HOME MyTRB CONTACT US DIRECTORY E-NEWSLETTER FOLLOW US RSS


The National Academies

Transit IDEA J-04/IDEA 16 [Completed (IDEA)]

Transit Restraint System for Wheel Chairs
[ TCRP J-04 (Innovations Deserving Exploratory Analysis--The Transit IDEA Program) ]

  Project Data
Staff Responsibility: Harvey Berlin

This project developed several restraint design concepts and tested one that brings the anchor location into proximity with the wheelchair seat. The unique design of this restraint system eliminated the disadvantages of the existing seat belt systems anchored on the vehicle floor and routed around the pelvis of the person seated in the wheelchair. The prototype was designed to offer an easier and faster operation, often eliminating the need for assistance by the bus operator. When the restraint is not in use, the adjustable rails are rotated into a stored position clear of interference with passenger seating and ambulation. The lap belt is also stored on a small retracting spool to remain clean when not in use. 
 

Project Results

Traveler protection during transit and vehicle impact is the primary objective of occupant restraint design, including occupant restraints of wheelchair-using travelers in transit vehicles. The objective of this project was to develop and evaluate new occupant restraint design concepts with focus on minimizing the efforts to operate the system while maintaining the crash protection of the wheelchair-using traveler.

The investigation started with the formation of the design criteria based on multiple inputs from a resource panel of experts, wheelchair users, transit administrators, vehicle operators, human factors testing of wheelchair-using travelers, and an experienced public transit vehicle designer.

A survey was developed and disseminated to administrators at 12 transit authorities throughout the country and vehicle operators involved with transportation of wheelchair users. Overall, the survey indicated conflicting information on priorities of safety, lack of use of lap and shoulder belts, fastening time between fixed route and paratransit application, and the need for alternatives to the existing occupant restraint designs. New design criteria were indicated for restraints to be used independently and rapidly by many wheelchair users with reduction of stop dwell time and driver involvement.

The human factors testing established anthropometric envelopes of a wheelchair occupant’s seated posture, reach, hand strength, and functional ability to position the wheelchair.

The design criteria from all these inputs were finalized and tabulated. The criteria established specifications for activation time, user independence, durability, component locations, operating hand function requirement, body size accommodations, and crash safety in terms of load and deflection parameters.

Using the design criteria, three conceptual models of wheelchair occupant restraint systems were developed and investigated. The early concepts of stanchion-mount and wall-mount designs were evaluated but not implemented because of obtrusive bulkiness for the first and incompatibility with vehicle structural design for the second. In previous sled impact testing (30 mph, 20-g and 5-g lateral impact) the stanchion-mount design performed well and appeared to be superior to the 3-point belt restraints.

The final panel-mount design was developed and refined, and a full-scale prototype was built for limited user tests and strength evaluation. The concept is illustrated in Figure 1. To minimize costs and to enhance commercial appeal, an effort was made for a simple design with off-the-shelf components and cost-effective tolerances.

Field testing

The prototype was built and installed in a 44-foot bus in service at the Greater Cleveland Regional Transit Authority that was driven to wheelchair users for a hands-on trial (Figure 2). The limited field trial in the nonmoving vehicle by experienced wheelchair travelers pointed out a general acceptance of the principles of the prototype design, a dissatisfaction with the current lap-belt system, and a need for further improvements in slimmer design and in the operation of the panel-mounted restraint design.

Pull testing

The final evaluation of the prototype restraint system was a static pull test to determine compliance with the Federal Motor Vehicle Safety Standard (FMVSS)-210 for seat belt anchorage. This test was performed at the NASA-John H. Glenn Research Center in Cleveland, Ohio. The test results indicated the ability of the restraint prototype to carry nearly half of the 5,000 lbs of target load, displacement, and duration. Failure of the body block in the prototype restraint system occurred at approximately 2,200 lbs in this test. The early failure did not occur in the design concept but was due to faulty welding and the incorrect accommodation of the belt anchor to the commercial wheelchair.

Product Payoff Potential

This project conducted surveys of transit administrators and fixed route and paratransit operators, which indicated conflicting understanding of crash safety and belt restraint use. This information reinforces the need for an educational effort to inform providers of the importance of properly positioned lap and shoulder belts for wheelchair traveler crash safety. The project has also shown why it is important to reduce operator assistance and enhance rapid user application of restraint systems, which would reduce bus stop dwell time and improve operational efficiency.

The final report for this IDEA project can be found at: 
http://www.trb.org/studies/idea/finalreports/transit/transit16_Final_Report.pdf

 

 

 

To create a link to this page, use this URL: http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=2225