Traffic numbers on the M6 Toll are continuing to fall behind figures achieved last year.
Vehicles on the 27-mile privatelyrun toll motorway in July were 15.3 per cent down on the same month last year.
Traffic on the neighbouring M6 was also down by 15 per cent compared with the same period last year. Daily traffic was 47,000 last month, compared with 55,000 in July 2004.
The figures published this week are the first to be published since the Government announced it would press ahead with plans for a northern extension to the M6 Toll - the M6 Expressway from Staffordshire to Manchester - as well as coming up with alternative road-widening proposals.
A spokesman for the National Alliance Against Tolls said: "The old M6 and other roads in the West Midlands are frequently congested because most drivers avoid tolls.
"The Government should abandon plans for the new M6 Expressway and press ahead with a non-toll solution to the area's traffic problems. Toll roads are bad for the economy, bad for the environment, and bad for drivers."
A spokeswoman for Midlands Expressway Ltd, which built and operates the M6 Toll, said there was one less work day during last month than July 2004.
She added there was a loss of 10,000 vehicles on one day due to a major accident on the M6.
She added: "There has been an enhanced take up of Tag accounts by regular users throughout June and July following the Tag incentive scheme offer which gives a five per cent discount off the tolls. Accounts now stand at well over 11,000."