County Route 1 Bridge over the Moose River

The Town of Webb, located in the Adirondacks in upstate New York, faced a challenge with a deteriorating bridge carrying traffic on county Route 1 over the north branch of the Moose River. The existing bridge was constructed in 1935 and was showing serious corrosion. Additionally, existing lane widths across the bridge were less than standard and the bridge rail was not up to current crash test design levels. If left unattended, the structure would quickly become hazardous to all motorists, so the project needed immediate attention. Herkimer County hired C&S to replace this critical portion of the road network in that region. Because the bridge was located in a remote Adirondacks location, no optional detour routes were available to support traffic if the bridge were closed. This meant that through traffic had to be maintained during the entire construction project, so a temporary one-way traffic signal had to be erected on site. This project faced a very compressed time frame. To accommodate seasonal fluctuations in traffic, the project needed to commence in June and finish no later than October—before the heavy snows set in.

Not only was the time frame very short, but the bridge needed to be constructed within strict parameters dictated by the Adirondack Park Agency (APA). To receive an APA permit, the design of the bridge had to mimic that of a “wild and scenic river.” In order for the structure to have a natural appearance, it needed to match the surrounding materials in the stream bed and bank. However, the sediments and rock from the existing bed and bank could not be used. Instead, the team came up with an innovative solution using boulders found during excavation in front of poured concrete walls, hiding the man-made components and leaving a natural, rustic exterior.

The new bottom of footing elevation had to be a minimum of four feet below the existing base of the streambed for increased scour protection. Because the existing soil was extremely dense, driving new piles was not an option, so spread footings were constructed. Because it was difficult to keep groundwater out of the excavation for the new footings, the team had to use a tremie pour, which is a method of underwater concrete pouring.

The new bridge is wider by approximately 15 feet, which enabled staged construction and permanently provides additional width for pedestrians and recreational vehicles—an important need in this popular tourist area. The replacement bridge better serves the needs of the community and all road users. The asphalt concrete roadway approaches were also reconstructed to match the new bridge.

This project received the Central New York Branch of the American Public Works Association’s 2010 Transportation Project of the Year award for projects less than $10 million.