The Lafayette Bascule Bridge

The Lafayette Bascule Bridge over the east channel of the Saginaw River, built in 1938, is the southernmost of four local street crossings of the river in Bay City, Michigan. Spanning 451 feet in an east/west direction on M-13/M-84, the bridge opens about 500 times annually for vessels and accommodates over 22,000 vehicles daily. Major rehabilitation in 1989 included replacing the rolling-lift bascule span superstructure, redecking approach spans, rehabilitating piers and abutments, replacing machinery and electrical equipment, installing new timber dolphins, and implementing scour countermeasures. Persistent problems with the bascule girder tread plates and tracks necessitated a 2012 detailed inspection, leading to a 2014 feasibility study that recommended replacement over rehabilitation. In 2016, Spicer Group joined the project team to design the bridge's complete replacement.

Spicer Group's responsibilities included developing plans and specifications for road and bridge approaches, pavement markings, permanent signing, municipal utilities, landscape architecture, and a construction cost estimate. The project encompassed a topographic survey for road, structure, hydraulics, and right-of-way, along with coordination with local government agencies. Special project elements provided by Spicer Group involved survey, roadway design, landscape architecture, bridge signal, hydraulics, and utility coordination services. The new bridge features enhanced bicycle and pedestrian facilities, a shared-use path under the east bridge approach for better crossing of M-13/M-84, improved safety and operational features at intersections, and mitigation of environmental impacts. A water quality basin was designed to improve stormwater runoff before it enters the river, and a new parking lot for bridge maintenance staff was created on the north side of M-13/M-84. MDOT identified poor subgrade soils under the road approaches and recommended a pavement design with lightweight backfill encapsulated by a geotextile separator, layers of sand subbase separated by biaxial geogrid, another geotextile separator, an aggregate base layer, and HMA surfacing.