Wheelchair securement and occupant restraint system (WTORS) practices in public transit buses.

The purpose of this study was to characterize wheelchair tiedown and occupant restraint system (WTORS) usage in public transit buses based on observations of wheelchair and scooter (wheeled mobility device: WhMD) passenger trips. A retrospective review of on-board video surveillance recordings of WhMD trips on fixed-route, large accessible transit vehicles (LATVs) was performed. Two hundred ninety-five video recordings were collected for review and analysis during the period June 2007-February 2009. Results showed that 73.6% of WhMDs were unsecured during transit. Complete use of all four tiedowns was observed more frequently for manual wheelchairs (14.9%) and power wheelchairs (5.5%), compared to scooters (0.0%), and this difference was significant (p=0.013). Nonuse or misuse (lap belt use only) of the occupant restraint system occurred during 47.5% of WhMD trips. The most frequently observed (52.5%) use of the lap belt consisted of bus operators routing the lap belt around the WhMD seatback in an attempt to secure the WhMD. These findings support the need for development and implementation of WTORS with improved usability and/or WTORS that can be operated independently by WhMD passengers and improved WTORS training for bus operators.

Investigation of wheelchair instability during transport in large accessible transit vehicles.

Large accessible transit vehicles (LATVs, fixed-route intracity buses), generally considered safe, may not be as safe for wheelchair-seated passengers. Transit provider practices vary regarding use of wheelchair tiedown and occupant restraint systems (WTORSs), while recent research suggests high levels of WTORS disuse and misuse. We sought to better understand wheelchair and wheelchair passenger instabilities related to WTORS disuse and misuse on LATVs. This article presents a retrospective review of 295 video surveillance records of wheelchair passenger trips on LATVs. Wheelchair trips involving disuse and misuse of WTORS were quantified and categorized based on WTORS configurations. Cases of wheelchair and wheelchair passenger instability were categorized based on severity, type, and direction. Three adverse events involving severe wheelchair and/or passenger instability were examined in greater detail. Results showed 20.3% of records involved wheelchair-related adverse events (95% minor instabilities, 5% severe instabilities). Scooters were most likely to be unstable, followed by manual and power wheelchairs. In most instability cases, no tiedowns were used to secure the wheelchair and no lap belt was used to restrain the wheelchair passenger properly. In many instances, the lap belt was misused in an attempt to secure the wheelchair, whereas the shoulder belt was never used.

Wheelchair tiedown and occupant restraint loading associated with adult manual transit wheelchair in rear impact.

Proper securement of wheelchairs in motor vehicles is vital to providing wheelchair users an adequate level of safety in a crash. Thus far, wheelchair tiedown and occupant restraint systems (WTORS) loading has mostly been examined under frontal impact conditions. Because of the inherent crash dynamic differences, rear-impact loading of WTORS is expected to differ greatly. In this study, three identical, reinforced, manual, folding, X-braced ANSI/RESNA WC19 wheelchairs were subjected to an International Organization for Standardization-proposed rear-impact crash pulse. WTORS loads (front tiedowns, rear tiedowns, lap belt, and shoulder belt) were measured and compared with frontal impact WTORS loading. Rear impact produced substantially higher loads (up to 7,851 N) in the front tiedowns than frontal impact. The rear tiedowns experienced relatively negligible loading (up to 257 N) in rear impact, while rear-impact dynamics caused the lap belt (maximum load of 1,865 N) to be loaded substantially more than the shoulder belt (maximum load of 68 N). Considering differences in frontal and rear impact WTORS loading is important to proper WTORS design and, thus, protection of wheelchair-seated occupants subjected to rear-impact events.

Development and validation of rear impact computer simulation model of an adult manual transit wheelchair with a seated occupant.

It has been shown that ANSI WC19 transit wheelchairs that are crashworthy in frontal impact exhibit catastrophic failures in rear impact and may not be able to provide stable seating support and thus occupant protection for the wheelchair occupant. Thus far only limited sled test and computer simulation data have been available to study rear impact wheelchair safety. Computer modeling can be used as an economic and comprehensive tool to gain critical knowledge regarding wheelchair integrity and occupant safety. This study describes the development and validation of a computer model simulating an adult wheelchair-seated occupant subjected to a rear impact event. The model was developed in MADYMO and validated rigorously using the results of three similar sled tests conducted to specifications provided in the draft ISO/TC 173 standard. Outcomes from the model can provide critical wheelchair loading information to wheelchair and tiedown manufacturers, resulting in safer wheelchair designs for rear impact conditions.