Traffic Study is “a study conducted during the development approval process to determine the impacts that traffic generated by the proposed development will have on the surrounding street network and the improvements needed to the transportation system in order to mitigate those impacts.” New Development prone to generate traffic that may give rise to congestion, safety issues, therefore, it demands the need for infrastructure improvement such as new signalization, turn lanes, or crosswalks. Traffic impact studies (TIS) are a common planning tool used by development authorities, such as Building Control Authorities, to foresee demands and impacts on the transportation network and determine transportation improvements that may be necessary to accommodate new development. Traffic access and impact studies are also intended to maintain a satisfactory level of service and the appropriate access provisions for a proposed development. Traffic signs or road signs are signs erected at the side of or above roads to give instructions or provide information to road users. The earliest signs were simple wooden or stone milestones. Later, signs with directional arms were introduced. Traffic signals are designed to ensure an orderly flow of traffic, provide an opportunity for pedestrians or vehicles to cross an intersection and help reduce the number of conflicts between vehicles entering intersections from different directions.

1. Pavement and Foundation
1
Traffic Studies
Definition
Objectives
 Basic characteristics
 Future planning
 Improvements of pavement geometric design
 Improvement of pavement structural design
 Economic analysis
 Safety aspects
 Land use
 Vehicle ownership
 Trip generation
 Demographic factor
 Socio-economic characteristics
 Environmental issues
Types of Traffic Studies
1. Traffic volume count
2. OD Surveys
3. Speed Studies
4. Travel time and delay studies
5. Parking studies
6. Accidents studies
1. Traffic volume studies
 Definition, purpose, merits, demerits,
 Manual counts
 Traffic census forms
 Hand tallies
 Automatic counts
 Pneumatic radar detector
 Magnetic loop detector
 Electrical tape switch
 Sonic and radar detectors
 Passenger car unit (PCU)
 Presentations of Results

2. Pavement and Foundation
2
2. Speed Studies
 Types of speed studies
 Spot speed
 Percentile speed
 Frequency distribution Table
 Formula
3. OD Survey
• Purpose
• Methods
 Recording registration numbers
 Handing postcards to drivers
 Road side interviews
 Tag-on vehicles survey
 Headlight survey
4. Travel Time and Delay Studies
• Definitions
• Methods
 License plate method
 Test car method
 Floating car method
 Arrival- output method
5. Parking studies
• Purpose,
• Methods
 Select the study area
 Carry out a parking inventory in the study area
 Carry out a cordon count
 Carry out a parking usage study

3. Pavement and Foundation
3
6. Accidents studies
• Purpose
• Accident reporting and recording procedure
 Data collection
 Need for data collection
 Conflicts (intersections)
Traffic Signs
 Traffic signs are “any object or device (whether fixed or portable) for conveying to traffic on
road, warnings, information, requirements, restrictions or prohibitions of any description
specified by regulations"
 Clear and efficient signing is a key element of traffic engineering.
 Road users rely upon signs for information and guidance, whiles highway authorities depend
upon them for efficient working / enforcement of traffic regulations, for traffic management,
and for promotion of road safety.
 In order to obtain the greatest efficiency of usage from highway signs in general, and
roadside signs in particular, the following principles should always be borne in mind:
 Signs must be designed for anticipated traffic volume and speeds on the roads on
which they are to be used.
 Signs should contain only essential information and their significance should be clear
at a glance so that the driver's attention is not distracted from" driving"
 Sign-lettering should be clear from sufficiently far away distance.
 They should be designed and sited so that, after reading the sign, the driver is left
with sufficient time to undertake any necessary action( s) with safety.
 Signs should be effective by day and night.
 There are three functional classes of traffic signs, namely
1. Regulatory,
2. Warning and
3. Guide / Informatory Signs.

4. Pavement and Foundation
4
1. Regulatory signs
Regulatory signs give motorists notice of traffic laws or regulations. Such signs designate right-
of-way, indicate speed controls, control movements, regulate parking and control/manage traffic
in various other ways. They are circular in shape, have a red border with a black legend placed
on a white background.
2. Warning sigs
Warning signs direct attention to conditions on highway that are potentially hazardous to traffic
operations.
 Such signs require motorists to exercise caution, reduce speed, or make some man oeuvre
in the interest of their own safety or that of other motorists or pedestrians.
 These are generally provided near dangerous bends, schools, pedestrian crossings,
converging lanes etc.
 Warning signs are distinguished by an equilateral triangle with a red border
encompassing a black symbol - usually a pictogram of the potential hazard -
superimposed on a white background.

5. Pavement and Foundation
5
3. Guide / Informatory signs
Guide / Informatory signs indicate route designations, directions, distances, points of interest
etc.; in short, they help the user along the way.
 Unlike most other types, information signs do not lose effectiveness by over-use and
should be erected wherever there is any doubt.
 Generally, these type of signs are provided on blue, orthogonal steel plates with a
white border.
 The black informatory symbol is placed on a white background for emphasizing the
message.
Traffic Signals
 Traffic signals are generally .provided at road intersections and other danger spots.

6. Pavement and Foundation
6
 They offer a cost effective solution to all traffic problems at these locations by directing
or warning motorists, cyclists or pedestrians.
 In addition, they also serve the following useful functions:
 Provide for orderly movement of traffic.
 Increase the traffic handling capacity of
intersections.
 Reduce the frequency of certain types of
accidents.
 Coordinate traffic under conditions of favorable signal spacing (timing), so that it flows
continuously and at definite speeds.
 Interrupt heavy traffic to permit crossings by other vehicles or pedestrians
 Control traffic lane use.
 Interrupt traffic for passage to emergency vehicles such as ambulances, fire fighting
vehicles, etc.
 In Pakistan, signals for vehicular control are classed as “pre timed" where specific time
intervals are allocated to the various traffic movements.
 Modern traffic signals for intersection control operate on electricity. Individual units must
have separate red, amber and green lenses, 8 to 12" in diameter, each illuminated by its
own light source.
 They are mounted on pedestals outside the roadway limits or are suspended above the
intersection by cables or other supports.
 For post-mounted signals, minimum and maximum vertical clearances of 15 and 19 feet
are recommended respectively.