57 113 122 27 26 291
Female 5 4 29 31 17 24 59 50 9 10 119
Overall 13 108 81 172 36 410
Table 7.14 Results by Gender – Excessive speed can be an important factor
in road traffic accidents.
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Male 163 167 104 100 8 9 15 14 - - 290
Female 72 68 37 41 5 4 5 6 - - 119
Overall 235 141 13 20 0 409
Disagree and Strongly disagree merged due to low numbers.

58
Table 7.15 Results by Mileage – Vehicle Activated Signs are effective in
enforcing speed limits.
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Under 4,000 - - 76 80 35 25 10 16 - - 121
4,000 - 8,000 - - 77 75 23 23 13 15 - - 113
8,000 - 12,000 - - 69 66 18 21 13 13 - - 100
12,000 - 15,000 - - 28 28 7 9 7 6 - - 42
Over 15,000 - - 25 26 3 8 12 5 - - 40
Overall 275 86 55 416
Agree and Strongly Agree merged due to low numbers
This value is higher than the table which shows us that there is a
difference of opinion between drivers who cover different annual
mileages.
Table 7.16 Results by Mileage – Is there a need for them in Edinburgh?
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Under 4,000 - - 61 66 50 38 11 18 - - 122
4,000 - 8,000 - - 66 61 32 35 15 17 - - 113
8,000 - 12,000 - - 56 54 30 31 14 15 - - 100
12,000 - 15,000 - - 18 22 10 13 13 6 - - 41
Over 15,000 - - 24 22 8 13 8 6 - - 40
Overall 225 130 61 416
mileages.

59
Table 7.17 Results by Mileage - Do you adjust your speed when you
approach them?
Answer
Options
Yes No Sometimes
Response
Count
Under 4,000 79 74 15 14 26 32 120
4,000 - 8,000 72 70 10 13 31 30 113
8,000 - 12,000 61 62 8 12 31 27 100
12,000 - 15,000 23 26 8 5 11 11 42
Over 15,000 21 25 7 5 12 11 40
Overall 256 48 111 415
mileages.
Table 7.18 Results by Mileage – What speed limit do you think they should be
used in?
Answer
Options
National
Speed
Limit
Response
Count
Under 4,000 50 59 79 91 54 46 27 23 34 25 115
4,000 - 8,000 61 55 94 86 42 43 20 22 16 23 108
8,000 - 12,000 52 50 81 78 35 39 19 20 22 21 99
12,000 - 15,000 40 39 62 61 27 30 14 15 14 17 77
Over 15,000 - - - - - - - - - - -
Overall 203 316 158 80 86 399
"12,000 - 15,000" has been merged with "Over 15,000" due to low numbers.
mileages.

60
Table 7.19 Results by Mileage - What speed reducing method do you think is
most effective?
Answer
Options
Traffic
Calming
VAS
Safety
Cameras
Response
Count
Under 4,000 70 59 25 27 23 32 118
4,000 - 8,000 57 54 24 25 27 30 108
8,000 - 12,000 41 48 23 22 32 26 96
12,000 - 15,000 17 20 9 9 14 11 40
Over 15,000 15 19 10 9 14 11 39
Overall 200 91 110 401
mileages.
Table 7.20 Results by Mileage - Which one do you think is more effective?
The flashing speed limit sign or the sign that tells you what speed you are
doing.
Answer
Options
Speed
limit sign
Speed
Indicating
Sign
Response
Count
Obs Exp Obs Exp
Under 4,000 40 38 77 79 117
4,000 - 8,000 43 36 68 75 111
8,000 - 12,000 29 32 69 66 98
12,000 - 15,000 12 12 26 26 38
Over 15,000 8 12 30 26 38
Overall 132 270 402
mileages.

61
Table 7.21 Results by Mileage – They cause an unwanted, dangerous
distraction.
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Under 4,000 - - 6 12 27 21 75 72 11 14 119
4,000 - 8,000 - - 14 12 13 20 76 68 10 13 113
8,000 - 12,000 - - 8 10 21 18 55 60 15 12 99
12,000 - 15,000 - - 15 8 12 14 42 49 12 9 81
Over 15,000 - - - - - - - - - - -
Overall - 43 73 248 48 412
"12,000 to 15,000" and "0ver 15,000" merged due to low numbers.
mileages.
Table 7.22 Results by Mileage – They should be more widely used.
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Under 4,000 - - 72 75 35 29 12 16 - - 119
4,000 - 8,000 - - 71 71 30 27 12 15 - - 113
8,000 - 12,000 - - 64 62 22 24 13 13 - - 99
12,000 -
15,000
- - 26 26 7 10 9 6 - - 42
Over 15,000 - - 26 25 5 9 8 5 - - 39
Overall - 259 99 54 - 412
Agree and Strongly Agree merged due to low
numbers
mileages.

62
Table 7.23 Results by Mileage – Should they be used as a stand alone
measure or as part of a wider scheme?
Answer
Options
Stand
alone
Part of
larger
scheme
Both
Response
Count
Under 4,000 10 14 74 66 31 35 115
4,000 - 8,000 11 13 60 62 38 33 109
8,000 - 12,000 18 12 47 55 31 29 96
12,000 - 15,000 8 9 43 41 20 22 71
Over 15,000 - - - - - - -
Overall 47 224 120 391
"12,000 - 15,000" and "Over 15,000" merged due to low numbers.
mileages.
Table 7.24 Results by Mileage – Long term exposure to these signs limits
their effectiveness.
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Under 4,000 - - 56 52 39 35 22 31 - - 117
4,000 - 8,000 - - 48 49 32 33 31 29 - - 111
8,000 - 12,000 - - 37 43 31 29 30 26 - - 98
12,000 - 15,000 - - 19 17 11 11 8 10 - - 38
Over 15,000 - - 18 17 6 12 15 10 - - 39
Overall - 178 119 106 - 403
Agree and Strongly Agree merged
Disagree and Strongly disagree merged
mileages.

63
Table 7.25 Results by Mileage – Is there an embarrassment factor if other
drivers see you triggering one of these signs?
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Under 4,000 - - 36 35 19 22 62 60 - - 117
4,000 - 8,000 - - 35 33 20 21 56 57 - - 111
8,000 - 12,000 - - 27 29 23 18 48 51 - - 98
12,000 - 15,000 - - 14 11 6 7 18 20 - - 38
Over 15,000 - - 8 12 7 7 24 20 - - 39
Overall - 120 75 208 - 403
Disagree and Strongly disagree merged due to low numbers
mileages.
Table 7.26 Results by Mileage – Excessive speed can be an important factor
in road traffic accidents.
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
Under 4,000 74 66 38 41 - - 5 10 - - 117
4,000 - 8,000 68 63 35 39 - - 8 9 - - 111
8,000 - 12,000 53 56 32 34 - - 12 8 - - 98
12,000 -
15,000 34 44 35 27 - - 8 6 - - 77
Overall 229 140 - 33 - 403
Disagree and Strongly disagree merged due to low numbers
12,000-15,000 and over 15,000 merged due to low numbers
mileages.

64
Table 7.27 Results by Age – Vehicle Activated Signs are effective in enforcing
speed limits.
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
17-21 - - 18 19 5 6 6 4 - - 29
22-30 - - 71 76 27 24 18 16 - - 116
31-40 - - 56 60 22 19 14 12 - - 92
41-50 - - 66 61 16 20 11 13 - - 93
50< - - 66 61 19 20 8 13 - - 93
Overall - 277 89 57 - 423
difference of opinion between different age groups.
Table 7.28 Results by Age – Is there a need for them in Edinburgh?
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
17-21 - - 13 16 8 9 8 4 - - 29
22-30 - - 53 63 42 37 21 17 - - 116
31-40 - - 50 50 31 29 11 13 - - 92
41-50 - - 55 50 23 29 14 13 - - 92
50< - - 57 50 29 29 7 13 - - 93
Overall - 228 133 61 - 422

65
Table 7.29 Results by Age - Do you adjust your speed when you approach
them?
Answer
Options
Yes No Sometimes
Response
Count
17-21 - - - - - - -
22-30 79 89 14 17 51 39 144
31-40 59 55 6 10 24 24 89
41-50 65 57 14 11 13 25 92
50< 54 57 15 11 24 25 93
Overall 257 49 112 418
"17-21" and "22-30" merged due to low numbers
Table 7.30 Results by Age – What speed limit do you think they should be
used in?
Answer
Options
Nation
Speed
limit
Response
Count
17-21 14 14 19 22 7 11 8 5 7 6 29
22-30 48 57 80 88 40 44 18 22 25 24 116
31-40 45 45 71 70 34 35 16 17 19 19 92
41-50 54 45 70 70 37 35 19 17 14 19 92
50< 45 45 79 70 42 35 19 18 22 19 93
Overall 206 319 160 80 87 422
difference of opinion between different age groups

66
Table 7.31 Results by Age - Which one do you think is more effective? The
flashing speed limit sign or the sign that tells you what speed you are doing.
Answer
Options
Speed
Limit
Sign
Speed
Indicating
Sign
Response
Count
Obs Exp Obs Exp
17-21 9 9 19 19 28
22-30 37 37 76 76 113
31-40 31 29 56 58 87
41-50 24 29 63 58 87
50< 33 31 60 62 93
Overall 134 274 408
Table 7.32 Results by Age - What speed reducing method do you think is
most effective?
Answer
Options
Traffic
Calming
VAS
Safety
Cameras
Response
Count
17-21 - - - - - - -
22-30 72 70 20 33 50 39 142
31-40 39 42 28 20 18 23 85
41-50 49 44 19 20 20 24 88
50< 41 45 27 21 23 25 91
Overall 201 94 111 406
"17-21" and "22-30" merged due to low numbers

67
Table 7.33 Results by Age – They cause an unwanted, dangerous distraction.
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
17-21 - - 7 3 8 5 13 20 - - 28
22-30 - - 10 12 26 21 79 82 - - 115
31-40 - - 11 9 15 17 65 65 - - 91
41-50 - - 9 9 12 17 71 65 - - 92
50< - - 6 10 17 17 70 66 - - 93
Overall - 43 78 298 - 419
This value is marginally higher than the table which shows us that
there is a difference of opinion between different age groups
Table 7.34 Results by Age – They should be more widely used.
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
17-21 - - 11 18 8 7 9 4 - - 28
22-30 - - 73 72 28 28 14 15 - - 115
31-40 - - 53 57 24 22 14 12 - - 91
41-50 - - 60 58 22 22 10 12 - - 92
50< - - 66 58 20 23 7 12 - - 93
Overall - 263 102 54 - 419

68
Table 7.35 Results by Age – Should they be used as a stand alone measure
or as part of a wider scheme?
Answer
Options
Stand
Alone
Part of
larger
scheme
Both
Response
Count
17-21 6 3 14 15 6 8 26
22-30 14 13 74 65 25 35 113
31-40 13 10 47 49 25 26 85
41-50 7 10 45 50 35 27 87
50< 7 10 48 49 31 26 86
Overall 47 228 122 397
This value is just lower than the table which shows us that there is no
Table 7.36 Results by Age – Long term exposure to these signs limits their
effectiveness.
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
17-21 - - - - - - - - - - -
22-30 - - 82 63 38 42 23 36 - - 140
31-40 - - 28 40 33 27 29 23 - - 90
41-50 - - 35 41 24 27 32 24 - - 91
50< - - 39 40 28 27 22 23 - - 89
Overall - 184 123 106 - 410
17-21 and 22-30 merged due to low numbers

69
Table 7.37 Results by Age – Is there an embarrassment factor if other drivers
see you triggering one of these signs?
Answer
Options
Strongly
agree
Strongly
disagree
Response
Count
17-21 - - 5 8 6 5 15 13 - - 26
22-30 - - 30 34 18 23 66 58 - - 114
31-40 - - 26 27 19 18 45 46 - - 90
41-50 - - 38 27 15 18 38 46 - - 91
50< - - 22 26 23 18 44 45 - - 89
Overall - 121 81 208 - 410
Table 7.38 Results by Age – Excessive speed can be an important factor in
road traffic accidents.
Answer
Options
Strongly
Agree
Strongly
disagree
Response
Count
17-21 - - - - - - - - - - -
22-30 79 80 50 48 - - 11 11 - - 140
31-40 48 51 33 31 - - 8 7 - - 89
41-50 57 52 25 31 - - 9 7 - - 91
50< 51 51 33 31 - - 5 7 - - 89
Overall 235 141 - 33 - 409
Not sure, disagree and strongly disagree have been merged due to low numbers
17-21 and 22-30 also merged due to low numbers

70
7.4. Questionnaire Conclusions
The chi squared testing has shown us that across the board there is
no statistically significant difference in the opinions shown by men
and women in regard to this questionnaire although there were a few
differences within the other two groups tested.
In the case of the cross tabulation between different annual mileages
it was found that a higher than expected percentage of drivers who
drove less than 4,000 miles a year were unsure whether the signs
were effective or even needed at all. At the other end of the
spectrum, a higher than expected number of high mileage driver’s
feel that the signs are not effective and that there is no need to erect
them in Edinburgh. This looks like it falls into line with a driver’s
experience, with drivers who cover more mileage perhaps being
better able to visually judge the posted speed limit and be more
aware of their own travelling speed.
These opinions can also be seen in some of the posted quotes on
the open comments section of the questionnaire. Firstly taken from
high mileage responses:
• “Speed is only part of the problem. Driver awareness and
ability are under-enforced and emphasised by law
enforcement.”
• “These signs are only effective in the immediate vicinity,
because drivers who do act on them only drop their speed
while they are passing the sign and generally speed up again.
I don't think that is deliberate, it's just the general driving style
here. The most effective method of keeping vehicle speeds
down to the limit is by using average speed cameras as

71
drivers know that they have to keep to the limit in the camera
zones.”
Secondly, responses taken from the lower mileage group:
• “I feel these signs are useful but most people speeding seem
to know they are doing it and may simply disregard the sign.”
• “Behaviour around signs - some drivers care not for being told
what to do so will flaunt the advice.”
A summary of the opinions of the different age groups shows that the
younger age groups tend to have a more negative view of this
technology as well as being more likely to ignore the signs all
together.
Again, this is reinforced by the following quotes from the
questionnaire:
• “I think speed cameras are the most effective for controlling
the speed of traffic. I hate speed bumps; they are not effective
and ruin your car.”
• “I consider Speed and red light violation cameras are most
effective in speed reducing measures.”
• “Speed cameras need to be more visible as a fine is a better
method of slowing people down than embarrassment. A VAS
just before a camera would greatly reduce the speed in an
area.”
• “I don't really slow down if I trigger one of those speed signs,
I'm usually quite aware of my speed and if I'm breaking the
speed limit the chances are it's because I'm late (not that that
is a good reason to break the speed limit, I agree that driving
faster can cause accidents). “

72
8. Conclusions
The results of this study have shown a positive downward trend to
both mean and 85%ile speeds at each site with reductions within an
average reduction of 1.5mph in a range of 3.8mph to 0mph in mean
speeds and an average reduction of 2.3mph in a range of 4.9mph to
0.5mph for 85%iles. This trend also applied to the speeds measured
at a point beyond the sign location, with a further average reduction
of 1.2mph in the mean speeds and 1mph in the 85%ile speeds.
Perhaps the most encouraging result of this research is the reduction
in the numbers of vehicles travelling at speeds above the posted
speed limit, with an average reduction of 19.3% in the total vehicles
travelling above the posted speed limit slowing to below the speed
limit which increases to 32.7% at a point 200m further down the
route.
Do you adjust your speed when you
approach them?
Answer
Options
Response
Percent
Response
Count
Yes 61.40% 256
No 11.80% 49
Sometimes 26.90% 112
Table 8.1 Responses to the survey question “Do you adjust your speed
when you approach them”
This figure of 32.7% does not seem to compare favourably with the
figure of 61.4% of questionnaire respondents (Table8.1) who claimed
that they would slow down if they triggered one of these signs
however when you consider that this covered a range of percentages
from 80% to 2% reductions it would appear that the effectiveness of
these signs can vary considerably from site to site.

73
The signs have shown a very positive feed back and acceptability
from the general public with an overall percentage of 65.4% of
respondents believing that VAS are effective as a speed enforcing
measure and 53.9% believing that there is a need for signs such as
these within urban Edinburgh. An encouraging 62.7% said that the
signs should be more widely used although the majority of 57.6%
stated that these signs would be more effective as part of a larger
road safety scheme and not as a stand alone measure.
The study has shown these VAS installations to be a successful
addition to the City of Edinburgh Council’s road safety arsenal
although the decision to expand this programme will be made once
the full 6 month study is complete.

74
9. Possible future research.
This study has looked at the effect one type of VAS has on vehicle
speeds within Edinburgh. Further research could be made using the
same premise but using the SID type of sign to determine which of
the two sign types is the most effective.
This project has also suffered from time constraints, a useful future
project could be carried out on the longer term results of these signs
and if their effectiveness is diluted over time. This could be achieved
by comparing speed data from the permanent sites set up for this
research and carrying out a similar study using portable equipment
which can be rotated around a number of sites.
The design of the questionnaire for this study deliberately avoided
asking for location details from the respondents. This was done to
promote a feeling of anonymity so that the respondents wouldn’t feel
pressured into giving the answers that they felt we would want to
hear. An interesting secondary study could issue a new
questionnaire asking for this information and comparing the
responses from drivers who live near to or drive past VAS with
drivers who very rarely encountered them.

75
References
Key 2008 Road Casualty Statistics
http://www.scotland.gov.uk/Publications/2009/06/19135601/0
Vehicle-activated signs – a large scale evaluation
TRL Report TRL548
M A Winnett and A H Wheeler (Winnett et al 2002)
Psychological Traffic Calming – Paper to the Road Safety Congress
2005
J V Kennedy (Kennedy 2005)
The effects of drivers speed on the frequency of road accidents.
TRL Report 421
Taylor M., Lynam D. and Baruya A. 2000 (Taylor et al 2000)
Road design measures to reduce drivers’ speed via “psychological”
processes: A literature review
TRL Report TRL564
M A Elliott, V A McColl and J V Kennedy (Elliot et al 2003)
Automatic close-following warning sign at Ascot
RD Helliar-Symons (Helliar-Symons 1983)
Automatic speed warning sign - Hampshire trials
RD Helliar-Symons, AH Wheeler (Helliar-Symons et al 1984)

76
ISA-UK Intelligent speed adaptation, Final Report
The University of Leeds, June 2008
Oliver Carsten, Mark Fowkes, Frank Lai, Kathryn Chorlton,
Samantha Jamson, Fergus Tate and Bob Simpkin (Carsten et al
2008)
ISA: panacea for speeding or a step towards a big brother future
(Intelligent Speed Adaptation), IN Local Transport Today, No 511 16
Jan 2009, pp10-11, 13
Intelligent Transport Systems
Parliament Office of Science and Technology Postnote
January 2009 Number 322
Scottish Safety Camera Programme Handbook Version 1.1
Tomorrow’s Roads: Safer for Everyone
Dept of Transport - 1 March 2000
http://www.dft.gov.uk/pgr/roadsafety/strategytargetsperformance/tomorrows
roadssaferforeveryone
Scotland’s Road Safety Framework “Go Safe on Scotland’s Roads –
it’s everyone’s responsibility”
Scottish Government 15th June 2009
Key 2008 Road Casualty Statistics
Scottish Government 22nd June 2009

77
Department of Transport Traffic Advisory Leaflet 1/03
Vehicle Activated Signs
March 2003 – Traffic Advisory Unit
Going green - the 'ITS' way (green intelligent transportation systems
initiatives), IN GEOconnexion International, Vol 8 No 7 Jul/Aug 2009,
pp38-39

78
Appendices
1. Weighting sheets (top 6 sites)
2. Priority List
3. Speed survey results
4. Questionnaire results
5. Questionnaire comments
6. Examples of Accident Plots and Stick Diagrams

79
Appendix 1 – Weighting Sheets (Top 6 sites)

85
Appendix 2 – Priority List

86
Appendix 3
Live Sites
Lauriston Farm Road Northbound
0
5
10
15
20
25
30
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotalvehicles
before
after
Lauriston Farm Road Southbound
0
2
4
6
8
10
12
14
16
18
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotalvehicles
before
after

87
Lauriston Farm Road Northbound
0
5
10
15
20
25
30
35
40
Mean Speed 85%ile Speed
Speed
before
after
Lauriston Farm Road Southbound
0
5
10
15
20
25
30
35
40
Speed
before
after

88
Craigleith Crescent Northbound
0
5
10
15
20
25
30
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotalvehicles
before
after
Craigleith Crescent Southbound
0
5
10
15
20
25
30
35
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotalvehicles
before
after

89
0
5
10
15
20
25
30
35
40
Speed(mph)
before
after
0
5
10
15
20
25
30
35
40
Speed(mph)
before
after

90
Willowbrae Road Northbound
0
2
4
6
8
10
12
14
16
18
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotaltraffic
before
after
after+200m
Willowbrae Road Southbound
0
5
10
15
20
25
30
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotaltraffic
before
after
after+200m

91
Willowbrae Road Northbound
0
5
10
15
20
25
30
35
Speed
before
after
after+200m
Willowbrae Road Southbound
0
5
10
15
20
25
30
35
40
Speed
before
after
after+200m

92
Craigentinny Avenue Northbound
0
5
10
15
20
25
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotalvehicles
before
after
after + 200m
Craigentinny Avenue Southbound
0
5
10
15
20
25
30
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotalvehicles
before
after
after + 200m

93
Craigentinny Avenue Northbound
0
5
10
15
20
25
30
35
40
45
Speed
before
after
after + 200m
Craigentinny Avenue Southbound
0
5
10
15
20
25
30
35
40
Speed
before
after
after + 200m

94
Hillhouse Road Eastbound
0
5
10
15
20
25
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotaltraffic
before
after
after+200m
Hillhouse Road Westbound
0
2
4
6
8
10
12
14
16
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotalvehicles
before
after
after+200m

95
Hillhouse Road Eastbound
0
5
10
15
20
25
30
35
40
45
50
Speed
before
after
after+200m
Hillhouse Road Westbound
0
5
10
15
20
25
30
35
40
45
50
Speed
before
after
after+200m

96
Redford Road Eastbound
0
5
10
15
20
25
30
1 - 2mph
>PSL
2 -5mph
>PSL
5 -
10mph
>PSL
10-
12mph
>PSL
12-
15mph
>PSL
15-
20mph
>PSL
20mph+
>PSL
%oftotalvehicles
Before
After at sign
After + 200m
Redford Road Westbound
0
5
10
15
20
25
30
35
1 - 2mph
>PSL
2 -5mph
>PSL
5 -
10mph
>PSL
10-
12mph
>PSL
12-
15mph
>PSL
15-
20mph
>PSL
20mph+
>PSL
%oftotalvehicles
Before
After at sign
After + 200m

97
Redford Road Eastbound
0
5
10
15
20
25
30
35
40
45
mean speed 85%ile speed
Speed
Before
After at sign
After + 200m
Redford Road Westbound
0
5
10
15
20
25
30
35
40
45
mean speed 85%ile speed
Speed
Before
After at sign
After + 200m

98
Control Sites
Balgreen Road Northbound
0.0
5.0
10.0
15.0
20.0
25.0
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotalvehicles
before
after
Balgreen Road Southbound
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotalvehicles
before
after

99
Balgreen Road Northbound
0
5
10
15
20
25
30
35
40
Speed
before
after
Balgreen Road Southbound
0
5
10
15
20
25
30
35
40
Speed
before
after

100
0
5
10
15
20
25
30
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotalvehicles
before
after
0
5
10
15
20
25
30
35
1 - 2mph
>PSL
2 -5mph
>PSL
5 -10mph
>PSL
10-12mph
>PSL
12-15mph
>PSL
15-20mph
>PSL
20mph+
>PSL
%oftotalvehicles
before
after

101
0
5
10
15
20
25
30
35
40
Speed(mph)
before
after
0
5
10
15
20
25
30
35
40
Speed(mph)
before
after

102
Appendix 4 – Questionnaire Results
How old are you?
Answer Options
Response
Percent
Response
Count
17-21 7.0% 31
22-30 28.3% 125
31-40 21.8% 96
41-50 21.5% 95
50< 21.3% 94
answered question 441
skipped question 0
What gender are you?
Answer Options
Response
Percent
Response
Count
Male 70.3% 310
Female 29.7% 131
skipped question 0
Are you a professional driver?
Answer Options
Response
Percent
Response
Count
Yes 20.2% 88
No 79.8% 348
skipped question 5

103
How regularly do you drive?
Answer Options
Response
Percent
Response
Count
Daily 47.4% 209
Two or three times a week 22.9% 101
Weekly 12.5% 55
Seldom 9.5% 42
Never 7.7% 34
skipped question 0
What is your average annual mileage?
Answer Options
Response
Percent
Response
Count
Under 4,000 30.2% 130
4,000 - 8,000 26.5% 114
8,000 - 12,000 24.1% 104
12,000 - 15,000 10.0% 43
Over 15,000 9.3% 40
skipped question 10
Vehicle Activated Signs are effective in enforcing speed limits.
Answer Options
Response
Percent
Response
Count
Strongly agree 12.1% 51
Agree 53.3% 225
Not sure 21.1% 89
Disagree 12.3% 52
Strongly disagree 1.2% 5
skipped question 19

104
There is a need for them in Edinburgh.
Answer Options
Response
Percent
Response
Count
Agree 43.7% 184
Not sure 31.6% 133
Disagree 11.6% 49
skipped question 20
Do you adjust your speed when you approach them?
Answer Options
Response
Percent
Response
Count
Yes 61.4% 256
No 11.8% 49
Sometimes 26.9% 112
skipped question 24

105
What speed limit do you think they should be used in? (You can tick
more than one box.)
Answer
Options
Response Percent Response Count
20mph 50.7% 205
30mph 78.7% 318
40mph 39.4% 159
50mph 19.8% 80
National
Speed Limit
21.5% 87
skipped question 37
What speed reducing method do you think is most effective?
Answer Options
Response
Percent
Response
Count
Traffic Calming 49.6% 201
VAS 23.0% 93
Safety Cameras 27.4% 111
skipped question 36
Which do you think is more effective? The flashing speed limit sign or the
sign that tells you what speed you are doing?
Answer Options
Response
Percent
Response
Count
Flashing Speed Limit Sign 32.9% 134
Speed Indicating Sign 67.1% 273
skipped question 34

106
They cause an unwanted, dangerous distraction.
Answer Options
Response
Percent
Response
Count
Agree 7.2% 30
Not sure 18.7% 78
Disagree 59.8% 250
skipped question 23
They should be more widely used.
Answer Options
Response
Percent
Response
Count
Agree 50.0% 209
Not sure 24.4% 102
Disagree 9.8% 41
skipped question 23
Should they be used as a stand alone measure or as one part of a
wider scheme?
Answer Options
Response
Percent
Response
Count
Stand alone 11.9% 47
Part of a larger safety scheme 57.6% 228
Both 30.6% 121
skipped question 45

107
Long term exposure to these signs limits their effectiveness.
Answer Options
Response
Percent
Response
Count
Agree 35.5% 145
Not sure 30.1% 123
Disagree 23.0% 94
skipped question 32
There is an embarrassment factor if other drivers see you triggering
one of these signs.
Answer Options
Response
Percent
Response
Count
Agree 26.4% 108
Not sure 19.8% 81
Disagree 41.8% 171
skipped question 32
Excessive speed can be an important factor in road traffic accidents.
Answer Options
Response
Percent
Response
Count
Agree 34.6% 141
Not sure 3.2% 13
Disagree 3.9% 16
skipped question 33

108
Appendix 5 – Questionnaire Comments
1 Didn't feel I could answer Q14 without knowing what the wider scheme
might be.
2 I also believe that speed limits should be raised on motorways and
there should be more driver education on how to drive safely -
speeding in itself doesn't cause accidents, it's driving at inappropriate
speeds for the conditions that does.
3 very useful
4 The terminology used in the survey is not familiar to most people I
think (e.g. VAS, or safety camera? I assumed this meant speed
camera). A brief explanation of all terms that might not be familiar to
everyone should be given within the survey or before taking it.
5 "Cut your speed, save fuel!" may be the more compelling argument as
the hydrocarbon era draws to a close.
6 don't mind getting penalty points if I was caught speeding in town
centre but don't agree with them on motorways
7 Road traffic accidents occur because of poor driving or a lack of
attention, not due to excessive speed. Improving the poor driving
standards in the UK with a wider ranging and more stringent practical
examination along with time based retests to ensure drivers do not
develop a lax attitude to their own driving.
8 got 1 speeding ticket from police hiding with speed cameras, I think
paying the fine would be the only way to make me slow down in that
area which it did, signs don't have the same affect
9 I can't comment on the need for these signs in Edinburgh as I am a
distance learning student living in England and have never driven in
Edinburgh.
10 I pass the VAS at the A1 near Queen Margaret Uni. It's largely ignored.
I have, however, seen an actual speed indicator work really well when
the speed limit changes from 60 to 30 or 20 entering a village or going
past a school

109
11 VAS’s are a non intrusive way of making you feel like you are
being watched and therefore should watch your speed. Cameras
work but their fines are completely unfair and mean you have to
always watch the side of the road instead of in front, but
flashing signs just give you a reminder in case you missed the
speed limit signs. Its kind of fun too, getting the happy face to
smile before you pass the sign! Also worth mentioning how
some 40 limits are unnecessary and make people more
frustrated. Also these signs are a visible use of renewable
energy (solar pV and turbine ones) so are good for public to see
that in use.
12 I think they would be an effective tool in alerting people to their speeds
around schools where few drivers adhere to the temporary 20mph
limits.
13 My general experience of VA signs that display your speed (should you
exceed the limit) is that some drivers take them as a challenge to see
how high a speed they can display (while I would not do this I can
certainly see its appeal/fun). I have heard that such a VA sign was
removed from a Renfrew residential street because of such behaviour.
I don't know if this was the real reason, but it was certainly removed.
14 Unsure of an answer for question 14 but there's no option for a “don't
know”.
"Excessive speed can be an important factor in road traffic accidents."
I would say they are many factors in road accidents but speed is the
most important factor in the outcome of accidents, which is a very
different aspect.
15 I am on the first year of the MSc and went to a VAS seminar about 5
years ago, when they were just becoming popular. One of the
speakers from TRL said that they were concerned drivers would
eventually become complacent, as they felt drivers had become with
many standard warning signs (hence yellow backing boards to try and
enhance their effectiveness). I think it's difficult to judge their
effectiveness, unless regular speed surveys are carried out at various
sites to monitor changes in mean speed over time.

110
16 Surely the last 2 parts of question 14 are the same. There should also
perhaps be the question “are you a motorist” I am not, so most of the
questions were irrelevant to me and my answers were just speculation.
Perhaps if question 1 was “are you a motorist” you would then not
need to answer the rest.
17 Putting (VAS) before speed camera or before curve will be more
effective. good luck
18 Speed is a factor but not the main cause. People are let on the road
too easily. More stringent testing should be done. Vehicle activated
signs are appalling, I don’t see the point in them and they must cost a
fortune. Regardless of cost, I don’t believe they are cost effective. I.e.
don’t think they have saved lives
19 I think VAS is used best when the need for lower speeds is clear or
where the hazard is evident e.g. outside a school,
20 They're pretty pointless, as they are pretty much never calibrated
appropriately, and honestly, I am sick to death of having signs flashing
at me when I am trying to concentrate on driving. It's dangerous and
irritating. Get rid of them!
21 Police Stats 19 is fundamentally flawed when considering the
relationship between speed and traffic accidents to such an extent that
speed is listed too often as a mere 'possible cause'
I am objected to speed limiting being installed on vehicles, but would
consider an acceleration limiter under the correct circumstances. This
would prevent 'boy-racer' type attitudes from manifesting themselves in
narrow low speed roads and streets.
22 Another type of VAS sign is available, one which measures your
speed and then tells you to slow down if you trigger the sign. Those
which just show a speed tend to encourage boy racers to compete
to get the fastest speed up!
23 I think speed cameras are the most effective for controlling the speed
of traffic. I hate speed bumps; they are not effective and ruin your car.

111
24 I speed up in order to activate the one on a road I travel on daily - I
am usually a fairly careful and sensible driver. This is one that flashes
"slow down". There are a couple in town that display the speed and I
try to keep my speed down for those, while it's not embarrassing, it’s
unnerving. I think those are a far better deterrent than the one that is
simply switched on or off, there is a challenge to activate it.
Many of these signs have solar and wind panels, these are presumably
very expensive to install and really look to be more of a statement than
of any real safety benefit. Having said that, some of them do shock if
you don't realise you speed in that area, which is a good thing, but
once you know it's there then it is relatively pointless. From that point
of view I would say that these signs are of more use on a rural road.
Please note, I do not live in Edinburgh, so I cannot comment on those
in Edinburgh, I am speaking generally, from the perspective of a
smaller town.
25 Drivers use these signs to show how excessively fast they are going to
their passengers
26 Excessive speed can be an important factor on the severity of any
injuries resulting from an accident. However, it is far from clear
(despite what some may say) that excessive speed is a primary
causation factor. It is thought that the variance of speeds could be
more important and VAS can help with this.
27 In Fife they move these signs about which i think is a good idea. I
believe this reduces the loss in effectiveness you would get if they were
always in the same location.
28 Could not answer question eight as I do not drive.
29 Wasn’t sure was VAS meant in one of the questions
30 a) I think that the speed notification signs may encourage boy-racers in
some areas.
b) Flashing speed signs in some areas may give the impression in
other, comparable areas, that speed reduction is not a priority.
c) I think in-car speed notifications are a better technology.
31 no Comments

112
32 VAS appear to be particularly effective on motorway roadwork areas,
where there is a high danger to motorway workers from speeding
traffic, especially when there appear to be number-plate reading speed
cameras in use, as well. VAS also effective on entering residential
areas, drivers do seem to drop their speed.
33 To me these signs seem most effective at town limits - entering a 30
zone.
34 Anyone caught breaking any speed limit should have their car removed
and crushed and forced to re-sit their driving test.
35 I think they should be used as part of a wider scheme. The flashing
speed signs encourage responsible drivers to adjust their speed,
though not sure they are a deterrent to those less responsible drivers.
36 These signs are only effective in the immediate vicinity, because drivers
who do act on them only drop their speed while they are passing the
sign and generally speed up again. I don't think that is deliberate, it's
just the general driving style here. The most effective method of
keeping vehicle speeds down to the limit is by using average speed
cameras as drivers know that they have to keep to the limit in the
camera zones. If we haven't got the money for these, put some
dummies up, on the main roads at least.
37 Behaviour around signs - some drivers care not for being told what to
do so will flaunt the advice.
38 These signs work for so long but should be backed up by the
occasional police speed check to get over driver complacency. Signs
that show your speed are likely to be abused by the boy racer
39 Signs currently in use in Edinburgh cannot be triggered by all classes of
vehicles
40 While you are at it can you improve things for cyclists (e.g. finish the
cycle path networks) and bus passengers, and discourage private car
commuting into town centre.
41 The current system that the City of Edinburgh Council use is to extreme
in that it would be more effective if more but reduced speed bump
heights were used rather than the current system of a small number of

113
them that are set at to high a level and cause more damage to vehicles
even when travelling within the speed limit laid down.
42 The illuminated signs are most effective on the approach to villages on
rural main roads, in the built environment I can see little use except
perhaps for an accident black spot over load of signs needs to be
avoided
43 Speed cannot be ascertained as being an important factor in (all) road
traffic accidents. I feel that question is incorrectly worded and may be
better broken into two questions including 'some' and 'all'.
44 Answered Do you adjust your speed when you approach them?
sometimes because would only do so if above limit
45 I like the ones in north east England used during road works which
flash your speed and also flash up your registration plate. It put the
fear of Barbara Castle up you. The trouble is people who speed
between cameras/signs.
46 There location should be carefully considered in light of the problem of
street clutter and the context should be taken into account as one size
solutions seldom are very effective
47 A bit more background to exactly what a VAS is and its purpose would
have helped inform my answers to this survey.
48 I felt that the questions were asking me to make judgements on
something that I have little knowledge of.
49 I don't really slow down if I trigger one of those speed signs, I'm
usually quite aware of my speed and if I'm breaking the speed limit the
chances are it's because I'm late (not that that is a good reason to
break the speed limit, I agree that driving faster can cause accidents).
Traffic calming in the form of speed bumps and those bollards in the
middle of a road I find quite irritating. I read about more psychological
ways of calming traffic like making the edge of the road and pavement
more ambiguous, forcing the driver to pay more attention to what's
around him/her (like pedestrians), if these measures do work I'd like to
see more of them.

114
50 My observations shows that the best VAS sign to use is the one that
shows what speed your are actually travelling at and where the sign
thanks you when you are below the speed limit like the one at
Wilkieston
51 The latest statistics show that speed is now rarely the single most
significant factor for road accidents.
There are far too many road signs on roads and electronic signs should
be used as a replacement to signs not an addition.
52 These signs need to be backed up by enforcement. I use Maybury
Road every day and lots of drivers ignore the signs (though many stick
to the new limit) the road is more dangerous as drivers weave in and
out to pass those sticking to the limit. Occasional enforcement would
help get the message over.
53 driver education through hard hitting adverts is more effective than
physical speed restraint measures
54 In some situations it is not clear that you have entered a zone with a
different speed limit - the VAS signs are a means of alerting drivers
who have not noticed the change in the speed limit for the zone they
have entered.
55 I pass a few of these signs on my daily commute and believe they do
make drivers more aware of their speed and many do reduce their
speed accordingly. Modern cars are very quiet and comfortable and
many drivers are simply unaware that they are driving significantly
above the speed limit. Others simply don't care and flashing signs will
never change their behaviour.
The signs that I believe are the most effective are the ones that show
your true speed and are combined with a happy or sad face.
The others that simply flash the speed limit are easier to ignore and I
regularly pass one of these in Midlothian, which is in a 30limit but the
average speed for all vehicles past it is probably at or very near 40mph.
This sign was poorly setup when first installed and would flash even

115
when passing at well below the speed limit. It remained like this for
months and local drivers don't give a monkeys about it now.
I think the problem with not displaying the true speed is that a driver
doing 31mph will trigger the sign just the same as a driver doing
40mph. No greater embarrassment factor and if 90% of drivers are
triggering the sign, then it quickly becomes completely ignored.
56 The real issue with road traffic accidents is the consistent lack of
driving tuition in hazard awareness perception and the requirement for
concentration on driving above all else. There are many situations
where a higher speed would be safe at certain times, whilst the same
road on a different day/time would dictate a slower speed, all easily
spotted if drivers understood hazards to a much higher degree than
can often be observed in many situations at present.
Money is spent on various measures, yet the real issue of re-training all
drivers to a higher standard is not taking place, except I understand
with PSV drivers with the new legislation appertaining to them.
57 Physical traffic calming is the only way to reduce speeds. I hate them
but it physically stops high speeds. Enforcement works but it cant be
present all the time.
58 If there was a comprehensive and joint up public transport strategy it
would be more cost effective and better for the environment as
everything implemented in Edinburgh causes more danger to all road
users other than speed reducing measures in side streets 20mph
maybe they should be less
59 I feel these signs are more effective than Safety cameras or speed
bumps that seem to make people speed up between them. I also feel
strongly that inappropriate speed is a factor in RTAs, not actual speed.
In my view, speed is seen as an easily regulated issue rather than
tackling the more subjective issue of dangerous / inattentive driving or
poor quality drivers. Also, speed reduction measure like bumps only
cause drivers to swerve all over the road trying to 'centre' themselves

116
on bumps, even going to the other side of the road to do so. I have
now stopped my son from walking to school on without an adult as the
route is now more dangerous than it was prior to bumps... as cars will
now manoeuvre unexpectedly catching children unawares.
60 Some drivers will always speed. The VSP is a good way of reminding
people that they are driving in a certain speed limit area. The VSP
seems to have the effect of a few vehicles slowing down, not just the
speeding driver who activated it.
61 VAS signs are good for making you aware that you are over the limit
and shock me into slowing down, but I don't believe that they will
overall help in reducing speed or accidents. They may instigate over
correction/accidents. In my opinion average speed cameras are the
way to go for a safer driving.
62 Unfortunately if someone is going to speed these signs don't make a
difference. I live beside a VAS in a 30mph zone but regularly see it
flash speeds well over 40.
63 VAS are effective due to their relative scarcity.
64 many of my comments are not sure. the reason being is that I have
been involved with various traffic management schemes with the
council involving these signs and traffic calming. with my experience it
depends on where the signs are located and the local knowledge of car
and lorry drivers. What we found was that a maximum speed limit was
put on the signs as irresponsible car drivers were betting against each
as to what speeds they could reach. I believed the signs with traffic
calming and ensuring the correct location of the signs can make a big
difference to the safety of the public and other car /lorry users.
65 Care should be taken in installation and 'turn-on' speeds as if the signs
appear to be going off under the displayed limit - the signs will be
ignored
66 The ones that tell you the speed you are travelling could be more
dangerous as they could be used as a test to see how fast they can
get. The signs are only effective initially, like speed static speed

117
cameras you know where they are perhaps there could also be mobile
versions
67 Speed cameras need to be more visible as a fine is a better method of
slowing people down than embarrassment. A VAS just before a camera
would greatly reduce the speed in an area.
68 The signs which have smiley and sad faces are also effective -
especially if they can be seen from a distance. Example of the type
that used to used occasionally on the approach from the north to
Eddleston in the Scottish Borders. I have witnessed this sign being
very effective in slowing down traffic on the approach to the village.
This has now been replaced by a permanent flashing speed sign.
69 Traffic calming measures are highly effective, but speed up the damage
done on suspension, so works out highly expensive in the long run for
the driver. Visual signs do absolutely nothing. Speed cameras are the
most effective, there should be no cash bonus, just two chances then a
six month ban. VAS WOULD be more useful on motorways to enforce
the three second rule, or telling people they are not under obligation to
give way at slip roads joining. more car accidents occur because of
people not knowing where they are meant to be on the road, not
because of speed in my opinion.
70 I think VAS are more appropriate in rural/outer urban environments - I
don't think they are suitable in more cluttered urban environments.
71 I think there are many more important factors t0 17 above. Health,
Experience, Weather, Drugs, Alcohol etc
72 Positive feedback units (28mph - Thank You!) are more effective
73
Speed is a factor in 100% of accidents - if the vehicle's not moving, it
won't have an accident. Poor driving standards are to blame mostly;
combined with the capabilities of modern cars (I saw a lot of this whilst
working as a van driver). I don't like the flashing hazard signs,
especially out of town - the one on the Currie - Heriot-Watt road
surprised me at night; this could have consequences as it's very close
to the corner it's warning of. The numbers are effective (as in
Wilkieston), as all drivers can see them. I don't think cameras, flashing

118
signs or humps are the answer, generally - nor a more restrictive
driving test, although more road miles instead of intensive courses is a
good thing. Maybe a power/cc restriction as imposed on motorcyclists?
NB I have both car and motorcycle licences, used to be a professional
driver (white van man, if you like) and have a car race licence (which
I've had for 12 years).
Listening to Radio 4 tends to calm your driving down too.
74 I feel these signs are useful but most people speeding seem to know
they are doing it and may simply disregard the sign
75 Raising the driving age to 18, as in France, is probably even more
effective. But if that's not possible, these signs are fairly effective, at
least initially.
76 In problem areas cameras with automated fixed penalties should be
used.
77 Please, NO MORE ruddy signs! There's too many already. Those
grimacing signs are a pain in the arse and are never calibrated correctly
anyhow. Stop wasting money!!
78 Not sure if there is an embarrassment factor with other drivers (Q.16)
but have heard of parents being told off by there kids and I personally
find them good for reinforcing me to check my Speedo especial when
entering villages or after coming off the motorway where speed
perception may be lacking.
79 VAS work better than speed cameras as you slow down then speed up
when past the speed cameras, where VAS brings to your attention that
you are above limit and you pay attention for some time afterward.
Poor driving skills and inconsiderate drivers are the most important
factor in road traffic accidents
80 Can be annoying if wrongly set ; e.g. flashing at 26mph in 30 zone
81 There are some drivers that would not pay attention to any speed
reducing measures that were taken. For them speed signs are a target
for breaking, NOT KEEPING UNDER BUT GOING OVER.

119
82 These measures are effective on certain types of road, mainly rural/
suburban residential and not usually effective in the city centre.
Overall street design should be considered in reducing speed limits and
not just rely on these measures over the long term.
83 Vehicle operated signs make it easier to slow down when you feel you
are holding up traffic by sticking to speed limit
84 Speed is only part of the problem. Driver awareness and ability are
under-enforced and emphasised by law enforcement.
85 Average speed cameras / systems are the most effective method of
controlling traffic speed.
86 I work for Cumbria highways and manage all the VAS for them. If you
need any more help then you can email me at
james.carruthers@capita.co.uk. Personally i have mixed feelings about
VAS. They are difficult to maintain and then i worry that failed signs
leave the authority liable. Also signs that have been in for along time
do get ignored as people know they wont be punished. Anyway any
questions just let me know.
87 I can see that VAS can have a useful role to play in reducing speeds in
certain places, mainly arterial roads. However I would be opposed to
their widespread use which can add to street clutter and degrade the
quality of the built environment.
88 More 20mph zones required in Edinburgh and car-free zones.
89 Excessive speed in urban areas can be reduced through road
alignment, carriageway widths, surfacing e.g. setts and the nature of
the surrounding environment. Removing excessive signs is supposed
to help. VAS may be suited to particular situations but should not be
viewed as the solution in every case. How are VAS used/or not used in
Europe?
90 Much more effective than speed bumps.
91 Regarding question about whether they should be used in Edinburgh. I
am a distance learner so do not know the city too well therefore cannot
comment if VAS is suitable for that location.
92
If I trigger a flashing sign , i usually adjust after the event.

120
In a camera I adjust before I approach the camera. i.e. before the
event and speed up afterwards
93 I consider Speed and red light violation cameras are most effective in
speed reducing measures
94 People driving too slowly in areas can also have an important factor in
road traffic accidents
95 Most drivers pay little regard to speed limits. Anything that helps
reduce speeds and save lives is a positive step.
96 targeted use in advance of blackspots
97 It should show the preferable speed for certain areas.

121
Appendix 6 – Examples of Accident Plots and Stick Diagrams

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