Invention Summary:

In a recent report sponsored by the New Jersey Department of Transportation, it was found that car/platform gap injuries accounted for 25% of all injuries on NJ TRANSIT Rail lines, including death. Similar findings have been reported by other agencies, including the Long Island Rail Road and the Metropolitan Transit Agency of New York. These results prompted the Federal Railroad Safety Advisory Committee to address the seriousness of the car/platform gap issue.

Researchers at Rutgers University have developed an apparatus that dynamically fills the gap between the door sill of a commuter rail train car and the station platform. This innovative trapdoor unit incorporates an automated slide for bridging a train/platform gap up to 15 inches wide. The unit is specific to train cars fitted with trapdoor system for high-low level platform service. The unit is based on the profile/ footprint of the existing trapdoors of multi-level cars currently in service on NJ Transit and other lines which allows the unit to be a retrofitted to an existing train car, with no structural modifications. The gap bridging slide is actuated by a simple motor/power screw arrangement for high reliability and direct operation by 72 volts DC, consistent with carriage equipment supply voltage.

This technology enables passenger safety, where the gap bridging slide extends until a proximity sensor detects engagement with any object, at which the extension promptly ceases. The gap bridging slide forms a rigid structure cantilever that is designed to handle traffic up to 1000 lbs., and extends up to 12 inches.In addition, the unit is fitted with a motion sensor that measures the actual size of the gap each time the slide is extended; thus allowing real-time measurements recorded to create a history of gap size at each station. The unit weights 140 lbs (less than currently fitted trap doors weighing 180 lb.) and costs about $2800 per unit. The unit has a built-in, hard wired control only requiring an etension/ retraction signal for operation/synchronization with the rail carriage doors’s open actuation.

The apparatus serves two current needs: 1) The Americans with Disabilities Act (ADA) requirement that passengers in wheelchairs and other mobility-impaired travelers have accessibility to get on and off passenger trains and 2) Protection against slip and fall injuries to passengers due to excessive gaps between the train and the platform.

Market Applications:

Can be used for passenger protection on railcars of a particular design in which high level platforms are serviced by a trap door, which is a common configuration on many U.S. commuter railcars.


  • Minimum implementation cost
  • Simple control/maintenance requirements
  • No modification to carriage structure

Intellectual Property & Development Status:

Patent pending

Patent Information:
ID: 2011-136

Basily Basily
Thomas Boucher
For Information, Contact:
Dan Benderly
Licensing Manager
Rutgers University