Masters Theses


"The variable speed limit (VSL) system has been adopted on more and more roadways across the globe as an engineering tool for controlling traffic flow, particularly during congestion situations. An important and fundamental question raised among traffic engineers is: Are the costs of installing and operating variable speed limits really justified? In order to answer this question, this thesis measures the effectiveness of the VSL system applying the VISSIM microscopic simulation model to a non-recurrent congestion situation. For the analysis, a section of interstate was modeled in VISSIM and calibrated so that the simulated results closely reproduce the observed data collected from traffic detectors. The calibration process is accomplished using a genetic algorithm (GA) programmed in MATLAB. Once the interstate system is calibrated to the static speed limit condition, the VSL system is portrayed on the model by temporarily blocking lanes to measure the effectiveness of VSL during an incident situation. Multiple incident locations and different VSL configurations are tested to investigate various possible forms of reality. The simulated results of with-VSL and without-VSL systems were compared and evaluated.

The results show that no significant changes in travel times are observed, but queue lengths and fuel consumption decrease by 10-20% and 3-5% respectively. The speed variances upstream of the incidents also decreased 10-25% depending on location, which in the end may lead to fewer crashes.

Before a VSL system is constructed a study should be conducted to determine if the cost of installing and maintaining the system is justified by the benefits. The benefits of a VSL system include a decrease in fuel consumption as well as a decrease in the deviation of speeds, potentially leading to a reduction in crashes. Further studies need to be done to determine exactly how much the number of crashes could potentially be reduced. If a governing authority has the means for a VSL system they could potentially be justified by a reduction in crashes on the roadway, but the breadth of this thesis does not have enough evidence to support the case that there will be a definite reduction in the number of crashes"--Abstract, page iii.


Baik, Hojong

Committee Member(s)

Park, Byungkyu
Burken, Joel G. (Joel Gerard)


Civil, Architectural and Environmental Engineering

Degree Name

M.S. in Civil Engineering


Missouri. Department of Transportation
Crawford Bunte Brammeier Traffic and Transportation Engineers


Missouri University of Science and Technology

Publication Date



xii, 91 pages

Note about bibliography

Includes bibliographical references (page 90).


© 2010 Brian Joseph Schaefer, All rights reserved.

Document Type

Thesis - Restricted Access

File Type




Subject Headings

Traffic flow -- Computer simulation
Express highways
Roads -- Interchanges and intersections
Evolutionary programming (Computer science)

Thesis Number

T 10280

Print OCLC #


Electronic OCLC #


Link to Catalog Record

Electronic access to the full-text of this document is restricted to Missouri S&T users. Otherwise, request this publication directly from Missouri S&T Library or contact your local library.

Share My Thesis If you are the author of this work and would like to grant permission to make it openly accessible to all, please click the button above.