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Variable Speed Limits aim to improve safety, traffic flow on the Schuylkill Expressway

May 04, 2021 12:00 PM
By: Brad Rudolph

​PennDOT Secretary Yassmin Gramian was joined by local and elected officials on April 8 to celebrate the installation of 72 Variable Speed Limit (VSL) signs and an end-to-end Queue Detection and Warning system (QDW) along 14 miles of Interstate 76 (Schuylkill Expressway) between King of Prussia and Philadelphia. The corridor serves more than 130,000 vehicles each day.

"These devices will help reduce congestion and greatly improve safety by warning drivers of changing conditions based on real-time expressway, traffic and weather events," said Secretary Gramian. "This is one of the ways we are using operational strategies and technologies to actively manage travel and traffic flow along this critical corridor."

The activation of the VSL and QDW systems along eastbound and westbound I-76 from the Pennsylvania Turnpike in Montgomery County to the U.S. 1 North Interchange in Philadelphia is the first phase of a long-range, comprehensive, multimodal transportation management plan designed to enhance travel and safety along the I-76 (Schuylkill Expressway) corridor between King of Prussia and Philadelphia.

Once the VSL system moves from static to automated on May 10, drivers will notice speed limits begin to change based on real-time travel conditions. This is an indication of congestion occurring ahead and an effort to improve the flow of traffic and reduce stop-and-go conditions and the potential for rear-end crashes.

The speed limits posted to the new VSL signs on I-76 will serve as enforceable, regulatory speed limits, not recommended speed advisories.

According to PennDOT data, there were 2,580 reportable crashes on I-76 in Montgomery County from 2015 through 2019. Of those, 1,741 were rear-end crashes. VSL deployments in other states have been shown to reduce crashes by as much as 30 percent.

Click this link for additional information about VSL signs and a list of frequently asked questions for further reference.

The next phase of PennDOT's I-76 Integrated Corridor Management program, currently in design, will include additional active traffic management strategies such as the modernization of traffic signal systems along several roadways running near the expressway. It will also transform the existing shoulders on portions of the Schuylkill Expressway to accommodate an additional travel lane, or "flexible" travel lane, during peak travel times.

For additional details on this corridor-wide improvement plan, visit

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