Two segments of I-70 in Pennsylvania are not designed to modern
Interstate standards: a segment from
Washington to
New Stanton and the aforementioned half-mile () signalized segment in Breezewood.
West Virginia to Washington I-70 enters Pennsylvania from
West Virginia, coming into
Donegal Township,
Washington County. The highway continues northeast as a four-lane freeway with a standard-size median up to
Interstate Highway standards through rural areas of woodland and farmland, coming to its first junction at a partial cloverleaf interchange with State Route 3023 (SR 3023), to the southeast of unincorporated village of
West Alexander. Past this junction, the freeway begins to parallel
US 40 on the northwest side of the road, before it enters a series of winding curves. From here, I-70 heads east to meet a
weigh station and a
welcome center in the eastbound direction, as well as an interchange with SR 3024 connecting to
Pennsylvania Route 231 (PA 231) via US 40 in the borough of
Claysville. The freeway curves to a more east-northeasterly direction, where it briefly passes through the borough limits of Claysville, before briefly reentering Donegal Township. I-70 enters
Buffalo Township, where it soon meets a pair of right-in/right-out ramps connecting to
PA 221, which serves the unincorporated village of
Taylorstown to the northeast, in adjacent
Blaine Township. The freeway comes into
North Franklin Township before crossing into
Canton Township at its partial interchange with US 40 which lacks a westbound entrance; the interchange is adjacent to the
Washington Crown Center shopping mall located to the southwest of the interchange. From here, I-70 crosses over an abandoned portion of the
Allegheny Valley Railroad's
W&P Subdivision line and enters mixed areas of development on the outskirts of the city of
Washington, which is also the county seat of Washington County. After passing through an interchange with Sheffield Avenue serving the industrial and commercial area of Jessop Place, the freeway enters the city limits of Washington, where it comes to a pair of right-in/right-out ramps that connect to
PA 18. A short distance later, I-70 enters
South Strabane Township and reaches its western junction with
I-79 at a directional interchange, which heads north toward the city of
Pittsburgh. The freeway turns southeast through the interchange and begins a
concurrency with I-79. A
Jersey barrier takes over in the highway's median as it comes to a diverging diamond interchange with
US 19 in a commercial area surrounded by strip malls. A short distance later, I-70/I-79 comes to a partial cloverleaf interchange with
PA 136 to the northeast of the borough limits of
East Washington that provides access to
Washington & Jefferson College; a
park and ride lot is located in the northeastern corner of the interchange. Past PA 136, the freeway heads back into rural areas with scattered residences, before reaching the eastern split between I-70 and I-79 at a directional interchange. I-79 turns south toward the city of
Morgantown, West Virginia, while I-70 continues east along the original roadway toward the borough of
New Stanton in
Westmoreland County.
Washington to New Stanton East of I-79, I-70 downgrades to a highway substandard of modern Interstate standards. This section of I-70 (old I-70S) has several dated design features. The median narrows to the point that there are no shoulders between the
median barrier and the passing lanes on both sides. On- and off-ramps at many of the interchanges are substandard in both length and geometry, which requires vehicles to decelerate in the travel lanes before entering the off-ramps, and also necessitates the use of
stop signs on the on-ramps instead of
yield signs. Several overpasses do not meet minimum clearance requirements, which has resulted in damage to and from
overheight trucks. Total reconstruction efforts are ongoing that will upgrade most of this segment of I-70 and its interchanges to modern Interstate standards, and various projects are scheduled through the early 2020s. The first interchange that the freeway meets past I-79 is with
PA 519, where the route crosses into
Somerset Township. I-70 continues through areas of rural farmland with surroundings of wooded rolling hills and turns to the east-southeast, coming to interchanges with SR 1055 south of the hamlet of Dunningsville and McIllvaine Road southeast of the hamlet of Kammerer, in adjacent
Nottingham Township, before reaching the borough limits of
Bentleyville at the
PA 917 interchange, which only contains an eastbound exit and westbound entrance. Shortly afterward, the freeway crosses over
Norfolk Southern Railway's Ellsworth Secondary and meets modified right-in/right-out ramps to Wilson Road, which provides complete access to PA 917 and the center of Bentleyville to and from both directions. Following Bentleyville, I-70 enters
Fallowfield Township, where it has a complete diamond interchange with
PA 481, a westbound exit and eastbound entrance to Twin Bridges Road to the northeast of the hamlet of
Lover, and a full cloverleaf interchange with the
Mon–Fayette Expressway (PA 43), as the route descends into the valley of the
Monongahela River. From here, the freeway curves east-northeast into the borough of
Twilight, before crossing into the borough of
Speers at the interchange with Maple Drive/Twilight Hollow Road. At this point, I-70 meets
PA 88 at a pair of right-in/right-out ramps, prior to crossing over Norfolk Southern Railway's
Mon Line, the Monongahela River, and
CSX Transportation's
Mon Subdivision on the
Belle Vernon Bridge, where the route leaves both Speers and Washington County. Beyond the Belle Vernon Bridge, the route enters
Westmoreland County within
Rostraver Township, just skirting the edge of
Fayette County, missing it by a few dozen feet. Here, it has a partial cloverleaf interchange with
PA 906, before it crosses into the borough of
North Belle Vernon and interchanges with Fayette Street, to the northeast of the borough center. From this point, the freeway heads back into Rostraver Township where it meets
PA 201 at a partial cloverleaf interchange northeast of the community of
Lynnwood-Pricedale that also provides access to
PA 837. I-70 continues through wooded areas with nearby development, reaching an interchange with SR 3011 north of the hamlet of
Arnold City in adjacent
Washington Township,
Fayette County, before coming to a cloverleaf interchange with
PA 51 as the route begins to enter the valley of the
Youghiogheny River. Past PA 51, the route crosses the
Smithton High-Level Bridge over the Youghiogheny River and CSX Transportation's
Keystone Subdivision, where it enters
South Huntingdon Township. From here, I-70 interchanges with SR 3031 north of the borough of
Smithton,
PA 31 at cloverleaf to the northwest of the
Pittsburgh Renaissance Festival grounds, and SR 3010 to the southeast of the unincorporated village of
Yukon, before it comes into
Sewickley Township. In this area, the freeway has an interchange with Waltz Mill Road to the south of the borough of
Madison, before it passes through
Hempfield Township prior to entering New Stanton. Within the borough limits, I-70 has a
dumbbell interchange with SR 3089, before it exits the mainline freeway at a trumpet interchange, to come to a
toll plaza for the New Stanton interchange on the
Pennsylvania Turnpike (
I-76). At this point, the mainline freeway continues east to a cloverleaf junction between
US 119 and the southern terminus of
PA 66. I-70 itself passes through the toll plaza and comes to another trumpet interchange, where the Interstate merges onto the turnpike and heads east towards
Harrisburg and
Philadelphia. In the opposite direction, the turnpike heads northwest toward Pittsburgh, then becomes the
Ohio Turnpike, which continues towards
Cleveland.
Pennsylvania Turnpike concurrency For from New Stanton to
Breezewood, I-70 shares a concurrency with I-76 along the Pennsylvania Turnpike. I-70 passes through a
wind farm in Somerset County and close to the 9/11
Flight 93 National Memorial in
Shanksville. It then has an indirect connection to
I-99 in Bedford County before reaching the eastern end of its concurrency with the Turnpike in Breezewood.
Breezewood to Maryland I-70 splits from the Pennsylvania Turnpike at the Breezewood Interchange in
East Providence Township,
Bedford County. The turnpike continues east toward Harrisburg and
Philadelphia, while I-70 passes through a toll plaza and travels along
the turnpike's old alignment to the Breezewood Interchange's original location, where it has a partial trumpet interchange with
US 30. Eastbound I-70 merges onto westbound US 30 to form a half-mile ()
wrong-way concurrency through the community of
Breezewood. This section of I-70 is one of the few instances of where an Interstate Highway follows a road that lacks grade separation and includes
traffic signals. I-70 follows US 30 west along a five-lane highway with a
center turn lane through commercial areas in Breezewood before it splits from US 30 and turns left onto another freeway alignment. US 30, meanwhile, continues west toward the borough of
Everett. Beyond US 30, I-70 heads south and becomes a four-lane freeway that once again conforms to modern Interstate standards. The median widens, before the freeway crosses over its preceding carriageways and under the Pennsylvania Turnpike. Shortly past the turnpike underpass, there is an interchange with South Breezewood Road before I-70 curves to cross
Rays Hill, crossing into Fulton County, and coming to a pair of right-in/right-out ramps with the southern terminus of
PA 915 in the unincorporated village of
Crystal Spring, in
Brush Creek Township. The freeway continues through a valley of farmland and comes to an eastbound rest area on the western slope of
Town Hill, which the highway crosses at an oblique angle. In the middle of the mountain crossing, I-70 has another pair of right-in/right-out ramps with the northern terminus of
PA 643, and then descends along the length of its eastern slope into another rural valley. Within this valley, the freeway enters
Union Township, turns generally more southeast and interchanges with the northern terminus of
PA 731, east of the unincorporated village of
Amaranth. Past PA 731, I-70 crosses
Sideling Hill and comes into
Bethel Township. The route heads through forested and mountainous surroundings in the watershed of
Tonoloway Creek, before coming to an interchange with the western end of the highway's concurrency with
US 522 in the unincorporated town of
Warfordsburg. Southbound US 522 merges onto eastbound I-70 and the two routes run concurrent across the
Mason–Dixon line into
Washington County,
Maryland. ==History==