I-280 Mississippi River Bridge Rehabilitation

Our team provided Phase I and II engineering services for the Interstate 280 bridge crossing the Mississippi River in the Quad Cities.

The tied arch bridge is a 28-span 4,193-foot structure that carries four lanes of traffic with a median barrier over a navigable portion of the Mississippi River.

Phase I included bridge inspections to evaluate rehabilitation needs of the substructure and superstructure. As we compared the bridge and approach pavements to the design criteria, we identified numerous substandard elements that could be upgraded instead of requesting a design exception from the Federal Highway Administration (FHWA). Our team prepared a project report that included several technical memos summarizing the evaluation for use by the Illinois Department of Transportation (IDOT) to justify design exceptions.

An extensive traffic management analysis was completed to compare the costs and impacts of a bridge closure vs. multi-phased staging of construction and traffic. In a crash analysis, we identified a significant number of poor weather crashes that may have been caused by a substandard cross slope. Based on these findings, the cross slope of the bridge was upgraded to meet current standards and improve safety.

Phase II included additional bridge inspections and an accelerated schedule to meet the desired letting date for the project. The substructure, superstructure and deck replacement improvements identified during Phase I were detailed for the preparation of contract documents. The tied arch was modelled with STAADPro software to confirm that the arch members were not overstressed due to unbalanced loads during the proposed construction staging and deck-pouring sequences. Other improvements included median crossovers to accommodate the construction staging, guardrail and median barrier improvements, and a new navigable lighting system. The design was completed in less than eight months to meet the letting schedule. The contract documents included the plans, specifications and a cost estimate, with construction support including shop drawing review and addressing RFIs.


Illinois Department of Transportation


Milan, Illinois





Traffic Engineering


Government, Military & Municipal