Behaviour in a traffic jam can be learnt

By Heiko Haupt Jan 24, 2007, 7:45 GMT

Berlin/Bonn - Traffic jams top the hate-list of problems facing motorists on the road and it is not hard to see why. The snarl-ups lead to delays, missed appointments and stress.

Things are made worse by the growing number of traffic jams around the world. Germany is particularly hard-hit, as figures from the country's ADAC car club show.

In summer 2005 there were 751 jams stretching for more than 10 kilometres and a year later that number had grown to 967 - quite apart from the numerous frustrating waves of stop-and-go traffic on the country's motorways - ironically the only ones in the world where large stretches are not governed by a fixed speed limit.

Such jams are a daily occurrence, yet many car drivers have not grasped how to cope with them properly, say experts. The first lesson includes a brief study of how and why congestion occurs in the first place.

'In 90 per cent of cases the cause of a snarl-up is easily determined,' said Peter Wagner, who conducts research into group dynamics at the Institute for Traffic Research (IVF) in Berlin.

Things grind to a snail's pace for what usually turn out to be obvious reasons, such as when the density of vehicles is simply too high for a particular route.

'For instance, traffic jams often build up around merge areas such as access and exit slip-roads,' said Wagner.

According to the ADAC expert Otto Saalmann, other classic bottleneck situations include construction work and road accidents. Saalmann maintains that the 'traffic jam out of nowhere' is a genuine rarity although it too can be explained.

'It can be triggered by a motorist who is so unsure of the route that he slows right down at a motorway junction to read the signs.' The first driver hits the brakes, the one behind him does the same and before you know it a whole wave of cars are flashing their rear lights in a chain reaction.

Regardless of what caused the snarl-up in the first place, the motorists affected must learn how to make the most of the situation.

'It is important to read the road signs carefully and well in advance too,' said Welf Stankowitz of the German Road Safety Council (DVR) in Bonn. Many motorways have electronic displays which warn of possible traffic jams. When entering a tailback, Wagner advises motorists to switch on their emergency warning lights to warn those behind. Stankowitz also advises against switching lanes at the last minute to gain a 'better position' in the queue. 'This just tends to confuse other motorists,' he said.

Standing still in a row of cars does mean the driver can just lean back and relax. Instead of waiting to see what happens, drivers should pay close attention to the speed of the vehicles moving around them. Zipping ahead and then having to brake abruptly during stop- and-go phases just wastes fuel, say the experts. Such behaviour also disturbs any semblance of traffic flow remaining. The same applies to switching lanes in an attempt to jostle for position.

As a matter of course, drivers should pull over and make way for emergency vehicles such as fire engines and police cars. In Germany there are even rules for doing so, explained Saalmann.

'On a two-lane highway, motorists should leave a gap in the middle between the two lanes while on a three-lane highway a gap between the left lane and the central lane should be kept clear. In other words drivers on the left pull over to the left side and those on the right pull over to the right.'

When highway construction obstructs traffic or lanes are closed, another phenomenon comes into play which often makes the situation worse.

'A lot of drivers simply don't understand the principles of merging,' said Saalmann. Yet the traffic only starts flowing properly again, when other cars are permitted to merge in front. It pays to be altruistic and let others drivers join the line in front of you or else risk queues stretching for many kilometres, said Saalmann.

Once the traffic starts moving smoothly again, drivers should progress forward swiftly but not race ahead. 'According to traffic flow theory, a bottleneck clears up much faster if motorists at the front speed up quickly,' said Wagner.

That doesn't mean drivers should accelerate out of the jam with maximum power. Motorists who try to make up for lost time by driving as fast as they can or those who indulge in hair-raising manoeuvres risk causing another accident - and triggering the next snarl-up.