Crashes during Snow Events Declined 42 Percent after Winter Season Variable Speed Limit Corridor Implementation in Ohio.

Before-After Study of Ohio DOT’s Variable Speed Limits Technology Deployment on I-90 Corridor Shows Reduced Crashes and Improved Incident Clearance Times.

Date Posted

Lake 90 Variable Speed Limit Corridor

Summary Information

A 12-mile stretch of Interstate 90 near Lake Erie, in Lake County, Ohio (between State Routes 528 and 44) frequently experiences low visibility and white-out conditions in winter due to lake-effect snow. Adverse weather conditions on this segment have caused more than 800 winter crashes over a ten-year span, often resulting in road closures and long delays. The Ohio Department of Transportation (ODOT) and local partners tried several approaches to reduce the frequency and severity of multi-vehicle and secondary crashes throughout this corridor. As a result of ODOT’s efforts, legislation was approved in Summer 2017 allowing the establishment of permanent Variable Speed Limit (VSL) corridors to better address changing road conditions.  Temporary, trailer-mounted VSL signs were first deployed along the corridor, with permanent installation completed prior to the 2018-2019 winter season.

Using a Transportation Systems Management and Operations (TSMO) approach, ODOT implemented a variable speed limit set by Traffic Management Center (TMC) staff based on road and weather condition data and using a spreadsheet application for recommendations. The speed limit of the road is reduced in 10 mph increments as conditions warrant. Equipment installed in the project to gather road condition data included Road Weather Information System (RWIS) stations and pavement sensors, and five additional closed-circuit television (CCTV) cameras. Speed limits and road conditions were communicated to motorists using 19 newly installed permanent VSL signs and six Digital Message Signs, and were also disseminated through ODOT’s online traveler information system.


ODOT conducted an analysis of winter season crash and incident data from before the VSL deployment (2014-2016) compared with the first two winter seasons after deployment (2017-2019).


  • Total crashes have decreased by 22 percent. Crashes during snow events were 42 percent lower than the previous peak. These positive safety improvements occurred even with an increase of 15 percent in snow days in the 2017-2019 post-deployment analysis period.
  • No fatalities or major pileups occurred in the corridor during the two winter seasons after VSL implementation.
  • Incident clearance times have been reduced by 31 minutes on average.
  • ODOT reported that secondary crashes have been reduced by 25 percent.
  • Associated user travel delay was estimated to be lowered from 87,949 hours to 14,777 hours, a decrease of approximately 83 percent.

* Case study findings are supplemented by information from ODOT's TSMO website.