What causes traffic jams?

On the Road 2 min read

Road construction, accidents, and rush hour are often the direct and observable causes of traffic jams. Road construction may require lane closures or reduced speed limits, while car accidents can cause traffic to slow due to vehicles blocking the roadway or drivers slowing down to look at the accident (commonly known as rubbernecking). And of course, traffic jams are common at rush hour, when the number of vehicles on the road increases quickly in a short timeframe.

Not all traffic jams have an obvious cause, however. A phenomenon known as “phantom traffic jams” can have a slowing effect similar to any other traffic jam but without a triggering event such as an accident or lane restrictions.

Common causes of traffic jams

1. Car accidents

A car accident is one of the most obvious causes of traffic jams. While a serious accident can block the roadway, require emergency vehicles to come to the scene, and potentially even require traffic to be rerouted, a minor fender bender pulled off to the edge of the road can cause people to slow down enough to have a significant impact.

2. Road debris

Items falling off vehicles or been left in the road can lead to traffic tie-ups. When an 18-wheeler blows a tire, for example, bits of material could not only strike passing vehicles but remain in the roadway, requiring drivers to swerve and cause a chain-reaction slowdown. When driving on the highway, a team of workers might be deployed to clear the road, resulting in even more delays while they do their job.

3. Road construction

Construction projects are notorious for causing traffic jams. While smaller projects require drivers to go slower and merge into another lane, larger-scale ones require vehicles to be diverted onto another route. Cars detouring onto alternate routes can bring heavier-than-normal traffic, leading to traffic jams.

4. Rush hour

When a sudden influx of cars enters the highway in a short amount of time, traffic jams are soon to follow. In many cities, the morning commute to work and the afternoon/early evening commute home are prime factors causing traffic jams.

5. Phantom traffic jams

A phantom traffic jam occurs when a car slows down while driving — either by quickly braking or not keeping up with traffic speed — on a busy roadway. The braking also causes vehicles behind it to slow down, and the chain reaction can lead to traffic tie-ups. In this way, it can seem like a traffic jam is happening for no apparent reason.

Are traffic jams bad for your car?

Unfortunately, traffic jams are not only annoying to drivers (check out our tips for preventing road rage) and time-consuming to people on the road, but they can also be bad for your car. Driving in stop-and-go traffic might affect multiple aspects of your vehicle, including:

  • Battery and alternator system
  • Cooling system
  • Engine performance
  • Brake wear and tear
  • Drive (serpentine) belt
  • Fluid degradation
  • Excess fuel usage

Which cities have the worst traffic jams?

Not surprisingly, some of the biggest cities in the country have some of the worst traffic. According to TheStreet, Chicago, Boston, New York City, Philadelphia, Miami, Los Angeles, and San Francisco all rank high on the list for traffic jams. In short, if you live in a densely populated area and want to drive, expect to spend many extra hours during a given year sitting in traffic.

Alternative forms of transportation might be your best bet to get around more efficiently: Consider taking the subway, riding your bike, or even walking if you don’t have too much to haul.

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