An emergency vehicle warning system is equipment fitted to, or carried by, an emergency vehicle, other than the equipment that a standard non-emergency vehicle is fitted with. Emergency vehicles of are highly likely to be involved in hazardous situations, including relatively common incidents such as a road traffic collision.

Emergency Vehicle Access

They are also required to gain access to incidents as quickly as possible, and in many countries, are given dispensation from obeying certain traffic laws; for instance, they may be able to treat a red traffic light or stop sign as a give way, or be permitted to break the speed limit. However, emergency vehicles usually are not able to treat a railroad crossing as a give way, because a train cannot be warned in time.

Emergency Vehicle Warnings

For these reasons, emergency vehicles in many countries worldwide, are fitted with a visual emergency vehicle warning system to alert members of the public (and in particular, other motorists and road users), either as they approach the vehicle, or it approaches them. Visual warnings can be of two types – passive warning or active warning.

Passive Warnings

The passive visual warnings are usually inherently linked to the design of the vehicle, and involve the use of high contrast patterns. Older vehicles (and those in developing countries) are more likely to have their pattern painted on, whereas modern vehicles generally carry the retro-reflective designs which reflect light from car headlights or torch.

Active Warnings

An American ambulance with all its lights turned on is an example of active warnings. The active visual warnings are usually in the form of flashing lights. These flash in order to attract the attention of other road users as the emergency vehicle approaches, or to provide warning to motorists approaching a stopped vehicle in a dangerous position on the road.

Emergency Vehicle Requirements

Many governments list specific requirements for emergency vehicle lighting. These requirements may address the color, visibility, intensity and location and of the lights, and whether they should flash or burn steadily. Laws also may regulate what vehicles may display these lights, and under what circumstances they may do so.