I-93 Exit 14 Accelerated Bridge Construction
Bow-Concord, NH | NHDOT
Project received the 2011 ACEC-NH Engineering Excellence Award.
MJ was involved in the initial phase of this project, which studied a range of alternatives for improving safety, enhancing mobility, and adding capacity to I-93 through Bow and Concord, NH. The project included an assessment of widening I-93, reconfiguration/addition of new interchanges, local roadway improvements, multi-modal improvements including commuter rail, macro environmental analysis and traffic demand modeling and analysis. MJ directed a dynamic and comprehensive public participation program that included a Citizen Advisory Committee, project website (www.i93bowconcord.com), project design center, design charettes and large scale public meetings. This project was one of the NHDOT's first to be processed using the Context Sensitive Solutions approach, in which the public and stakeholders are involved from the outset, and the community, environmental, and transportation context and needs are all considered.
Due to uncertainties regarding the implementation of the corridor improvements, the NHDOT identified the need to replace the superstructure of the structurally-deficient, single span I-93 Exit 14 bridge in Concord. The bridge carries Interstate Route 93 over Loudon Road, one of the main arteries serving the state capital.
After evaluating several conventional rehabilitation options, MJ developed an innovative Accelerated Bridge Construction (ABC) solution that allowed each half of the bridge superstructure (one interstate barrel) to be replaced over a single 60-hour weekend closure period. Due to the short construction duration, the work could be scheduled during a period of seasonally low traffic volumes utilizing temporary lane closures. Other conventional options that were initially considered required the construction of a long-term detour roadway and temporary bridge on the interstate, at an additional cost of $1.5 million.
This ABC option utilized full-depth, precast concrete deck panels in combination with high-early strength concrete and longitudinal post-tensioning for long-term durability. Other project enhancements included the development of detailed traffic control plans and an extensive public outreach campaign to minimize impacts to the traveling public and local businesses. We believe strongly in the merits of Accelerated Bridge Construction, and we are pleased to be at the forefront of this emerging design and construction method.