Traffic Operational Performance Evaluation and Enhancement of Roundabout: A Case Study of
Lakhan Thapa Chowk, Butwal
Student: Durga Paudyal
Supervisor: Dr. Pradeep Kumar Sharestha
Submitted Date:
July, 2024
Abstract
The main aim of this study is to explore alternatives to enhance the traffic operational
performance and enhancement of the Lakhan Thapa Chowk, Butwal in terms of LOS, delay,
LOS. A VISSIM microsimulation model for the roundabout intersection was developed,
calibrated and validated to the existing traffic conditions to determine the current operational
performance of roundabout. The microsimulation model was then further used to analyse
the operational performance of the roundabout under four improvement alternatives:
alternative I (Improvement of geometric parameters of roundabout), alternative II
(Improvement the number of lane and lane width as Per Upgradation Plan at Bardaghat leg),
alternative III (Grade separated intersection at Siddhartha highway road section), and
alternative IV (Grade separated intersection at Siddhartha highway and roundabout at
grade). The evaluation of the alternatives has been conducted for both base year traffic and
forecasted (5 year and 10 year) traffic scenarios.
For base year traffic; comparative analysis has been carried out with respect to existing
geometric scenario. After comparative analysis for base year traffic, all the performance
indicator was improved with the use of alternative I, II, III and IV. Whereas for 5 year and
10-year traffic alternative I and II were not effective in terms of improvement of
performance parameter. Among all four alternatives, It was found that alterative IV was the
best alternative with improvement i.e., in terms of LOS, delay, Queue length and average
operational speed were LOS B, 12.06 sec, 18.06 m, 37.19 kmph respectively. Moreover, the
average operational speed also found higher with comparison to other three alternatives.
For forecasted traffic; comparative analysis has been carried out with respect to existing
geometric scenario. After comparative analysis, it was found that alterative IV was the best
alternative with improvements in LOS, delay, Queue length and average operational speed
LOS B, 12.06 sec, 18.06 m and 37.19 kmph for base year traffic, LOS C, 24.4 sec, 36.95 m
and 33.03 kmph for 5-year traffic, for 10- year traffic LOS E, 47.68 sec, 37.72 m, 26.95
kmph respectively. Moreover, the average operational speed also found higher with
comparison to other two alternatives. Therefore, traffic operational performance measures,
alternative IV (Grade separated intersection at Siddhartha highway and roundabout at grade)
were found best improvement option under forecasted traffic condition as well.
Keywords
Calibration, Validation, LOS, Delay, Queue length, Operational speed