Even these measures taken together may not solve the problem. However hard the motorist is hit in the pocket and however attractive alternative modes are made, there will still be those who refuse to change their travel habits. It is therefore also important to consider the issue of highway capacity. It is now widely accepted that road building generates more traffic. Building roads makes driving easier, encouraging more road use.
Traffic then increases to the point where roads once again become congested.
This suggests that whatever the capacity of a given road network there will be a tendency for traffic to increase to just below saturation point. Increasing road capacity will simply raise the saturation point. This effect is not confined to road building. It may also result from measures to reduce car use. This improved congestion for a period but gave other people the opportunity to bring their own cars into town.