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The LimeKiln Bridge connects the town of Colchester and South Burlington in Northern Vermont. The historic structure crosses the Winooski River and the New England Central Railroad. The roadway itself is located between two abandoned quarries. The state of Vermont wanted to replace the 1913 concrete arch bridge with one of similar architecture.
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Because of the historic nature of the existing bridges, a high level of collaboration was required to conquer an array of project challenges like obtaining permits, preservation issues, navigating the difficult terrain of the Winooski Gorge and maintaining access to Vermont’s largest airport and St. Michael’s College. Partners in this project included the communities of Colchester and South Burlington, Vermont Agency of Transportation, Vanasse Hangen Brustlin, Inc, the bridge designer and Kubricky Construction.
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The existing bridge was squeezed between two cavernous rock quarries filled with water, and located over a deep rocky gorge and the New England Central Railroad.
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Since the bridge served as an indispensable traffic link, construction had to be completed on a very tight 14-month schedule, with crews maintaining vehicular, rail and pedestrian access the entire time.
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Work began in August, 2005. Crews relocated multiple utilities and placed approximately 12,000 CY of fill to create the northern approach to the bridge. During the winter, the arch foundations were constructed in “rock sockets” and 250 CY of rock was excavated from the steep slopes of the gorge.
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The entire substructure is cast in place concrete, including the 122 foot arches that span the gorge 80 feet above water level. The superstructure is precast beams with a cast-in-place riding surface.
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Instead of the cast-in-place concrete used for the deck in 1913, pre-stressed concrete slabs were used. This allowed a design that simulated the original bridge’s decorative geometrical features and modernized it to include wider sidewalks, a safer travel way, ornamental railings, street lighting, and architecturally treated abutments and retaining walls. The bridge’s surface was outfitted with de-icing membranes to prevent the kind of deterioration that plagued the original structure.
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The new concrete arch bridge was built as close as 5 feet to the old structure.
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Vehicular traffic was maintained for all but two weeks in order to relocate storm sewer, install sidewalks and pave the roadway.
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Awards included: first runner-up in 2006 Roads and Bridges Magazine; project of the year (2007) from the Assocaition for Consulting Engineering companies and featured in the February, 2007 issue of Enigineering News Record.
