The Department for Transport generally estimates changes in congestion between future scenarios to calculate the benefits of potential transport interventions. However, it has also used analysis from the National Transport Model to estimate what the change in the cost of congestion is likely to be between a base year and a future year.
The 2006 Eddington study estimated that the increase in time lost in England due to road congestion between 2003 and 2025 for all travellers including business and freight would be worth £23 to £24 billion in 2025 (2002 prices). The Eddington study is available at:
No such assessment for 2015, 2020, 2035, or 2060 is available.
The latest forecasts of congestion are available in "Road Traffic Forecasts 2008: Results from the Department for Transport's National Transport Model", which is available at: