EGR Floating Bridge Approach Passes Two-Year Evaluation
December 20, 2017
Reeds Lake Boulevard in East Grand Rapids passes over a small channel connecting Reeds Lake and Fisk Lake. The large culvert carrying flow between the lakes had been slowly sinking, but repair crews kept the road surface from dipping by adding asphalt layers periodically.
In 2014, the City of East Grand Rapids decided it was time for a new structure due to unfavorable soil below the culvert. An adjacent walking bridge over the channel was also sinking and deteriorating, so the City used this opportunity to replace it with a parallel boardwalk over the channel and complete the non-motorized trail loop around Reeds Lake.
Prein&Newhof was hired by the City to do a hydraulic study and lead the team of specialists to design the new culvert and pile foundation. P&N was also hired at this point to finish the design for the boardwalk’s pile foundation and administer the MDOT-funded construction contract.
The City chose a 18-ft.-wide by 4-ft.-tall precast concrete culvert to replace its aging 108-in.-wide corrugated steel pipe culvert. The new bridge and boardwalk are supported on 34 pilings, some as deep as 90-ft. to ensure stability. The pile-supported bridge and boardwalk are designed to remain in place, but the road approaches to the bridge are susceptible to sinking just like the old road. To minimize sinking, P&N designed a reinforced, lightweight soil for the approaches. The lightweight soil was designed to ‘float’ above the poor underlying soil, while the soil reinforcement holds it together and helps it resist sinking or moving. Contractors finished the work at the end of 2015.
P&N inspected the project in late November of 2017 – two full years after the new Reeds Lake Boulevard bridge re-opened to traffic. Happily, no evidence was found of settlement or pavement cracking. Evidence of movement usually appears within the first two years, so while it’s still early, the long-term outlook for the floating bridge approach remains optimistic.