Date of Award


Document Type


Degree Name

Master of Science (MS)

Legacy Department

Civil Engineering

Committee Member

Dr. Wayne A. Sarasua, Committee Chair

Committee Member

Dr. Jennifer H. Ogle

Committee Member

Dr. William J. Davis


Access management and driveway design guidelines are critical in providing safe and controlled access to any land use adjacent to a highway. Two of the most common driveway types that provide viable access to land developments are full access and right-in, right-out (RIRO) driveways. Numerous studies in the past have shown that RIRO driveways are safer than full access driveways and can provide operational benefits. However, the effectiveness of a RIRO driveway is greatly dependent on driver compliance with turn restrictions. This research primarily focusses on the safety benefits of RIRO driveways and how these benefits can be compromised if drivers can make illegal movements into and out of RIRO driveways. A before and after case study quantifies the driver non-compliance to turn restrictions at a well-designed RIRO driveway, that meets the design criteria. The installation of longitudinal bollards resulted in immediate compliance improvements without negatively effecting driver patronage for the adjoining business. A safety analysis of 3,774 driveways, including 268 RIRO driveways, along 6 major corridors in South Carolina provides evidence that crash rates for RIRO driveways without provision of a physically left turn prohibiting median treatment are higher than that of isolated RIRO driveways with beneficial treatments. A negative binomial model was developed using crash and driveway data from the 6 corridors and crash modification factors (CMFs) were developed for multiple cases which indicate that RIRO driveways with physical median treatment are safer than RIRO driveways without a physical median.



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