Plans to slash Severn Crossing tolls by up to 75% have been criticised for not going far enough.
Drivers and businesses will benefit from proposed cuts to the tolls following the return to public ownership, Transport Secretary Chris Grayling has said.
The Government's proposals would see the prices paid for all vehicles halved, with some drivers seeing savings of more than 75%.
Liberal Democrat transport spokeswoman Baroness Jenny Randerson said that while the reduction is welcome, the tolls should be removed.
She said: "We welcome that this starts to address a major impediment to the development of the Welsh economy, and indeed that of South West England, and the Bristol area.
"However, this does not go far enough. Lib Dems have campaigned for decades for total removal of tolls.
"Why should people using this bridge pay for its upkeep when they already pay for road repairs through the tax system, just as users of other motorways do?"
The lower toll charges would be introduced when the crossings return to public ownership and it is expected that the new toll charges would begin in 2018.
The Government is also looking at removing toll barriers and introducing free-flow tolling on the Severn Crossings that could help cut congestion and journey times.
Under the proposals, cars will pay £3.00 instead of £6.70, small buses or vans will pay £3.00 down from £13.40, and lorries and coaches will pay £10 instead of £20.
Blue Badge holders and motorcycles will continue to be exempt from the tolls, and the money raised will pay for the operation and maintenance of the crossings as well as future improvements, the Department for Transport said.
Mr Grayling said: "The Government is determined to make the right decisions for Britain's future and reducing the tolls on the Severn Crossings will cut costs for businesses, helping boost jobs and trade in Wales and across the South West.
"The future toll prices announced today will not only guarantee the future and safety of the crossings for generations to come but will also boost the economy whilst offering the best value for money for motorists and the taxpayer."