Statewide Major Bridge Investment Study

Benesch assisted the South Dakota Department of Transportation (SDDOT) in developing an asset management system to use in planning for long-range needs associated with a total of 16 structures classified as major structures. SDDOT chose these bridges because the cost to replace just one of them could be more than the typical cost of all bridge replacement projects in a given year.

Many of the major bridges in South Dakota identified for evaluation were originally constructed in the late 1950s through the 1970s. The importance of these critical structures to South Dakota’s transportation system led to the need for this Major Bridge Investment Study.

The engineering uncertainty for each of the structures was assessed during the initial phases of the project. Criteria such as inspectability, predictability, critical factors, historical evidence, impact to users and frequency of inspection were taken into account. Once engineering uncertainty was identified, SDDOT could implement mitigation actions, such as maintenance, inspection, retrofit or replacement.

Financial risk mitigation took into consideration the timing of maintenance, retrofit and replacement tasks. The cost of bridge replacement was then compared to the savings of future maintenance costs beginning the year it is replaced. Management mitigation related to a decision by SDDOT to adjust the timing of events to match the desired annual program.

With this information in hand, SDDOT is able to base its decision to implement a management risk mitigation strategy on funding availability, cost of replacement and desired cash flow.