Signal Redesign at Intersection Using Irc and Webster Method: A Case Study of Vadodara

: Traffic congestion is a major issue for all the developing cities. Traffic congestion has emerged as one of the main challenges for engineers, planners in urban areas. Modern, social and economic structure shaped by car ownership and rapid growth in the rate of vehicles is main reason for traffic congestion. The project has been carried out in order to analyze and redesign the traffic signal at a fatehgunj post office circle, Baroda Gujarat in order to solve the problem of traffic congestion. Detailed volume count survey was carried out for the selected intersection by videography. The signal is redesigned by using Webster and IRC method. After redesigning the signal by both the methods highest cycle time amongst both the method will be adopted.


INTRODUCTION
India is a developing country and its cities are undergoing rapid urbanization and modernization as a result there is rapid growth in the road traffic.There are major issues related to traffic movement due to heterogeneous traffic.As vehicular traffic is increasing day by day which is creating congestion on road and hampering safety and efficient movement of traffic.It is therefore necessary to increase the operational characteristics of highways.Therefore provision of traffic signals with proper timing is essential.Traffic signals are control devices that directs the traffic to proceed and stop at the intersections.At intersections where number of crossings and right turning vehicle are more there are chances of accidents.Hence this research study is carried out to re design the signal at one of the busiest intersection in Vadodara city.

II.
NEED OF THE STUDY Intersection plays an important role in the road network, where traffic directions converge.Due to the disturbance of pedestrian, bicycle to vehicles and loss of green time for beginning and clearance and so on reduces the capacity of intersections.Thus, the intersection acts as bottlenecks of the network as it is the prime cause of traffic jams and traffic accidents.

III.
AIM OF THE STUDY To analyze the characteristics of mixed traffic flow at signalized intersection and to redesign the traffic signal at a selected intersection.

IV.
OBJECTIVES • To estimate the basic parameters for the selected roads.
• To identify the traffic conflicts.
• To evaluate the performance of the signal and redesigning the signal.
• To suggest remedial measure.

V. SCOPE OF THE STUDY •
To collect the information of the study area in detail.

XI. DESIGN OF SIGNAL A. By Webster's Method
Webster's method for traffic signal design is an analytical approach of determining optimum cycle time corresponding to minimum total delay to all the vehicle at the approach road of the intersections.Studies have shown that the average and overall delay at the intersection varies with the signal timings.Delay at the intersection depends upon the cycle time.If cycle time is short the delay caused is considerably large whereas when the cycle time is large the delay at the intersection is less.The optimum cycle time depends on the geometric details of the intersection and the volume of traffic approaching the intersection from all the approach roads during the design hour.The field work consists of determining the following two sets of values on each approach road near the intersection: The normal flow, q on each approach during the design hour and the saturation flow S per unit time.The normal flow values, q1, q2, q3 and q4 on roads are determined from field studies conducted.The saturation flow of vehicles is determined from careful field studies by noting the number of vehicles in the stream of compact flow during the green phases and the corresponding time intervals precisely.

By IRC Method
The Indian Road Congress (IRC) is the apex body of highway engineers in the country.The IRC was setup in December 1934 on the recommendation of best known Jayakar Committee for road development in India.
According to IRC vehicle arriving on an approach distribute equally on different lanes meant for a particular direction.Number of vehicle arriving on approach have identical cycle length.The reaction time of first vehicle on the approach is 6 seconds and consecutive vehicles follow uniform headway of 2 seconds.Green time is equal to width of the carriage way in meters divided by assumed walking speed of 1.2 m/s plus reaction time of 7 seconds.Optimum cycle length should be such that the delay at the intersection is minimized.The cycle length should not exceed 120 seconds and it should be taken in multiple of five.Optimum cycle length is calculated using Webster's method.
Step-3 Adding respective amber time and 2 seconds for inter green period.

CONCLUSION
From the data analysis saturation flow as well as normal flow was determined and traffic signal is designed and compared with the existing traffic signal.This study can be used as a baseline for research work for Traffic analysis at signalised intersections at Vadodara or any urban areas.It has been determined from the signal design that the existing signal needs to be modified in order to reduce delay and jams at the intersections.From the data analysis it can be concluded that IRC method is best suitable for re designing the existing signal.
The passenger car is considered as the standard vehicle unit to convert other vehicle classes and this unit is called Passenger Car Unit.In mixed traffic flow, the traffic volume and capacity are generally expressed as PCU / hour or PCU / lane / hour & traffic density as PCU / km length of lane.Different classes of vehicles as cars, vans, buses, trucks, auto rickshaw, motor cycles, pedal cycles, bullock carts etc. are found to use the common roadway facilities.The flow of such vehicles on roadway forms the heterogeneous or mixed traffic flow.It is difficult to estimate the traffic volume and capacity of roadway facilities under mixed traffic flow.So, the different vehicle classes are converted to one common standard vehicle unit.

•
To collect preliminary data.•To understand different parameters and variables associated with the study.

Table - 3 PCU Equivalents for Traffic Signal Computation TYPE
OF VEHICLES PCU EQUIVALENT Heavy or medium goods vehicles 1.75 Light goods vehicles 1.00 • Email: editor@ijfmr.comIJFMR230610862 Volume 5, Issue 6, November-December 2023 4