Document Type

Thesis

Date of Award

12-31-2025

Degree Name

Master of Science in Transportation - (M.S.)

Department

Civil and Environmental Engineering

First Advisor

Joyoung Lee

Second Advisor

I-Jy Steven Chien

Third Advisor

Branislav Dimitrijevic

Abstract

Managing speed limits in adverse weather is crucial for highway safety. Variable Speed Limit systems aim to adjust speed limits according to weather conditions, yet many traffic management centers depend on manual operator judgment. Rapid visibility fluctuations, along with operators handling multiple responsibilities, can cause delays in responding to deteriorating conditions, increasing the risk of rear-end collisions. A VSL control strategy is developed using real-time Road Weather Information System data to enable more proactive and effective adjustments. Microsimulation analysis indicates that visibility-responsive VSL operations can reduce conflicts by 59% in fog. Applying VSL only to fog-affected sections yields clear safety benefits while limiting the drop in average speed compared to area-wide application. In addition, scenarios with higher Connected Vehicle penetration showed comparable safety performance without roadside VSL infrastructure and produced positive net benefits. These results indicate timely, localized VSL strategies can improve safety while maintaining traffic flow during adverse weather.

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.