We like to keep our eye on bridges here at TN. Especially new bridges and new techniques for building them. That could be anything from new ways to finance megaprojects, the politics behind tolling, or engineering feats like floating a bridge down a river and hoisting it in place.
Building a bridge offsite and transporting it to it's final location saves money when it is possible. Similar construction techniques are credited with completing the Lake Champlain, NY bridge ahead of schedule (see video.) This weekend we got word of a mini-milestone in that trend.
On Saturday, Chicago says the city in partnership with the state and several railways, installed the largest truss bridge ever built off site and moved into place fully assembled. A truss bridge is what most people think of as the classic railroad bridge, it looks like a steel cage over the roadway forming box or triangle shapes on the sides for support.
Here are a few shots courtesy of the Chicago Department of Transportation, and the press release with background on the project below.
400-FOOT RAILROAD BRIDGE ROLLED INTO PLACE ACROSS TORRENCE AVENUE
Believed to be Largest Truss Bridge Ever Moved into Place after Assembly
A nearly 400-foot-long, 4.3-million-pound railroad truss bridge was rolled into place
A nearly 400-foot-long, 4.3-million-pound railroad truss bridge was rolled into place over Torrence Avenue near 130th Street today, and is believed to be the largest truss bridge ever to be moved into the place after being assembled off site.
The new bridge for the Chicago South Shore and South Bend commuter rail line is a key project in the $101 million reconfiguration and grade separation of the intersection of 130th Street and Torrence Avenue, which part of Mayor Rahm Emanuel’s Building a New Chicago infrastructure program.
It is also a part of the CREATE project – a partnership between U.S. Department of Transportation, the State of Illinois, City of Chicago, Metra, Amtrak, and the nation's freight railroads – to invest billions in critically needed improvements to increase the efficiency of the region's passenger and freight rail infrastructure.
“The moving of this new truss bridge is an incredible feat of construction and engineering,” said Chicago Department of Transportation (CDOT) Commissioner Gabe Klein. “It also demonstrates the strength of the CREATE partnership between government, the railroads and other stakeholders to bring complicated projects like these to fruition to improve the quality of life for Chicago-area communities.”
The goal of the 130th and Torrence grade separation project is to eliminate the two at-grade crossings of the Norfolk Southern tracks with the two roadways to improve the traffic flow of all modes of transport at this complicated intersection.
The project will include the lowering of both roads to fit under the new bridges to be built for the Norfolk Southern freight tracks. The new truss bridge, put in place today, goes overthe freight tracks. The entire intersection reconstruction project includes: six new bridges (railroad, roadway, and pedestrian/bicyclists bridges); a mixed-use path for pedestrians and bicyclists; retaining walls; drainage system; street lighting; traffic signals; roadway pavement and extensive landscaping.
Today, the project General Contractor, Walsh Construction, used four Self-Propelled Mobile Transporters (SPMTs) to relocate the fully assembled 4.3 million pound, 394-foot-long, 67- foot-high truss bridge from its assembly site to its final position on the new bridge piers a few hundred feet away. It is believed to be the largest truss bridge ever assembled then moved.
A truss bridge is one whose load-bearing superstructure is composed of a truss, which is a structure of connected elements forming triangular units.