Nearly a third of Britain’s single carriageway A roads have white lines so worn out that they do not meet recognised safety standards.
The shocking state of the nation's road markings is revealed in the LifeLines Report which looked at more than 1,500 miles of the network.
The Road Safety Markings Association report revealed that of more than 60 single-carriageway A-roads surveyed, totalling more than 1,000 miles, on average 14% of road markings are completely worn out while just 29% of lines reach the acceptable level of visibility.
On one of the worst roads in the survey – a five-mile section of the A6135 between Ecclesfield and junction 36 of the M1 (Hoyland) – three-quarters of the markings are barely visible.
On larger roads, a high proportion of markings - 39% dual carriageways and 38% motorways - make the recommended rating used by the industry but there has been a significant drop in the quality since 2008, when 69% of markings on duals reached this grade and 49% on motorways.
Association national director George Lee said: “These motorways and strategic A-roads are managed by the Highways Agency, which has clearly specified standards for the quality of road markings.
“Two years ago, just two per cent of our major road network had markings that rated virtually non-existent. This figure has risen at an alarming rate, and now, nearly a tenth of the centre lines our trade routes are dangerously worn.
“Most of the single-carriageway A-roads in the survey are managed solely by local authorities. We are concerned that Highways Agency ratings for road markings have never been formally adopted by local authorities, leading to inconsistent maintenance standards on UK roads and the potential for the significant maintenance shortfalls identified in the report.
"The high risk of head-on collisions on single-carriageways means centre-line markings are critically important to guide road-users safety on these roads."