Pennsylvania Route 318

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Pennsylvania Route 318

Route information
Maintained by PennDOT
Length15.916 mi[1] (25.614 km)
Major junctions
West end SR 304 at the Ohio state line near West Middlesex
Major intersections I-376 in West Middlesex
East end PA 158 in Mercer
CountryUnited States
Highway system
PA 317 PA 319

Pennsylvania Route 318 (PA 318) is a 15.9-mile-long (25.6 km) state highway located in Mercer County, Pennsylvania. The western terminus is at the Ohio state line in Shenango Township near West Middlesex where the road continues as Ohio State Route 304. The eastern terminus is at PA 158 in Mercer.

Route description

PA 318 eastbound past PA 718 in Shenango Township

PA 318 begins at the Ohio border in Shenango Township, where the road continues west into that state as SR 304. From the state line, the route heads east on two-lane undivided Hubbard-Middlesex Road, passing through areas of farms and woods with some homes. PA 318 reaches an intersection with PA 718 and continues through more forested areas with residences. The route heads into the borough of West Middlesex and becomes Main Street, crossing the Shenango River into residential and commercial areas. In the center of town, the road crosses PA 18. PA 318 continues past more homes prior to heading back into Shenango Township, where it becomes Mercer West Middlesex Road. The route heads east-northeast through rural areas of residences, reaching an interchange with I-376.[2][3]

Past this interchange, PA 318 continues through areas of farmland and woodland with homes, passing under I-80. The road continues into Lackawannock Township and runs through the communities of Bethel and Greenfield. Upon heading into East Lackawannock Township, the route curves south then east, passing through agricultural areas. PA 318 passes through a mix of fields and forests as it turns northeast onto Pulaski Mercer Road. The road makes a curve east and enters the borough of Mercer, where the name becomes West Butler Street. In Mercer, PA 318 passes homes before reaching its eastern terminus at PA 158.[2][3]


On December 7, 2023, the bridge over I-376 (with a vertical clearance at 14'-2", which is lower than the federal standard of 16'-6") was struck by a tractor trailer resulting in the closure of PA 318 and the eastbound direction of I-376.[4][5] I-376 eastbound was reopened once the bridge there was removed.[6] Construction on the replacement bridge for PA 318, which will have a vertical clearance that meets the federal standard of 16'-6", over I-376 began on April 15, 2024.[7]

Major intersections

The entire route is in Mercer County.

Shenango Township0.0000.000
SR 304 west (East Liberty Street) – Hubbard
Western terminus of PA 318 at Ohio state line
PA 718 north (Seig Hill Road) – Wheatland, Sharon
Southern terminus of PA 718
West Middlesex3.4955.625 PA 18 (Sharon Road)
Shenango Township4.2796.886
I-376 (Beaver Valley Expressway) to I-80 – Hermitage, Sharon
Exit 1C (I-376), originally westbound entrance to / eastbound exit from I-376 only. Became a full interchange in October 2014.[8]
Mercer15.91625.614 PA 158 (South Shenango Street)Eastern terminus of PA 318
1.000 mi = 1.609 km; 1.000 km = 0.621 mi

PA 318 Alternate Truck

Alternate truck plate.svg

PA Route 318 Alternate Truck

LocationMercer County, Pennsylvania

Pennsylvania Route 318 Alternate Truck is a truck route around a weight-restricted bridge over the Little Neshannock Creek on which trucks over 33 tons and combination loads over 39 tons are prohibited. The route follows PA 18, US 62, and PA 158. The route was signed in 2013, but it was decommissioned in 2018 following a bridge repair.[9]


  1. ^ a b "Pennsylvania state roads". Pennsylvania Spatial Data Access. Pennsylvania Department of Transportation. 2013. Retrieved March 14, 2013.
  2. ^ a b Google (May 19, 2011). "overview of Pennsylvania Route 318" (Map). Google Maps. Google. Retrieved May 19, 2011.
  3. ^ a b Mercer County, Pennsylvania Highway Map (PDF) (Map). PennDOT. 2011. Retrieved May 19, 2011.
  4. ^ "PennDOT - District 1 News: Route 318 and Interstate 376 Eastbound Closed in Mercer County". Pennsylvania Department of Transportation. Retrieved April 15, 2024.
  5. ^ "PennDOT - District 1 News: Route 318 Bridge over Interstate 376 Eastbound in Mercer County to be Removed Following Crash". Pennsylvania Department of Transportation. Retrieved April 15, 2024.
  6. ^ "PennDOT - District 1 News: Interstate 376 Eastbound Reopened in Mercer County". Pennsylvania Department of Transportation. Retrieved April 15, 2024.
  7. ^ "PennDOT - District 1 News: Replacement of the Route 318 Bridge in Shenango Township, Mercer County Started Today". Pennsylvania Department of Transportation. Retrieved April 15, 2024.
  8. ^ "Interstate 376, Route 318 Ramp Construction to Begin in Mercer County" (PDF) (Press release). Pennsylvania Department of Transportation District 1. March 5, 2014. Archived from the original (PDF) on March 4, 2016. Retrieved February 25, 2015.
  9. ^ "Risk-Based Bridge Postings - State and Local Bridges" (PDF). Pennsylvania Department of Transportation. October 8, 2013. Retrieved August 17, 2017.

External links