A report from the Comptroller and Auditor General has said there should be a significant reduction in waiting time for driving tests this year.
But the report pointed to a number of problems that are preventing the service from providing value for money, including traffic congestion and work practices.
The average waiting time has fallen from 34 weeks in 2005 to 27 in February this year, still well above the target of ten weeks.
Progress in reducing the backlog was hampered by industrial relations problems, particularly a dispute over outsourcing.
The report said the union IMPACT had 'strenuously resisted' the designation of more of the existing test centres as headquarters, a move which would cut travel and subsistence payments.
This lack of flexibility restricted management's ability to deploy testers where and when they were needed, the report said, though negotiations on this issue were under way.
The report was part of a series which looked at the response of various parts of the public service to previous C&AG reports. It pointed to driver testing as an area where only 'limited progress' was made in addressing concerns.
