Merrimac Bridge Rehabilitation Project

​​​​​The Merrimac Bridge is a railroad structure over Lake Wisconsin, a reservoir of the Wisconsin River, in south central Wisconsin along the Reedsburg Subdivision. The Reedsburg Subdivision is owned by WisDOT and the Wisconsin River Rail Transit Commission (WRRTC) and operated by Wisconsin & Southern Railroad, LLC (WSOR) through an operating agreement with WRRTC. WSOR provides freight railroad service to rural communities in Sauk County, including Reedsburg, Rock Springs, and Baraboo, Wisconsin. The current bridge super structure was constructed in 1895 with select portions of the superstructure rehabilitated in 1903 and 1930, and older portions of the stone substructure remain as originally constructed in the 1870s.

Map of Project Area


The Reedsburg Subdivision has seen considerable freight rail growth since 2009. It serves 13 companies in Sauk County, including bulk material hauling, plastics, lumber and building materials, refrigerated food products, and agricultural products such as feed, grain and energy products. In 2017–2019, the average rail cars shipped and received annually was 3,194.

Due to the deterioration of the bridge and the resulting weight limitations and speed restrictions, WisDOT and WSOR completed multiple​ studies to determinate restoration options for the bridge in 2016. WisDOT and WSOR subsequently determined they would proceed with rehabilitation of the bridge in three phases.

  • Phase 1 of the Merrimac Bridge Rehabilitation and Span Replacement Project was completed in 2018 and included emergency repairs on one span to improve immediate structural requirements and design engineering for Phase II rehabilitation work.
  • Phase II was completed in May of 2021 and included replacement of the steel components of nine of the bridge spans.
  • Phase III of the project was selected in 2020 for a U.S. DOT Infrastructure for Rebuilding America (INFRA) grant in the amount of $6,750,000. Final design was completed in the summer of 2022.

The Phase III project work plan includes replacement of 13 bridge spans and 1,400 linear feet of bridge deck, repair of five masonry piers, and minor repairs of bearings, pedestals and concrete surfaces. Project work to replace deficient spans is anticipated to be completed by 2024 to prevent requiring the de-rating of maximum loading to 230,000 pounds. Upon completion of the project, the Merrimac Bridge will be able to accommodate 286,000 pound railcars at 25 miles per hour (mph) and continue to provide an economic link to the rural areas in Sauk County, Wisconsin that rely on the Reedsburg Subdivision for access to the national freight railroad system.

The project was let in July 2022. Michels Construction was awarded the contract to construct the Phase III improvements in October 2022 and began mobilization and work on the causeway in February 2023.

Rehabilitation Timeline


  • Bridge is rated at 268,000-lb. carload capacity.
  • April - WisDOT issues report on condition of the underwater components of the bridge.
  • December - WisDOT acquires the Reedsburg Subdivision from Union Pacific Railroad.


  • July - WisDOT approves plan for restoration of the bridge to attain 40 years of service with 286,000 pound carload capacity at 25 mph.
  • September - WisDOT awards state Freight Railroad Preservation Program (FRPP) grant funding to WSOR to rehabilitate the bridge (Phases I - III).


  • August - Phase 1 begins: WSOR begins engineering design work.


  • February - WSOR contractor 80 Plus Constructors begins emergency repair work.
  • March - Phase 1 emergency repair work completed.


  • February - Phase II engineering design work begins.
  • August - Phase III span replacement project is awarded $6,750,000 INFRA grant by US DOT.​​
  • September - FRA approves the 30% design plan for Phase III​.


  • February - FRA signs the project Categorical Exclusion Checklist, providing environmental clearance for the project.
  • March - FRA grants WisDOT pre-award authority to begin Phase 3 work on the bridge.
  • May - Phase II component replacement work is completed by contractor Koppers.


  • ​January - FRA and WisDOT execute the INFRA grant agreement.
  • Summer - Phase 3 design work completed.
  • July - Phase III let.
  • November - Michels Construction awarded project as lowest bidder at $21,695,000.


  • Winter/Spring - Phase III construction begins.
  • Replace spans 1, 4–13.


  • Replace spans 17 and 18; substructure rehabilitation.


  • Timber component replacement; replace rails, construct walkway, handrails.

Project Phases and Funding

​​Project P​ha​se

​​Start Date

​​Total Cost​

​Funding Contributions​

​WisDOT ​WSOR ​​WRRTC ​Sauk County
​Phase I: Emergency Repairs & Design​Fall 2017​$394,575​$315,660​$78,915
​Phase II: Component Replacement & Phase III Design​October 2018​$2,994,796​$2,395,837​$598,959
​Phase III: Bridge Span Replacements and Pier Repair​Winter 2023​$22,169,000*​$10,985,220​$2,703,310​$865,245​$865,245
​Totals ​​$25,558,371 ​$13,696,697 ​$3,381,184 ​$865,245 ​$865,245

*​Note: Phase 3 funding includes a $6,750,000 US DOT INFRA grant.​


Rich Kedzior​
​Railroads and Harbors Section, WisDOT​
(608) 266-7094​