Larson Transportation Institute researchers to study financial impact of access management treatments


By Danica Laub

UNIVERSITY PARK, Pa. – As anyone who has ever lived or traveled along a congested two-lane highway can attest, transportation can prove to be problematic. Factors like the number of driveways within a given stretch of roadway, access to turning lanes and even the size of each driveway can impact transportation systems across the country. To remedy the issues, roadways may be widened; additional access points may be added; or, a completely different solution may be necessary. But, sometimes, the best solution is not always the most feasible.

To help shed light on this increasing transportation concern, Vikash Gayah and Ilgin Guler, assistant professors of civil engineering at Penn State University, along with Jonathan Wood, assistant professor of civil and environmental engineering at South Dakota State University (SDSU), will study the financial impacts of various access management treatments through research funded by the South Dakota Department of Transportation (SDDOT). The research project was made possible through the Larson Transportation Institute (LTI).

Having first-hand experience as a graduate student at Penn State and LTI, Wood said he contacted the team at Penn State and LTI, because he knew Gayah and Guler could offer a vast array of skills and experience to the project. Wood said, “In particular, they bring expertise in traffic operations, linking changes in traffic operations to environmental impacts and evaluation changes in traffic operations to economic impacts.”

The project will attempt to provide guidance to SDDOT on the financial impact of various access management treatments (e.g., reducing access points, eliminating or adding median left turn into access points, etc.). The study will evaluate factors such as congestion, safety, economic activities of surroundings businesses and environmental impact.

“We are very excited to work on this project with SDSU and SDDOT. Access management impacts everyone who wants to use the highway transportation system, but is sometimes overlooked,” said Gayah. “We hope this work will help provide SDDOT with guidance to improve traffic, safety and other aspects, by identifying the best access management treatments for various situations.”

The team will consider common strategies, including the installation of a raised median, adding a three-quarter opening at a driveway (that allows right turns into and out of and left turns into, but not left turns out), restricting driveways to only right turn in/out and installation of a two-way left turn lane to facilitate movements into and out of driveways. 

“Our team at SD State brings experience in transportation safety and geometric design to this study, as well as having local connections in South Dakota. And, the Penn State team brings the additional experience and knowledge necessary to complete the study,” said Wood. He added, “Given that the project has a wide range of skills that are required to complete the study, teaming up with Penn State resulted in a diverse team with a strong set of skills that impressed SDDOT and lead to our team receiving the research grant.”

When the study is completed, LTI and SDSU will provide SDDOT with a working spreadsheet-based tool, to help quantify the impacts of the various factors. The tool will allow SDDOT personnel to consider a variety of alternatives and provide a measure of comparison in terms of traffic operations, safety, environmental impact, economic impact and other metrics.

The Penn State team received a grant from the South Dakota Department of Transportation for this one-year project.


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Danica Laub

Image of designated left turn only lane on street

Researchers from Penn State and South Dakota State University will study the financial impacts of various access management treatments, such as dedicated turning lanes, as part of a one-year project, funded by the South Dakota Department of Transportation.



The Thomas D. Larson Pennsylvania Transportation Institute is Penn State’s transportation research center. Since its founding in 1968, the Larson Institute has maintained a threefold mission of research, education, and service. The Institute brings together top faculty, world-class facilities and enterprising students from across the University in partnership with public and private stakeholders to address critical transportation-related problems.

Thomas D. Larson Pennsylvania Transportation Institute

201 Transportation Research Building

The Pennsylvania State University

University Park, PA 16802-4710

Phone: 814-865-1891