The Highways Agency has called for expressions of interest in a contract worth up to £478M to reduce congestion on the notorious Dartford crossing section of the M25.
Contractors are sought to manage the transition to an automated toll system using vehicle recognition technology.
More than 40 million vehicles each year use the tunnel and bridge that carries the M25 over the River Thames in east London.
Interested parties have until 29 October to register an interest in the scheme, expected to be worth between £237M and £478M.
Bids will be judged 70 per cent on quality and 30 per cent on price.
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