(06 Sep 2014, 4:02 pm)aureolin wrote X6 - Durham to Darlington, via this route: https://goo.gl/maps/sf26I
I don't think it's worth going head to head with Arriva's 7 straight down the A167, hence turning on to the A1 between junctions 59 and 60. This, and the short stretch along the A689 between junction 60 on the A1 and Sedgefield, would allow the bus to catch up to timetable if delayed in either Durham or Darlington.
It would of course provide new links, such as Darlington, Sedgefield, Coxhoe, Bowburn, Shincliffe, Durham Uni, and New Elvet, in what I'd reckon could be done in an hour. 9 minutes faster than the 7. If it were timed right, and linked with the X21 for connections, then you're providing an hour and a half express between Darlington and Newcastle. Very similar to the Pronto X21 between Bishop and Newcastle.
Potential operation for Crook too!
It would roughly take around the same amount of time as the 7 between Darlington and Durham. It would offer new links to Darlington from Coxhoe, Bowburn and Shincliffe and a faster service from Sedgefield to Darlington than the 21. Not sure if it would be a success though as Arriva used to run service 13 from Durham to Darlington and it carried not many passengers although that was probably because it used to take all eternity to get to Darlington, I did the 13 from Durham to Newton Aycliffe once when I was a kid and I lost the will to live as it took forever because it seemed to go via the world.