Inspections Required for Bridge Owners with NBIS Structures

August 2013 – TWM has recently begun bridge inspections as part of a statewide contract with the Illinois Department of Transportation’s Bureau of Bridges and Structures.  Under this contract, TWM engineers are traveling to various counties around the state to perform load rating inspections and analyses for existing structures for which plans could not be located.  TWM will determine if these bridges are capable of carrying the legal loads or if legal loads must be restricted on these structures.

In July, TWM completed 20 inspections: 6 in Mercer County, 3 in Randolph, 2 each in Cumberland and Montgomery, and 1 each in Bond, Champaign, Clinton, Crawford, Edgar, Hancock and Vermilion Counties.  Our staff conducted 17 more in August, and have now begun to analyze the bridges that have been inspected.

TWM expects additional work orders with projects varying in size, complexity, and timing over the next two years with an option for a renewal contract that will last another two years.  Under the contract, future work orders could include National Bridge Inspection Standards (NBIS) and element level damage inspections, or plan preparation for the repair, rehabilitation, or replacement of structures, drafting services and field investigations.

Under the NBIS, publicly owned bridges greater than 20 feet long that carry highway traffic must be inspected every 24 months. Some lower-risk bridges may be inspected on a 48 month interval.  With five licensed structural engineers and three of those qualified as NBIS Program Managers and Team Leaders, TWM is highly qualified to perform inspections on behalf of the state as well as local agencies.

In addition to TWM’s work on the state contract, our structural engineers serve as NBIS Program Managers and Team Leaders for several local municipalities who own bridges subject to the NBIS requirements.  TWM’s staff provides routine bridge inspections and manages the inspection programs for the municipalities, who don’t have room in their budgets to employ a trained inspector as part of their own staff.  TWM’s structural engineers therefore allow those municipalities to be more cost effective in complying with the NBIS requirements and in assuring that their structures are inspected and safe.

For a short video highlighting the NBIS Inspection requirements, visit the Federal Highway Administration’s web site at