Automotive lighting
This results in substantially increased glare for oncoming drivers and also poorer illumination of the near side of the roadway in comparison to headlights conforming to UN ECE regulations.
[18][19] They may produce white or selective yellow light, and were designed for use at low speed to increase the illumination directed towards the road surface and verges in conditions of poor visibility due to fog, dust or snow.
[25] Cornering lights have traditionally been prohibited under international UN Regulations, though provisions have recently been made to allow them as long as they are only operable when the vehicle is travelling at less than 40 kilometres per hour (about 25 mph).
National regulations in Canada, Sweden, Norway, Slovenia, Finland, Iceland, and Denmark require hardwired automatic DRL systems of varying specification.
For many years, turn signals' on-off operation was activated by a thermal flasher unit which used a heating element, leaf spring, and a bimetallic strip.
When the bimetallic strip cooled down, it would pull the leaf spring back over centre in the other direction, closing the contacts and again sending power to the lights and heating element.
[55] The modern flashing turn signal was patented in 1938,[56] and shortly after, most major automobile manufacturers offered this optional feature before it became mandatory in 1967.
As an alternative in both the United States and Canada, the front amber side marker lights may be wired to flash with the turn signals, but this is not mandatory.
The driver raises or lowers the outboard end of the stalk in accord with the clockwise or anticlockwise direction the steering wheel is about to be turned.
Beginning in the late 1960s, using the direction-indicator lights to signal for a lane change was facilitated by the addition of a spring-loaded momentary signal-on position just shy of the left and right detents.
The earlier, fitted to the 1965 through 1968 Ford-built cars and the 1971–1972 Nissan Cedric, employed an electric motor driving, through reduction gearing, a set of three slow-turning cams.
In Belgium, Brazil, Canada, the GCC countries, Israel, Luxembourg,[71] the Netherlands, Switzerland, and the US, the rear signals may be amber or red.
Other specialised fitments are sometimes seen; the Jeep Wrangler and Land Rover Freelander have the CHMSL on a stalk fixed to the spare wheel carrier.
[citation needed] The 1968–1971 Ford Thunderbird could be ordered with optional supplemental high-mounted stop and turn signal lights integrated into the left and right interior trim surrounding the rear glass.
[101][102] The Oldsmobile Toronado (from 1971 to 1978) and the Buick Riviera (from 1974 to 1976) had similar dual high-mounted supplemental stop/turn lights as standard equipment; these were located on the outside of the vehicle below the bottom of the rear glass.
Effective with the 1986 model year, the United States National Highway Traffic Safety Administration and Transport Canada mandated that all new passenger cars come equipped with a CHMSL.
Early studies involving taxicabs and other fleet vehicles found that a third high-level stop light reduced rear-end collisions by about 50%.
The systems used by BMW, Volvo, and Mercedes differ not only in operational mode (growing vs. intensifying vs. flashing, respectively), but also in such parameters as the deceleration threshold of activation.
[110] An experimental study at the University of Toronto[111] has tested stop lights which gradually and continuously grow in illuminated area with increasing braking.
Audi, Jaguar, Mercedes-Benz, Mini, Land Rover, Porsche, Saab, and Volvo provide functional rear fog lights on their North American models.
The rear registration plate is illuminated either by a single or a pair of yellow or white light(s), affixed within the indentation of the trunk or bumper.
[47] Until about the 1970s in France, Spain, Morocco, and possibly other countries, many commercial vehicles and some Soviet Sovtransavto road trains had a green light mounted on the rear offside.
[123] However, in the United Kingdom, they must not be used except to warn others of either a temporary obstruction when the vehicle is stationary or a hazard ahead on a dual carriageway with a speed limit of at least 50 mph.
[129] In 2014, the idea was suggested by Slovakian Lubomir Marjak (of manufacturing company Lumaco, which makes front brake lights) to German EU parliamentarian Dieter-Lebrecht Koch.
Many vehicles have expanded this feature, causing the overhead interior light to remain on after all doors are closed, allowing passengers to fasten seat belts with added illumination.
[139] The prescribed colours differ by jurisdiction; in most countries, blue and red special warning lights are used on police, fire, and medical-emergency vehicles.
Standard taxicabs for street hire are distinguished by special lights affixed to the vehicle's roof in accordance with local regulations.
Bases may be bayonet-type with one or two contacts, plastic or glass wedges, or dual wire loops or ferrules used on tubular "festoon" lights.
LEDs also offer a potential safety benefit when employed in stop lights; when power is applied, they rise to full intensity approximately 250 milliseconds (¼ second) faster than incandescent bulbs.
Adoption of LEDs for other signal functions on passenger cars is gradually increasing with demand for the technology and related styling updates.
