Lake Champlain (Crown Point) Bridge | Crown Point, N.Y.

Emergency replacement completed in 2011

The new Lake Champlain Bridge (also known as the Crown Point Bridge) is composed of a total of eight spans with one network tied-arch signature span. The $76 million emergency replacement structure crosses a narrow spot in Lake Champlain, reconnecting the towns of Crown Point, N.Y., and Chimney Point, Vt. It was completed slightly more than two years after the former Lake Champlain Bridge concerns about the integrity of its piers forced its sudden closure. On October 16, 2009, the original bridge was closed as an underwater inspection indicated significant deterioration of the bridge's foundations. 

The fabrication and construction time considerations involved in replacing a critical piece of infrastructure made structural steel the ideal material for the new Lake Champlain bridge. Steel facilitated the fast-tracked project schedule and removed the potential weather-related delays that could have had an impact on cast-in-place concrete alternatives. In fact, construction of the approach steel superstructure took place throughout the winter months. The team was able to conduct fabrication and construction activities associated with the approach spans and the network tied-arch simultaneously, all in an effort to reduce the amount of time the crossing was out of service. Steel got the local community back on the road faster than other materials would have.

The total bridge length is 2,200 ft, with seven approach spans, measuring up to 250 ft each, connected by a 402-ft-long steel arch span anchored by two 40-ft-deep rigid frame delta-leg girder assemblies. The project used 4,021 tons of metalized steel.

The use of multi-girder delta frames offers a unique and highly redundant way in which to support the arch. Additionally, heavy lateral bracing connects all five girder lines, and a continuous transverse box beam connects the top of the delta frames. This arrangement provides for redundancy such that the system can tolerate the loss of any one of the delta frames through redistribution of load. The system of inclined hangers also offers redundant load paths in the case of tie girder damage (click here to learn more). And the precast deck slabs also were designed to span the extra length in the unlikely event of a floorbeam failure, so that all fracture-critical elements were eliminated.

The structural steel is readily accessible both for inspection and future maintenance. The tie girder is a bolted box with inspection access from the inside, and the arch and all approach girders are I-sections. The height of the arch rib above the deck was limited to allow for inspection access via man-lift.

Barges floated the center arch span, assembled on the shore of Lake Champlain, two miles to the awaiting approach spans, and the center arch span was then lifted 75 ft into place. This allowed for construction of the approaches and construction of the center arch span to take place at the same time, reducing the overall length of construction. Watch a time-lapse video of the process below. 

Find more details about the rapid replacement of the Lake Champlain Bridge in Modern Steel Construction.

You can also learn more from the 2012 World Bridge Symposium session that detailed the design and construction of the new Lake Champlain Bridge.