WTORS Worked Examples
Scope of these examples: The five scenarios below explain when a geometry assessment may need to be repeated. They are qualitative examples, not numerical calculator outputs or tested installation results. For your project, use measured inputs and review the resulting WTORS geometry report.
These worked examples show how common changes in a wheelchair accessible vehicle can change the WTORS assessment question. They are illustrative only and do not provide a certified result or substitute for an actual vehicle measurement, manufacturer instruction or standards assessment.
Example 1: The wheelchair is moved forward in the vehicle
Scenario: The same wheelchair and occupant are used, but the wheelchair position is moved forward to improve cabin space or access.
What changes? The measured relationship between the occupant’s shoulder and the vehicle-side upper anchorage changes. A previously assessed anchorage cannot automatically be assumed to produce the same shoulder-belt geometry.
Engineering action: Re-measure the relevant vehicle/wheelchair relationship and reassess the upper shoulder-belt anchorage geometry for the new position.
Example 2: A taller passenger uses the same wheelchair position
Scenario: The vehicle layout and wheelchair position remain unchanged, but a taller occupant uses the vehicle.
What changes? The shoulder reference position changes. The belt path from the upper anchorage to the occupant may therefore change even though the wheelchair has not moved.
Engineering action: Assess the intended occupant range rather than assuming one occupant size represents every passenger.
Example 3: A different wheelchair has a higher seating position
Scenario: A fleet vehicle is used with different wheelchairs. One wheelchair places the occupant higher relative to the floor.
What changes? The occupant shoulder position and potentially the wheelchair securement geometry change. The existing occupant-restraint path needs to be checked for the new wheelchair configuration.
Engineering action: Record the wheelchair and occupant configuration used for the assessment and verify that the installed system remains suitable for the intended operating range.
Example 4: A four-point tiedown is replaced by a docking system
Scenario: A compatible docking system is installed to replace a four-point strap-type wheelchair securement arrangement.
What changes? The wheelchair securement method changes, but the need for an appropriate occupant restraint does not disappear. The docking device secures the wheelchair; the occupant-restraint arrangement still needs to be suitable for the occupant and vehicle geometry.
Engineering action: Confirm docking compatibility and installation separately from the pelvic and upper-torso restraint assessment.
Example 5: A repeat-build WAV model uses the same nominal layout
Scenario: A WAV builder produces multiple vehicles using the same design and restraint layout.
What changes? Repeat builds can improve consistency, but production tolerances, trim changes, seating changes or installation variation can alter the actual geometry.
Engineering action: Define the controlled design dimensions, retain the calculation/report as part of the build record and establish checks that confirm production vehicles remain within the intended configuration.
What these examples demonstrate
- Wheelchair securement and occupant restraint are separate functions.
- One anchorage position should not be assumed to suit every wheelchair and occupant.
- Changes in wheelchair position, seating height or occupant size can change the restraint geometry.
- Repeatable measurement and documentation are more defensible than visual judgement alone.
- Structural approval, product compatibility and regulatory certification remain separate responsibilities.
Use the examples with the Estraints workflow
Review shoulder-belt geometry fundamentals | See the sample report structure | Compare standards
Content status: Created by the Estraints Technical Team on 2 October 2026. See how Estraints develops and reviews technical guidance.