Traffic signals are vital to helping vehicles and pedestrians safely travel. They increase the efficiency and order of traffic to reduce the number of accidents. They provide clear guidelines regarding when cars or pedestrians can enter an intersection or when they should stop and wait. While they are necessary to control traffic and keep commutes as smooth as possible, there are both advantages and disadvantages of traffic signals.
TL;DR (Too Long; Didn't Read)
Despite their many benefits, traffic signals come with disadvantages. These include an increase in accidents, delays and aggressive driving.
Increase in Rear-End Collisions
When it comes to accidents, there are strong advantages and disadvantages to traffic signals. Traffic signals can reduce certain types of car accidents, most commonly broadside collisions. One of the primary disadvantages of traffic signals is that they lead to an increase in rear-end vehicle collisions. Rear-end vehicle collisions occur more frequently when a driver abruptly stops at a yellow or red light, causing a distracted driver behind him to ram into the rear of his car.
Rear-end collisions aren’t typically as severe as broadside collisions, so this trade-off can be seen as worth it. However, in an intersection where broadside accidents are not a concern, installing traffic lights can mean an increase in accidents at the intersection. Traffic engineers do a risk-benefit analysis as part of determining whether to install a traffic light. Engineers must weigh both the advantages and disadvantages of traffic signals. In many instances, it is still worth installing a traffic signal despite a slight increase in rear-end vehicle collisions.
Excessive Traffic Delays
While they do help manage the flow of vehicular traffic, one of the other disadvantages of traffic signals is that they can cause traffic delay. Waiting for a traffic light to turn green or waiting for a car in a turn lane to safely cross an intersection can result in long wait periods. Excessive delays can translate to wasted fuel, air pollution and costs to motorists. These are often hidden costs that aren't always apparent to drivers.
Aggressive, Impatient Driving
Partially as a result of excessive delay and partially as a result of unwarranted or improperly functioning traffic signals, drivers can get unnecessarily impatient and aggressive when driving. When that happens, more red lights may be run, more traffic laws are broken and drivers may veer off onto neighborhood streets. Aggressive driving can mean increased accidents, congestion, and air and noise pollution. These are just some of the many disadvantages of not following traffic rules or getting frustrated by traffic signals.
Cost of Traffic Signals
One of the other disadvantages of traffic signals is the cost, especially when a less expensive stop sign will do. The cost of installing and maintaining a traffic signal varies, depending on the state. In Missouri, it costs between $100,000 and $150,000 to install and about $4,000 a year to maintain a traffic signal. In Washington, it costs between $250,000 and $500,000 to purchase and install a signal and about $8,000 a year to maintain. A basic stop sign, on the other hand, can average around $400 to manufacture and install. Maintenance costs of a stop sign are significantly lower than a signal, since there is no electrical system to maintain. When they make sense to install, stop signs may be a more viable alternative for keeping city costs down.
Traffic engineers consider the advantages and disadvantages of traffic signals when determining whether to install them. Once they are installed, signals are monitored and adjusted on an ongoing basis to make sure they are as beneficial as possible. If it turns out they are doing more harm then good, the installation of a traffic signal will be reevaluated to make sure it's the best way to go.