Modjeski and Masters was selected to lead the Henry G. Gilmerton Bridge Replacement Project by the Virginia Department of Transportation. Shown here is a copy of the Preliminary Conceptual Study prepared by Modjeski and Masters and major subconsultant Gannett Fleming which detailed replacement alternatives.
In 2001, Modjeski and Masters went to work on design plans for the selected Vertical-Lift Bridge alternative. The new bridge would be 250-feet long and 89-feet wide which would make it one of the widest lift spans ever designed. The bridge was designed to be constructed over-top of the existing bascule span so that traffic would be minimally interrupted.
After completion of all design work on the new bridge, construction starts on the new Gilmerton Bridge substructure in November 2009. Shown here is construction progress on the approach structure (designed by Gannett Fleming) and new piers for the vertical-lift bridge (designed by Modjeski and Masters). Due to the exceptional width, four 15-foot diameter sheaves were needed on each tower. Eight 12-foot diameter drilled shafts were designed to reach 120 feet below ground and are some of the largest ever constructed using the oscillating method.
With only 25 feet between the Gilmerton Bridge and an adjacent railroad bridge, seismic instruments were used to monitor potential settlement of the railroad bridge foundations during installation of the new drilled shafts.
With construction of the vertical-lift superstructure significantly completed, the float-in operation of the main lift span could begin. On January 7, 2013, the main span was successfully floated in place and connected by the project contractor, PCL. Construction of the approach spans would continue for several more months.
On January 14, 2014, the new Henry G. Gilmerton Bridge was completed. The new bridge successfully met the need for increased traffic capacity while not interrupting traffic flow throughout construction.
The Gilmerton Bridge Replacement Project receives numerous awards including the ACEC Virginia "Grand Award", the Virginia Transportation Construction Alliance "Transportation Engineering Award" and the ABCD Susquehanna Chapter "Outstanding New Long Span Bridge".