Nervous driving test pupils could have their big day cancelled at the last minute due to a strike.
Examiners are set to walk out on Monday and Tuesday amid a row over the safety of changes to the test, due to be introduced from Monday.
A new reverse manoeuvre on the wrong side of the road is the main sticking point with instructors saying it is dangerous.
The manoeuvre requires a driver to pull up on the right hand side of the road facing oncoming traffic, reverse two car lengths and then rejoin the traffic.
The Public and Commercial Services Union (PCS) says its members will walk out for 48 hours in dispute over the Driver and Vehicle Standards Agency’s (DVSA) changes and other working conditions.
Huddersfield Test Centre in Waverley Road, Huddersfield, has not been listed as one of the PCS picket lines but a local instructor has said some of the Huddersfield examiners are in a union.
Graham Pickup, who has been an instructor for 38 years, said: “We consider this manoeuvre to be unsafe.
“The Highway Code advises against it but it’s not illegal. From what we understand the examiners agree with us.
“Pupils with tests booked for Monday or Tuesday are being told to turn up anyway.
“It doesn’t help the pupils who are nervous anyway, it’s a really big day for them.
“There’s seven examiners, some are in the union and some aren’t. You might be lucky and get one who’s not striking.
“If not, your test will be re-arranged, but it will probably be after Christmas now. If you don’t turn up you’ll lose your money.”
About 14,000 tests are expected to be cancelled because of the strike.
Hundreds of tests have already been cancelled across the country by PCS action short of a strike.
Roadside checks and enforcement action will also be reduced.
The union said: “In a perverse move, the DVSA has withdrawn overtime from striking workers and also imposed leave schedules meaning that an even greater backlog of thousands of tests is inevitable due to the imposed reductions in service.”
PCS general secretary, Mark Serwotka, said: “PCS members in the DVSA have tried to negotiate around their concerns but the door has been slammed shut in their face.
“They now feel they have no alternative but to take industrial action to bring home to the public how damaging the DVSA proposals are.
“No one takes strike action lightly and we acknowledge the disruption to the driving tests for learner drivers keen to pass their test, but the Government could avoid this strike even now at the eleventh hour by agreeing to serious talks and withdrawing their most damaging proposals.
“I have written to the Transport Minister Chris Grayling urging him to intervene.”
Responding to the strike action, DVSA chief executive, Gareth Llewellyn, said: “The fact PCS is trying to undermine the launch of the new test by calling for strike action shows a shameful disregard for both road safety and learner drivers who have worked so hard to be ready to take their test.
“The new driving test has been designed to make sure new drivers have the skills they need to help them through a lifetime of safe driving.
“During the last three years the changes – which are welcomed by most examiners, road safety experts, disability groups and instructors – have been developed and trialled extensively with a wide range of our staff, learners and other organisations.”