Marine Parkway-Gil Hodges Memorial Bridge
This vertical lift bridge, opened in 1937, spans across the Rockaway Inlet to Jamaica Bay connecting the Boroughs of Queens and Brooklyn. The bridge has a total length of 4022 feet with a vertical lift section which is 150 feet long. In the raised position it provides a clearance of up to 57 feet. In 2006, 7.8 million passed over the bridge. The vertical lift was raised 157 times in 2006 to allow vessels to pass through the Rockaway Inlet.
Maintaining lifting capability is critical due to the presence of the U.S Coast Guard Station and a Sanitation facility in Jamaica Bay as well as access to JFK Airport and other critical infrastructure. To preserve functionality the MTA requested our team, led by HDR, to protect the pulley cable sockets that anchor the lift cables to the lifting girder. The client’s vision and approach was to provide a steel box around the sockets to provide protection from tampering, fire and potentially explosive attack modalities. Notably, this bridge served as the primary route for emergency services during Superstorm Sandy to access Breezy Point which sustained major fire damage as a result of the storm. Operability is a requirement of the U.S. Coast Guard for access to Jamaica Bay. Vessels pass under the bridge to access JFK Airport as well as a NYC sanitation plant.
Hinman used the Fire Loading and Mitigation Evaluator (FLaME), developed in-house for structural fire modeling.
Hinman used the Fire Loading and Mitigation Evaluator (FLaME), developed in-house for structural fire modeling. FLaME models the direct radiation from a hydrocarbon fire to the structural steel elements, as well as:
- Re-radiation from the inside of the steel cover to the cables and cable sockets
- Conduction from the steel cover, through the connections to the cable sockets
- Convection inside the steel cover heating up the cables and cable sockets
Critical temperatures for the cables and cable sockets were evaluated based on the auto-ignition temperature of the lubricant. Hinman showed that, in a severe vehicle fire, the steel covers added 5-25 minutes of fire resistance to the lifting mechanism. Once the steel covers were shown to increase fire resistance of the lifting mechanism, Hinman collaborated with HDR’s mechanical and structural engineers to create a constructible method to install the covers. The final design met all the functional needs of the MTA, including:
- Extent of covers governed by conflicts to existing structure
- Swinging doors on span side of girder for accessibility
- Removable hatches on tower side of girder for accessibility
- Open sides and ventilation holes to allow for air movement
- Holes at the bottom to allow for water drainage
- Reduced steel thickness with intumescent paint to reduce weight
- Wire mesh covering large openings to prevent bird nesting