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February 17. 2013 6:38PM

Engineers Week: Waterville Valley pedestrian bridges?serve again after redesign by CMA

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WATERVILLE VALLEY - Since 2009, CMA Engineers, under a multi-year, multidisciplinary engineering services contract with the town of Waterville Valley, designed two new pedestrian bridges and upgraded a third bridge for the town.

CMA Engineers designed a pedestrian walkway along the downstream side of the vehicular bridge that carries West Branch Road over the Mad River. The bridge spans 65 feet and was widened by adding a timber walkway to provide safe off-road, year-round pedestrian access across the river. The project site was severely flooded during the 2011 construction season by storm surge from Tropical Storm Irene, which washed out the westerly roadway approach. In addition to pedestrian improvements, CMA Engineers provided scour countermeasure design and deck repair designs so the bridge could be quickly repaired while the roadway approaches were simultaneously stabilized, minimizing overall down-time of the road.

Additionally, a causeway bridge with a total length of 140 feet was added along West Branch Road to provide safer pedestrian connection between the residential area adjacent to the Waterville Valley Academy and the new timber walkway over the Mad River. The two walkways provide safer public access to the recreational trail system that converges at West Branch Road adjacent to the river.

CMA Engineers also provided design and construction phase services in 2012 to FEMA-funded replacement of the pedestrian bridge that carries the Inner Mad River Recreational Trail over the Mad River, which is also part of the cross-country ski trail network. The original 100-foot-long single span bridge, which was installed in the early 1980s was lifted off its bearings by storm surge from Tropical Storm Irene and deposited approximately 1,200 feet downstream.

CMA Engineers assisted the town with plans to extract the original bridge from the Mad River and evaluation of the damaged structure for possible reuse. Although some sections were intact, the original bridge was not suitable for safe re-use for a 100-foot span. The new bridge, opened for the 2012 ski-season, is a 110-foot long single span truss bridge that connects the Village of Waterville Valley to more than 60 kilometers of recreational trails in the White Mountain National Forest.