More than 20,000 potholes were repaired on the road network around Hertfordshire last year.

The astonishing figure was highlighted to councillors on Friday, as part of a report scrutinising the value for money of highways services.

According to the report, all potholes – which must be five centimetres deep to qualify for repair – are fixed within 20 days. The most serious are fixed within 24 hours.

In addition to these ‘reactive’ repairs the council has a programme of ‘preventative’ treatments designed to protect the road and extend its life.

And at the meeting members of the county council’s resources and performance cabinet panel heard preventative work was more cost effective.

These schemes generally apply an additional layer of 15mm to 20mm of surface dressing or micro asphalt to seal the existing surface – halting further deterioration.

They cost between £4 and £8 per square metre, extending a road’s life by 10 years and reducing the need for urgent repairs.

However they are not effective if deterioration of a road surface has progressed too far – and they cannot be applied indefinitely.

Pointing to data that shows that the proportion of roads ‘requiring maintenance’ in the county is in line with, or ahead of, national trends – the report to the panel suggests the priority on prevention is proving to be cost effective.

“When benchmarked against statistical neighbours, Hertfordshire performs well in terms of the condition of its carriageway asset, validating the service’s decision to prioritise resources towards planned maintenance programmes, rather than reactive repairs,” says the report.

Across the county there are 5,100km (3,169 miles) of carriageway. According to the report the proportion of roads requiring maintenance have fallen to record lows – falling to two per cent of A roads, five per cent of B and C roads and 10 per cent of unclassified roads.