Modern ambulances are now often custom built, and as well as the specialist medical equipment now built in to the ambulances, industry wide improvements in vehicle design have had an impact, including improvements in audible and visual warning equipment to help protect crews in vulnerable situations (such as at a Road Traffic Collision), and general improvements such as ABS (Anti-lock braking system), which are particularly valuable for ambulances, due to the speeds reached and the weight carried. There have also been improvements to help safeguard the health and welfare of ambulance crews, such as the addition of patient tail lifts, ramps and winches, to cut down on the amount of manual handling a crew must perform. More information from AireWeb.
Ambulance design is still evolving, largely due to the growing skills and role of Paramedic and other ambulance crew, which require specialist equipment. Other factors driving improvement include the need to help protect ambulance crews from common accidents, such as traffic collisions and rarer, but potentially catastrophic incidents such as terrorist activities.