Saturday, October 27, 2007

Mounting of traffic lights

A typical exemplar of how traffic lights are mounted in California. Wealthy cities like Cerritos frequently have elaborate traffic light gantries. There are important differences from place to place in how traffic lights are mounted or placed so that they are visible to drivers. Depending upon the place, traffic lights may be mounted on poles positioned on street corners, hung from wires strung over the roadway, or even hung from horizontal poles or installed within large horizontal gantries that make bigger out from the corner and over the right-of-way. In the previous case, such poles or gantries frequently have a lit sign with the name of the cross-street.

In some places mount lights with their multiple faces set horizontally and others vertically. California is particularly fastidious in ensuring that drivers can see the current state of a traffic light. One entrance to a typical large intersection, with three through lanes, two dedicated left-turn lanes, and a crosswalk, may have as many as three traffic lights for the left-turn lanes, three for the through lanes, and a pedestrian signal for the crosswalk. And those numbers must be multipled by four to cover all four ways to enter a typical intersection. Additionally to being positioned and mounted for preferred visibility for their personal traffic, some traffic lights are also meant, louvered, or shaded to reduce mis-interpretation from other lanes. For instance, a Fresnel lens on a neighboring through-lane signal may be intended to prevent left-turning traffic from anticipating its individual green arrow.

The Traffic signals in Germany are placed at the stop line on same side of the intersection as the forthcoming traffic and are often mounted overhead with on the right and left sides of the road. The stop line position is done to stop crosswalk blocking and permit for better pedestrian traffic flow.

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