S. Coffey, S. Park
Part-time shoulder use (PTSU) is an active traffic management (ATM) strategy recommended by the Federal Highway Administration (FHWA) to improve the capacity of a roadway, known internationally as hard shoulder running. PTSU is implemented to aid in reducing congestion during peak commuting periods or other similar congestion periods, both recurring and non-recurring. This study aims to evaluate the congestion relief benefits of PTSU when a lane is blocked in such incidents as crashes or construction. The blocked lane scenario within this study focuses on a crash blocking the lane as it is more common than construction for most roadways. Interstate 476 (I-476) in southeast Pennsylvania (PA) was assessed for PTSU implementation. The southern 13.4 kilometers of I-476 reduces from a six-lane interstate to a four-lane interstate. The hourly traffic volumes are around 2,350 vehicles per hour per lane in specific segments of I-476. The higher lane volumes create significant congestion. Four locations were determined to maximize the possible effects of the blocked lane scenarios. The left lane was blocked in the base scenario with the left and shoulder lanes blocked in the two PTSU scenario. The variety of locations and lanes blocked in each scenario will further explore the knowledge of the PTSU effects. The results indicate that PTSU can greatly reduce the area impacted by the blocked lane. Negative operational effects are upstream of the crash location, but the extent of congestion caused by the blocked lane are minimal.
Keywords: shoulder use; blocked lane; lane density; travel time; operational performance; level of service