Rapid bridge replacement
Rapid bridge replacement or accelerated bridge construction (ABC) is a technique that allows bridges to be replaced with minimum disruption to traffic. The replacement bridge is constructed on a site near the bridge to be replaced. When it is completed, the old bridge is cut away and removed using self-propelled modular transporters (SPMTs). Then the SPMTs lift the new bridge, transfer it to the work site and put it in place. Often the highway or railroad carried by the bridge is closed for just one weekend. Conventional techniques typically replace half a bridge at a time, with all highway traffic crammed into the other bridge half, often for a year or more, while construction progresses.