A COUNCIL is restricting the use of salt to preserve supplies during the ongoing cold snap.

Durham County Council is prioritising the use of salt to ensure all A and B-class roads are maintained, ensuring most bus routes remain open.

But the council will also attempt to keep open all main roads with steep gradients.

The shortage in expected deliveries of salt supplies has led to the latest re-prioritisation of which roads are gritted.

A statement issued by the council last night said: "Due to the current under-supply and future uncertainty regarding the supply of salt, it is necessary to prioritise gritting to all A and B roads throughout the county.

"This covers the vast majority of bus routes.

"Every effort will also be made to maintain main thoroughfares where there are significant gradients."

The council will continue to plough all routes given "priority 1 and 2" ranking in its winter road salting leaflet issued to all households recently.

But, from last night, only A and B category roads will be salted.

The council said it will keep the situation "under review", but as soon as more salt becomes available the situation will be "re-prioritised".

"It is important that everyone understands we are managing very difficult ongoing winter conditions with restricted supplies.

"So far we have spread more than 30,000 tonnes and have spent in excess of 3m maintaining the highway network and priority footpaths."

It has made up to 200 of its 'Streetscene' staff available to clear footpaths and town centres each day from mid-December.

Since the cold weather began, the council said it has received "significantly less" salt than it has ordered.

But the statement added: "The council continues to do everything it can to maintain the highway network and to keep footpaths clear, although we are reliant on having sufficient supplies of salt to enable us to do so."

The public is advised to be aware that while salt is good at preventing ice formation just below zero-degrees (freezing point) its effectiveness reduces considerably as temperatures decrease below -5 degrees.

Overnight temperatures have dropped to -8 degrees in recent days and are often not rising above freezing point during the day.

Reasonable traffic levels are needed to improve its effectiveness and to grind it into any lying snow, explaining why even well-gritted roads are taking time to clear.

High national demand for salt has led to the shortfall in the amount delivered.

The county council made sure all salt barns were filled at the start of the winter, but continued use of salt keeping roads open has meant it has become a difficult situation to manage.

Last night's announcement comes only two months after the council announced it had more vehicles and staff than ever gritting an additional 40-miles of bus routes, with an additional £1m supplied by the county's priority care trust used to ensure pavements and surrounding areas are made safer during winter months.