Ralph Modjeski (and later the consulting firm Modjeski, Masters, and Chase) was awarded the study and design of a new bridge across the Mississippi River for the Public Belt Railroad Commission. Some pilings were actually driven that year to prevent expiration of congressional authority and provide further information for the design. As the magnitude of the project became apparent and projected costs escalated, financing difficulties compounded by the Great Depression delayed the project.
After much legal maneuvering between various Federal, State, and Local project stakeholders and the Public Belt Railroad Commission, an agreement was reached to set construction in motion. The original bridge design was ultimately altered to accommodate 2 18-foot roadways and 135 feet of vertical clearance above the Mississippi River.
Shown here (from right to left) are Governor Huey Long, (standing in the background) Ralph Modjeski and Frank Masters.
Due to the difficulty in determining adequate foundation designs in the "gumbo" clay of the lower Mississippi, Daniel Moran (foundations expert) and Karl Terzaghi (soil mechanics expert) were brought in early in the design process further develop the proper foundations . Construction work started on the bridge substructure in February 1933. Work on this portion of the project would be finished in November 1934 with the completion of Pier IV in the Mississippi River.
Special high strength steels were developed specifically for this bridge. This is also one of the first bridges to use perforated cover plates on main box members rather than lacing bars - partially driven by a desire to reduce maintenance/surface areas for painting.
With construction completed on the substructure, construction of the main span superstructure started in February 1934. Superstructure construction on the East and West approach structures would be completed during the same year.
Work on the main span superstructure was completed in November 1935 with the final paving of the roadway and rail installation.
Huey P. Long Bridge opens to traffic on December 16th, 1935. The bridge was dedicated to the memory of Governor Huey P. Long whom had recently passed away and was instrumental in getting the bridge built.
In November 1986, the LADOTD authorized Modjeski and Masters to perform conceptual studies to widen the original Huey P. Long Bridge. Widening the original bridge would increase its traffic capacity and improve motorist safety by providing additional lanes, wider lanes, and outside shoulders. Furthermore, by widening the original structure rather than constructing a new river crossing, environmental impacts, property takings, and project costs would be greatly reduced because the widening option would remain within the existing bridge right-of-way and traffic corridors.
The report for the conceptual widening study was published in April 1988 and it recommended widening the bridge roadways to 40 feet using the parallel truss widening method.
The first task was to perform a preliminary design of the main bridge widening and establish the design criteria that would be used for the widened structure. The proposed design was unique in that it consisted of a multi-plane truss in a combined railroad and highway structure.
A fatigue evaluation of the original bridge was the second task performed during this time period. The study investigated the remaining fatigue life of the various structural components of the bridge. The results of the study showed that many of the components of the highway floor system had a low remaining fatigue life; however, these components would either be removed from the bridge as a result of the widening or would have the loads lowered or reversed, such as in the case of the floorbeam bracket that would remain part of the permanent floorbeam. Main truss members and floorbeam hangers, which support both highway and railroad loads, had an estimated remaining safe fatigue life in excess of 100 years in most cases, which made the widening of the bridge feasible.
The majority of the final design work for the project was performed between 2000 and 2007. During this period, the Environmental Assessment document was prepared and submitted to the U.S. Coast Guard. Final contract plans and specifications were prepared separately for the main bridge widening, the approaches, and the modifications to the railroad towers on the east and west bank sides of the river. During this time, the final alignment for the approaches was further refined.
Construction commenced in the spring of 2006. The entire widening project was performed under four construction contracts for the main bridge superstructure widening; main bridge substructure widening; approaches and main deck widening; and railroad modifications.
The main bridge superstructure widening was completed and accepted in October 2011. After the final bolting, the original and widening trusses became one integrated structure. Final work to finish the approach structures, tie in the existing road network, and demolish the old approach structures would continue.
The Huey P. Long Bridge was recognized as a Historic Civil Engineering Landmark by the American Society of Civil Engineers at a dedication ceremony on the East Bank. The landmark designation was marked by a dedication plaque, which was formally unveiled at the on-site ceremony on Friday, September 28th, 2012.
On June 16, 2013, this $1.2 billion widening project was completed and opened to motorists. In total, this massive project is arguably the largest rehabilitation project in North America.
Modjeski and Masters has performed the bridge's 83rd continuous bridge inspection since the bridges opening.