Bridge Description

Over US 131 southwest of Kalamazoo in Kalamazoo County

Tier 5 (within 3 months)

ABC: less than three months for original schedule; two-month delay for re-casting panels; Conventional: minimum six months

reduced traffic impacts, improved site constructability

249-ft-long and 55-ft wide, three-lane, four-span bridge (37.5 ft – 83.25 ft – 83.25 ft – 44.75 ft); 67º skew

44000

Traffic management alternative, if constructed conventionally: extended detour on city streets

Built in 1962, the two-lane, four-span steel W-beam bridge needed an additional lane and increased vertical under-clearance over US 131.

During the study phase of the project, precasters and contractors in the state partnered with MDOT. Skewed deck panels were determined to be more economical than rectangular panels, to eliminate the closure pours at abutments or lengthening the bridge to square the abutments. To simplify panel fabrication, grouted transverse deck joints and a longitudinal cast-in-place closure pour to eliminate a crown in the panels were selected.The replacement bridge consists of precast integral abutments on single rows of H-piles, precast caps on precast multi-column piers, seven AASHTO Type III pretensioned beams spaced at 9 ft in each span, and skewed full-depth precast longitudinally post-tensioned deck panels. The precast beams and substructure components were fabricated in Kalamazoo, Michigan while the 48 full-depth deck panels were fabricated at a plant 170 miles from the site in Midland, Michigan.

The 64-ton abutment was precast in two segments to facilitate handling, with a cast-in-place closure pour connecting the segments. The abutments were cast with oversized pockets for the steel H-pile connections. The four 10-ton round precast columns at each interior support were supported on cast-in-place spread footings. The 65-ton pier caps required two cranes for erection. The 19-ton skewed full-depth precast longitudinally post-tensioned deck panels had grouted transverse joints and a closure pour at the crown point. The female-to-female transverse deck joints were grouted with a backer rod sealing the bottom joint; a heat-shrink wrap connected the ducts in blockouts at post-tensioning duct locations. Inserts were cast into the beams at shear pocket locations, with coil bolts threaded into the inserts after panel placement. An aesthetic Michigan bridge railing was cast in place following panel erection.The deck panels were instrumented with a structural health monitoring system that recorded strain and temperature data for one year following completion of the bridge.The project was let through the standard design-bid-build process. The contractor had an expedited schedule with the open to traffic date one month prior to completion.

This project was the first ABC project in the state, and much was learned (see Lessons Learned). MDOT expects that ABC costs will be reduced as fabricators and contractors become more familiar with its use, and as the prefabricated elements are standardized.