The project included dismantling the existing Gerald Desmond Bridge, including the 1,053-ft steel truss bridge with a channel crossing of 526-ft span and the approach bridge structures of composite steel plate girders.

JMEC has been structural consultant for the design and preparation of PS&E for the bridge demolition.  Work includes evaluating various dismantling sequences and potential strengthening needed to ensure a safe and stable dismantling operation to meet the Port's and various regulatory agencies requirements.

The dismantling sequence for the 1,053-ft truss bridge was analyzed by using SAP2000 computer program.  This was done by first performing a stage by stage bridge forward erection analysis to determine the forces in the existing bridge, then followed by a stage by stage dismantling analysis taking into account the lock-in forces due to the original bridge construction (obtained from the forward erection analysis).  Member stresses and displacements under various dismantling sequences and loads were checked per AASHTO Manual for Bridge Evaluation, Second Edition, 2011 Edition.

Project Status:   Design was completed in 2020. The main span was successfully dismantled and lowered onto a barge on July 10, 2022.

Special Issues:  Challenges in developing several feasible demolition sequences that minimize the impacts to Port's operations and the new bridge, environment and wild life habitats, Hazmat, the permitting process as needed to obtain an environmental approval; and to ensure overall bridge stability and seismic resistance during various phases of dismantling operations.