Road pricing and congestion charging would be "politically and economically impossible" unless some of the money raised is spent improving the transport network, an RAC Foundation chief said.
Money from any planned charges must be used to relieve congestion by the expanding the road network, according to foundation director Professor Stephen Glaister.
He told the House of Commons Transport Committee he did not accept the argument that there was "no point in building new roads as that just leads to more traffic".
Prof Glaister said that if congestion was bad enough for congestion charging to be considered, it indicated that there was a good case for extra capacity being provided in that area.
He told the committee, which is taking evidence in an investigation into taxes and charges for road users, that revenue from road-user charges should be spent on the road network.
If new roads were built in the right place they could accommodate more traffic but lead to less congestion, he added.
Asked if transport taxes were well co-ordinated, Prof Glaister said the state of affairs in which road taxation now far outweighed the amount spent on roads had "happened by accident".
He said the Treasury failed to take into account the influence it had on policies. He went on: "The Treasury should consult more."
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