All ETDs from UAB

Advisory Committee Chair

Virginia P Sisiopiku

Advisory Committee Members

Jason Kirby

Talat Salama

Document Type


Date of Award


Degree Name by School

Master of Science in Civil Engineering (MSCE) School of Engineering


Rainy conditions typically have an impact on the behavior of drivers and in turn can affect traffic flow characteristics in transportation networks. As a result, signal timing plans developed for dry conditions may be unsuitable or sub-optimal during periods of rain, and changes in such plans may be desirable to account for changes in environmental conditions. Current technology in the field of traffic signal control and communications make it possible to change the signal controller settings remotely, a capability that offers opportunities for signal timing adjustments during rain conditions. This study explores the feasibility and benefits of implementing alternative signal-timing plans during rainy conditions. The current study has two main objectives: a) Assess the impacts of rain events on traffic flow parameters, and b) evaluate the benefits of implementing changes in signal timing plans in response to rainy conditions. The study objectives were addressed through a case study in Birmingham, AL, that collected and analyzed traffic and signal data under dry and rainy conditions. More specifically, traffic volumes and speeds were collected under normal and rainy conditions at a study corridor located on Alabama Highway 79 (HWY 79) in Birmingham. Statistical analysis revealed that traffic volumes during rainy conditions were typically decreased by 4% in the peak hour and that the 85th percentile speeds were reduced by an average of 7% during rain. Special signal-timing plans tailored for rainy conditions were developed for a nine-intersection study corridor using the simulation and signal iii optimization model called Synchro. The likely benefits of implementing these specialtiming plans were then determined in greater detail using a microscopic simulation model called SimTraffic. The results from the study indicated that the average delay per vehicle could be reduced by up to 31 seconds/vehicle by replacing the regular signal-timing plan with a weather-specific timing plan. With the assumptions made in this study the annual benefits may vary from $20,300 to $81,900 per year, depending upon the duration and timing of the rainfall.

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