IntroductionIntroduction

Growth Of A Country Largely Depends Upon Its Efficient Transportation System.

• road network of 33 lakh kilometer,and for this we have spent Rs.5,20,000 kr

• the ability of road transport to move people and goods efficiently,particularly within cities has fallen to a low level because of:-

During past 3 decades the number of motor vehicles are growing at a rapid rate.

• The growth rate of various vehicle classes like :-• CARS -- 7.5%.• BUSES -- 5.3%.• TRUCKS -- 6.2%.• TWO WHEELERS -- 17.2%.

• Traffic is increasing both in terms of volume and intensity.

ROAD TRANSPORTATION IS INCREASING AT THE

RATE OF 7 TO 10% EVERY YEAR.

• THE NUMBER OF VEHICLES PLYING ON THE ROAD IS INCREASING BY 12% ANNUALLY.

• THIS TREMENDOUS GROWTH OF AUTOMOBILE AS ONE OF THE MOST CONVENIENT MODES OF

TRAVEL HAS BROUGHT PROBLEM OF PARKING,ACCIDENTS,DELAY,CONGESTION AND ENVIRONMENTAL DEGRADATION

The investment on roads have not kept pace with the growth of traffic.

• Speeds are low and vehicle operating costs are high.

• This all is because of

• CONGESTIONCONGESTION

Roads Are Congested, Broken And Dangerous

• why our roads are why our roads are congested?congested?

Everyone Wants His Own CarEveryone Wants His Own Car

And Due To This, The Problem Is Not Only Of Congestion But,

• the atmosphere is thick with exhaust fumes,polluted with carbon monoxide and other poisonous gases affect ozone layer

creates problem of global warming.

What We Need Is -What We Need Is -

• we need a traffic/ transport system which is:-

• cheapcheap

• fastfast

• safesafe

• stress freestress free

• Which can reduce traffic congestion

WHAT IS TO BE DONEWHAT IS TO BE DONE

• it is not sufficient to build roads of adequate structural strength,to cater

needs of vehicles,but it is equally important that the safe efficient and comfortable movement of traffic and other road users is ensured on these

roads.

• “Traffic engineering is defined as that part of engineering which deals with the traffic planning and design of roads,parking facilities and with control of traffic to provide safe, convenient and economic movement of vehicles and pedestrians”.

• 1) Traffic engineering provide a valuable tool to understand the problem and evolve suitable measures to overcome the deficiencies.

• 2) The basic object of traffic engineering is to achieve efficient,free and rapid flow of traffic.

• 3) Factual studies of traffic operations provide the foundation for developing methods to improve in general and for solving specific problems.

FUNCTIONFUNCTION

• With systematic traffic studies,scientific analysis and engineering application,improvement of traffic performance of road network is the main function of traffic engineering.

• Traffic engineering therefore deals with the application of scientific,

• 1) Principles. 2) Tools.

• 3) Techniques 4) Findings.

•

THERE ARE SEVERAL PHASES OF TRAFFIC ENGINEERING LIKE TRAFFIC

CHARACTERISTICS,STUDIES AND ANALYSIS,OPERATION CONTRAL AND

REGULATION,GEOMETRIC DESIGN,MANAGEMENT,RESEARCH

• VARIOUS PHASES OF TRAFFIC ENGINEERING ARE IMPLEMENTED WITH THE HELP OF 3EES

• 1) E - ENGINEERING1) E - ENGINEERING -deals with improvement of road geometric and providing additional road facilities.eg. Circles,islands,medians,zebra Circles,islands,medians,zebra crossing,footpaths,curves,signals,signs,road crossing,footpaths,curves,signals,signs,road furniture etc.furniture etc.

• 2) E - ENFORCEMENT2) E - ENFORCEMENT - it is usually through traffic laws,regulation and control.eg.HELMET HELMET PEHANO, SEAT BELT LAGAO.PEHANO, SEAT BELT LAGAO. JO KARO AISA NAHI TO CHALAN KATAO.

• 3) E - EDUCATION3) E - EDUCATION - it is possible by sufficient publicity,through schools and television.eg. TECHNOLOGY PARK,TRAFFIC PARKTECHNOLOGY PARK,TRAFFIC PARK

• –

TRAFFIC CHARACTERISTICS.

T R AFFIC EN G IN EER IN G

H U M AN ELEM EN T M AC H IN E ELEM EN T SC IEN C E/ PR OFESSION OF AN EN GIN EER

• ROAD USER CHARACTERISTICS.ROAD USER CHARACTERISTICS.

• The human element as pedestrian,cyclist,cart driver or motorist.The physical,mental and emotional characteristics of human being affect their ability to operate motor vehicle safely or to service as a pedestrian.

• Factors affecting road user characteristics :-

• 1) Physical 2) Mental

• 3) Psychological 4) Environmental.

• Physical characteristics.Physical characteristics.• 1) Permanent :- vision,hearing,strength and the

general reaction to traffic situations.• 2) Temporary :- fatigue,alcohol or drugs and

illness.All these reduce alertness and increase the reaction time.

• A) Vision • Acuity of vision,peripheral vision and eye

movement,glare(adaptability to change of light) vision, glare recovery and depth judgment.

• Field of clearest and acute vision is within 3 degrees to 20 .The field of peripheral vision ranges from 120 to 160 degrees.

• B)The depth judgement is important for judging distance,speed of vehicles and other objects ahead.

• C)Hearing is important for pedestrians and cyclists.

• D)Lack of strength may make parking manoeuvers difficult,particularly for heavy vehicles.

• E)The reaction to traffic situations depends on the time required to perceive and understand the traffic situation and to take the action.

• Mental characteristics.Mental characteristics.• Knowledge,skill,intelligence,experience and

literacy.• A)Knowledge• of vehicle characteristics,traffic

behavior,driving practice,rules of road and psychology of road users.

• B)Reactions to certain traffic situations become more spontaneous with experience.

• C)Understanding the traffic regulation and special instructions and timely action depends on intelligence and literacy.

• Psychological factors.Psychological factors.

• These affect reaction to traffic situations of road users.

• The emotional factors such as attentiveness,fear,anger,superstition, impatience,general attitude towards traffic and regulations and maturity.

• Environmental factors.

• Environmental conditions affecting the road users are traffic stream characteristics,facilities to traffic,atmospheric conditions and locality.

• Driver characteristics such as the simple reaction time,depth judgement,field of vision,visual acuity,glare recovery etc. may be measured in the laboratory using

• DRIVER TESTING UNIT.DRIVER TESTING UNIT.

• PERCEPTION,INTELLECTION, EMOTION AND VOLITION,

• Time taken for these processes is known as PIEV time. PIEV time.

• PerceptionPerception is the process of perceiving the sensations received through the eyes,ears,nervous system and the brain.

• IntellectionIntellection is the identification of the stimuli by the development of new thoughts and ideas.

• EmotionEmotion is the personal trait of the individual that governs his decision making process,after the perception and intellection of the stimuli.

• VolitionVolition is the will to react to a situation.

• The perception time is the time required for a driver to come to the realization that brakes must be applied.

• The brake reaction time is that time lag between the perception of danger and the effective application of brakes.total perception and brake reaction time is 2.5 seconds.

• VEHICULAR CHARACTERISTICS.VEHICULAR CHARACTERISTICS.

• It will not be economically feasible to keep on increasing the geometric standards and thickness of pavement from time to time to meet the needs of a few vehicles whose dimensions and weights are increased.

• The vehicle standards should be uniform atleast within a country.

• Vehicular characteristics affecting the road design may be classified as static and static and dynamic characteristicsdynamic characteristics.

• STATIC -STATIC - Dimensions,weight and maximum turning angle.

• The height of vehicle affects the clearance of overhead structures.

• The height of driver seat affects the visibility distance.

• The height of head light affects the head light sight distance at valley curves.

• The length of vehicles affects the capacity,overtaking distance,maneuverability of vehicles.

• The width of the vehicle affects the width of the traffic lanes,shoulders and parking facilities.

• Maximum dimensions of road vehicles.

• Width 2.5 m.

• Height single decked 3.8 m.

• Double decked 4.75 m.

• Length varies from 11.0 m to 18 m.

• weight of loaded vehicle .

• 12.0 to 52.2 tones.

• Axel weight do not exceed from more than 10.2 tones per axel except in case of tandem axel fitted with 8 tyres.

• The minimum turning radius depends upon length of wheel base and the features of the steering system.

• Gross weight ,axel and wheel loads of vehicle govern the structural design of pavements.

• DYNAMICDYNAMIC characteristics of vehicles affecting the road design are speed, acceleration and braking characteristics.

• From the total hauling capacity and the power required to overcome the total tractive resistance(inertia,rolling resistance,air resistance and grade resistance) it is possible to determine the speed and acclerationof the vehicle which in turn useful in traffic regulation,planning and design.

• Speed of vehicle.Speed of vehicle.

• The vehicle speed affects sight distance,design gradient, capacity of traffic lane,width of shoulders and many other geometric features.

• Braking characteristics.Braking characteristics.

• Depends on the design and type of braking system and their efficiency.

TRAFFIC STUDIES.

• TRAFFIC STUDIES AND SURVEYS ARE CARRIED OUT TO ANALYSE THE TRAFFIC CHARACTERISTICS.THESE STUDIES HELP IN DECIDING THE GEOMETRIC FEATURES AND TRAFFIC CONTROL FOR SAFE AND EFFICIENT MOVEMENTS.

VARIOUS TRAFFIC STUDIES VARIOUS TRAFFIC STUDIES GENERALLY CARRIED OUT ARE :-GENERALLY CARRIED OUT ARE :-

• 1) TRAFFIC VOLUME STUDY.

• 2) SPEED STUDIES.

• 3) O & D STUDY.

• 4)TRAFFIC FLOW CHARACTERISTICS.

• 5) TRAFFIC CAPACITY STUDY.

• 6) PARKING STUDY.

• 7) ACCIDENT STUDIES.

TRAFFIC VOLUME STUDY.TRAFFIC VOLUME STUDY.• Traffic volume is the number of vehicles crossing a

section of road per unit time .vehicles per day , vehicles per hour.

• 1) Traffic volume is generally accepted as a true measure for deciding the priority for improvement and expansions.

• 2) It is used in planning,traffic operations and control of existing facilities and also for planning and designing the new facilities.

• 3) It is used in the analysis of traffic patterns and trends.

• 4) used in structural and geometric design of road.

• 5) Used for planning one-way and other regulatory measures.

• 6) Pedestrian traffic volume study is used for planning side walks,cross walks,subways,pedestrian signals.

• Traffic volume count may be done by mechanical counters or manually.

SPEED STUDIES.SPEED STUDIES.

• Speed of the vehicles over a particular route may fluctuate widely depending on several factors such as geometric features,traffic conditions,time,place,environment and driver.

• Travel timeTravel time is the reciprocal of speed and is a simple measure of how well a road network is operating.

• Spot speedSpot speed is the instantaneous speed of a vehicle at a specified section of location.

• Average speedAverage speed is the average of the spot speeds of all vehicles passing a given point on highway.

• SPOT SPEED STUDY.

• 1) In planning traffic control and in traffic regulations.

• 2) In accident studies.• 3) Study the traffic capacity.• 4) To decide the speed trends.

• Spot speeds are affected by physical features of road like pavement width,curve,sight distance gradient,pavement unevenness,environmental conditions,driver etc.

• One of the simplest method of finding the spot One of the simplest method of finding the spot speed is by using ENOSCOPE which is just a speed is by using ENOSCOPE which is just a mirror box supported on a tripod stand.mirror box supported on a tripod stand.

• The observer is stationed on one side of the The observer is stationed on one side of the road and starts a stopwatch when a vehicle road and starts a stopwatch when a vehicle crosses that section.crosses that section.

• The time required for the vehicle to cross the The time required for the vehicle to cross the known length is found and is converted to the known length is found and is converted to the speed in kmph.speed in kmph.

• Other equipments used for spot speed Other equipments used for spot speed measurements are graphic recorder,electronic measurements are graphic recorder,electronic meter,radar speed meter etc meter,radar speed meter etc

• SPEED & DELAY STUDY.

• This study gives the running speeds,overall speeds fluctuations in speeds and delay between two stations.

• The results of speed and delay studies are useful in detecting the spots of congestion,and their causes.

• These are also utilized in finding the travel time and the benefit cost analysis.

• The time lost by traffic during the travel period may be either due to fixed delays or operational delays.

• Fixed delays occurs primarily at intersections due to traffic signals and at level crossings.

• Operational delays are caused by interference of traffic movement,such as turning vehicles,parking and un parking vehicles,pedestrians etc.And by the internal friction in the traffic stream due to high traffic volume.

• METHODS OF CARRING OUT SPEED DELAY STUDY :-

• Floating car method.• License plate method.• Interview technique.• Elevated observations • photographic technique.• In floating car method one observer is seated in

floating car with 2 stop watches--• 1- to record the time at various control points like

intersections ,bridges or any other fixed points in each trip.

• 2- to find duration of individual delays.

• The time location, and cause of these delays are recorded by 2nd observer either on suitable tabular forms or by voice recording equipment.

• The no. of vehicles overtaking the test vehicle and that overtaken by the test vehicles are noted in each trip by the 3rd observer.

• The no. of vehicles travelling in opposite direction in each trip is noted by 4th observer.

• However in mixed traffic flow ,more no. of observers will be required to count the vehicles of different classes.

• In license plate or vehicle number method,synchronized stop watches or voice equipments are used.

• Observers are stationed at the entrance and exit of a test section where information of travel time is required.

• The timings and vehicle nos. are noted by the observers of the selected sample.

• Drawback-this method does not give imp. Details such as causes of delays and duration and no. of delays within the test section.

•In the interview technique, the work can be completed in short time by interviewing and collecting details from road users on the spot.

•Elevated observation and photographic technique are useful for studying short test sections like intersection,etc.

ORIGIN AND DESTINATION STUDIESORIGIN AND DESTINATION STUDIES•O&D study is carried out mainly to

-plan the road network and other facilities for vehicular traffic..

-plan the schedule of different modes of transportation for the trip demand of commuters.•O&D studies of vehicular traffic determines

-their number,origin and destination in each zone under study,purpose of each trip,intermediate stops made and reasons etc.

O & D study gives information like the actual direction of travel,selection of route and length of trip.

•Scientific planning of transportation systems and mass transit facilities in cities should be based on O&D data of passenger trips.

•Also future traffic needs may be estimated by extrapolating the data from O&D study.

•1)to judge the adequacy of existing routes and to use in planning of new network of roads.

•The various applications Of O&D study may be summed up as follows:-

•2)to plan transportation system and mass transit facilities in cities including routes and schedules of operation.

•3)to locate expressway or major routes

•4) to locate terminals and to plan terminal facilities.

•5)to locate new bridges as per traffic demands.

•6)to locate intermediate stops of public transport.

•7)to establish design standards for the road,bridges and culverts along the route.

•Methods for collecting O & D data.

1-] road-side interview method

2-] license plate method

3-] return post card method

4-] tag-on-car method

5-] home interview method

• ROAD SIDE INTERVIEW METHOD.• Vehicles are stopped at peviously decided

stations,by a group of persons and answers to prescribed questionnaire are collected on spot.

• The information collected include the place and time of origin and destination,route ,location of stoppages,the purpose of trip,type of vehicle and number of persons in each vehicle.

• Percentage of sample interviewed out of the total traffic in each selected period should also be noted from appropriate traffic volume study taken simultaneously.

• LICENSE PLATE METHOD.• The entire area under study is cordoned out and

the observers are simultaneously stationed at all points of entry and exit on all the routes leading to and out of area.Each party at the observation station is given synchronized time pieces and they note the license plate numbers of the vehicles entering and leaving the cordoned area and time.

• After collecting the field data computation and analysis of this data is done.

• This method is easy and quick.• This method is advantageous when the area under

consideration is small.

• RETURN POST CARD METHOD.

• Prepaid business reply post card with return address are distributed to the road users at some selected points(like toll both,pumps etc.) along the route or the cards are mailed to the owners of vehicles.

• This method is suitable where traffic is heavy.

• TAG ON CAR METHOD.

• In this method a pre coded card is stuck on the vehicle as it enters the area under study.

• When the car leaves the cordon area the other observations are recorded on the tag.

• This method is useful where the traffic is heavy and moves continuously .

• The method gives only information regarding entry and exit and the time taken to traverse the area.

• HOME INTERVIEW METHOD.

• A random sample of 0.5 to 10% of the population is selected and the residences are visited by trained personnel who collect the travel data from each member of house.

• Detailed information regarding the trips made by the members is obtained on the spot.

• Collected data may be useful either for planning the road network and other roadway facilities ,also for planning the mass transportation requirements.

• WORK SPOT INTERVIEW METHOD.

• O & D data at work spots like offices,factories,educational institutions by personal interview.

• While planning for origin and destination studies at a place it is necessary to decide the method of study.

• The selection of method is dependent on the objective and location.

• TRAFFIC FLOW CHARACTERISTICS TRAFFIC FLOW CHARACTERISTICS AND STUDIES.AND STUDIES.

• Traffic stream generally has flow and Traffic stream generally has flow and counter flow along a common counter flow along a common

route,unless the stream is separated into route,unless the stream is separated into pair of one way flows by proper design pair of one way flows by proper design

and regulation.and regulation.

• The basic traffic maneuvers are The basic traffic maneuvers are diverging,merging and crossing.diverging,merging and crossing.

• Transfer of a vehicle from one traffic Transfer of a vehicle from one traffic lane to the adjacent traffic lane is called lane to the adjacent traffic lane is called lane change and this involves diverging lane change and this involves diverging

and merging. and merging.

• Of all these diverging,merging and crossing ,diverging on left is the easiest movement causing least problem of traffic conflict.This is because of the traffic is regulated on left side .Merging from the left side also does not cause much of conflict.

• But the diverging and merging from right create conflicts and hazard to the traffic moving.

• The crossing traffic is the greatest problem in case of road intersections at level.

• When a vehicle moves obliquely across the path of another vehicle moving in the same direction at relatively small angle of crossing the action termed as weaving.

• In two way movements there may be crossing and overtaking maneuvers.The traffic stream characteristics are affected by wide range of vehicles and road users,geometric features of road,intersections and other regulatory measures.

• The environmental conditions also affect the traffic stream flow.

• The time interval between the passage of successive vehicle moving in the same lane and measured from head to head as they pass a point on the road is known as the time head way.

• The distance between successive vehicles moving in the same line measured from the head at any instance is the space headway or the spacing of the vehicle in the stream.

• Study of traffic flow characteristics is useful in geometric design features such as traffic capacity,volume,number of lanes,and width of carriageway,it is also needed to decide traffic regulatory and control measures.

• This study is essential for large This study is essential for large intersections. intersections.

Traffic capacity study.• Traffic volume :- Is the number of vehicles

moving in a specified direction on a given lane or roadway that pass a given point or cross section during specified unit of time.Traffic volume is expressed as vehicles per hour or vehicles per day.

• Traffic density :- Is the number of vehicles occupying a unit length of lane of roadway at a given instant,usually expressed as vehicles per kilometer.

• Traffic capacity :- Is the ability of a roadway to accommodate traffic volume.It is expressed as the maximum number of vehicles in a lane or a road that can pass a given point in unit time,usually an hour,that is vehicles per hour per lane or roadway.

• Volume represents the actual rate of flow and responds to variation in traffic demand.

• capacity indicates capability or maximum rate of flow with a certain level of service characteristics that can be carried by the roadway.

•

• The capacity of roadway depends on prevailing roadway and traffic condition.

• Passenger car unit.

• The different vehicle classes have a wide range of static characteristics such as length,width etc.and dynamic characteristics such as speed,acceleration etc.It is difficult to estimate the traffic volume and capacity of roadway facilities under mixed traffic flow,unless the different vehicle classes are converted to one common standard vehicle unit.

• It is common practice to consider passenger car as the standard vehicle unit to convert the other vehicle classes and this unit is called as passenger car unit or PCU.

• Thus in mixed traffic flow ,the traffic volume and capacity are generally expressed as PCU per hour or PCU/lane/hour and traffic density as PCU per kilometer length of lane.

• FACTORS AFFECTING THE PCU VALUES.FACTORS AFFECTING THE PCU VALUES.• 1) Vehicle characteristics such as 1) Vehicle characteristics such as

dimensions,power speed,acceleration and braking dimensions,power speed,acceleration and braking characteristics.characteristics.

• 2) Transverse and longitudinal gaps or clearances 2) Transverse and longitudinal gaps or clearances between moving vehicles,which depend upon the between moving vehicles,which depend upon the speeds,driver characteristics etc.speeds,driver characteristics etc.

• 3) Traffic stream characteristics.3) Traffic stream characteristics.• 4) Road geometric.4) Road geometric.• 5) Regulation and control of traffic such as speed 5) Regulation and control of traffic such as speed

limit,one way,presence of different traffic control limit,one way,presence of different traffic control devices.devices.

• 6) Environmental and climatic conditions.6) Environmental and climatic conditions.

Tentative equivalency factors Tentative equivalency factors suggested by IRC.suggested by IRC.

• 1) Car,tempo,autorickshaw,tractor - 1.0

• 2) Bus,truck,agri.tractor trailer unit - 3.0

• 3) Motor cycle,scooter & cycle - 0.5

• 4) Cycle rickshaw - 1.5

• 5) Horse drawn vehicles - 4.0

• 6) Small bullock cart & hand cart - 6.0

• 7) Large bullock cart - 8.0

Accident studies.Accident studies.• The problem of accident is very acute in

highway transportation due to complex flow patterns of vehicular traffic,presence of mixed traffic and pedestrians.

• One of the main objectives of the traffic engineering is to provide safe traffic movements.Road accidents cannot be totally prevented but by suitable traffic engineering and management measures the accident rates can be decreased considerably.

• It is essential to analyze every individual accident and to maintain zone wise accident records.The statistical analysis of accidents carried out periodically at critical locations of road stretches or zones will help to arrive at suitable measures to effectively decrease the accident rates.

• Objectives :-

• 1) To study the causes of accidents and to suggest corrective treatment at potential locations.

• 2) To evaluate existing designs.

•

• 3) To support proposed designs.

• 4) To carryout before and after studies and to demonstrate the improvement in the problem.

• 5) To make computations of financial loss.

• 6) To give economic justification for the improvements suggested by the traffic engineer.

• Cause of accidents.

• A) Drivers, B) Pedestrians, C) Passengers,

• D) Vehicle defect, E) Road condition,

• F) Road design, F) Weather G) Animals.

• Steps involved in traffic accident study are :

• 1) Collection of accident data.

• General - date,time,persons involved in the accident and their particulars,classification of accident like fatal,serious,minor etc.

• Location - description and details of the location of accident.

• Details of vehicle involved.

• Nature of accident.

• Road and traffic condition.

• Primary causes of accidents.

• Accident cost.

•

• 2) Accident report.

• 3) Accident records.

• Location files.

• Spot maps.

• Condition diagram.

• Collision diagram.

Measures for the reduction in Measures for the reduction in accident rate.accident rate.

• EngineeringEngineering

• EnforcementEnforcement

• Education. Education.

• Engineering measures :-Engineering measures :-

• 1) Road design.1) Road design.

•

• 2) Preventive maintenance of vehicles.2) Preventive maintenance of vehicles.

• 3) Before and after studies.3) Before and after studies.

• 4) Road lighting.4) Road lighting.

• Enforcement measures :-Enforcement measures :- • 1) Speed control -1) Speed control - Surprise check on on spot

speed of fast moving vehicles at selected locations.

• 2) Traffic control devices -2) Traffic control devices - Proper traffic control devices like signs,marking or channelizing islands may be installed wherever necessary.

• 3) Training and supervision -3) Training and supervision - The transport authority should be strict in testing and issuing license to drivers,drivers should be provided proper training.

• 4) Medical check -4) Medical check - The drivers should be tested for vision and reaction time at prescribed intervals.

• 5) Special precautions for commercial 5) Special precautions for commercial vehicles -vehicles - It may be insisted on having a conductor or attendant to help and give proper direction.

• 6) Observance of laws and regulations -6) Observance of laws and regulations - Trained personnel,assisted by police to check whether the traffic regulation are being followed by the road users or not and also to enforce the essential regulations.

• Educational measures :-Educational measures :-

• 1) Education of road users -1) Education of road users - The passengers and pedestrians should be taught the rules of the road,correct manner of crossing etc.school for the children.Posters,banners etc.

• 2) Safety drive -2) Safety drive - Imposing traffic safety week, showing films and documentaries.Training courses may be conducted for drivers.

PARKING STUDIESPARKING STUDIES

Parking studies.Parking studies.• Demand of parking space is one of the

major problem of highway transportation,especially in metropolitan cities.Parking studies are useful to evaluate facilities available.

• 1) Parking demand : one of the method to know the parking demand is by making cordon counts of the selected area and recording accumulation of vehicles during peak hours by subtracting the outgoing traffic from the traffic volume entering the cordoned area.

• Second method is by counting the number of vehicles parked in the area under study during different periods of the day.

• Third method of field study is by interviewing the drivers of the parked vehicles,shop owners and other vehicle owners in the locality.

• 2) Parking characteristics : Present parking practices prevalent in the area under consideration and the general problem in parking.Parking patterns,interference to smooth flow of traffic and the accidents involved during parking and unparking operations.

• 3) Parking space inventory : The area under study is fully surveyed and a map is prepared showing all places where kerb parking and off street parking facilities can be provided to meet the parking demands.

• In cities the problem of parking vehicles is becoming more and more acute day by day.

• When vehicles are parked on road side ,even for a short while there is restriction to other vehicles passing by,resulting in congestion and accidents .

• In shopping centers,public places and localities with offices there is shortage of parking facilities.

• Proper design of parking facilities is essential in cities and large towns.

• It is roughly estimated that out of 8760 hours in a year, the car runs on an average for only 400 hours,leaving 8360 hours when it is parked,this results in a great demand for parking space.

• A systematic study of parking characteristics and demand and regulatory measures that are possible for controlling parking is of great help to a traffic engineer as well as a town planner.

On street parking.On street parking.• Common methods of on street parking are :-

• 1) Parallel parking.

• 2) 30degree angle parking.

• 3) 45degree angle parking.

• 4) 60degree angle parking.

• 5) Right angle parking.

• Parallel parking consumes the maximum kerb length which decreases as the angle of parking increases. The minimum kerb length is consumed by right angle parking,which accomodates nearly 2 times the number of vehicles as parallel parking.

• Parallel parking makes the least use of the Parallel parking makes the least use of the width of the street, and this is an important width of the street, and this is an important consideration in narrow streets.consideration in narrow streets.

• From the point of view of From the point of view of maneuverability,angle parking seems to be maneuverability,angle parking seems to be better than parallel parking.Delay to traffic is better than parallel parking.Delay to traffic is minimum with angle parking.minimum with angle parking.

• As regards safety, it has been noticed that angle As regards safety, it has been noticed that angle parking is more hazardous than parallel parking is more hazardous than parallel parking.parking.

• In general parallel parking should be favoured In general parallel parking should be favoured on streets. On exceptionally wide and low on streets. On exceptionally wide and low volume streets angle parking considered. volume streets angle parking considered.

Off street parking.Off street parking.• On street parking can only solve a part of

parking problem of major cities.Off street parking has become necessary looking on to the present parking demand and vehicle population growth.

• The prime consideration should be the nearness to the place of useage by the prospective customers.The proposed facility should be close to major parking generators.Examples of such locations are major airport terminals,railway terminals,shopping complexes stadium etc.

• Common type of off street parking are :-• 1) Surface car parks -1) Surface car parks - These are properly

located and developed on piece of vacant land or surrounding an office complex or super market ,are very popular with the motorists.The overall aesthetics of the area should receive due attention.

• 2) Multi-storey car parks -2) Multi-storey car parks - Surface parks consume too much of the precious land in the heart of the city and are not therefore,always feasible.One of the alternatives when land is costly is to provide multi-storey car parks.

• Some of the desirable standards for designing of the multi storey car parks are :

• 1) Gradient of the ramp - 1 in 10 and 1 in 8 for very short ramp.

• 2) Clear height between floors - 2.1 m.• 3) Parking stall dimensions - 2.5m*5.0m .• 4) Inside radius of curve - 7m.• 5) Width of traffic lane on ramps & entrances -

3.75m.• 6) Gradient of sloping floors - not steeper than 1

in 20.• 7) Loading standards - 400kg/msqr.

• 3) Roof parks -3) Roof parks - It’s a very popular method of solving the parking problems adopted in many cities is to park the vehicle on roof tops. Access ramps or mechanical lifts provide the necessary access to the roofs.To economize,many roofs may be linked together served by a single access ramp.

• 4) Mechanical car parks -4) Mechanical car parks - mechanical car parks provide for lifting of the cars from floor to floor by means of a lift and transfer of cars to and from the parking stall by means of wheeling or mechanically operated transfer dollies.

• It is more economical in space as compared to the ramped system,multi-storeyed garages. The disadvantages are the higher maintenance costs and the possibility of breakdown due to mechanical or power failure.

• 5) Underground5) Underground car parks - car parks - The advantage of underground car parks is the least intrusion they cause to the aesthetics of a place.An excellent example is the underground parking space below Hyde park in London and in Connaught place,New Delhi.These parks can be built in the basement of any multistoreyed building.Such car parks tend to be very costly.

• The various aids and devices used to control,regulate and guide traffic may be called as traffic control devices.

• These are A) Signs.• B) Signals.• C) Markings.• D) Islands.

• In addition, road lights are useful in guiding traffic during night.

Importance of traffic signs.

• 1) They give timely warning of hazardous situations when they are not self evident.

• 2) Help in regulating traffic by imparting messages to the drivers about the need to stop,give way and limit to speeds.

• 3) They give information as to highway routes,directions and points of interest.

• General principles of traffic signing.General principles of traffic signing.

• 1) Traffic signs should be installed only by the authority of law.

• 2) For imparting a sense of respect towards signs,proper enforcement measures should be undertaken.

• 3) Signs should be put up only after traffic engineering studies and sound engineering judgment.

• 4) The sign should be designed for the foreseeable traffic conditions and speed on the roads.

• 6) The basic requirements of a sign is that it must be understood in time to produce a proper response.This means :-

• high visibility- night and day.

• Lettering or symbols of adequate size.

• Proper location - 0.6m away from the edge of the kerb;on roads without kerb the nearest edge may be 2.0m to 3.0m from the edge of the carriageway.

• Simplicity and uniformity in design,position & application.

• Types of traffic signs.Types of traffic signs.• Traffic signs have been divided into three

categories according to Indian motor vehicle act :-

• 1) Danger sign,also known as warning 1) Danger sign,also known as warning signs or cautionary signs.-signs or cautionary signs.- These are used when it is necessary to warn traffic for potentially hazardous conditions on or adjacent to a highway.These are to be located at sufficient distance 120,90,60,40 meter respectively on NH/SH,MDR/ODR etc.

• 2) Regulatory signs -2) Regulatory signs - These are meant to inform the road users of certain laws,regulations and prohibitions;the violation of these signs is a legal offence.

• These are further classified as :-

• a) Stop and give way signs - The STOP sign is intended to stop the vehicles on a roadway.The Give way sign is used to control vehicles on a road so as to assign right of way to traffic.

• b) Prohibitory signs - Are meant to prohibit certain traffic movements,use of horn or entry of certain vehicle class.

• c) No parking and No stopping signs.

• d) Speed limit and vehicle control signs.

• e) Restriction ends sign.

• f) Compulsory direction control and other signs.

• 3) Informatory signs -3) Informatory signs - These are used to guide the road users along routes,information of destination,distance and provide with information to make travel easier,safe and pleasant.The information signs are grouped under the following sub-heads : -

• a) Direction and place identification sign.

• b) Facility information sign.

• c) Other useful information sign.

• d) Parking signs.

• e) Flood Gauge.-e) Flood Gauge.- installed at all causeways and submersible bridges or culverts to indicate the road users the height of flood above the road level.

Traffic signals.

• Traffic signals are control devices which could alternately direct the traffic to stop and proceed at intersections using red and green traffic light signals automatically.The main requirements of traffic signal are to draw attention,provide meaning and time to respond and to have minimum waste of time.

• Advantages of traffic signals :-

• 1) They provide orderly movement of traffic and increase the traffic handling capacity of most of the intersections at grade.

• 2) they reduce certain type of accidents,notably the right angled collisions.

• 3) Pedestrians can cross the road sfely at the signalized intersection.

• 4) The signals allow crossing of the heavy traffic flow with safety.

•

• 5) When the signal system is properly coordinated ,there is a reasonable speed along the major road traffic.

• 6) Signals provide a chance for crossing traffic of minor road to cross the path of continuous flow of traffic stream at reasonable interval of time.

• 7) Automatic signals workout to be economical when compared with manual control.

• 8) The quality of traffic flow is improved.

• Disadvantages of traffic signals :-

• 1) The rear end collision may increase.

• 2) Improper design and location of signals may lead to violations of the control system.

• 3) Failure of the signal due to electric power failure or any other defect may cause confusion to road users.

• The period of time required for one complete sequence of signal indications is called CYCLE.

• A part of the signal cycle allocated to a traffic movement or a combination of traffic movement is called PHASE.

• Any of the division of signal cycle during which signal indications do not change is called the INTERVAL.

• TYPE OF TRAFFIC SIGNALSTYPE OF TRAFFIC SIGNALS

• 1) Traffic control signals.

• a) Fixed time signal.

• b) Manually operated signal.

• c) Traffic actuated (automatic) signal.

• 2) Pedestrian signal.

• 3) Special traffic signal.

• The traffic control signals have three coloured light glows in each direction of traffic flow.

• RED - Stop.RED - Stop.• GREEN - Go.GREEN - Go.• YELLOW - Clearance time.YELLOW - Clearance time.• Fixed-time signal or pre timed signals are set

to repeat regularly a cycle of red,amber,and green lights.

• Traffic actuated signals are those in which the timing of the phase and cycle are changed according to traffic demand.