Unit 3 i ppt
- 1. Traffic Engineering Mr.P Umasai Krishna M.tech,(Ph.d)
- 2. Scope of traffic Engineering: Traffic Characteristics Traffic studies and analysis Planning and analysis Geometric design Traffic operation, regulation and control Road safety Administration and management
- 5. Traffic volume studies Spot speed studies Speed and delay studies O & D studies Parking studies Accident studies
- 6. Units-No of vehicles/ time In order to express the total traffic flow on road per unit time, it is necessary to convert the flow of different vehicle classes into one standard vehicle type, such as the ‘Passenger Car’. Therefore each vehicle class is assigned an equivalency factor called ‘passenger car unit(PCU)’ Peak hourly volume is generally much higher than the average hourly volume of the entire day.
- 7. To decide the priority for improvement & up gradataion of roads For re-design of road facilities. For analysis of traffic patterns For computing roadway capacity To plan traffic operation & control of existing facilties To plan and design new facilities Turning movement studies at intersection are used to design signals For structural strengthening of pavement and other road way system
- 12. Planning traffic regulation and control measures Design or redesign if various geometric elements To decide design speed of existing or new facilities In accident studies and preventive measures Study of traffic capacity To final the speed trends with respect to last several years
- 13. Pavement width Horizontal curve Sight distance Gradient Pavement unevenness intersections Road side developments
- 14. Speed distribution tables: From the spot speed data of the selected samples, frequency distribution table of spot speed is prepared by arranging the speed groups covering desired speed ranges and the number of vehicles in each speed range The A.M of the measured speeds is taken as average spot speed of all the vehicles in the stream.
- 16. Methods of conducting speed and delay studies: a) Floating car method b) License plate c) Interview technique d) Elevated method e) Photographic method
- 21. Mean values of speed and delay Directio n N-S Journey time Min-sec Stopped delay Min-sec Overtaki ng Overtak en In opposite direction Total 26-00 6-00 14 20 1088 Mean 6-30 1-30 3.5 5 272 S-N Total 30-24 7-12 12 8 716 Mean 7-36 1-40 3 2 179
- 22. North-south direction Ny = avg no of vehicles overtaking minus overtaken = 3.5-5= -1.5 Na= avg no of vehicles during trips in opposite direction = 179 Tw = avg journey time with the stream q =6.5min Ta= Avg journey time during trip against the stream =7.6 Avg volume = 179-1.5 7.6+ 6.5 = 12.59 veh/min Avg journey time = 6.62min Avg journey speed = 3.5*60/6.62 =31.7kmph Avg stopped delay = 1.5min Avg running time = Avg journey time- avg stopped delay =5.12min Avg running speed= 3.5*60/5.12 = 41kmph Similarly we can calculate for S-N direction
- 23. License plate method Synchronized stop watches or voice recording equipment are used Observers are stationed at the entrance and exit of the test stretch where information of travel time is required. The timings and vehicle numbers are noted. From the office travel time of the each vehicle could be found But the method does not give important details such as causes of delays and duration and number of delays within the test stretch.
- 24. Interview method The work can be completed in a short time by interviewing and collecting the required details from the road users on the spot Data on delays collected depend on the assessment of each individual driver This method may not provide with all the required details correctly Photographic technique: Observers with timers are located at an elevated observation point from where the movement of most of the vehicles within the desired stretch Alternatively cameras or video equipment are located and the desired observations recorded. It is suitable for short stretches
- 25. O & D studies: It provides the basic data for determining the desired direction of vehicular flow or passenger trips in terms of the desired lines. Desired lines are straight lines joining the points of o&d of each trip
- 26. Methods of conducting O & D studies Road side interview method License plate method Return post card method Tag-on-car method Home interview method
- 27. Road side interview The vehicles are stopped at selected interview stations by a group of persons. The data is collected on spots in the prescribed formats. The information includes place, time of origin & destination, route, location of intermediate stoppages. Part of the traffic may be filtered and diverted through a prescribed lane with the help of police and warning signs. The answers to the set of questionnaire are noted by the enumerators and the vehicles are allowed to proceed with minimum possible delay. Data can be collected in short duration and team can be trained quickly. The main drawback is some delay to road users and also congestion due to the stopped vehicles.
- 28. License plate method The entire area under study is surrounded by police and the enumerators are stationed on all observation stations on all the roads leading in and out of the area. Enumerators note the registration number of the vehicles entering and leaving the cordoned area and the time Separate recording sheets are maintained for each direction of movement for a specified time interval. The major work will be office computations and analysis, by tracking each vehicle number and its time of entering and leaving the area. This method is quite easy and quick as far as the field work is concerned.
- 29. Return post card method: Reply post cards with return address are distributed to the road users at some selected points along the route The questionnaire to be filled in by the road users is printed on the card, along with a request for co-operation and purpose of the study. The distributing stations for the cards may be selected where vehicles have to stop as in case of a toll booths or signals. This method is suitable where the traffic is heavy . The personnel need not be skilled or trained just for distributing the cards. Only a part of the road users may return the cards promptly after filling in the desired details properly and correctly.
- 30. 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.
- 31. Home interview method This method is preferred when comprehensive traffic and transportation requirements are to be planned for a city. A random sample of 0.5 to 10 percent of the population it selected depending on the total number of residences. It is desirable to classify the types of the households in the entire study area and then randomly select the samples from each class. The residences are visited by the trained personal and they collect the travel data from each member of the house hold. Detailed information regarding the trips made by the members is obtained on the spot. The data collected will be useful either for planning the road network and other roadway facilities for the vehicular traffic or for planning the mass transportation requirements of the passenger trips or for both the requirements Socio-economic and other details may be collected so as to be useful for forecasting traffic and transportation growth.
- 32. Presentation of O-D data O and D tables are prepared showing number of trips between different zones. Desire lines are plotted which is graphical representation prepared in almost all O and D surveys. They are straight lines connecting the origin points with destinations, summarized into different area groups. The width of the such desire lines is drawn proportional to the number of trips in both direction. The desire lines helps to find the necessity of a new road link, a diversion, a by-pass or a new bridge. The lines are used to plan mass transport facilities. Contour lines may be plotted similar to topographic contours.