State's first Diverging Diamond Interchange completed in Washington County

PennDOT and Gov. Tom Wolf Thursday marked the completion of Pennsylvania's first Diverging Diamond Interchange, meant to enhance safety and improve the flow of traffic at the junction of Interstate 70 and Route 19 in South Strabane, Washington County.

The $51.6 million project is part of PennDOT's improvement of a section of I-70 between the north junction with Interstate 79 and the Route 136 (Beau Street) Interchange, as well as other ongoing upgrades along the I-70 corridor in Washington and Westmoreland counties.

According to state officials, the diamond configuration was chosen because it occupies much of the same footprint as a previous, substandard cloverleaf interchange and had a minimal impact on nearby businesses.

In the Diverging Diamond design, the 73rd such in the nation, traffic on Route 19 crosses to the left side of the road as it passes under the interstate. As a result, motorists can turn left to enter or exit I-70 without having to cross opposing travel lanes.

According to PennDOT, signs, road markings and curbed islands were installed to help guide motorists though cross-over points on Route 19, which are controlled by traffic signals. A concrete glare screen was placed between those points to prevent motorists from being distracted by the sight of opposing vehicles passing on their right side.

A video simulation below demonstrates the new traffic patterns at the interchange. Information on other I-70 improvements can be seen at www.I-70projects.com .

Jeff Himler is a Tribune-Review staff writer. Reach him at 724-836-6622, jhimler@tribweb.com or via Twitter @jhimler_news.