Bridge Information

With 25,000 state owned bridges, Pennsylvania has the third-largest number of bridges in the nation, but we lead the nation in the number of bridges classified as “structurally deficient.” The average age of bridges on the state system is over 50 years old.

Being rated structurally deficient does not mean that a bridge is unsafe; rather it means that it has deterioration to one or more of its major components. Although deterioration is present, a structurally deficient bridge is safe. Safety is our number one priority and if a bridge is found to be unsafe, it's closed. If a bridge can only carry certain loads, it's restricted.

Approximate Vehicle Weights

Risk-Based Weight Restrictions

To preserve bridge safety, PennDOT, along with local bridge owners are in the process of adding new weight restrictions or lowering existing weight restrictions on approximately 1,000 bridges statewide.

A full list of bridges that will receive new restrictions or have their current weight limits lowered can be seen here.

Secretary Schoch's presentation on bridge postings.


Bridges are designed to carry loads above the weights of fully loaded tractor trailers (80,000) pounds - bridge engineers call this ability to carry weights in excess of 80,000 pounds, a factor of safety. The American Association of State Highway Transportation Officials (AASHTO) has bridge weight-limit postiing criteria ranging anywhere between where that factor of safety starts to decline all the way down to where the has lost about half of its factor of safety.

Bridges that have lost half of their factors of safety are still safe and can remain open with no posting however, their deterioration will be accelerated. Without additional revenues, PennDOT will be forced to curtail bridge repairs meaning bridges that were not posted because they were scheduled for repairs would now be added to the posted list since the money is no longer available to restore them back to that acceptable factor of safety.

Information for Emergency Services

PennDOT has not changed its permit process. Permits may be obtained for emergency vehicles with a gross vehicular weight in excess of the bridge posting limits. These permits should be obtained for posted bridges within your normal response area as well as response areas your company assists. Completed M-4902 application forms (see link below) should be sent to the applicable contact person from the PennDOT District Bridge Emergency Services Contact List (see link below). No fee is charged to emergency services for the permits. Approval of each permit is conditional, based upon bridge analysis.

Form M-4902 – Application/Permit to Exceed Posted Weight or Size Limit

PennDOT District Bridge Emergency Services Contact List

Inspection Facts

PennDOT has an aggressive bridge inspection program that regularly inspects all of Pennsylvania’s bridges at least once every two years. Structurally deficient bridges are inspected more frequently if their condition warrants. We do not hesitate to impose weight restrictions and close bridges if deterioration causes safety concerns.

  • PennDOT Bridge Safety Inspection FAQ'S

  • PennDOT Bridge Inspection Terminology

    At the peak, PennDOT had 6,034 SD bridges. To reach the national average of SD bridges, PennDOT needs to reduce the number of SD bridges to approximately 2,700 – this would equate to nearly 400 bridges each year for the next 21 years.

    Bridge Preservation Program

    PennDOT is committed to keeping non-SD bridges in good repair through bridge preservation activities, including painting, deck joint repair or replacement, rigid deck overlays, etc. In the long run, preservation saves money by extending bridge service life, thus deferring the need for major rehabilitation of bridges. In the past five years, PennDOT has invested approximately $670 million to preserve more than 2,200 bridges.

  • 25,000 bridges State Routes - Sufficiency/condition ratings

  • 6,400 bridges on Locally owned roads - Sufficiency/condition ratings