Desiard Street Bridge Replacement

Louisiana DOTD needed to take great measures to improve the end user’s experience and safety on the existing narrow bridge. They also wanted to increase the navigational channel clearance on the Ouachita River. This meant replacing the 100-plus-year-old truss swing bridge. At the same time, LADOTD needed a firm that could perform the necessary tasks while minimizing the bridge outage time for construction.

The existing equal arm truss swing bridge provided a navigational channel clearance of 130 feet. To increase channel clearance to 150 feet, Modjeski and Master's (M&M) movable bridge experts designed a new bob-tailed steel girder swing bridge with unequal arms of 112 feet and 185 feet. This meant that construction of a new pivot pier and drilled shaft foundation could take place under the bridge and adjacent to the existing pier, without interrupting traffic. This simple solution reduced bridge outage time for construction by nearly one full year. M&M also proposed an innovative method for accelerating erection of the superstructure. Our design called for floating out the old truss swing on a barge, with the new swing girder bridge floated in immediately afterwards. Construction of the new swing bridge was completed in 2003.