The United States has evolved into a society of commuters due to the rate of urban sprawl or city development. Many residents have to drive every day to work or school, and getting stuck in traffic is a frustratingly common experience for most. A bigger concern may be the fact that major cities do not have public transportation systems that cover the large suburban area, forcing people to rely more heavily on their automobiles. As a result, the high usage of automobiles and other vehicles on the road causes daily traffic congestion and delays.
Purpose of Traffic Signals
The system has three basic components: a detector, a controller unit, and the signal heads (traffic lights). The purpose of a detector is to detect the presence and volume of vehicles on the road. There are many different types, including the inductive loop, magnetometer, magnetic, and microwave radar detectors. According to Myer Kutz, author of the Handbook of Transportation Engineering, “the inductive loop detector is by far the most common form of detector used for both traffic counting and traffic management purposes. It is used to measure traffic volume, flow rate, vehicle speed, and occupancy” . An inductive loop detector has loops of insulated wires that interpret changes in the electrical properties of the loop when a vehicle passes over it (see Fig. 1). Installed under the pavement, this detector (see Fig. 2) can accurately measure the density of traffic and presence of congestion .
The second type, the full-actuated controller, is used for roads that have fluctuating patterns in the volume of vehicles throughout the day, such as roads heavily-trafficked during rush hour. This type of controller is the most preferred because of its accuracy and efficiency. The system requires detectors on every road in every direction, allowing it to have comprehensive traffic information. Based on this data, the system is able to prioritize the right of way as needed. Moreover, the controller will establish the cycle and green light time that is necessary in order to maintain the most efficient flow of traffic in the area .
Maintenance of Traffic Signals
Besides the basic equipment upkeep, there is a need for responsive maintenance that troubleshoots and repairs the system after it malfunctions. Budget cuts to regular preventative maintenance have made responsive maintenance the most common type. It is important that responsive maintenance of this type is completed in a timely manner, because a broken traffic signal causes even more congestion than no signal at all. A record is kept of all such incidents so that any malfunction patterns can be noticed and potential corrective action taken before they occur next.
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