diamond shape, and red – a square (somewhat larger than the ball shape). In Quebec, most horizontal traffic lights have a red signal on both sides of the fixture (left and right). They are also now replacing the shaped traffic lights for color-blind people with regular round signals. Some signals have two red lights, one on each end. In some Texas urban areas including Houston and Dallas, the use of a double red light is different. It is typically used on left turn signals. For horizontally mounted signals, typically hung or mounted over the lanes, it is configured with two red balls or arrows, one yellow arrow or ball, and a green arrow (from left to right). For vertically mounted signals, the two red balls or arrows are on the top, then a yellow arrow or ball, and a green arrow. It is usually accompanied by signs saying "left turn signal" or "left on arrow only". Signals for traffic going straight use standard signals, usually mounted horizontally over the road. The use of two red lights on the left turn signal allows for redundancy in case one of the red lights burns out, while saving money by requiring only one signal for left turns per direction that needs one. It also prevents the yellow trap that would occur at night if a single red signal burned out, and left-turning vehicles obeyed the circular signals instead. One type of installation in Texas uses a double red light instead of a single red light to make the red light more pronounced and visible from a distance. In this installation, it is the first traffic light on a rural highway for miles, and traffic approaches at highway speed (65 mph). The double red light makes the red phase of the light visible at a greater distance than the yellow and green on the same signal. This installation is also used on rural highways in California, always in a vertical configuration, and in either configuration in some cities of Mexico such as Guadalajara. The double-red light also makes an appearance in North Carolina in left-hand turn lanes. It serves the same purpose as the vertical Texan configuration, and mainly appears on boulevards with multiple lanes of traffic where a left turn may become catastrophic due to visibility. Double red arrows are used for left turn installations on some county-managed roads in Henrico County, Virginia