This research proposes a new signal operation strategy aimed at efficient utilization of
green time by cutting down on the start up and response loss times. The idea is to have a
"pre-signal" on each main approach a few hundred feet upstream of the intersection in
addition to the main intersection signal, which is coordinated with the pre-signal. The
offset between the main and pre-signal ensures that the majority of start up losses does
not occur at the main signal. The benefits of the system under various traffic conditions
were evaluated based on analysis of the queue discharge process and Corridor
Simulation (CORSIM) study. The proposed measure should reduce the travel time and
total control delay for the signalized network.
To attain the objective the following two studies were undertaken:
1. Development of a queue discharge model to investigate the expected benefits of
the system.
2. Simulation of the system: In the second part of the research, the proposed
strategy was tested using CORSIM to evaluate its performance vis-ÃÂ -vis the
baseline case.
The queue discharge model (QDM) was found to be linear in nature in contrast to prior
expectations. The model was used to quantify the benefits obtained from the pre-signal
system. The result of this analysis indicated that the proposed strategy would yield
significant travel time savings and reductions in total control delay. In addition to the QDM analysis, CORSIM simulations were used to code various
hypothetical scenarios to test the concept under various constraints and limitations. As
per expectations, it was found that the system was beneficial for high demand levels and
longer offsets. The upper limit on offsets was determined by visual observation of
platoon dispersion and therefore the maximum offset distance was restricted to 450 feet.
For scenarios where split phasing was used, the break even point in terms of demand
level was found to be 2500 vph on a three lane approach, whereas that for a lag-lag type
of phasing strategy was found to be 1800 vph, also on a three lane approach.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/4279 |
| Date | 30 October 2006 |
| Creators | Palekar, Trishul Ajit |
| Contributors | Zhang, Yunlong |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 682961 bytes, electronic, application/pdf, born digital |
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