So, what if congestion is the solution?

But then, what is the solution to easing traffic congestion? According to several studies conducted to address these problems, reducing road space can result in traffic reduction.

In the mid-1990s, UK government policy changed radically on the premise that increasing road capacity could generate more traffic. Although the term “induced traffic” was now recognised, the opposing theory that reducing road space could reduce traffic was not so widely accepted. Therefore, London Transport and the Department of the Environment, Transport and the Regions commissioned a research study in 1997. The study provides information on 100 cases from around the world where road space had been reduced due to various circumstances (planning, temporary closures for road maintenance or renewal, natural disasters, etc.).

Of the 100 cases analysed, 60 of them provided sufficient evidence for an in-depth analytical review. The main findings were the following as reported in 2001 by Cairns, Atkins and Goodwin in the UK Municipal Engineer magazine:

• When road space is reallocated for cars, traffic problems are often much less severe than anticipated.
• Overall traffic levels can be reduced by significant amounts.
• The reduction in traffic is partly explained by recognising that people react to a change in road conditions in much more complex ways than has traditionally been assumed in traffic models.

This result was described as “evaporating traffic”. The report showed that, after a period of settlement, there was an overall average 21.9% reduction in traffic. The results on a case-by-case basis vary substantially and the context in which the capacity reduction policies are implemented is important, but in many cases, when road capacity is reduced, motor traffic does not seek another route but “disappears” or “evaporates”. Because of this variability of results, it is more accurate to use the median as the trend parameter. This indicates a 10.6% reduction in traffic. In other words, in half of the cases, approximately 11% of the vehicles that previously drove in the area where capacity was reduced were not in the surrounding area afterwards.

The studies also show that for infrastructure reductions to be effective, they must be well organised, planned and co-ordinated within a clear strategy developed by a multidisciplinary technical advisory team. These strategies must also be combined with effective communication and debate campaigns with the public and the media.

Many examples can be found in the publications cited above where capacity reduction policies have been successful.

Here are some examples from a document published by the European Commission in 2004 “Reclaiming city streets for people. Chaos or quality life?

KAJAANI, FINLAND

In 1996, the local authority initiated an active strategy to regenerate the city centre.

This strategy was made possible by the alliance of the local authority, developers, traders and residents realising that action was needed to stop the decline of Kajaani city centre.

Traffic closures were implemented in the main square and a section of the main street in Kajaani.

Before the action, approximately 13,000 vehicles a day passed through the main square. Now there is no car traffic. Traffic volumes on the streets adjacent to the square have increased from 1,000 to 6,500 vehicles per day, while other streets have seen no change in traffic flows. Some of the traffic has “evaporated” and more trips are now made on foot in the city centre.

WOLVERHAMPTON, ENGLAND

In 1986, the local authority commissioned ‘The Black Country Integrated Transport study’ which concluded that building more roads would not solve the growing transport problems. A more effective strategy would be to give greater priority to public transport and place greater emphasis on improving the urban environment by creating an attractive physical space that meets public expectations.

The response was a four-stage strategy, in which approximately 8,000 vehicles per day were removed from the city centre. The anticipated traffic congestion did not occur.

NUREMBERG, ALEMANIA

Forecasts predicted that the pedestrianisation of Rathausplatz/Theresienstrasse Square would lead to traffic chaos in the surrounding streets.

After one year, traffic monitoring revealed that the overall traffic flow in the historic centre was reduced by up to 25 %, and the increase in traffic in the adjacent streets ranged from 4 to 19 %.

ESTRASBURGO, FRANCIA

In Strasbourg, action has been taken to restrict private vehicle access to the city centre. Two new tram lines have been built using road space previously occupied by cars.

Predictions of traffic chaos following the restrictions have not materialised. Prior to the implementation of the strategy, the number of vehicles in the city centre was approximately 240,000 vehicles per day. By the year 2000, after the implementation of the action, this had been reduced by more than 16% to 200,000 vehicles per day. Analysis indicates that if the strategy had not been adopted, 300,000 vehicles would have been expected in the city centre in 2000, an increase of 25%.