For many years, passenger service vehicles (PSVs) have been fitted with rubber bellows (also known as airbags) supplied with air from the vehicle's air compressor. These allow the height to be varied to suit certain needs, for example lowering the front step for improved access for the elderly and disabled persons.
Vehicle ground clearance can suddenly and unexpectedly change due to a drop in air pressure. This presents crushing and trapping hazards to technicians recovering or repairing vehicles, especially if working beneath them. There is also a risk of trapping around the wheel arch.
The risk of this happening is significantly reduced if two basic principles are adopted:
- Never crawl beneath a vehicle fitted with air suspension unless it is properly supported.
- Never tamper with the ride height for the purposes of recovery or repair.
It should be possible to follow these principles if the task is adequately planned and enough time is allowed (ie recovery operatives should not be pressurised to take short cuts). Sufficient planning means that:
- the risks associated with each task are adequately assessed;
- each task is explained so the technician understands it fully.
- their roles and responsibilities must be clearly understood, as well as those of their colleagues (eg police, highways officers);
- all technicians have specific knowledge of the affected vehicle and carry the necessary equipment to undertake the job safely;
- the technician arrives with a suitable recovery vehicle (if recovery is necessary);
- working procedures are planned and fully implemented;
- equipment is in a safe condition by virtue of adequate inspection and maintenance and where appropriate has been subject to statutory examination;
- technicians know which contingency procedures to follow if their training and instructions do not cover the situation encountered;
Comprehensive guidance is available in the free HSE publication PM 85 Safe recovery (and repair) of buses and coaches fitted with air suspension.
Other vehicles
More recently, many more cars and smaller vehicles are manufactured with air suspension. The principles behind the advice in this guidance equally applies to these cars etc although the good ground clearance under these vehicles may not present the same crushing risks. It would be for the technician to identify such risks (eg low ground clearance) before attempting any repair or recovery.