From David Bleicher
In his article on traffic modelling, Philip Ball makes the highly dubious
claim that reducing congestion will also reduce pollution
(15 January, p 34).
Like many traffic engineers, he chooses to ignore the effects of induced
traffic. Many decisions such as how to get to work or where to locate a business
are based on the relative availability of different modes of transport. If
journey times are reduced by widening roads, building a new underpass, or
providing drivers with more up-to-date information, some people who previously
walked or took the train will switch to driving, and a number of businesses will
move to areas with better road access.
Any decrease in exhaust emissions caused by faster flowing traffic will be
negated by the overall increase in car use. If governments were serious about
reducing congestion, pollution and road accidents, they would not spend billions
increasing road capacity, or plan towns around the needs of cars. They would
instead invest in buses, trams and trains, and build communities where you could
get about easily on foot.
dsb@cdae.com
