The BYD deckers are perfectly capable of fitting under that bridge btw, but low bridge rules have gotten tighter and the Enviro400s only manage to do the 6 because they always have done the 6 since 2011 and taking them off wouldn't make sense. I don't doubt that these tighter restrictions are for the best, but at some point when the Enviro400s get critically old (2029ish), either the BYDs are going to just have to do or the 6 will face becoming single deck only.What do you do with the 6? Arguably it struggles with the lower frequency and single deckers- upping the frequency is a lot more resource and cost. Deckers are simple but nothing made to fit...
That will be a hard decision to make. The BYDs are unfortunately proving themselves to be terrible buses at 5 years old, and a notable problem they tend to have is with the kneeling system, something which is vital to keep in order if you're wanting to take a bus under a tight fit of a bridge like Busby, and it is seemingly a lot more difficult to work with than the system on an Enviro400.
Drivers are also told to take any bus that leans to one side off the road, but sometimes you will get the odd driver who doesn't notice or forgets it's an issue, and a leaning bus could be enough to cause a collision.
So the Enviro400 stays on the 6 for now because it always has done the 6. After that, I won't be surprised if it gets put down as a strict single deck route.
