Turkey Hill Road Bridge Rehabilitation over Souhegan River

Merrimack, New Hampshire

Client: Town of Merrimack, New Hampshire


  • Bid Administration
  • Construction Administration
  • Construction Observation
  • Cultural Resources Coordination
  • Design
  • Engineering Study
  • Load Rating Analysis
  • Permitting
  • Temporary Traffic Signal Analysis
  • Traffic Control/Management

Project Summary

The Turkey Hill Road Bridge is located in a suburban area of western Merrimack and provides one of only two connections over the Souhegan River within the Town. This important collector road carries approximately 10,000 vehicles per day and serves as a connection for commuters to F.E. Everett Turnpike at Exit 11. The existing roadway approaches were quite narrow and consisted of two 11 foot travel lanes with 1′ shoulders on either side. This narrow cross section did not allow for pedestrian and bicycle traffic to cross the bridge safely in this largely residential area.

The goal of the project was to rehabilitate the superstructure of the NHDOT Redlisted bridge, due to its deteriorating deck, and make improvements to the roadway approaches and adjacent intersection. Hoyle, Tanner provided roadway and structural engineering services for the study, design, and construction administration of the bridge.

The bridge is located between reverse curves requiring large banking. In order to provide proper superelevation and transitions, the bridge was designed with a reverse crown. Our roadway design involved the reconstruction of 1,500 linear feet of Turkey Hill Road including minor horizontal alignment and profile revisions. The new roadway cross section includes wider lanes, 5′ shoulders and a 5′ sidewalk to improve pedestrian safety. The existing closed drainage system was also upgraded to ensure adequate capture of stormwater and to prevent runoff from crossing the new bridge.

A key component to the project was the traffic control planning for the proposed bridge construction. Being one of few local river crossings, the shortest off-site detour route was five miles in length and was quickly dismissed due to emergency response times and traffic impacts to other town roads.Another investigated alternative was the possibility of utilizing a single lane alternating traffic pattern with a temporary traffic signal; this was also dismissed due to an anticipated poor Level of Service and the potential for large queues which could block adjacent intersections. The ultimate solution that Hoyle, Tanner proposed was a 1,100 linear foot detour roadway with a temporary bridge. Hoyle, Tanner’s context sensitive design limited impacts to the river, Right-of-Way, and remnants of the original timber covered bridge which spanned the river.

Hoyle, Tanner also provided construction administration services and full-time resident engineering allowing the project to be completed on-time and on-budget.

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