21 Maintaining the long-term benefits of the project depends on completion of separate demand management techniques which have taken a long time to develop. Previous experience shows that new road capacity rapidly fills, reducing the benefits of making more road available. When the Agency committed to widening the road it was approved on the understanding that measures to manage demand would be developed in parallel. However, in 2010 the Agency is still testing the viability of the demand management measures it started considering in 2003. It does not expect results until May 2012, just before the planned completion of the first sections of widening. The Agency sees the demand management project as delivering additional benefits in reducing M25 congestion at additional costs. We believe, however, there are risks to maintaining the long-term benefits of the widening project and its potential value without the early implementation of demand management.