Car head restraint geometry

Whiplash injuries in low-speed car crashes have been identified as resulting in high associated costs to insurers and to society as a whole. For example, these injuries were recently estimated to cost the UK insurance industry over £1 billion annually. Long-term whiplash injury in frontal and rear impact car crashes in the UK was also estimated to cost £3 billion per annum using the Department for Transport’s “willingness to pay” cost model. In an effort to reduce these costs, there has been considerable effort invested to introduce consumer information rating schemes and regulatory rear impact seat tests. These tests have been designed to encourage development and deployment in the fleet of seats that reduce the risk of whiplash injury in a low-speed rear impact. As part of this effort, good head restraint geometry has been identified as a basic requirement for seats that are designed to reduce the risk of whiplash injury, and a number of methods for measuring head restraint geometry have been developed for consumer information and regulatory testing. These methods assess geometry either statically or dynamically, depending on the test method. This Insight Report summarises research conducted at TRL and elsewhere to provide a reference document and critical review of the various methods of measuring head restraint geometry that are in use or have been proposed.