The goal of the Wisconsin Department of Transportation (WisDOT) Structures Inspection Program is to compile accurate inventory and condition data, along with the functional, structural, maintenance, and safety conditions of transportation-related structures in the state in order to provide a safe and economically prudent infrastructure. The information in these records is gathered through thousands of structure inspections conducted at regular intervals. WisDOT is responsible for inspections of all bridges along the state highway system and local governments handle inspections for bridges along the local roadway system. WisDOT and local governments closely follow federal guidelines in their bridge inspection and maintenance procedures.
Along with inspecting and maintaining its own bridges, WisDOT works closely with counties, cities, villages and towns to rehabilitate and replace aging bridges. For example, WisDOT oversees the
Local Bridge Improvement Assistance program that helps rehabilitate and replace, on a cost-shared basis, bridges generally found to be in poor condition along the local highway system. A
Lift Bridge Aids program reimburses several Wisconsin cities for costs associated with the maintenance and operation of lift bridges on
connecting highways (local streets/roads marked as state highways). Each year, WisDOT returns a portion of all state-collected transportation revenues to local governments in the form of General Transportation Aids (GTA) to help municipalities build and maintain local roads and bridges.
- WisDOT generally defines a bridge as - any structure spanning more than 20 feet carrying motor vehicle traffic.
- Wisconsin has more than 14,000 bridges statewide.
- More than 5,000 bridges are along the state highway system (numbered state and federal highways) and are the responsibility of WisDOT.
- Nearly 9,000 bridges are located along local roadway systems (county, city, village, and town roads and streets) and are the responsibility of local governments.
- The state highway system carries about 60% of the state’s overall traffic load.
- The overall number of bridges can fluctuate from year to year as new bridges are added to the system as part of construction projects, while some older bridges may be permanently removed.
Inspections
All of Wisconsin’s bridges are inspected at intervals of 12 to 48 months based on their condition, more commonly every two years and more frequently depending on a bridge’s age, traffic load and any known deficiencies or load restrictions. Inspection dates and reports for all Wisconsin bridges can be found on the
Structures portion of the WisDOT website.
Bridge inspectors use a 'reach all' to inspect the two bridges above.
There are several different types of bridge inspections from routine to in-depth depending on a bridge’s individual characteristics and needs. WisDOT’s trained bridge inspectors follow Federal Highway Administration (FHWA) standards and guidelines. Some smaller bridges can be inspected on foot, while others require use of a special "reach-all" vehicle with a jointed arm and bucket that provides inspectors an up-close look at the underside of a bridge. Depending on the size of a bridge, weather conditions and other factors, a bridge inspection can take under an hour to more than a week. During bridge inspections, certified inspectors inspect:
- the superstructure or beams that support the deck looking for cracks, rust, or any problems with bolts or rivets.
- the substructure units (support the superstructure).
- bridge approaches and the deck or surface of the bridge.
- on bridges over large bodies of water, inspections require underwater divers to inspect substructure units where water is too deep to wade.
WisDOT uses the data from inspection reports and other factors to help prioritize bridge improvements. Each year, all states including Wisconsin are required to submit a report to the FHWA that reviews the condition of its bridges.