SR 15 Curve Safety Improvements
McCormick Taylor designed and implemented an automated, real-time warning system along southbound SR 15 in Williamsport, using data-driven messaging and dynamic signage to reduce truck-related and speed-related crashes at a high-risk interchange approach.
The Challenge
The Pennsylvania Department of Transportation (PennDOT) District 3-0’s SR 15 Curve Safety Improvements project was developed to address a documented history of truck-related and speed-related crashes along southbound SR 15 approaching the sharp curve leading into the I-180 eastbound/SR 220 northbound interchange in the City of Williamsport, Lycoming County, Pennsylvania. This corridor carries an average daily traffic volume of 13,669 vehicles, including approximately 15% truck traffic. As motorists approach the curve, the speed limit transitions from 55 MPH to 45 MPH. Between 2017 and 2024, 25 reported crashes occurred within the project area, including 10 truck-related crashes and 10 crashes involving speeding vehicles.
Prior efforts to improve safety relied on traditional warning treatments, including overhead signage with static flasher assemblies, post-mounted truck rollover warning signs, and solar-powered illuminated dynamic curve warning signs. While these measures increased driver awareness, crash trends demonstrated the need for a more advanced solution capable of influencing driver behavior through analyzing real-time conditions.
How We Helped
McCormick Taylor worked with PennDOT to design three alternatives that adhered to the established concept of operations while varying equipment locations and staging. The selected alternative utilizes an automated system that collects real-time data from roadway detectors to identify approaching vehicles and deliver targeted warnings through changeable message signs (CMS) and flashing beacons. Designed to reduce vehicle speeds before drivers enter the southbound SR 15 curve and transition into the interchange area, the system provides multiple opportunities for motorists to receive and respond to safety messages. The design includes radar sensor units, truck rollover signing with dynamic flasher assemblies that activate messaging on the CMS boards. This system is installed upstream of dynamic curve warning signs, reinforcing speed reduction messaging throughout the approach. An existing sign structure and ITS facilities were incorporated into the design to reduce project costs and maintenance requirements. By separating the system into multiple stages of operation, the selected alternative enhances driver awareness, messaging reinforcement and provides redundancy.
Results
The placement of each device was carefully determined using anticipated driver reaction times and stopping sight distance criteria. Driver reading comprehension speeds were conservatively calculated at 70 MPH, exceeding the posted speed limit, to ensure adequate time for drivers to perceive, process, and react to the information presented. The project began in spring 2025 and was completed in July 2026. The team included Bruce-Merrilees Electric Company and Signal Service. Through the implementation of automated, data-driven warning technology, the project advances a proactive approach to reducing truck-related and speed-related crashes at a known high-risk location.
Awards
- 2026 Project of the Year, ITSPA
2026 Project of the Year, ITSPA 
