From Arriva's Facebook:

Service Update. Services 1 and X1 between Darlington, Bishop Auckland and Crook/Tow Law are subject to severe delays due to a 5 vehicle accident at Redworth. We are trying to divert round the accident but the diversion route is backed up with heavy traffic

Just looked at the live map and seen a 1 running 42 minutes late.

Also no mention that this will have a knock on effect to the 5/5A! One is currently running 30 odd minutes late.

Also the X1 could have more struggles as Tow Law has had a fair bit of snow.