(07 Nov 2019, 4:57 pm)Dan wrote
We'll find out the true answer to that once we start running the E400s.
The difficulty with the X21 is that it's a cross-town service. There's no where you can stop running a double-deck and start running a single-deck, both efficiently and without causing disruption to customers' journeys with a changeover.
With other services like the 60, they terminate in Park Lane Interchange, so you can quite easily have another vehicle step in on an evening.
On an evening the X21 runs as a 21 to Durham, so to me it wouldn't be much of a hassle to just change over at Durham and have 2 Streetlites going between Bishop and Durham. I'd also ditch the X21 and renumber it on an evening to the 21B since it's not express either