Interstate 70 in Pennsylvania

In the U.S. state of Pennsylvania, Interstate 70 runs east–west across the southwest part of the state serving the southern half of the Pittsburgh metropolitan area. About half of the route is concurrent with Interstate 76 along the Pennsylvania Turnpike (this is the oldest segment of I-70 in Pennsylvania, having been completed in 1940). I-70 is one of only a few Interstate Highways to have a traffic signal - in this case, with U.S. Route 30 at Breezewood, where it leaves the Turnpike and heads south towards Maryland.^[2]

The portion of I-70 between Washington, Pennsylvania (immediately after it ends its brief concurrency with Interstate 79) and New Stanton, Pennsylvania falls well below modern Interstate Highway standards. This section, among other things, employs a jersey barrier in the very narrow median as well as very short entrance ramps at several interchanges, requiring a stop sign to be employed at these ramps instead of the typical yield sign. As the Pennsylvania Turnpike is grandfathered from Interstate standards as well as the aforementioned traffic signal in Breezewood, this makes the majority of I-70 not up to standards, with the short section south of Breezewood to Maryland as well as the 21-mile section from I-79 to West Virginia being the only sections of I-70 in Pennsylvania being up to Interstate standards.

I-70 crosses the Monongahela River on the Speers-Belle Vernon Bridge and the Youghiogheny River on the Smithton High Level Bridge.

History

By 1947, present Interstate 70 across Pennsylvania was included in the planned Interstate Highway System. The route from West Virginia split at Washington, with one branch heading northeast to meet the Pennsylvania Turnpike near Pittsburgh and the other heading east, bypassing Pittsburgh to the south (via a planned bypass of Pennsylvania Route 71) to the New Stanton interchange. The piece south from the Breezewood interchange into Maryland was also in the network.^[3] The route between US 30 in Breezewood and US 522 in Warfordsburg was originally known as Pennsylvania Route 126. In 1957, preliminary numbers were assigned; the longer route via Pittsburgh (now Interstate 79 and Interstate 376) became the main line of I-70, while the southern bypass (now I-70) became Interstate 70S.^[4] A southern extension of Interstate 79 (which had previously only run from Erie south to Pittsburgh) to Charleston, West Virginia in 1963 resulted in changes to I-70. On February 26, 1964, as part of the formation of Interstate 76 (east of downtown Pittsburgh), AASHTO approved a rerouting of I-70 along I-70S. The former I-70 became I-79 from Washington to downtown Pittsburgh and I-76 to and along the Turnpike to New Stanton.^[5] This brought the routing of I-70 to its present form.

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