Last month, a new study called 'Orbit: Transport solutions around London' concluded that area-wide road-user charging was the only way of dealing with increasing congestion and rocketing numbers of road-users.
But in a speech to leading industry figures, Darling has warned that even if work was to start in earnest immediately, it would be years before there was any chance of considering such a system. He said that although there are plans to introduce distance-based charges for lorries in 2004 using sophisticated satellite tracking equipment, developing any system for cars was a much more difficult project.
Darling said: 'In my previous roles, I have had great experience of large IT projects. It is a massive step-change between doing this for 400,000 lorries and 25 million cars.
'The debate about how to price roads will have to continue, but with the immense technological challenge involved, I would not see it around in the next decade. However, if you don't look at these things, then you are not doing the job you are supposed to do.'
Darling emphasised that road-user charging was very different to congestion charging and added that the eyes of the world would be on London when the system went live in February.
But he warned: 'Congestion charging can be done if it is done properly. But you have to get the detail right. It is in no-one's interest for it not to work.'