Blackout Driving

Blackout Driving refers to the act of driving at night without headlights. During the Second World War, aerial reconnaissance and the threat of aerial attack at night resulted in a blackout order to civilians in the United Kingdom; no lights were permitted to be shown at night lest they advertise the position of population centres to German night bombers. In the field, headlights were not normally used in the vicinity of the front lines for tactical reasons.

"Convoy lights" were fitted to military vehicles at this time (usually singly rather than in pairs as with headlights); rather than providing broad beam illumination as standard headlights did, they focuses a small spot of light onto the ground just ahead of the vehicle; enough to illuminate a few feet ahead of the vehicle but with a hood to shield the light from view from greater distances. Small lights were also fitted under the rear of some vehicles, sometimes illuminating the rear axle (painted white for visibility), to aid drivers in convoy keep station with vehicles in front. When driving in a packet or convoy, only the lead vehicle would need to use the front mounted convoy light.

After the Second World War, a system of "blackout lights" was developed. A front mounted convoy light (also known as a Blackout Driving Light) was retained the purpose of which was to:

• provide the vehicle operator with sufficient light to operate the vehicle in total darkness

• provide minimum lighting to show vehicle position to a leading or trailing vehicle when illumination had to be restricted to a level not visible to a distant enemy.

The blackout driving light provided white light of 25 to 50 candlepower to a distance of 10 feet directly in front of the vehicle, shielded so that the top of the low beam was directed not less than 2 degrees below the horizon, and with a beam distribution on a level road at 100 feet from the light 30 feet wide.

On the rear were mounted Blackout Stop/Taillights and Marker Lights. These were designed to be visible at a horizontal distance of 800 feet and not visible beyond 1,200 feet, as well as being invisible from the air above 400 feet with the vehicle on upgrades and downgrades of 20 percent.

The horizontal beam cut-off for the lights was 60 degrees right and left of the beams' center line at 100 feet. Composite lights combined service, stop, tail, and turn signals with blackout stop and tail-lighting.

The Marker Lights, (also known as "cat's eyes") consisted of two sets of four small lights. The lights were configured so that a following vehicle could guage distance from how many lights appeared - if following too close, the four lights could easily be distinguished. When following at the correct distance, the human eye would merge the sets of four lights into just two. If too far away, the lights merged into one.