What determines the lifespan of railway vehicles?

Victor

What determines the lifespan of railway vehicles?

Age?
Mileage?
Milage at a particular speed / load?

thejollyrodger

when there is a massive pile up on the railways ?

John R

Victor wrote:

What determines the lifespan of railway vehicles?

Age?
Mileage?
Milage at a particular speed / load?

When the railway company buys/builds a replacement.

Unlike other forms of surface transport, railway rolling stock undergo extensive mechanical checks regularly; weekly to daily depending on the stock and mileage involved. They are constantly being maintained and repaired.

Power units generally expire long before coaching stock or the locomoive shells so it is not uncommon for locos to go through several power units in their lifetime. Some companies switch old ones out for reconditioned/new ones every few years as part of a regular maintenance cycle, it is quicker to do that than have the loco wait for it's original power unit to be returned.

There is a wide range of lifespans depending on the reliability of a class and the requirements of the operator. Compare the IE 121/141/181 class built 1960/62/66 most of which are still in use today and some are likely to see out another 10 years in service. On the other end of the scale is the BR class 58, built 1983-87 for power station coal trains, by the late 90's they were being replaced and most are now withdrawn.

The Mk3 coaches are a perfect example of perfectly good stock going far earlier than they could. The IE coaches were the last of this type to be built in 1984-86 and could well be the first of the type to be scrapped en-masse barring accident damage. the earliest examples of these coaches are the inter-city 125 coaches built between 1975 and 1980, most of these are still in service and will remain so on top rank duties for at least 5 more years or more. The reliability of the power cars and the ever encroaching nanny regulations will see them off long before any mechanical defects become a problem.
IE have stated that they will keep the Cravens coaches (1963) for specials not Mk2 (1972) or Mk3. This is not because they are better coaches but because they arebetter suited to lying around idle for weeks on end than the Mk3s and the Mk2s have been poorly maintained leading to serious body corrosion.

In the poorer parts of Asia and South America there are entire networks running with colonial era steam traction and rolling stock, they have been unable to buy replacement stock and like all the 50's American cars in Cuba have had to keep the vintage stock running.

MarkoP11

Its a function of design, typically you are looking at 35 years. Solid build quality has a large say as well as continuing usefulness. There are electric locomotives in Europe dating from the 1930's.

If kit is troublesome it will get ditched as soon as possible, when the A and C class locomotives gave CIE trouble, CIE begged GM to sell just the engine and in doing so turned a machine destined for the scrapheap into a machine which lasted 40+ years

The original DART fleet was designed with a 30 year life through the refurbish program they are expected to last till 2025, 42 years. Why ? because they are well built and well looked after. A lot of risks where taken when the DART was ordered, great faith was place in technolgy to delivery lower running costs and high reliability. It worked in Dublin because the engineers from CIE and GEC tested it to death and applied a lot of TLC which ironed the bugs out. The technology under the floor was cutting edge for 1983 and came from GEC of the UK not Germany. The whole electronic package was designed from scratch, fixed frequency chopper drive had never been done in a DC train until then.

The trusty cravens coaches date from 1963 and continue since they have aluminium bodies and thence can't rust, they are simple require minimal maintenance and can be left parked up from weeks on end without any worries

The MK2 had a weak point of corrosion which makes them structurally unsafe, the MK2 was not really a true modern coach at least until the d revision which marked the change to air conditioning and sealed windows, they where a transition design

The MK3 is the first truly modern coach, it may come as a surprise the entire engineering concept is based on a toilet roll. The design dates from 1969 and they where still being built in 1988 to the exact same dimensions which is a testament to the massive step forward. The Irish batch incorporated some improvements but the bodyshell and suspension where left alone. It is still the cheapest and lightest air conditioned 23m 200 kph coach in the world. It rightly holds legendary status. Approaching 30 years in UK service the HST version will be around till at least 2012. There is no reason why the Irish batch can't last till 2020

Victor

MarkoP11 wrote:

The MK3 is the first truly modern coach, it may come as a surprise the entire engineering concept is based on a toilet roll.

I'm not sure if you've said that quite right. :D:D

MarkoP11

Victor wrote:

I'm not sure if you've said that quite right. :D:D

100% right, the toilet roll inspired the lightweight tubular integral bodyshell which made the MK3 one of the safest coaches in the world in a high speed crash

Every coach built since has adopted a similar design

antoinolachtnai

It is certainly difficult to compare the lifespans of vehicles like buses with rolling stock. The environment is different, but more importantly, the service regimen is completely different like has been said. A railway carriage may be rebuilt and refitted a few times during its lifetime.

To understand the economics, you have to look at depreciation schedules and depreciation per mile travelled or per potential or actual person carried.

When considering the economics, you also can't separate rolling stock from the rails that the trains run on. You have to take that cost into account as well. You can think of the rails and the rolling stock as two parts of the same machine. Issues with the rolling stock (like very heavy locos) will cause stress on the rails. The same also works in the opposite direction - tracks that are somehow below-par will have an impact on performance (and possibly also on lifetimes, but I couldn't say for sure).

But in broad general terms, I think it is fair to say that the things that cause wear on the train would probably be:

- time - stuff slowly corrodes whether you use it or not

- distance - the meta and electricall components that rub against each other wear out

- weight carried. For heavy goods trains, bigger weights are going to cause more wear. I wouldn't think this is such an issue for passenger trains though.

- people carried. Just having a lot of people in there must cause wear on the trim and so on, but there wouldn't be too much wear on the machinery as a result.

MarkoP11

The accounts have rolling stock depreciation life as 20 years max. Different lifespans apply to track, until recently it was not uncommon to have track from the 1890's still in service. This is the classic issue rail operators carry the depreciation costs of the infrastructure for decades while the bus operator gets a new road, don't see Dublin Bus paying for the QBC's do you ? nor do you see the government accounting for the depreciation costs of a motorway.

Trains tend to last better if in continous use, sitting around has major negative effects on parts, air conditioned coaches start to eat themselves from the inside if left unplugged for more than a few weeks

To avoid rust and reduce weight extruded aluminum bodyshells became common in the mid 1990's.Stainless steel is used in the Japanese built DART fleet, again it can't rust and is actually stronger than mild steel

Most rail vehicles are totally rebuilt at least once in there lives. Axles, wheels, springs, dampers are replaced frequently as a routine matter. Full rewiring is fairly common, electrical parts can be replaced. Rubbing plates etc are bolted on, if it wears it is designed to be replaced. The core frame suffers only the loading and faitgue, which are non issues if properly designed, that said welding up cracks is fairly routine. Engines get new pistons, crankshafts etc. At the end of a trains life about the only thing left from the orignal is the bodyshell and bogie frames. Parts are replaced more on a distance travelled than an age basis. Provided the bodyshell doesn't corrode and parts are available the train can go on and on the question becomes is it cost effective to keep going since there comes a point when you reach the design life of parts. Then safety people don't like old equipment. They planned in the UK to reuse all the underfloor gear from 45 year old trains by sticking a new body on the top in recent years. The old kit worked and was more reliable than 21st century gear

antoinolachtnai

Well, on the depreciation front, the investment in new parts, rebuilding and so on is regarded as a capital cost, surely? That means that as you invest more money in the vehicle, the projected lifespan is gradually extended. As I understand it, that's why rolling stock and other heavy goods nearly always lasts longer than the initial projected figure in the accounts.

I can't see how carrying depreciation for decades would be an issue. Surely it is better to spread depreciation over decades than to take it over just six years? Obviously, the rails need a maintenance investment along the way, which lengthens their lifespan (and that is why they last such a long time, and why they cost so much to keep open).

It's certainly great fun to try to compare the cost of a QBC with the cost of a railway line! I'm not sure it's a particularly productive pastime though.

On the one hand, the QBC can be maintained less expensively and with less disruption than a railway. On the other hand, the QBC only makes sense in the context of existing major road projects.

In practical terms, the depreciation on the road network is the total expenditure on roads minus the expenditure on new roads and improvements. They don't account for it as 'depreciation', because public sector accounting is done more-or-less on a cash basis. In theory, depreciation is not the same as maintance costs, but in practice it amounts to more-or-less the same thing, provided the government has a proper maintenance schedule in place. The bus company does make some contribution to this cost through road and vehicle taxes.

Thanks for the good description of lifetimes of rolling stock.