Details:

Creators:
Fontaine, Michael D. ; Ma, Jiaqi ; Hu, Jia
Fontaine, Michael D. ; Ma, Jiaqi ; Hu, Jia Less -
Corporate Creators:
Virginia Center for Transportation Innovation and Research
Corporate Contributors:
Virginia. Dept. of Transportation
Subject/TRT Terms:
[+]
Adaptive Control Bayes' Theorem Benefit Cost Analysis Periods Of The Day Pilot Studies Traffic Signal Control Systems Traffic Signal Timing
Publication/ Report Number:
VCTIR 15-R24
Resource Type:
Tech Report
Geographical Coverage:
Virginia
Corporate Publisher:
Virginia Center for Transportation Innovation and Research
Abstract:
Currently, most traffic signals operated by the Virginia Department of Transportation (VDOT) use actuated plans that vary

by time of day (TOD) and day of the week. These timing plans are typically developed off-line using traffic count information

collected in the field and then processed using signal optimization software. This method works well as long as traffic volumes

remain consistent with the conditions used to develop the timing plan, but timing plans can become suboptimal if traffic demands

deviate from those conditions. Traffic growth over time, seasonal changes in traffic, special events, or incidents can all cause

TOD plans to perform poorly, resulting in increased delays to drivers. As a result, VDOT must regularly retime signalized

intersections to deal with long-term changes in travel patterns, which incurs costs to VDOT. Even so, non-recurring events can

still cause TOD plans to perform poorly.

Adaptive signal control technology (ASCT) is one tool that has been proposed to handle variable traffic demand better.

VDOT’s Traffic Engineering Division began a pilot program to install the InSync ASCT developed by Rhythm Engineering on

13 corridors around the state beginning in 2011. The InSync system uses enhanced detection along a corridor to adjust signal

timing parameters dynamically to meet observed demand in real time, eliminating the need to develop static timing plans. This

allows the ASCT system to adjust signal timing parameters to account for variations in flow attributable to special events,

seasonal flows, incidents, or simply the increase of volumes over time. In this case, signal timings are not pre-defined based on

historic data, so ASCT systems can potentially reduce delays created by outdated static TOD plans.

These pilot deployments were evaluated to determine if ASCT created operational and safety improvements large enough

to justify the additional costs to install ASCT. Data on mainline traffic operations, side street delays, and intersection crashes

were collected with and without ASCT active. The results showed that mainline traffic operations generally improved if (1) the

corridor was not oversaturated; (2) the corridor did not have characteristics that encourage platoon dispersion; and (3) the

corridor did not already function well. Side street delays generally increased, although net benefits in overall corridor travel time

were usually still observed. An empirical Bayes safety analysis of crashes at the intersections where ASCT was installed also

found a 17% decrease in total crashes. Overall, ASCT generally produced a favorable benefit/cost ratio. The findings from the

pilot tests were used to identify key considerations for future ASCT deployments so that VDOT could better identify future sites

that might benefit from ASCT installation.


Format:
PDF
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:c938abc7094719af2c8aea705b4a876b104e6300ca83af8ae3459eae4b2ee528
Download URL:
https://rosap.ntl.bts.gov/view/dot/29013/dot_29013_DS1.pdf
File Type:

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