The International Harmonised Research Activity (IHRA) on compatibility has focussed on research with the aim of improving occupant protection by developing internationally agreed test procedures designed to improve the compatibility of car structures in front to front and front to side impact. A secondary aim was to consider protection in impacts with pedestrians, heavy goods vehicles and other obstacles.

Compatibility is a complex issue, but offers an important step towards the better protection of car occupants. Group members continue to work on active research programmes, which have aided better understanding. The report of the group gives an overview of the broad thrust and approaches of the work and associated research. Progress has been made towards the prospects for improved frontal evaluation procedures, although side remains a complex area.

Potential candidate test procedures have been identified and the current position is discussed. The key prerequisite is better structural interaction to facilitate strength matching to maintain passenger compartment integrity. Compatibility also requires other aspects, such as deceleration characteristics, to be considered.

Although the complex nature of compatibility was recognised when work began, and significant work remains, the prospects are that a worthwhile step forward is achievable.