The Disadvantages of Traffic Lights

By Leslie Bloom - Updated March 12, 2018

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, traffic signals do pose some disadvantages.


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, traffic signals are sort of a mixed bag. Traffic signals can reduce certain type 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 collisions. Rear-end 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 automatic increase in accidents at the intersection. Traffic engineers do a risk-benefit analysis as part of determining whether to install a traffic light.

Excessive Delays

While they do help manage the flow of traffic, one of the other disadvantages of traffic signals is that they can cause traffic delay. Waiting for a traffic light to turn 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.

Aggressive Driving

Partially as a result of excessive delay and partially as a result of unwarranted or improperly functioning traffic signals, drivers can get 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 some of the many disadvantages of not following traffic rules.

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.

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.

About the Author

Leslie is a Los Angeles native with more than 20 years of experience writing for a variety of online and print publications. She has degrees in both journalism and law.

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