After reading through a post on Elightbars about the excessive use of LED’s and viewing a video (embedded below), I thought it might be the right time to have another look at the warning light guidelines from Ambulance Visibility. Here is a brief summary of the eleven-point toolkit.
AMBULANCE VISIBILITY Warning Light Guidelines for Emergency Vehicles
1. Attempt to standardise warning lamp colours: All the vehicles in your fleet should display identical lamp colours during response. A mixture of different colour combinations can confuse other drivers and slow their reaction times. If possible, rationalise your colours across the various agencies; In Australia, most of the police, fire, ambulance and rescue vehicles display red & blue warning lights, all based on research to maximise night/day performance.
2. Ensure effective warning lamp output both day/night: This point is really obvious for daylight; maximise lamp output to combat bright sunlight and promote long distance viewing. At night it may be necessary to dim lamp output to prevent excessive glare, although well-designed optics should reduce the extraneous light effects and glare to a minimum – see point 3.
3. Help to control glare by fitting lamps with larger lenses: Well designed warning lights with larger lenses provide better control of the light angles – the large optics can be accurately engineered to direct the light efficiently. Smaller lamps or micro-lights are often constructed with clear domes or coarse diffusers due to their size limitations. Space-saving micro-lamps must produce a high light output along with the inevitable excess glare to compete with the larger lamp designs.
4. Try not to mix different the lamp types: Halogen lamps/rotators, strobe lights and LED’s all possess different visual characteristics. It is difficult to synchronise or program the different types so they work together in a co-ordinated display. The flash profile of the three lamp types vary in duration, intensity and output so a combination display can seem very random, despite being wired to flash together. One exception to this guideline is fitting a single rotator in a high central position surrounded by a ring of synchronised lamps around the vehicle perimeter.
5. Synchronise all flashing lights: Research completed by Flannigan and Devonshire in 2008 clearly demonstrated that emergency vehicles with all warning lamps flashing in phase (simultaneously or unison) had a higher attention-getting ability and longer detection distance. The vehicle profile appears unified, especially when surrounded by other vehicles with their warning lights activated. In addition, personnel in reflective vests are more easily seen as the scene is illuminated by alternating periods of light and dark.
6. The ideal flash pattern is a double or quad flash: Lighting displays that are random or use frequently changing patterns tend to slow reaction times of approaching drivers. A regular and uniform pattern produces viewing predictability with periods of darkness to assist in differentiating people standing around the scene
8. Lamp ON time should be greater than the OFF time: Short duration or rapid flashing can be disorienting to the viewer. Longer flash periods offer more time for the viewer to find and track the emergency vehicle.
9. Consider steady burn lights: Many vehicles are equipped with low-level or high- level running lights that can be integrated through 360 degrees into the warning light layout. Mercedes Sprinter vans have several low-level amber lamps on each side at door-sill height. Steady-burn lamps support the main warning light configuration by maintaining a constant reference point for the viewer to locate and track the emergency vehicle at night
10. Switch off any white flashing warning lights at night: White flashing lights disrupt the night adaptation of other drivers, causing significant glare. White flashing lamps can cause Wake Effect accidents and trigger night-blindness in nearby drivers. Poorly positioned white lamps can also mask other coloured warning lights mounted either alongside or in close proximity.
11. Avoid fitting warning lamps along the vehicles sides at the eye-level of other drivers: It is becoming common to see brilliant light heads mounted at the eye height of the drivers in passing cars. These small bright flashing lamps mounted on wing mirrors and along the vehicle sides may be less than a meter away from the other driver’s eyes as they draw alongside. A single flash at can destroy the passing driver’s vision. The lamp manufacturers also advise that most light heads must not be viewed at close range which may cause permanent eye damage.
More information on the Ambulance Visibility website or in the AV Reference Library listed under Warning Lights.
Ambulance Visibility Blog 