A turn on red is a principle of law permitting vehicles at a traffic light showing a red signal to turn into the direction of traffic nearer to them (almost always after a complete stop, depending on the jurisdiction) when the way is clear, without having to wait for a green signal. North American traffic engineers first introduced this rule as a fuel savings measure, despite detrimental effects to the safety of pedestrians. Turns Right on red The simplest version is commonly known as a right turn on red (or simply right on red) in countries that drive on the right side of the road, or a left turn on red in countries that drive on the left side of the road. A right turn requires checking only two nearby crosswalks (at least one of which will show "don't walk") and vehicular traffic moving towards the driver, while a left turn or going straight requires checking two crosswalks and vehicular traffic moving in multiple directions. When turning right on red, the vehicle typically has to yield to traffic coming from the left, and the crosswalk parallel to that stream if there is one. If turning right at a three-way junction from a major road onto a minor road, the vehicle has to yield only to the crosswalk since there is no road on the left side. Sometimes, the opposing side has a protected left turn, requiring the vehicle to yield to opposing vehicles turning left, but not any crosswalks. In any case, the vehicle turning right on red has to yield only to one stream of vehicles (out of two possible streams) and zero or one crosswalk. Many jurisdictions that allow right turns on red will allow it to be done in any lane, including the outer lane of a dual or triple right turn. In some intersections, allowing a right on red would be unsafe, such as when there is a train running parallel to the road on the right side, synchronized to the traffic light timings. In places where right on red is allowed by default, a sign would be placed to disallow it. Left on red Another version is commonly known as a left turn on red (left on red) in countries that drive on the right side of the road, and would be a right turn on red in countries that drive on the left side