3. The Issue of Speed
Speed is a key issue in street design
– Impact on safety
– Impact on enjoyment, vitality,
use by more
sustainable/active modes
• Road Safety Authority Free Speed
Survey 2008, 2009, 2011
– Consistent findings, on
average 3 out of 5 drivers
on urban roads driving in
excess of the posted speed
limit.
– On Primary/Secondary
routes, 2 out of 5 drivers
were driving 10km/h or more
over the posted speed limit
4. The Issue of Speed
• There is a long established
relationship between speed and street
design
• Transport Research Laboratory (UK)
reports 322, 325 and 551
– Driver speed based on a visual
and psychological interpretation
of street environment
– Legislation and regulation play a
secondary role
5. Speed and Street Characteristics
• Self-regulating streets instinctively tell
drivers what speed they should be
doing (i.e. visual and psychological
interpretation)
• Self regulating streets are established
by a combination of 'soft' and 'hard'
measures.
• Softer 'place' based measures include
– Built form
– Landscape
– Activity
• Harder measures are more
associated with conventional road
design, i.e. street geometry
6. Speed and Street Characteristics
• Physical and psychological, or harder and softer measures, that influence driver
behaviour illustrated in the Adamstown Street Design Guide (2010).
• No single measure is effective on it own. Physical and psychological measures are most
effective when used in combination (Transport Research Laboratory 2005).
7. Speed and Street Characteristics
• Preparation of DMURS included an analysis of recent Road Safety Authority Free Speed
Surveys to establish influence of 'hard' and 'soft' measures on drivers in Ireland
• RSA Free Speed Survey 2008, 2009 and 2011 recorded speeds of some 9,500 vehicles
in free flowing conditions along 23 streets, that varied in function and context, within
metropolitan Dublin were recorded
Glasilawn Road Abbey Park Delwood Road Lwr. Kilmacud Road (R825)
Clonkeen Road (R827) Morehampton Road (N11) Navan Road (N3) Stillorgan Road (N11)
8. Speed and Street Characteristics
• The results demonstrated a strong trend whereby as the frequency and strength of the
'softer', or psychological, and 'harder', or physical, design measures increased, operating
speeds lowered significantly
Average Operating Speed (All Streets)
Stillorgan Road
(60 km/h)
Ave. 71.6 km/h
Lwr Kilmacud Rd
(50 km/h)
Ave. 48.7 km/h
Brian Rd
(50 km/h)
Ave. 31.0 km/h
Frequency and Intensity of Psychological and Physical Measures
9. Speed and Street Characteristics
• and the number of drivers exceeding the posted speed limit significantly decreased
% of Drivers Exceeding the Posted Speed Limit (All Streets)
Stillorgan Road
(60 km/h)
83.6%
Lwr Kilmacud Rd
(50 km/h)
37.6%
Brian Rd
(50km/h)
1%
Frequency and Intensity of Psychological and Physical Measures
10. Speed and Street Characteristics
• As would be generally expected the presence of deflections (such as ramps) had a
strong influence on reducing speed. However trend of lower operating speeds was
consistent on streets without ramps where other measures were present.
Average Operating Speed (Streets Without Ramps)
Morehampton Rd
(50 km/h)
Ave. 53.3 km/h
Delwood Road
(50 km/h)
Ave. 44.8 km/h
Lorcan Rd
(50 km/h)
Ave. 34.7 km/h
Frequency and Intensity of Psychological and Physical Measures
11. Speed and Street Characteristics
• Other ‘softer’ measures, such as a sense of enclosure, surveillance and activity created
by landscape treatments and development (esp. where fronting directly onto the street)
also had a significant influence on lowering speed.
Average Operating Speed (Enclosure and Frontage)
Malahide Road
(60 km/h)
Ave. 69.8 km/h
Morehampton Rd
(50 km/h)
Ave. 53.3 km/h
Brookwood Rise
(50 km/h)
Ave. 38.3 km/h
Frequency and Intensity of Psychological and Physical Measures
12. Speed and Street Characteristics
• Significantly, where there are limited psychological and physical design measures on
streets with a speed limit of 50 km/h, most drivers exceeded the speed limit by 10 km/h
or more.
% of Drivers Exceeding the Speed Limit by 10km/h or more (50 km/h streets)
Frequency and Intensity of Psychological and Physical Measures
13. A Balanced Approach
• Research highlights the need to re-
evaluate much of what has been
accepted as convention
• DMURS highlights issues with
conventional design approaches that
seek to minimise risk and delay for
motor vehicles
• This approach is counter productive in
urban areas as drivers are more inclined
to drive at inappropriate speeds and
behave more aggressively
• Further implications for sustainability
and quality of life. If streets are not
perceived to be safe, people will retreat
to the safety of their cars
14. A Balanced Approach
• To moderate speeds, streets need to
be fronted with development and
overlooked with only as much space
dedicated to motor vehicles as is
reasonably necessary
• DMURS equips designers with the
tools to create more equitable
distribution of risk and responsibility
• DMURS presents designers with a
holistic package 'soft' and 'hard'
measures to manage driver behaviour
and increases pedestrian/cyclist
mobility
• 'win win' - more attractive, better
managed streets promote the
development of more sustainable
communities
15. A Balanced Approach
50 km/h 30 km/h 10 km/h
Mid Level Place Function Mid Level Place Function High Level Place Function
Mid Level Movement Low level Movement Low level Movement
Function Function Function (Cars)
High Level Movement
Function
(Pedestrians/Cyclists)
16. A Balanced Approach
50 km/h 30 km/h >30 km/h
Mid/High Level Place High Level Place High Level Place Function
Function Function
Mid Level Movement
High Level Movement High Level Function (Cars)
Function Movement
High Level Movement
Function
Function
(Pedestrians and Cyclists)
17. Conclusion
• Legislation and enforcement alone will not adequately manage vehicle
speeds.
• Research also tells us that conventional design measures alone do not
sufficiently manage driver speeds
• Driver speed is best managed by a combination of 'hard' and 'soft' measures
• Place based design promotes a 'win win' scenario, where streets are more
attractive, more sustainable and safer.
