Maximum DMU Length
 

Hi All. I was wondering if anyone can tell me if there is a maximum length on a DMU consist. I have seen 3 and 4 car consists and joined consists but what about forming one that was up to 15 cars long that you could access from one end to the other.
Any thoughts??
Cheers

Scott

DMUs in Passenger Service can run up to 12 cars thats with Trailer Cars (3car units) being used as well I think the maximum with non Trailer (2 acr Units) cars is a total of 9 cars ie. 3x2car units.

The Par to Newquay line used to run 9 car 118 DMUs back in 70s
They also used to take a parcel van on the back of DMUs on the Barnstaple line,
ccmmick

Thanks for the feedback Gents. That's great. Do you happen to know what the limiting factors would be to going longer?

A general 'rule of thumb' is that, owing to platform lengths at many stations. the maximum length would be 10 cars (2 X 5 car units), or 12 cars (3 X 4 car units); these and other combinations may exceed this, but if you see longer formations, they would more than likely be either: A) failed units being rescued by other unit(s) already in service, or B) empty coaching stock workings, which have no need to call at stations, hence the relaxation of rules. I'm reliably informed by a driver friend that the former accounts for most instances of overlong trains.

Thats very true indeed but yet other issues include cost of runing ie..viable or not viable for a service to be formed of a certain ammount of cariages / units plus the fact that TOCs theesedays like to make as much money as possible and that to save money on running costs at the same time in what ever way they can ie..Arriva are very keen on saving money on fuel by means of encouraging economic driving.

If you take alook the skegness service in the summer and the use of the HST set on this route it is if im right formed of 9 cariages and from my experence of it it is always packed out therefore being viable for EMT to run as is also with the maximum lenghth as notibley this only calls at certain stations en route.

If they where to use say 4x class 158sor 156s making eight cariages and the runing of eight engines which efectivley would cost more money as there is more fuel being used compared to using a HST set with only two engines being used though much bigger engines there is still less fule being consumed therefore viable for EMT to run a HST set and not DMUs on this extra service.

Thanks so much for that feedback. The reason I ask is that I'm involved in a study that is looking at the replacement of a large loco hauled sleeper & sitter consists of up to 23 carriages with other more modern configurations. The platform length would not be a problem but I'm definately interested in the fuel consumption comments. We have also started to investigate noise issues with DMU's in relation to sleeper. The feedback we have so far is that the new generation DMU's are now much quieter. Any comment on that please?

In the UK, apart from at unsignalled halts, it is the signalling system that primarily determines the maximum train length that can stop at a station platform.

Chris

The idea of using a DMU for a sleeper service is just evil.

How dare you even consider it!

Even the quietest modern DMU's are surprisingly noisey and have a degree of vibration. I remember reading in a magazine that this is one of the reasons that NR here are leaning towards proper power cars for the next generation of Intercity express sets, where the contract to investigate the options was only recently signed. There will be a DMU derivative but I think its going to be for fast commuter routes only, with the longer range and Bi-modal sets having power cars when diesels are used.