Gearboxes improve safety barrier performance
Last June, the Louisiana Department of Transportation and Development (LDOTD) replaced several inoperable gearboxes on safety barriers that guard the entrance to swing bridges. The new gearboxes, located on bridges in Dulac and Galliano, work with existing equipment to improve efficiency and reduce maintenance of the safety barriers.
Typically, swing bridges are built to allow two navigation channels. Unlimited overhead clearance is created when sections of the bridge move aside, allowing large boats to pass through the channels. When the bridges swing into action, safety barriers are needed to stop traffic from entering the bridge.
Installed in 1971, the gearboxes on the Dulac and Galliano safety barriers had reached the end of their useful lives. The units had corroded because of saltwater exposure, and they required frequent maintenance. When replacement parts could no longer be found, the bridge maintenance department had to make them.
In June, LDOTD replaced the gearboxes with gearboxes provided by Milwaukee-based Rexnord Geared Products. Consisting of a motor and brake, the gearboxes have double-extended output shafts that makes them compatible with the existing bridge gate mechanisms.
The motors have weather protection, making them suitable for use in dusty or highly humid conditions. The units also are protected against fungal and algae growth and condensation that might occur along the bridge.
The LDOTD is considering using the same type of drive package to replace existing units on other bridges as they reach their service limits.