Abstract:
Traffic congestion due to ever-increasing number of vehicles and pedestrians is one of the
major problems that need to be tackled especially in metropolitan areas. Numerous methods
are available to reduce delays and financial losses as well as environmental problems
caused by road traffic in major cities. Signalizing is one of the main methods to control traffic
at intersections. Most of the signalized junctions Sri Lanka are isolated fixed-cycle type.
Signal coordination is considered as one of the cost effective and successful strategies to
reduce congestion problems worldwide. When traffic signals work together (or are
coordinated), they provide a greater opportunity for motorists to travel through adjacent
traffic signals without making unnecessary stops. This reduces fuel use, saves motorists
travel time, diminishes wear and tear on vehicles, and cuts vehicular emissions.
Sri Lankan road development and management agencies are in their planning stage to
implement this system for signalized intersections. However, little has been done to quantify
the benefits that can be obtained from coordinated traffic signal systems. Although it is
important to have quantified measure of the benefits compared to prevailing system, such
measure is not yet available in Sri Lankan context. Therefore, objective of this research is to
evaluate the benefits from Traffic signal coordination in reducing delay and reducing travel
time to vehicles.
As a case study, closely spaced three signalized junctions are selected at for the analysis.
The junctions selected are Park Road Junction, Narahenpita Junction and Kirimandala
Mawatha Junction on Baseline Road. SIDRA, Signalized (and unsignalized) Intersection
Design and Research Aid is used to generate the timing plans for each junction. Each
junction is analyzed considering as a non-coordinated isolated junction and also as an
individual junction of a coordinated system. Travel time, delay, effective stop rate and
proportion queued are identified as important parameters to evaluate the benefit/impact of
the coordinated system. Data related to above parameters taken from the SIDRA output is
used to calculate the travel time and delay of the coordinated system and in the isolated
system separately. Using the evaluation results, travel time saving, reduction of delay and reduction of stop rate are presented as percentages, as quantified measures of the benefits
of the signal coordination. Limitations of signal coordination such as time for pedestrians,
non-uniformity of intersections are identified and evaluated to take a quantified measure of
the negative impacts of the system.
Citation:
Wannige, E.P., & Bandara, J.M.S.J. (2015). Evaluating the impacts of coordinated traffic signal systems [Abstract]. In H.R. Pasindu (Ed.), Proceedings of the Transportation Research Forum 2015 (pp. 38-39). Department of Civil Engineering, University of Moratuwa. https://uom.lk/sites/default/files/civil/files/TRF%202015_0.pdf