Highway Research Record

Economic Evaluation of Grade Separation at Signalised Intersections

Date of Start: January 2005
National Institute of Technology, Tiruchirappalli (R, S)

Scope and Objective
Signalised intersections become saturated when the traffic volume passing through the intersections increased beyond certain levels. This leads to long delays for the traffic at the intersections. This problem can be solved only by providing suitable grade separation at the intersection
(i) To study the operating condition including the delay aspects of the existing traffic signal
(ii) To conduct a questionnaire survey for determining the average monetary value of travel time for different classes of      passengers based on their average monthly income and trip purpose.
(iii) To conduct a survey for the average occupancy of different categories of vehicles.
(iv) To estimate the year-wise monetary benefits gained due to the reduction in delay and fuel consumption and to compare it      with the total initial cost and maintenance cost of grade separation throughout the design period
(v) To find out the internal rate of return of the money invested on grade separation

Methodology for Data Collection
• General layout of the existing at –grade signalised intersection.
• Existing signal setting details with regard to cycle time, phase split and timings
• Volume and composition of the different streams of traffic passing through the intersection during peak hour
• Occupancy of the different categories of vehicles passing through the intersection
• Idle Fuel consumption rate of the different categories of vehicles using the intersection
• Collecting data for Value of Travel Time

Methodology for analysis
• Measurement of average stopped Delay (Queue – count method)
• Total monetary value of fuel savings per year for each type of vehicle
• Total monetary value of travel time savings per year for each type of vehicle
• Estimation of capital cost
• Economic evaluation using IRR method

Findings and Conclusions
(i) The economic evaluation of the project involving construction of flyover at signalised intersection, done based on estimation      of money value of travel-time savings using wage-rate approach, has resulted in an IRR more than the market value.
(ii) The study intersection is located in the suburban area of Tiruchirappalli city and general economic background of he people      living in the locality will be relatively better. Hence, the mean wage-rate and hence the money value of travel-time of the      users of the intersection is bound to be high.