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Attachment A

Feasibility Review:

Proposed Wheelchair

Securement System

Staff Contact: James Wilhelm

Associate Mechanical Engineer Automotive Systems Bus Maintenance Engineering
 

INTRODUCTION

In recent months, VTA staff has been approached by Mr. Martin Bishop regarding an alternative mobility device securement concept he has designed. Mr. Bishop is a community activist and advocate who has served on several boards addressing the needs of the disabled community. At the request of VTA’s Transit Planning and Operations Committee, staff reviewed the feasibility of implementing Mr. Bishop’s idea on VTA buses.

EXECUTIVE SUMMARY

The concept Mr. Bishop proposes has several design issues. The main problems concern interfaces with the structure on the different bus models within the VTA fleet and the complexity of designing adjustments to make the concept universal to accommodate the many different mobility devices in use. Additionally, implementing the concept raises liability concerns and would require extensive testing.

Therefore, staff has determined that developing the proposed concept is beyond the resources of VTA. Among public transportation agencies nationwide, only New York City and one or two others possibly have the ability to attempt development of the proposal. The proposal is better directed towards university-based research groups and commercial firms. Staff recommends those development avenues to Mr. Bishop.

ANALYSIS

The concept proposed by Mr. Bishop is illustrated and described in an earlier document included at the end of this report (Appendix A). The concept is an attempt to realize several improvements over the current wheelchair securement methods, which consist of four or more retractable belts attached to the bus floor.

CONCEPT INTENTION

The intended improvements of Mr. Bishop’s concept include:

• 1.The device being deployed by the bus Operator from a standing position, with the intent of reducing the chance for back, hip or knee injuries from having to reach floor-mounted belts/retractors. The further intention is mitigating increased Worker’s Compensation claims for transit properties that mandate mobility device securement.
• 2.The Operator not having to stretch into uncomfortable positions to reach floor-mounted belts and possibly reducing concerns about infringing on passengers’ personal space to attach securements.
• 3.Reducing the chance of wheelchair tip-overs, which are thought to be the most common wheelchair incidents where injuries occur.
• 4.Use with virtually all styles of wheelchairs and avoiding contact with the wiring of electric wheelchairs, which is a possible claims issue for belt-style securements.
• 5.Allowing quicker deployment than belt-style securements to minimize service delays on bus routes.

DESIGN EVALUATION

VTA staff evaluated the design and foresees several issues and disadvantages precluding further development for transit operations:

• 1.The proposed securement device does not meet ADA requirements.
• 2.It may not be possible to design the device and its pivoting mountings points to be strong enough in an accident.
• 3.Different wheelchairs and scooters locate their occupants at different heights. Therefore, the device described will not be adequate, and may even be hazardous, to some users.
• 4.There are potential safety hazards to non-wheelchair passengers.

EVALUATION DISCUSSION

Mr. Bishop does not believe the first two design issues raised by VTA staff apply, pointing out that while the ADA has very high standards for mobility device securements and mandates that securements be provided on the bus, it does not mandate that the securements be used.

However, using this logic, the proposed concept would then be analogous to an intended replacement for something like grab-handles – devices that provide a clear benefit for a standing passenger while the bus is moving, turning, or stopping, but which are not designed to protect the user from injury in the event of an accident – rather than for the belt securements on the bus.  Under the ADA, this interpretation would require that the belt-style tiedowns VTA already has in place remain in the bus for passengers who want full securement, rendering the proposed device unnecessary.

Irrespective of intent, VTA staff is extremely concerned that, to a reasonable person, the proposed device would appear to be a new safety system – one that would be assumed to be just as safe as belt-style securements. The fact that the device would need to be deployed by the bus Operator would increase the chances of this misperception occurring. Grab-handles, by contrast, are passive convenience items that pre-date all safety regulations (there are no regulatory requirements for them) and have well-known, commonly understood limitations.

With the potential liability that would arise from individuals over-estimating the capabilities of the proposed device, VTA staff strongly believes that the first two disadvantages should apply, and that the device, therefore, must be designed to meet ADA securement system requirements.

MEETING ADA STANDARDS

ADA standards require that, when secured, a wheelchair must not move more than 2 inches in any direction. The proposed concept currently has no way to prevent large movements of a wheelchair in an upward direction and, for smaller wheelchairs, would permit large sideways movement.

These problems might be mitigated by additional adjustments bars, like the one designed to limit fore and aft movements shown in the attached design document, but that would reduce the main suggested advantage of the concept, its simple, easy, and quick deployment.

FEDERAL MOTOR VEHICLE SAFETY STANDARDS

Federal Motor Vehicle Safety Standards (FMVSS) aim for successful securement in impacts of up to 20g force. Amusement park ride bars, which have been cited by Mr. Bishop as the model for the device, are not designed for more than 1g or 2g forces. For amusement park rides, all the major accelerations are into the seats, and the bars normally are only for preventing climb-outs and for retaining passengers in the event of a stall while the ride is upside down. Therefore, any concept that uses the design for a transportation application would need to be much more robust and would require an extensive testing program.

FMVSS typically requires a 5000-lb. pull test (2500 lbs. for each anchorage), which would place severe loads on the pivots, on the adjustment bar, and on the sidewalls of the bus. The sidewalls of buses are not designed to accept such point loads, except at the shoulder-belt mounting points for the driver and wheelchair passenger seatbelts. The bar that is being proposed would be mounted between those two “strong points” on the bus sidewall, in an area where there is no additional reinforcement.

Therefore, testing would be required to determine if there is a need for additional reinforcement of the sidewalls, and the tests would almost certainly prove that there is a need for additional reinforcement. The testing requires applying a large pulling load to the securement device installed in the vehicle, and typically results in permanent deformation or breakage of the vehicle structure.

A further important complication is that VTA, like most transit properties, has multiple models of buses from several manufacturers. Each has a different sidewall design, therefore requiring different reinforcements be designed and fully tested for each one.

ADJUSTMENTS TO REDUCE MOVEMENT

The third disadvantage has not been discussed with Mr. Bishop, but is also a critical one. The proposed method of reducing wheelchair passenger movement while within the confines of the device is a bar that would be adjusted towards the passenger. Since the passenger’s seated height will depend on the particular design of his/her wheelchair or mobility device, the bar could contact the passenger in the chest, the stomach, or close to the neck. Depending on the passenger’s disability, the chest or the stomach may be particularly sensitive to impact, and any impact in the neck area is clearly unacceptable.

The only way VTA staff sees to mitigate this problem would be to add some vertical adjustment to the bar. As with additional lateral adjustments, mentioned above, this would again reduce the concept’s ease and quickness of use. It would also force each bus Operator to use his or her best judgment, in negotiations with the wheelchair passenger, on how to most properly adjust the device, cutting further into any advantage the device has in decreasing service delays.

The fourth disadvantage is due to two factors. First, the simple adjustment proposed to deal with fore and aft travel results in rods protruding forward from the device. Second, the added adjustments VTA sees as necessary to restrain the passenger in all directions and to eliminate contacting the wheelchair passenger in vulnerable areas, and the need for enough strength to pass the pull tests, would make the device much heavier than originally proposed. Therefore, if the device comes loose from its stowed position, the potential for injuries to passengers, due to its weight and protrusions, is significant.

RECOMMENDATION

VTA staff recommends that Mr. Bishop direct any further pursuits on the development of his idea to any of the several universities that have been researching improved ways to secure wheelchairs in transit vehicles.

Oregon State University has been looking into a system similar to Mr. Bishop’s that would not require any belts, but it has the disadvantage of requiring the passenger to ride facing rearward. It needs to be noted that the research team at Oregon State has been working on the concept for several years, indicating the complexity of what, at first glance, may appear to be a simple issue.

The University of Pittsburgh and the Cleveland Clinic are two other research institutions that have had teams of engineers and designers trying for several years to find improved ways of restraining wheelchairs, without yet having designs they can show to be superior to belt securement systems. However, they would be additional appropriate organizations for Mr. Bishop to approach with his concept.

Mr. Bishop has also been given the names and contact information of the major securement device manufacturers serving this industry, which may be another appropriate development avenue for his design.

APPENDIX A -- CONCEPT DESIGN

Front view, with wheelchair in streetside securement area (Flip-up seat not shown for clarity, but would be below securement device shown in blue)

Ceiling

Pivots at mounting brackets

Securement device stowed

Streetside bus wall

Bus Floor

Ceiling

Streetside bus wall

Bus Floor

Securement device deployed

Top and Side views, with Wheelchair in Streetside securement location.

Securement device stowed

Securement device stowed

Bus windows

Top and Side views, with Wheelchair in Streetside securement location.

Securement device deployed

Note, adjustable bar to slide back towards passenger to reduce impact in the event of an accident.   Bar would be adjusted by Operator to fit passenger and then held in place with sturdy pins.

Securement device deployed

Bus windows

All sides of the device, and the adjustable bar, would be padded.  A latch would be provided near the pivot points at the mounting brackets to retain the device when not deployed.