The UK Department for Transport recently published updated road traffic forecasts based on its National Transport Model. Continued growth is expected. By 2040 road traffic is forecast to be 46% higher than in 2010, implying an increase in congestion (measured as time lost) of about 114%. Despite this increase in traffic, CO2 emissions are forecast to decline by around 15% from 2010 levels, reflecting fuel efficiency improvements and use of biofuels.
In the view of many of us, these forecasts are implausibly high. For instance, the increase in car traffic in London by 2040 is put at 40%. Yet car traffic in London has hardly changed in 20 years, reflecting the constraint imposed by road capacity which no one is proposing should be relaxed significantly. More generally, the DfT forecasters reject the idea that car use has peaked on a per capita basis, evidence for which is emerging in most developed economies. It is probably too much to expect the forecasters to revise downwards traffic projections at a time when the Government has announced a big increase in expenditure on the roads system.