AOM Road/Bridge and Merit Award, Safety: Third Avenue Bridge

Rehabilitation of the Tercera Avinguda bridge (CMGC).

Minneapolis

Merit Awards

Sent by: HNTB Corp.

Owner: Minnesota Department of Transportation

Main design company: HNTB Corp.

General contractor: Ames Construction

An extensive and careful restoration effort has corrected the deteriorating condition of the Tercera Avinguda Bridge and extended its useful life. The downtown Minneapolis bridge was originally designed and built in the early 1900s and will soon be placed on the National Register of Historic Places for its historical and engineering significance.

The scope of work included the repair, strengthening and implementation of a robust corrosion protection scheme to the Melan steel truss arches, which had significant section loss. The river docks had large portions of delaminated and cracked concrete that were restored. Crews also replaced the spikes and concrete deck and renovated the historic ornamental railings.

Foundation repairs required extensive and prolonged dewatering. Construction access to the bridge over the water was severely limited due to the bridge’s proximity to a hydroelectric plant, a historic horseshoe dam, and a permanently closed lock. Three of the seven bays were inaccessible by water, while the remaining four were accessible only by small barges. To remove and replace the structural concrete and perform surface repairs, the team took a top-down approach with the help of an elaborate system of suspended multi-level scaffolding under the bridge. Large sandbags diverted the flow of the river to allow the rehabilitation of two piers, and for four others, the team used pans. Although the tower cranes limited the load on the bridge, they allowed for a downstream access lane and gradual construction.