What causes traffic jams?

"Jam Busters"

Traffic jams are becoming a regular part of urban life. Initially city dwellers were blighted by the traffic jam.

With the increase in car ownership this has spread to many other urban areas, including formerly free running highways and motorways, particularly at peak times.

TorqueCars will look at some of the causes of traffic jams and identify some driving methods which will help to reduce this problem.

We will also look at the problems caused by sitting in traffic with the engine running.

On the freeways and motorways where you expect to travel great distances in a short time you will start to get  a slowdown of traffic. Often the traffic will come to a complete halt for no apparent reason. Enter the ripple effect which goes something like this.

Driver 1 briefly touches his brakes, the driver behind him has to respond and slow his car up so his brakes go on as well. The second driver, however, has to break harder to take into account of his thinking distance. The thinking distance is the time it takes for the message to apply your foot to the break pedal to get from your brain.

The third driver will also have to break. He will need to break harder than driver 2. The ripple effect goes on throughout the cars until cars have to come to a complete standstill. When cars stop and then have to move off the delay becomes much greater and you end up with a jam.

One of the main causes of a traffic jam are motorists known as "rubber neckers". If there is an accident or breakdown they will slow down as they pass to have a look. This starts off the ripple effect and actually becomes doubly hazardous. As the traffic starts to slow right up the next drivers are also distracted by the events going on the other side of the road. This delays their thinking time/reaction time even more and causes more sudden breaking.

There are 2 defences that would reduce the incidence of traffic slowdowns, apart from the obvious, ie: resisting the temptation to rubber neck!

1) Leave plenty of distance between yourself and the car in front. Using a marker at the side of the road count 2 seconds after a car passes it and make sure you cross that point after the 2 second gap. The old mantra "only a fool breaks the 2 second rule" take a full 2 seconds to say. This will at least give you time to slow up more gently without using your breaks. Dropping down a gear will help slow you sufficiently in most cases.

2) Never come to a complete halt. If it looks like a halt is coming in the traffic ahead, leave a large gap and slowly roll into this. The cars behind you will keep moving at the slower pace and you will have saved a longer delay. Lorry drivers are naturally good at this as it is hard to pull away in a lorry with all the gear changes required, so they will aim to keep the car moving.

If you are stuck in a traffic jam, turn off your engine. There is no point just increasing the heat in your engine and wasting fuel. Most breakdowns in jams occur due to overheating caused by running the engine. If you are in crawling traffic and you notice your engine temperature rising then turn on the cars heaters. In most cars this will help to take some of the heat from the engine and can enable you to survive longer.

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