What happens if a power outtage hits a running electric train?

[NekoMaster]

I've heard of power outtages stopping trains from running, that is, no new service until the power is restored....

But what happens if a train is running, especially a subway or high speed train and the power just "Dies" while the train is moving?

Are there automatic break systems that stop the train without power? Or will the train coast until it slows down or derails? I believe some trains have magnetic breaks that need power, so a power outtage would make these useless, unless the train has a on board back up to enable using the breaks.

[Leanden]

http://www.theguardian.com/uk-news/2015 ... -power-cut

[Geo Ghost]

Depends on the type of unit usually.
In the vast majority of cases, if not all, a lose of power from the overhead or 3rd rail won't put any brakes on. It'll just mean the unit loses traction power and some important systems.

This makes sense especially for CRE lines where there are gaps in the 3rd rail. Trains will travel without line power for a short distance until they come in contact with another 3rd rail.
Likewise with OLE lines, there are similar gaps or 'Dead Sections' in the overheads known as Neutral Sections. These are basically there to separate the different power supplies (in a nut shell that's it). Train passes through them, cuts power automatically, then regains it after proceeding back onto the live sections again.
Whilst the unit is 'coasting' with no line power, air brake systems are unaffected completely as they are powered from the auxiliary system - I.e, the battery. So a driver can still slow the speed of the train normally without power from the CRE or OLE.
Some tests have been done on trains running on very large battery packs that power traction motors... but I don't know enough about how their systems work to comment on it

The problem begins if you stop in a gap and no shoes are in contact with the 3rd rail, stopped in the neutral section of the overhead lines, or the power goes out completely. The train will be running most of the important systems using auxillery battery power (such as the radio, emergency lighting, marker/tail lights, PA systems etc). But the bigger and more important systems like main air compressors, battery charger, traction motors, MA-Set on certain older units etc, won't be running. If the train is stuck like this, the brakes will eventually apply fully as the train loses air. In a power-outage situation, that's not really a big problem as you just need to wait for the power to be turned back on. If you're 'gapped' (stuck at a stand in between sections of the 3rd rail) or at a stand in the middle of a neutral section with no gradient... you are stuffed basically. No power to get out of it, and you'll need another train to push/pull you out. It's a rarity, but does happen

Our Class 313s are a bit of a pain if they end up 'gapped'because the DC voltage from the shoes isn't carried between the train coaches or couplings, so it means you could gap just one end and end up stuck. If you gapped the end with just the MA set but the other end was fine, then all good and dandy! Just drive out using the powered end. If you gapped the end with the main compressor though and the air dropped too low... oh balls. Your brakes are now stuck on!
Whether or not the ones on the Southern Network have been retrofitted with jumper cables between the coaches from the shoes, I'm not too sure.


To sum it up...
At speed, nothing will happen apart from the train will stop accelerating and coast to a stand. Brakes wouldn't be affected however. Dynamics wouldn't work, but the air-brakes would still do all the work there. Can't speak for magnetic brakes however.
If however, complete power was lost to a train at speed and the train becomes dead (battery, line voltage, everything gone.) then yes, the full brakes would automatically apply as all the systems have been de-energised.

But anyway! Hope that answers your question

[Translink]

Some tests have been done on trains running on very large battery packs that power traction motors... but I don't know enough about how their systems work to comment on it

In 1939, the Great Southern Railway of Ireland experimented with battery trains, they got 4 units up and running in 1931 and the worked really well (or so they say). They could go 100 miles between charges which required 1 minute/mile.
https://www.google.co.uk/search?q=drumm ... CCgD&dpr=1

[supermop]

Sort of relevant - I once walked passed a B class tram in Melbourne that had got itself gapped on the insulated connector between regular trolley wire and the square at an intersection when a car in front braked suddenly. Eventually they evacuated the tram and the one following so that the following unit could 'bump' it along. Even tapping it at about 0.5 mph still made quite a loud noise.

[doktorhonig]

The problem begins if you stop in a gap and no shoes are in contact with the 3rd rail, stopped in the neutral section of the overhead lines, or the power goes out completely.

If it's a passenger train, it's no problem at all: http://www.liveleak.com/view?i=5f9_1393 ... comments=1

[Geo Ghost]

If it's a passenger train, it's no problem at all: http://www.liveleak.com/view?i=5f9_1393 ... comments=1

That is brilliant! Just goes to show how easy it is to get a train rolling.

[Translink]

If it's a passenger train, it's no problem at all: http://www.liveleak.com/view?i=5f9_1393 ... comments=1

I can't believe the river got into crap for that, he should have been rewarded for getting the railway up and running rather than holding the line up.

[Translink]

Sure, just take a look at level crossings on 3rd rail systems, the 3rd rail stops well ahead of the crossing.

[Geo Ghost]

I can't believe the river got into crap for that, he should have been rewarded for getting the railway up and running rather than holding the line up.

No he shouldn't. Sack on the spot for endangering peoples lives and not following proceedure. One of the primary concerns in any failure is to keep passengers on your train. If someone opens a door out of a station, let alone disembarks, it becomes an emergency situation as there are now people on the running lines.
ANY moving train, or train that can move is dangerous. Regardless of speed, and regardless of whether you're a passenger or track worker. It is still incredibly dangerous.

[Translink]

So apparently trying to help people is not allowed now? Seriously, people need to toughen up, so what they were on the running line? Track workers bes out on the running lines all the time, you really have to be a stupid idiot to be run over by a train, you can hear the wind gushing on the track when the train is far away

[Geo Ghost]

Anyone working on the track, or going lineside has to be trained to do so. Only those who need to do it are trained, and they are fully aware of what they are doing and their surroundings at all times. But even then some, there have been cases where workers have been hit. Newark North Gate a few years ago was one such example.

It isn't the responsibility of passengers to help a train. If it has started to roll back, the people behind would have been crushed and killed. If someone tripped and fell along the side the the wheel ran over their arm, then who would be to blame? If the train comes back into power with the AC system and starts moving under its own power, the people leaning on that train are at risk again. If the transformer were to blow and all the AC voltage feeds back through the track with people standing on it. if the adjacent line wasn't blocked and was open to traffic and someone walks round the corner into the path of another train...
So what you may ask? Rules are there for a reason.

It is rare you can hear a train coming until it is right on top of you. Especially today with modern electric trains and improved track work. You can't just 'hear them from far away'. Trust me, I have found that out many times and it is still rather frightening sometimes. Slow speed in a yard, or high speed on the mainline. Both are equally as dangerous as the other.
Going on or near a running line with the idea that 'Oh I'll hear it coming' is probably the reason so many people get hit by a train in the first place.

[Translink]

It isn't the responsibility of passengers to help a train.

Ever heard of "kindness" or "compassion?" It's not your responsibility to help that person push start their car, either, is it?

It is rare you can hear a train coming until it is right on top of you. Especially today with modern electric trains and improved track work.

Yes you can, you can hear the whooshing of the wind and the vibration of the track long before you can see or hear the train, especially with "improved track work," As track with concrete sleepers will carry sound further than track with wooden sleepers, as the concrete won't absorb the vibration and will send it along the track instead.

[Geo Ghost]

Ever heard of "kindness" or "compassion?" It's not your responsibility to help that person push start their car, either, is it?

It is not kindness of compassion. It is against railway law. Whether their rules are slightly more relaxed perhaps (though I doubt it) but certainly here that is a straight up sack on the spot along with a ORR investigation, legal action, and possibly even a prison sentence.
End of the day, passengers should never be allowed on or near a running line unless it is during an evacuation and all procedures have been followed.
It's easy to joke about 'getting out and pushing' and the idea is quite comical. The reality though is far from it. It is incredibly dangerous. A train is not a car.

Yes you can, you can hear the whooshing of the wind and the vibration of the track long before you can see or hear the train-

I've been lineside before walking around units and had trains shoot past me doing upwards of 90mph. Also been standing right next to units crawling along without a single sound apart from the occasional 'clunk' on the track. In fact, the first true shock I had of how quiet trains were was walking along a platform, looking up every 5-10 seconds or so for any trains. Then the next time I looked up, the train was passing me at about 15mph. Luckily I wasn't close to the edge at all, but that was the first time I realised how quiet trains really were and how truly easy it was for them to sneak up on you.
Take it from me mate. You DON'T always hear them before they are next to you. Especially if there is something between you and the origin of that train. Factor in the environment such as being out in the open, local noise, location, type of trains, and your own concentration... odds are unless you're looking in that direction at the time, you won't know of a train till it is passing you.
I'm not saying all the time, as you can sometimes indeed hear the vibration in the tracks, horn, or the train/unit itself. But to suggest that you'll always hear that is fantasy and leads to a ridiculous complacent which places you in severe danger.
Seriously, don't believe that you'll always hear such and everything would be fine. That's how people have gotten themselves killed before and it is very worrying when people simply don't understand the dangers and risks of a running railway. I hope this has explained things and I've changed your view ont he subject

[Translink]

Fair enough

[Pyoro]

Oddly enough there was another incident, this time people pushed a S-Bahn in Munich.


Maybe this happens more often then anyone thought and it just wasn't in the news before? ^^;


(on a personal note, I took that S6 to Tutzing precisely twice and both time I was delayed over an hour )

[Geo Ghost]

Good grief. The ORR and RSSB would flip their lid if that happened here

[Kevo00]

The Munich S-Bahn does seem oddly delay vulnerable.