Details:

Creators:
Sullivan, Andrew J. ; Sisiopiku, Virginia P. ; Reddy-Surhabi, Suman
Sullivan, Andrew J. ; Sisiopiku, Virginia P. ; Reddy-Surhabi, Suman Less -
Corporate Creators:
University Transportation Center for Alabama
Subject/TRT Terms:
[+]
Congestion Management Systems Rain Traffic Congestion Traffic Signals, Closed-loop Signal Systems, Weather-related Congestion Traffic Signal Timing
Publication/ Report Number:
UTCA Report 07211
Resource Type:
Tech Report
Geographical Coverage:
Alabama
Corporate Publisher:
University Transportation Center for Alabama
Abstract:
It is known that inclement weather can affect traffic volumes, vehicle speeds, speed variance, saturation flow rates, and sometimes

discharge rates from traffic signals. These parameters in turn can have a significant impact on the efficiency of traffic signal

timing plans. Timing plans developed for dry conditions with good visibility may not be as effective under wet conditions with

poor visibility, even for the same traffic volumes. Previous studies have looked at the effects of poor weather on traffic signal

efficiency but they have focused primarily on winter weather conditions involving snow and ice, which have much more dramatic

impacts on traffic flow. In regions like the South, rain is the primary adverse weather event and even though its effects on traffic

flow may be smaller than snow or ice, its impacts can still be seen.

This study sought to assess the impact of rain on traffic flow and determine whether there can be a meaningful benefit to

developing and implementing signal timing plans specifically for rain events. Using simulations for two study corridors in

Birmingham, Alabama, it was found that moderate and heavy rain events do impact traffic flow, increasing stops and average

delays up to 6% compared to dry conditions. Signal timing plans optimized for wet conditions were found to reduce these delays,

though in absolute terms the benefits were modest. It was found, however, that the effectiveness of rain-specific timing plans

depended to a large extent on prevailing traffic volumes. An evaluation of potential costs and benefits resulting from rainoptimized

signal timing plans found that the net benefits, at least in the two study corridors, are questionable. The analysis found

that projected costs over a five-year life cycle would significantly exceed potential benefits. Rain-specific timing plans may have

useful applications in certain corridors but the potential benefits and costs should be carefully evaluated beforehand.


Format:
PDF
Collection(s):
US Transportation Collection University Transportation Centers
Main Document Checksum:
[+]
urn:sha256:2a32c790192374ce9e5b4aaf0e776088ea3854bbccb768908974e6974c9fa412
Download URL:
https://rosap.ntl.bts.gov/view/dot/18549/dot_18549_DS1.pdf
File Type:

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