- Merchants Bridge Replacement
Our team is providing design and environmental services for the Merchants Bridge over the Mississippi River. The bridge carries five Class I railroads. The double-track structure, built in 1889, has three main truss spans of 520 feet each that need to be replaced. In addition, the unreinforced masonry piers have been significantly scoured and do not provide AREMA-level seismic resistance.
During the 30% design phase, the project team studied several scenarios: open deck and ballasted deck options, E80 and E90 live loading, various truss panel configurations, truss float-in scenarios, seismic resistance of existing foundations, seismic retrofit schemes, seismic isolation bearings and barge vessel collision analysis.
Final design of the three new 520-foot truss spans will include strengthening of the existing masonry foundations to withstand seismic and barge collision events, as well as a combination of float-in, lifting spans with strand-jacks, and lateral slide-into-place.
We are also providing environmental documentation services, including coordination with such agencies as:
- U.S. Coast Guard
- U.S. Army Corps of Engineers
- U.S. Fish & Wildlife Service
- State historic preservation offices
- Missouri Department of Natural Resources
- Illinois Department of Natural Resources
- Alternate span layouts
- Constructability studies
- Cost estimates
- Foundation improvement analysis
- Main truss span design
- National Environmental Policy Act (NEPA) agency coordination
- Seismic analysis
- Structure type studies
- Truss float-in scenarios