Also discussed here: Traffic Evaporation(One Street Blog, Resources for Increasing Cycling)
And here: Reclaiming city streets for people - Chaos or quality of life?(52 page pdf, European Commission, And here: Braess's paradox(Wikipedia)
In past reviews, we have looked at how congestion pricing reduces both congestion and improves air quality in the urban core. Today we examine another approach, widely used in Europe over the last 20-30 years, which combines the removal of road capacity and adding pedestrian areas to the space freed up. The results from 70 case studies in European cities and New York City point to the many improvements and reduced congestion with examples from the UK, Germany, France, Denmark, Belgium and other countries. Vehicle emissions in downtown areas decreased by 15-30% one year after road removals.
Key Quotes:
“taking away space for cars can improve traffic while making the city safer and more enjoyable for everyone on foot. There are sound theories that help explain why this happens -- concepts like traffic shrinkage and Braess's paradox which are getting more and more attention”
"For each point of a road network, let there be given the number of cars starting from it, and the destination of the cars. Under these conditions one wishes to estimate the distribution of traffic flow. Whether one street is preferable to another depends not only on the quality of the road, but also on the density of the flow. If every driver takes the path that looks most favorable to him, the resultant running times need not be minimal. Furthermore, it is indicated by an example that an extension of the road network may cause a redistribution of the traffic that results in longer individual running times." (Braess’s Paradox)
- When roadspace for cars is reallocated, traffic problems are usually far less serious than predicted.
- Overall traffic levels can reduce by significant amounts.
- Traffic reduction 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.”
“[Nuremburg, Germany]After one year, traffic monitoring revealed that overall traffic flow in the historic city was reduced by up to 25 %, and the increase in traffic in adjacent streets proved very limited, ranging between 4 and 19 %, well below experts’ forecasts (in some cases a decrease was observed)..there was an overall reduction of approximately 10 000 vehicles between 1989 and 2000, despite an overall increase in car ownership during this period ….in the historic city centre emissions of nitrogen dioxides decreased by about 30 %, carbon monoxide and particulate matter by about 15 % — this was predominately driven by pedestrianisation..”
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