Two trains on the same track

[MarcVD]

I just read an article in the last edition of the French railways magazine "rail passion", explaining that French railways are currently testing a new signaling system that will allow two trains to share the same track in stations, as a way to increase the capacity of heavily congested stations without having to add new tracks.

I'm a bit surprised to read that a special signaling system is needed for that. As far as I remember, this has been standard practice in Belgium with no special devices needed, other than an entry signal that can display the "admission on occupied track" aspect.

What is the situation in other countries ? Is it done on a regular basis and, if yes, are there special signals or devices deployed for that purpose?

 

[DanielB]

In The Netherlands a specific aspect is used as well. The entry signal will display flashing yellow which admits a maximum speed of 40 km/h and instructs the driver to continue by sight.
Most common use is however to couple two trains. Using the same platform by two trains in this way is less common.

When platforms are to be used by multiple trains simultaniously, there often are points in between trains and those are protected by signals (splitting the platform in an A- and B-side)
There are exceptions: in a recent refurbishment the points between platform 5A and 5B at Amersfoort Central where removed and the boundary between the two was moved. Those two platform phases are now separated by signals only.

Using one platform by multiple trains would require instructions to the driver as well, as most larger stations where this may happen have signs indicating where the driver has to stop. And obviously he'd have to stop somewhere further along the platform when a second train should fit behind it.

A unique situation is present at Amsterdam Central station where so called "middenvoetbrugseinen" are present (which got their name from being underneath the foot bridge between both former signal boxes). These signals have a red aspect (stop) and a white aspect (no specific order) and where used to enable parking two trains head-to-head. Their third aspect is covered by a yellow triangle to distinguish them from regular signals.

 

[StephenHunter]

We have A and B platforms in the UK as well.

 

[JonasB]

It's very common in Sweden and is perfectly normal on many stations.

I'm not sure what kind of signalling is needed though.

 

[AlexNL]

The "special signalling device" the French need is... a mid-platform signal.

 

[stuving]

I was puzzled by that too. The key seems to be in their operating rules, and the amount of supervision needed to share a platform. That limited the number of times it could be done to seven per day (at Rennes). So if you want to run an hourly service (or more) of trains originating here that depart in opposite directions, and are short of platforms, this is cheaper than building more. Having platforms 400m long helps, of course.

 

[jamesontheroad]

It's very common in Sweden and is perfectly normal on many stations.

I'm not sure what kind of signalling is needed though.

Although I have noticed that some Swedish drivers proceed very cautiously in this circumstances.

There’s a moment every morning when trains from Vännäs and Örnsköldsvik arrive almost simultaneously at Umeå Östra 2a/2b. They tend to enter the station as slow as 10km/h, perhaps because of the heightened risk involved with stopping distances in snow and ice.

 

[AndrewE]

The "special signalling device" the French need is... a mid-platform signal.

except that signal overlaps seem to preclude general use of that here. I don't know how it is that it happens in some places but not others.
2 trains in the same platform used to be common, indeed stopping a train briefly at a red signal then clearing it was equivalent to a "calling on" signal and told the driver he was entering an already-occupied section.

 

[edwin_m]

except that signal overlaps seem to preclude general use of that here. I don't know how it is that it happens in some places but not others.
2 trains in the same platform used to be common, indeed stopping a train briefly at a red signal then clearing it was equivalent to a "calling on" signal and told the driver he was entering an already-occupied section.

Some UK stations just signal a second train into the platform with a subsidiary aspect, whether they are joining together or staying separate (Derby, Nottingham). Others have a mid-platform signal with a short overlap and a correspondingly low approach speed (Birmingham New Street, Bristol Temple Meads, Manchester Piccadilly P13/14), which usually also have subsidiary aspects to allow trains to be joined in one half of the platform. I can't think of any terminus with a mid-platform signal except those where there is a set of points near the platform end that necessitate a separate signal for shorter trains that don't foul the points.

I guess the choice is all down to risk assessment. I imagine curved platforms, where the driver may have a limited view of a train ahead, make mid-platform signals more likely.

 

[Taunton]

I can't think of any terminus with a mid-platform signal except those where there is a set of points near the platform end that necessitate a separate signal for shorter trains that don't foul the points.

What were/are the signals at London Victoria, which was specifically built like this 100 years ago for electric services. First train in stopped at the buffers, second in stopped behind it. First train then departed via a crossover to a middle road, second train pulled forward to the buffers, third train came in behind it. And so on.

 

[30907]

What were/are the signals at London Victoria, which was specifically built like this 100 years ago for electric services. First train in stopped at the buffers, second in stopped behind it. First train then departed via a crossover to a middle road, second train pulled forward to the buffers, third train came in behind it. And so on.

Normal signals (colour lights from the 30s) were used to protect the crossovers.

https://www.wbsframe.mste.co.uk/public/Victoria_Central.html
As far as I can make out from the linked plans, the Middle Roads were not signalled for arrivals.

Interestingly, the yellow aspect was used on the SR for admission to an occupied platform. where now a subsidiary would apply - remember hat it was standard practice to leave a 3-car plus trailer set on the buffers mid-day.

 

[edwin_m]

What were/are the signals at London Victoria, which was specifically built like this 100 years ago for electric services. First train in stopped at the buffers, second in stopped behind it. First train then departed via a crossover to a middle road, second train pulled forward to the buffers, third train came in behind it. And so on.

I was thinking of the outer end of the platform. For example some platforms at Manchester Piccadilly have converging tracks which can't be used if the train occupies the full length.

I assume Victoria would have had a mid-platform signal protecting the crossover, but whatever was acceptable 100 years ago would probably be very different now. Crossovers near buffer stops are usually controlled by ground frames so don't have any signalling.

 

[iknowyeah]

Surely they already have the basis of this signalling, otherwise how are locomotives signalled in and remarshalling done?

 

[Re 4/4]

The "special signalling device" the French need is... a mid-platform signal.

I seem to remember that the way it's done in parts of France at the moment is that a member of station staff places a portable mid-platform signal on the platform itself. This obviously has staff and time costs.

Edit: here is an image, that I copied under "fair usage" rules from a post by user Schwellenmaus on the Swiss rail forums.

 

[Pakenhamtrain]

We just use a low speed caution(Red over Red over Yellow) if two trains need to occupy the same block in Victoria.

 

[JonasB]

Although I have noticed that some Swedish drivers proceed very cautiously in this circumstances.

There’s a moment every morning when trains from Vännäs and Örnsköldsvik arrive almost simultaneously at Umeå Östra 2a/2b. They tend to enter the station as slow as 10km/h, perhaps because of the heightened risk involved with stopping distances in snow and ice.

Snow and ice can increase stopping distances. But it might also be the case that ATC limits the speed to 10 km/h, that can happen in certain situations.

 

[MarkyT]

I wonder if this is some sort of supervised permissive working arrangement where a localised 'moving block ' ATP overlay using ETCS equipment exists just in the platform and it's approaches from the protecting signal, allowing safe separation to be maintained at moderate to low speeds.

Traditional unprotected permissive working has always been allowed in platforms for various purposes, but it is always more risky than absolute authority into a clear section, especially a concern if passengers are aboard either train involved. Hence new installations heavily discourage it where possible or require very detailed risk assessment and appropriate mitigations. Without mitigations, It would not be permitted in UK for instance for repeated entry of following busy full length commuter trains into platforms still partially occupied by preceding long trains departing simultaneously

A technical solution to maintaining safe separation in this scenario would be an absolute boon for capacity and performance, especially if it could be selectively overlayed locally just where desired, rather than requiring wholesale resignalling.

After stopping patterns and traffic mix, platform reoccupation time is often the crunch point for capacity. In my opinion stations are one of the most promising area for selectively applying 'level 3' ETCS techniques to safely close up and call on routinely for repeated fully loaded trains. Elsewhere on the open road at speed, fixed blocks (whether real or virtual) are fine for throughput and minimise computational and communication complexity and load in control systems both trackside and onboard.

 

[The exile]

I may be imagining things (it’s been over 35 years) but I’m sure I can remember the Valleys lines platforms at Cardiff sometimes having three trains moving at once - one departing; one drawing up along the platform and a third arriving. Was that the case - or is my fevered imagination just making that up!?

 

[Falcon1200]

A few years ago a member of staff reported being on a train arriving at Glasgow Central and while approaching the platform, they could see another train, still moving; Into the same platform in which their train then arrived! The incident was investigated but concluded to be normal, and safe; The trains were using one of the long platforms, with multiple track circuits (TCs), and the first train was far enough into the platform to allow sufficient TCs to clear for the second train to receive a subsidiary proceed aspect into the same platform.

 

[AndrewE]

A few years ago a member of staff reported being on a train arriving at Glasgow Central and while approaching the platform, they could see another train, still moving; Into the same platform in which their train then arrived! The incident was investigated but concluded to be normal, and safe; The trains were using one of the long platforms, with multiple track circuits (TCs), and the first train was far enough into the platform to allow sufficient TCs to clear for the second train to receive a subsidiary proceed aspect into the same platform.

Oh for the luxury of multiple track circuits on a shortish-bit of track! I guess this would be the analogue version of what was described in #17...

I am really frustrated that Manchester Picc platforms 13 & 14 are hamstrung by not having anything like this. 2 good really long platforms, only ever 1 train at a time on either because nowadays we can't make it work!

 

[edwin_m]

I am really frustrated that Manchester Picc platforms 13 & 14 are hamstrung by not having anything like this. 2 good really long platforms, only ever 1 train at a time on either because nowadays we can't make it work!

P13 and 14 do have mid-platform signals, two trains can stop there and occasionally they do. But from time to time some minor disruption would cause a train to stop at the wrong end. Anyone who's seen that happen can testify that for the time taken to get all the departing passengers down the platform, running head on into the arriving ones trying to get to the exit, they would have been better waiting until the usual end of the platform was clear. A further problem is that the number of passengers waiting for a departure means there wouldn't be space for a similar number waiting for another one on the opposite side of the same bit of platform.

 

[Watershed]

P13 and 14 do have mid-platform signals, two trains can stop there and occasionally they do. But from time to time some minor disruption would cause a train to stop at the wrong end. Anyone who's seen that happen can testify that for the time taken to get all the departing passengers down the platform, running head on into the arriving ones trying to get to the exit, they would have been better waiting until the usual end of the platform was clear. A further problem is that the number of passengers waiting for a departure means there wouldn't be space for a similar number waiting for another one on the opposite side of the same bit of platform.

The mid-platform signals' overlaps are positioned such that with modern train lengths, a second train can't share the platform unless it gets a calling-on route (whose use is prohibited in those platforms, except during contingencies).

The main benefit of having the mid-platform signal is that pretty much as soon as a typical 2-4 coach train departs, the preceding signal will clear to allow the next train to enter the platform - there's no need to wait until the starting signal's overlap has cleared.

 

[edwin_m]

The mid-platform signals' overlaps are positioned such that with modern train lengths, a second train can't share the platform unless it gets a calling-on route (whose use is prohibited in those platforms, except during contingencies).

The main benefit of having the mid-platform signal is that pretty much as soon as a typical 2-4 coach train departs, the preceding signal will clear to allow the next train to enter the platform - there's no need to wait until the starting signal's overlap has cleared.

That's actually a good outcome, though probably not intentional. Trains at the departure end of the platform stop nearest the exit, which obstructs that overlap and ensures no other train can be signalled in behind. If it was, and came to a stop, then people would start moving down the platform towards it.

 

[MarkyT]

That's actually a good outcome, though probably not intentional. Trains at the departure end of the platform stop nearest the exit, which obstructs that overlap and ensures no other train can be signalled in behind. If it was, and came to a stop, then people would start moving down the platform towards it.

Effectively closing up signals. A forward train movement detection system. Very similar to countless installations on the Southern and elsewhere in busy networks including many pre-CBTC Metros, where closing-up signals are placed in some cases right on the running-in end of a platform with the overlap and stop markers strategically positioned to 'catch' typical train lengths ahead. Soon after the forward train starts moving, the overlap becomes clear and the following movement can safely start over throat junctions to approach the platform, with little chance of being stranded, straddling the pointwork, blocking the show.

Another example in the UK of mid-platform signals being provided explicitly for capacity is the Thameslink core during modernisation, but pre-ETCS. With ETCS the platform blocks were then further divided and delineated by marker boards, some as little as 75 metres apart. All the signals, including the mid-platform ones and legacy warning systems also remain in the core alongside the ETCS kit for backup.

I may be imagining things (it’s been over 35 years) but I’m sure I can remember the Valleys lines platforms at Cardiff sometimes having three trains moving at once - one departing; one drawing up along the platform and a third arriving. Was that the case - or is my fevered imagination just making that up!?

Famous for it I recall. I think they filtered out multiple empties from the depot into service behind loading trains. Signallers sometimes did the same at Reading sending trains out from the triangle via the old platform 5, until one day an empty DMU bumped into the up HST it was following closely when that aborted its initial departure and came to a sudden stand.

 

[Re 4/4]

Without mitigations, It would not be permitted in UK for instance for repeated entry of following busy full length commuter trains into platforms still partially occupied by preceding long trains departing simultaneously

This happens every day on the Zurich Stadelhofen and main station subsurface lines. I'm sure there's a careful risk assessment but it's been going for many years without incident, and it cuts half or a full minute off platform reoccupation time.

 

[Gordon]

I just read an article in the last edition of the French railways magazine "rail passion", explaining that French railways are currently testing a new signaling system that will allow two trains to share the same track in stations, as a way to increase the capacity of heavily congested stations without having to add new tracks.

I'm a bit surprised to read that a special signaling system is needed for that. As far as I remember, this has been standard practice in Belgium with no special devices needed, other than an entry signal that can display the "admission on occupied track" aspect.

What is the situation in other countries ? Is it done on a regular basis and, if yes, are there special signals or devices deployed for that purpose?

Fairly certain this is just a new high tech device, not a new rule. Sharing the same platform has been standard across France for ever as far as I am aware.

 

[AlexNL]

YouTube recommended me the following video about this very subject. It explains the rationale behind the 2TMV project and its history, the practical implementation (including an explanation of what a driver sees) and has good footage of the whole thing.

The video is in French, English subtitling is available.

 

[railfan99]

In Victoria, Australia, Melbourne's Southern Cross has A and B V/Line (rural rail operator) platforms, separated by a crossover and signalling.

At Ballarat in Victoria the arrival in the morning from Maryborough couples to the arrival from Ararat prior to the coupled VLocity railcar sets ('units') proceeding to Melbourne's Southern Cross. I haven't been there recently to observe this: not sure if there's a staff member on the platform.