SP-3c: Development and Evaluation of Universal Docking Devices for Use in High-g Private Vehicle Environments

Task leader: Douglas Hobson, Ph.D. (rehabilitation engineer)

Co-investigators: Linda van Roosmalen, Ph.D. (industrial designer/ rehabilitation scientist); Lawrence W. Schneider, Ph.D. (transportation safety specialist); Paul Dick (primary user/ Advisory Board member)

Other advisory participants: Lucy Spruill (primary user); Joe Tackas (securement manufacturer); Doug Cross (public transporter/ Advisory Board member); TBD (bus manufacturer); Jean Marc Girardin, Q'Straint (securement manufacturer)

Duration/ staging of task: This 24 month development task will be conducted in months 49-60 of the 60 month RERC cycle

Importance of the problem

Description of the need, target population and state of the art

The following is intended to supplement the more general description of need and state of the art provided in the priority introduction section. Wheelchair or WMD securement devices, including docking systems, must be capable of withstanding a 20g, 30mph deceleration crash pulse (i.e. high-g) to comply with national standards (Society of Automotive Engineers, 1999). High-g securement will always be necessary when the WMD user is riding in lower mass vehicles, such as private vans, para-transit vans, and school buses. Four-point strap-type systems are capable of sustaining these higher loads and are used routinely to secure WMDs in motor vehicles. However, docking technology offers a unique opportunity to eliminate many of the inherent deficiencies of strap-type systems described in the introduction to SP-3.

To have universality of securement across all wheelchair types and all transit vehicles, universal interface hardware must be available on the WMDs with the geometric specifications known to docking system designers. The University of Pittsburgh team has pioneered proposals for a universal docking interface geometry (UDIG) standard in collaboration with respective industry representatives and wheelchair users (Bertocci, Karg et al., 1997; Karg, Bertocci et al., 1998). The draft specifications have been disseminated and have now been adopted by ANSI/RESNA –SOWHAT and ISO-WG-6 as the starting point for focused debate. Support and effort for the continuation and achievement of the UDIG initiative is the essence of task SP-3a (Years1&2). As indicated, Task SP-3b will build on the early work of the University of Pittsburgh team to address the low-g securement issues (Years 3&4). This task, SP-3c, will demonstrate high-g docking technologies and designs for use in private vehicles that are compatible with the newly adopted UDIG standard (Year 5).

The development team is aware of existing commercial high-g docking-type devices, such as EZ-Lock and the prototype developed by Oregon State University and unsuccessfully marketed by Mobile-Tech Systems Inc. EZ-Lock is considered to be the most widely used independent docking securement device installed in private vehicles today. While EZ-Lock has passed the J2249 test using two points of vehicle attachment (securing front and back of WMD), it is dependent on the addition of unique interfacing hardware to each WMD frame, which in turn is not necessarily safety tested on that WMD. However, its main limitation is that this type docking only works for one combination of WMD and vehicle.

This task extends the universal docking option to include both public and private vehicles, thereby allowing seamless transfer between both transport modes. Task SP-3c has been scheduled to occur in the last year of the five-year cycle for two important reasons.

  • First, it is most likely that it will take several years following the initial acceptance of the UDIG industry standard before the market place will be receptive to the introduction of innovative docking securement designs that comply with the standard.
  • Secondly, the University of Pittsburgh team has a phase II-STTR grant with a private commercial partner to develop a docking securement system for use in public vehicles. This STTR project, while terminating in 2003, will provide valuable insights into the realities of the marketplace related to docking securement that will, in part, transfer directly to this task that will focus on private vehicles.


The general objectives for this Task are the following:

  1. Develop a high docking system design which utilizes the UDIG standard
  2. Fabricate 2 prototypes of high-g docking systems for use in private vehicles
  3. Evaluate high-g concepts dynamically using a 20g/30mph frontal impact.

Potential for commercial development

Given that this task is the assimilation of knowledge and experiences gained on docking technology over a period of about 10 years, with the goal to transfer this into a commercially viable product that responds to the new UDIG industry standard, the potential for commercial acceptance should be high.


Bertocci, G., Karg, P. & Hobson D.A. (1997). “Wheeled Mobility Device Database for Transportation Safety Research.” Assistive Technology 9.2: 102-115.

Karg, P., Bertocci, G. & Hobson D.A. (1998). Status of universal interface design standard for mobility device docking on vehicles. Annual RESNA Conference, Minneapolis, MN.

Society of Automotive Engineers, S. (1999). SAE J2249: Wheelchair Tiedowns and Occupant Restraint Systems - Surface Vehicle Recommended Practice. Warrendale, PA, SAE.

Progress Report May 1, 2006

The original focus of this task was to develop and test wheelchair securement docking technologies for use in private vans. However, through work on a prior RERC-STTR funded project, considerable work had already been accomplished on a private docking device --so considerable time and effort was expended early in the task to re-clarify the objectives to the best take advantage of this experience and not duplicate prior work. Given the slow start and the need to take advantage of opportunities related to ongoing Task 3b tasks, task 3c is now about 2-3 months behind schedule. This one year task is now moving forward with the conceptualization and design phase of alternate docking designs and should be able to close the gap in the remaining months of the project. The conceptual designs of docking devices for private vehicles are in process. These devices will build and improve upon the experience gained in the STTR project that occurred at the beginning of the grant cycle.

Last updated: August 18, 2006