Common fleet mileages and lifecycles

[scosutsut]

As someone that works outside the industry but have a keenness in understanding it, I wanted to ask these engineering type questions knowing fine well there won't be a hard and fast answer, just looking for general responses.

Big fleets (Stagecoach/First/Arriva/NX Group/Lothian etc) all generally speaking run vehicles to a ball park figure of 15-20 years before they are retired.

I'm talking about conventional diesel buses here, say current generation stuff reaching these age milestones - Dart SLFs, Tridents, early B7RLEs, B7TLs etc.

But what sort of mileage would you say is customary for them to rack up in that lifetime, as my only reference point is cars - where anything north of 100k miles is seen as scary - I'd imagine service buses will rack these sort of miles up multiple times over.

Also, typically, how much of a 15 year old buses drivetrain is original? Will it be original engine? Original turbo(s)? Original gearbox? Original axles, for example?

Are certain types, or certain vehicles used in certain ways more prone to major failures and what sort of drivetrain failure of typically the end of the road, and what sort of thing is just replaced as a matter of routine?

Just curiousity, I'll emphasise again this is all a) subjective to use case of the vehicle b) operator maintenance standards and c) luck of the draw to an extent - I accept there are no solid rules here.

 

[Tom Gallacher]

It almost certainly won't be the original engine or at least it will have been rebuilt within the lifetime of any bus. With a bus, as opposed to a coach, you have to factor in that any engine will have probably done the equivalent of double whatever mileage the tacho shows due to the amount of time it spends idling at stops, lights and general traffic conditions in towns.

 

[L401CJF]

Regarding engine life it really is down to a mix of maintenance quality ie service intervals etc and the type of engine itself.

For example 13 plate Volvo B5LH Hybrids are blowing engines left right and centre. Whereas the R plate Scania L113CRLs we had with First Birkenhead all lasted the full 15years on original engines. Cummins L10s are notoriously reliable too, of the 36 Cummins engined Volvo Olympians at Arriva Birkenhead I believe only 2 had replacement engines during their 15years with Mtl/Arriva.

Regarding mileage, it depends on the routes the bus does, does the operator run late shifts or finish at tea time etc. 13 plate Hybrids at Arriva Birkenhead (7yrs old) are all around 400,000 miles now.

A number of the 2005 Scania L94UBs at First/Stagecoach Birkenhead had clocked over 1million miles by the time they were withdrawn in 2016/17.

 

[busken]

Obviously buses have a harder life, short journeys and a lot of stop/starting, but trucks with the same or similar drivetrains can easily do 1,000,000km+ with the original engine, gearbox and drive axle. The company I used to work for had vehicles which were multiple shifted doing in excess of 300,000k a year.

 

[Brooke]

Obviously buses have a harder life, short journeys and a lot of stop/starting, but trucks with the same or similar drivetrains can easily do 1,000,000km+ with the original engine, gearbox and drive axle. The company I used to work for had vehicles which were multiple shifted doing in excess of 300,000k a year.

My experience in the trucking industry is similar: long haul, trunkers easily managing 250k km plus per year, and being run for five years from new before much work was done.

Mostly it was not the drivetrain that started to break down first: it was the electrics, plus anything which could rattle or vibrate apart (think mudflaps, light brackets, air deflectors etc).

I imagine it’s similar with buses and coaches: drivetrain is expensive but lasts a good while, ancillaries are quite cheap but replaced at higher frequency.

 

[CN04NRJ]

Mileages can vary wildly between the same batches - out of the 351-400 batch of B9TLs at Lothian some are north of 600k miles while the rest are just passing the 400k mark.

Some of the 13 plate B7RLEs are on 500k miles while the 13 plate 7900s are all around 320k.

When I left Cardiff Bus to move here all of the 57 plate Scania N230UDs were on around 270k miles, while the equivalent age B9TLs here were on almost double that. Mileage can vary wildly even with the same operator depending on what kind of work they're used for.