Greybeard33
Established Member
...so you now agree that the Northern 769s, maintained at Allerton, will likely have worse availability than the Northern 319s maintained at the same depot?
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Porterbrook Cl.769 'Flex' trains from 319s, initially for Northern
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Where did I say that?
Greybeard33
Established Member
Your argument in post #4097 was that the 769 traction motors will have an easier life than the identical ones in the 319 and so will be more reliable, offsetting the failure rate of the 769 gensets. I pointed out in post #4105 that that is unlikely to be the case on Northern 769 routes.
In any case, do you have any statistics to support the assumption that unavailability of Northern 319s is mostly due to traction motor failures, versus other causes such as door faults or wheel flats?
samuelmorris
Established Member
I'm highly doubtful the longer service life of traction motors owing to reduced workload will anywhere near offset the reduced reliability of introducing diesel traction power to the units, especially in a conversion project rather than an original build. Best case scenario I'd expect the 769s to have a similar MTIN to 150s. Still an improvement as that's one unit rather than two coupled together either of which could fail, but I'm pretty confident they won't reach the reliability levels of EMUs (other than when operating in AC-only areas).
We never seem to hear of 150s failing in service.
superkev
Established Member
Difficult to see how traction motor life will be improved much if at all as there still in use when in diesel mode admittedly at a lower rating.
Reliability prob worse as either an electrical fault or a diesel fault would cause a failure. Mitigation may be the diesel may get you home (slowly) if the pan or 25kv bit fails.
K
samuelmorris
Established Member
With MTIN figures in the 8000 range for Northern (and 4000 for GWR), it will definitely happen, regularly.
In the event of failure of the 25kv supply, or its collection by the train, diesel mode would get you home at the same speed that it would on non-electrified sections of line, i.e. at 75mph max rather than 100mph max, but there isn't all that much scope for 100mph running between Bolton and Alderley Edge, for example.
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samuelmorris
Established Member
Last time it was reported it was about the same, 8000. The most recent month recorded at the time the annual figures came out was much better at 16000 but it's not obvious whether that represents a particularly good month or genuine improvement as the annual average for both 2017 and 2018 were almost the same (8200 and 8400 respectively). West Midlands' examples which were also panned for unreliability versus the 321s they replaced fared a little better at 12000. By comparison, Northern's 323s score around 15000.
Back 2 years ago the class 319 was said to have a MTIN across the whole fleet of around 20,000 Hrs. The gensets use mature class 3b designs and have been used extensively on other European units with the same ABB alternator. So in service with partial DEMU usage, the overall MTIN might drop slightly, but the engines will be from new so it is doubtful that it would drag the reliability down significantly. Compared with a 2x2-car class 150 combo where the four car train reliability would be much lower than the current 8000 MTIN range, the 769 should reach an MTIN in excess of 15,000. If one 2-car unit of a 2+2 class 150 consist fails, not only is the already lower passenger capacity halved, there is also the problem of 72 tonnes of non-functional DMU blocking the line.
samuelmorris
Established Member
I think the general consensus was the reliability of 319s dropped considerably when they moved from GTR to other operators. The 321s at GA are in the 20,000 range so that's the expectation with Mk3 EMU stock (the decrepit 317s notwithstanding). As stated above, the MTIN MAA for 319s at Northern was in the 8000s for both 2017 and 2018.
The 800s used new engines on a well-reviewed electric traction platform but they had a myriad of problems running on the correct power mode. I could yet be pleasantly surprised but I wouldn't be too surprised to see similar on 769s at least for the first 12-18 months of use.
If the current MTIN is around 8000, the impact of the new kit will have less of an impact than it would on 20,000 levels, so for practical purposes, the impact might be negligible on services upgrading from 2x2-car 150s.
... and the traction electronics/motors will be subjected to a maximum of around 60% of their continuous rating.
samuelmorris
Established Member
if this were new stock replacing 319s I'd agree but as they're conversions from 319s that will only add complexity, I would still expect them to be a derivative of that level of performance - e.g. if 319s had an MTIN of 20,000 before, perhaps we'd expect 769s to gradually work their way up to 12,000. Being that the 319s at Northern are only achieving 8000, 769s will therefore probably only reach, say, 5000, unless whatever issues that give Northern's 319s such a poor score get resolved. If it's simply a byproduct of how few of them there are versus the whole fleet and staff being less experienced with them, then 769s are not going to help in either of those situations unfortunately.
The 769s are units with additions in as much that the gensets are a substitute for the 750VDC source. The two gensets wok together to establish and maintain the bus line voltage under most load conditions. There are of course some functional items that also connect such as the hotel supply inverters, but that would be a system integration add-on and problems there would most probably show up with the design still bedding-in. We do know that there was an issue where the two generators would not load-share correctly, sometimes causing instability in the DC bus. That we are told has been resolved, so the subsystem that creates the bus voltage from diesel power should be largely dependent on the genset reliability itself, hence the selection of a well proven design elsewhere in Europe. The rest of the train's hardware sees the DC bus much the same as when the 319s were running on 3rd rail. So I would not expect any significant change in the reliability of that subsystem.
As with any rolling stock introduction, most of the posts in this thread about how the trains will behave on introduction are speculation, some suitably flavoured with hope or advanced schadenfreude.
So, 8000 miles per technical incident for 150s, which equates to about three per day over the whole of Northern. I've seen 'technical incident' defined as one which causes a delay of at least three minutes, well lots of things can cause a delay of that sort of magnitude, so I'm not surprised that I don't seem to hear about them.
Compare that with the following catalogue of disasters from 4 May 2016, all presumably involving 319s.
Compare that with the following catalogue of disasters from 4 May 2016, all presumably involving 319s.
samuelmorris
Established Member
Of course, and yes I expect most of the issues that crop up will be related to the 'bedding in period', however, with the shorter lifespan of these units, that bedding in period will be a greater proportion of their working life. It took 18 months for the 800s to reach a similar failure to that we're discussing here (7000-10000 MTIN and on much longer distance diagrams so worse in practice) so expecting similar for the 769s, if/when they are finally introduced seems reasonable. If they do finally enter service, say next Summer, that means we'll probably be well into 2022 before they surpass the reliability of the DMUs they are replacing.The 769s are units with additions in as much that the gensets are a substitute for the 750VDC source. The two gensets wok together to establish and maintain the bus line voltage under most load conditions. There are of course some functional items that also connect such as the hotel supply inverters, but that would be a system integration add-on and problems there would most probably show up with the design still bedding-in. We do know that there was an issue where the two generators would not load-share correctly, sometimes causing instability in the DC bus. That we are told has been resolved, so the subsystem that creates the bus voltage from diesel power should be largely dependent on the genset reliability itself, hence the selection of a well proven design elsewhere in Europe. The rest of the train's hardware sees the DC bus much the same as when the 319s were running on 3rd rail. So I would not expect any significant change in the reliability of that subsystem.
As with any rolling stock introduction, most of the posts in this thread about how the trains will behave on introduction are speculation, some suitably flavoured with hope or advanced schadenfreude.
I'm sure similar days have had a much longer laundry list of failures across the 142, 150 and 156 fleets but so what? The 319 failures were noteworthy because they were recent additions that were performing far worse than they did in their previous role. A day featuring numerous DMU failures at Northern would just be a bad day at the office. I'm not sure what point your post is making.
Greybeard33
Established Member
Per unit MTIN can be better when operating in multiple than solo. For example, a brake compressor failure in a solo unit can be terminal, but it may be able to keep going if paired up. Or a double formation may be able to keep to time with one motor or engine failed, whereas a single unit would rack up delays. I believe the 319s normally worked in tandem at Thameslink, whereas Northern uses them individually.
Also there is no direct correlation between MTIN and the proportion of the fleet available for traffic. Some types of fault can be fixed quickly, so that the unit is back in service the next day. Whereas in other cases repairs may take days or even weeks. Some faults do not show up at all in the MTIN statistics, because the unit is able to complete its diagram without delays or cancellations, but nevertheless require the unit to be withdrawn from service for repair (e.g. a wheel flat).
Therefore a given fleet can have a good MTIN but poor availability, resulting in short forms, or vice versa.
Also there is no direct correlation between MTIN and the proportion of the fleet available for traffic. Some types of fault can be fixed quickly, so that the unit is back in service the next day. Whereas in other cases repairs may take days or even weeks. Some faults do not show up at all in the MTIN statistics, because the unit is able to complete its diagram without delays or cancellations, but nevertheless require the unit to be withdrawn from service for repair (e.g. a wheel flat).
Therefore a given fleet can have a good MTIN but poor availability, resulting in short forms, or vice versa.
Not necessariy, much to the howl of commuters, there were still 4-car trains in the peak, only being alleviated after eight 377/2s from Southern and 23 new 377/5s were parachuted in to lengthen some of the most crowded trains. 4-cars was often what turned-up off-peak especially during leaf-fall season.
Although I used the railway expression MTIN, which is an operational metric, I had in mind MTBF with which I am more familiar, as ultimately most failures on a mature product are consequences of individual system components failing. For instance, when one of the four class 319 motors fails, it might not result in immediate removal of the unit from service even if operating singly in the NW*, but it would still be logged as a failure somewhere (I hope).
* I believe that the exceptional gradients in the TL core would probably rule against running a single unit with a motor not working.
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The class 800s (and all new trains) have failures and malfuctions that are part design related, and part physical hardware infant mortality related which in itself can be design issues. Hence the progression to the stable part of the reliability cycle when random failures contribute most to the MTBF. I believe that the subsystems used when running under wires (pantograph/transformer/rectifier and traction electronics/motors) are mature items and run as they have been for up to 30 years. The new subsystem, genset and a few additional integration items such as contactors and earth wiring, although new manufacture and design proven on other railway vehicles (genset) will have the not unexpected early life issues, but that would be considerable less than experienced on all-new complex trains like the class 800/802/803 trains.
samuelmorris
Established Member
I do genuinely hope you're right, but even though it was the electric traction side that was changed, I feel similar could be said about the 321 Renatus project - that's a conversion of a Mk3 EMU with some of the existing infrastructure left in place and new traction technology fitted. As of October 2018 (I can't remember how long that is after the units were introduced but it's at least a year isn't it?) the Renatus 321 fleet had not quite reached 10,000 MTIN as an annual average, versus the original units' 21,000 (rapidly descending from over 30k the year before), so still less than half as reliable than they were before conversion.
Greybeard33
Established Member
Hmm. The flaw in this line of reasoning is that the MTBF/MTIN of the unit is driven by the least reliable component. If one critical widget keeps failing every other day, it is little help if all the other subsystems and equipment work flawlessly for thousands of hours. Certainly there are less new subsystems and equipment on a 769 than on all-new units, but that only reduces the risk of a design issue causing chronic unreliability. It does not mitigate the effects of such an issue if it is actually present.
A design proven on other vehicles can still have major unanticipated issues, due to differences in the installation or interfaces. The mature engine on the Class 230 was let down by the unexpected problem of pollen clogging the radiators. The "all-new" 195s, 331s, Mk5s and Mk5As are actually adaptations of mature CAF designs to the British loading gauge. Most of their sub-systems and equipment were proven on other CAF rail vehicles, but that has not prevented major issues on entry into service.
We will have to cross our fingers, touch wood and hope for the best for the 769, but the development issues that have delayed the programme do not inspire confidence in the robustness of the engineering design processes at Porterbrook/Wabtec.
Class 170101
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Reduced carbon emmissions at source.
You don't need the "at source" bit, maybe 5 or now years ago, however there's been some significant changes to the way our electricity is generated so that it is significantly less reliant on fossil fuels.
First up we now use ~15% less electricity than in 2010, with it being the lowest since 1994 and the lowest per person since 1984.
Next the use of coal has fallen from 30% in 2014 to 5% in 2018 (which is actually a bigger fall than those percentages indicate as the amount of electricity being used has fallen). With gas, although it has increased a little since 2014 it is still a lot lower than in 2010.
Renewables have already exceeded the predictions made in 2010 for 2020, with more due to come online in the next few years.
Of course we are still a long way short of where we could be, however there's still a good environmental case for the electrification of the rail network.
The other thing to bear in mind is that there can be advantages to the traveling public from electric traction over diesel trains. Although there's some doubt over the actual impact from the "sparks effect" due to it also often resulting in increased in frequencies which increase rail use anyway regardless of what type of power is used. The advantages tend to be:
- there can often be an increase in capacity due to the length of electric trains (typically 4 coaches) trending to be longer than diesel trains (typically 2 or 3 coaches)
- the trains are quieter
- the trains are more pleasant to be near (no diesel fumes)
- the trains are cheaper to lease, fuel and maintain, as well as there being a much larger overall fleet size, which makes it cheaper and easier to lengthen trains when they get busy (up to the maximum length which the routes can accommodate)
- is easier for people to see that they are doing the right thing environmental
Although these may not increase passenger numbers as much as increasing frequencies they are all going to have a small impact.
If they create enough of an impact then it could then lead to an increase in frequency.
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a_c_skinner
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We don't actually need to consider the immediate or even decade-al case for electrification because the change we need to make over the next three decades demands electrification of any busy line unless a new technology for self powered units comes along. Battery will hinge on most/many miles being electrified. Hydrogen at present probably the same if I've understood range limitation (and hydrogen manufacture!). Should we electrify Bolton to Wigan, indeed Wigan to Southport are debates that we need to abandon and move on to a different understanding with cost benefit overtaken by simple needs. All the above about power generation is of course true. Diesel bi-mode too is a time limited technology, but happily the 769s are time limited too (though they are spinning that out by their tardy progress!).
samuelmorris
Established Member
This is definitely quite significant - the RHTT with its pair of 37s visited Liverpool Street a week or two back when I was in the station and in that relatively confined space the fumes that had built up meant I could hardly breathe, there was a thick haze blanketing those platforms. An unusual case, but it's a timely reminder of how things used to be and in the case of stations like Birmingham New Street, still are to some extent.
edwin_m
Veteran Member
To get the power of four cars of a 150 into half the space (two gensets versus four underfloor engines) they must have packed things in a lot more. I hope the cooling doesn't let them down when it gets round to next summer.
I think, but I'm not certain, that you intended to refer to just coal rather than coal gas, which went out in the 60s.
Certainly the electrical generation side has done better than expected in decarbonizing, although the reduction in consumption may be partly due to industry being exported to other countries where the generation mix is less environmentally friendly. However on the whole the UK is heading for missed targets on decarbonization, with transport emissions one of the main offenders. There's actually an argument to say we should accept continued use of diesel traction on routes that are too lightly used for electrification, because battery or hydrogen will increase costs or reduce capacity and result in more people driving instead.