Winter Service Information

Keeping Traffic on the Move - Our Aim

We aim to help main road traffic move safely and freely in wintry conditions by spreading salt at the most effective times. 


Although we have no statutory obligation to salt roads, Transport NI receives sufficient funding to salt main routes in accordance with our aim.

Which Roads are Salted

  • We focus our resources on roads carrying most traffic.
  • A schedule of salting routes has been drawn up covering main through routes carrying more than 1,500 vehicles per day.
  • Other roads carrying more than 1,000 vehicles per day may also be included if they are in hilly areas or there are other difficult circumstances.
  • Special allowance is made for school and other buses by a weighting factor. For example a 40 seater bus is counted as 40 vehicles.
  • Almost 7,000 km (4,300 miles) of roads are salted which is 28% of the length of the road network and salting it costs £4.5M in an average winter.
  • This caters for 80% of all traffic. To cover 90% of traffic the length of roads salted would be doubled, at twice the cost.
  • On more lightly trafficked roads salt boxes or grit piles may be placed at hills, bends or junctions for use by the public.

When Does Salting Take Place?

Transport NI duty controllers are on call 24 hours a day in each of our 4 Divisions. Based on all of the forecast data and local knowledge, they will make the appropriate decision for their local area.

The season usually lasts from early November to late March but winter service will be provided outside this period if necessary.

Salt is not normally Spread

  • During heavy rain, as the salt will simply be washed away.
  • On dry roads, since ice will not form even if the temperature falls below zero.
  • In the middle of the night, because there is not enough traffic to turn the salt and ice into solution and make it effective.

The best advice to motorists is given in rules 203-206 of the Highway Code for N.I.

"When driving in icy or snowy weather:

  • drive with care even if the roads have been gritted
  • be prepared for the road conditions changing over relatively short distances
  • take care when overtaking gritting vehicles."

Heavy Snow Conditions

  • If roads become impassable due to deep snow we will divert all our resources to clearing routes in priority order.
  • In heavy snow conditions Transport NI will initially clear the Trunk Road Network.
  • The remainder of the salted network will then be cleared of snow.
  • Once the salted network has been dealt with, resources will be directed to the rest of the public network.

Can Ice Free Roads be guaranteed?

  • Ice-free roads cannot be guaranteed.
  • The Met. Office can only guarantee 80% accuracy in their forecasts. Northern Ireland has a high proportion of marginal nights when temperatures are very close to zero. This makes it more difficult to forecast than in colder countries where frost is more certain.
  • It takes up to 3½ hours to salt a route, so your journey may start or end on an un-treated section of the route.
  • If it rains, the salt will be washed away and the wet surface may freeze if the temperature falls below zero.

To download our Winter Service public information leaflet click here

Seasonal Advice for Driving in Winter

The links below provide advice to motorists when driving in wintry conditions.

Met Office

The Met Office web site provides a guide to Severe Weather Warnings and useful information on preparing for Winter.