(20 Feb 2014, 11:13 pm)G-CPTN wrote Arriva used to (until quite recently) run coaches on the Newcastle-Carlisle 685 route. They stopped because the ageing coaches were becoming increasingly unreliable.
Now they have 'buses' (albeit with leather seats) - but the passengers are unhappy.
As far as coaches and buses are concerned there are (in some cases - subtle) differences, but to me, coaches have plug doors and, usually, high floors, but, specifically are geared for higher cruising speeds (or lower engine noise at cruising speed) and may have more sound insulation.
Nobody would want to travel 300 miles in a Routemaster.
However, what we describe as a 'bus' could be fitted with 'coach' gearing (rear axle ratio or overdrive gearbox) but might need additional low ratios for steep hill gradeability. That shouldn't be a problem nowadays with multi-speed automatic gearboxes. I know that ZF were offering a seven speed wide-ratio Ecomat 7HP600 at least 20 years ago (though it was mainly intended for heavy commercial vehicles).
I don't know what current buses (or coaches) are using.
I'm afraid I was always a supporter of the coaches particuarly when the X9 was launched with cascaded Volvo NX coaches it was a fantastic idea which, looked great on paper that we went with however the reality were it was impractical due to the loadings.
I am a great supporter of coaches on express routes such as X9/X10 and then 685. Buses aren't the right choice. When I worked for Ulsterbus all interurban work is provided by coaches at the Volvo b10ms and later Scania coaches.
NX cascaded levanter triaxle version would be perfect as some versions have up to 71 seats and the Scania engines is almost like a bus one so good for pulling away etc..
However there is no way GNE would consider this at the moment that said that in a few years unless they want to constantly buy new buses are going to need to think of something not sure what the right answer is though..