Traffic lights In other contexts
The symbolism of a traffic light (and the meanings of the three primary colors used in traffic lights) are frequently found in many other contexts. Since they are often used as single spots of color without the context of vertical position, they are typically not comprehensible to up to one in ten males who are color blind.
Traffic lights have also been used in pieces of artwork, particularly the Traffic Light tree in London, UK.
Racing
Automobile racing circuits can also use standard traffic signals to indicate to racing car drivers the status of racing. On an oval track, four sets may be used, two facing a straight-away and two facing the middle of the 180 degree turn between straight-aways. Green would indicate racing is under way, while yellow would indicate to slow or while following a pace car; red would indicate to stop, probably for emergency reasons.
Scuderia Ferrari, a Formula One racing team, formerly used a traffic light system during their pit stops to signal to their drivers to when to leave the pits. The red light was on when the tires were being changed and fuel was being added, yellow was on when the tires were changed, and green was on when all work was completed. The system is (usually) completely automatic. However, the system was withdrawn after the 2008 Singapore Grand Prix, due to the fact that it heavily delayed Felipe Massa during the race, when he was in the lead. Usually, the system was automatic, but heavy traffic in the pit lane forced the team to operate it manually. A mechanic accidentally pressed the green light button when the fuel hose was still attached to the car, causing Massa to drive off, towing the fuel hose along. Additionally, Massa drove into the path of Adrian Sutil, earning him a penalty. He finally stopped at the end of the pit lane, forcing Ferrari’s mechanics to sprint down the whole of the pit lane to remove the hose. As a result of this, and the penalty he also incurred, Massa finished 13th. Ferrari decided to use a traditional “lollipop” for the remainder of the 2008 season.
As a rating mechanism
The colors red, amber and green are often used as a simple-to-understand rating system for products and processes. It may be extended by analogy to provide a greater range of intermediate colors, with red and green at the extremes.