A ban on driving 4x4s and quad bikes on a number of tracks in the Yorkshire Dales has come into force.
Off-road driving has become more popular in recent years
The ban means that "off-roaders" will not be able to drive along four ancient tracks - once used by horse and carts - which cross the national park.
Drivers have been blamed for damaging the so-called green lanes. Off-roaders say their vehicles have little impact.
The lanes have been designated access only until 1 September 2006, extending a ban first brought in last year.
The issue of drivers using green lanes has become a contentious one in recent years.
Because the tracks were once used by horse and carts they can be claimed by off-road enthusiasts as open to all traffic.
GREEN LANES AFFECTED BY BAN
Mastiles Lane, Kilnsey
Topmere Road / Starbotton Cam Road, Kettlewell
Long Lane, Clapham
Halton Gill, Yockenthwaite (Horsehead)
But countryside campaigners say the vehicles erode the paths and ruin the enjoyment of the routes for walkers, cyclists and horse riders.
However, off-road groups say they have minimal impact on the condition of the tracks and say vehicles are only allowed on 5% of the rights of way network in the UK.
The ban, which was agreed in July, was welcomed by the Yorkshire Dales National Park Authority.
Jon Avison, head of park management, said at the time that he welcomed the extension but he was disappointed there was not a long-term solution.
"We had hoped that we would not be revisiting the issue on these routes in a year's time," he said.
The issue of vehicular access to green lanes is being addressed in the Natural Environment and Rural Communities Bill.