Why are platforms so low?

[BoD]

Silly question time.

 

I have recently been checking platform heights for my model. Most sources gave them as 12mm (3ft) above rail height. Upon reflection I thought this quite low in the prototype. I looked at lots of photographs and indeed most platforms are well below the 'solebar' and often you can see the wheels and other undergubbins.

 

Ok then - the silly question - why? Would it not be easier if platforms were at or just below door height?

 

Were carriages at one time much lower than they are today?

 

Edit: corrected silly autocorrect

Edited March 29, 2018 by BoD

[Compound2632]

I think the question is: how did platforms get to be as high as they are, given that they started being at little more than rail level, as they still are in places in many other countries today?

 

Carriage floors have been at around 4'3" or so above rail level since at least the mid-nineteenth century. Consider where the passenger carriage came from: how do you get into a horse-drawn carriage?

[Dunsignalling]

Rail height tends to be higher nowadays because mechanised maintenance involves a thicker layer of ballast, causing an apparent reduction in platform levels..

 

On some routes (e.g.) Salisbury - Exeter in the early 1990s, platform heights, and at some locations, lengths were increased in conjunction with the introduction of more modern trains.  Even so, the step-down from a 159 unit is still around eight inches.

 

At some other, usually lesser-used, stations in various parts of the country, a short raised portion of one or two carriage lengths has been added to platforms, with car-stop signage positioned to suit.  

 

John

Edited March 29, 2018 by Dunsignalling

[Mike Storey]

Broadly speaking, the UK loading gauge allows freight and passenger vehicles to be wider above a height of around 3ft 6ins above top of rail height (originally 9ft, but varies by line now), than the width below that (originally about 8ft 6ins), with the floor of carriages generally above that, at about 4ft to 4ft 3ins above rail top.  But not all vehicles are the same width - that is just a maximum.

 

Hence platforms which serve all types of passenger and freight rolling stock have to allow for that, and are thus limited to a height of around 3ft (915mm approx) in order to keep the stepping distance (as opposed to the step height) as narrow as possible. To raise the platform height to the average bottom of door level would mean moving the platform edge away from the largest possible train profile allowed at that height, thus increasing the gap between platform and door step (the stepping distance). It is assessed that it is safer to have as small a stepping distance as possible, rather than being as level as possible, despite the difficulties that creates for the less able and others, which is borne out  by the number of accidents that still occur, where people fall between the platform edge and a train in the platform.

 

Where only specific types of trains are allowed to use, or run past, a platform then the height can be increased to around the same height as the bottom of the train doors, because the stepping distance can be minimised for just one type of train, such as on some parts of the London Underground, and the dedicated Heathrow Express stations, and soon in the tunnel sections of CrossRail.

 

 

This thread may explain it better than I have - http://www.rmweb.co.uk/community/index.php?/topic/6638-platform-height-query/

Edited March 29, 2018 by Mike Storey

[Mike Buckner]

Rail height tends to be higher nowadays because mechanised maintenance involves a thicker layer of ballast, causing an apparent reduction in platform levels..

 

 

A good example of a pronounced step-up/down is at Clapham Junction. Not helped by the curvature on some platforms. Correcting this would be prohibitively costly - digging a lower bed would mean rebuilding the tunnels underneath.

[Titan]

Rail height tends to be higher nowadays because mechanised maintenance involves a thicker layer of ballast, causing an apparent reduction in platform levels..

 

 

No, the rail height is critical at platforms and any height increase is strictly forbidden. If a thicker layer of ballast is required then the formation will have to be dug out to maintain the correct level. The only reason for a high rail level at a platform is if it has been historically like that, perhaps due to some restriction like a shallow subway. Nevertheless, an increase in rail height at that location would still not be permitted.

Edited March 29, 2018 by Titan

[Compound2632]

Broadly speaking, the UK loading gauge allows freight and passenger vehicles to be wider above a height of around 3ft 6ins above top of rail height (originally 9ft, but varies by line now), than the width below that (originally about 8ft 6ins), with the floor of carriages generally above that, at about 4ft to 4ft 3ins above rail top.  But not all vehicles are the same width - that is just a maximum.

 

But isn't that chicken & egg? Isn't the restricted width at low level a consequence of having raised platforms, even if only 1'6" above rail height - a common dimension for many stations as built. Most of the comments above cover recent practice but the early story has its points of interest too. Early platforms often sloped gently down towards the line, for drainage I presume, to that 1'6" at the edge. Around the last couple of decades of the nineteenth century there seems to have been a move towards increased platform height - up to 3'0" above rail - which led to platforms sloping away from the edge. The tragedy of the Wellingborough accident of 1898 was that the up main platform was the only one at the station that hadn't been raised, so that unattended trolley was able to roll off the platform onto the line. 

 

Goods and cattle platforms were generally higher - 3'6"-ish - to make life easier when barrowing goods or walking livestock over the drop-flap wagon door. But these platforms weren't on running lines.

 

At many stations that still have their nineteenth-century buildings, sunken or modified thresholds bear witness to increases in platform height, as do changes in the brickwork at the platform edge. Always an interesting study to while away the time waiting for your train!

Edited March 30, 2018 by Compound2632

[Trog]

Silly question time.

 

I have recently been checking platform heights for my model. Most sources gave them as 12mm (3ft) above rail height.

 

If the platform is on a curve don't forget to add or subtract half the cant from the platform height, depending on which side of the curve it is on. It may not show all that clearly at 4mm/foot but you will feel so much better knowing that you have got it right.

[wombatofludham]

I was always given to think that part of the issue was the "kinematic envelope" which I think is now called something else, basically the amount of bouncing around a train does as it moves at speed, in very rough layman's terms. It cropped up when I was involved with specifying the Midland Metro project where we wanted level boarding. Obviously on a light rail scheme used by identical vehicles all stopping to identical stops you can get quite close to the vehicle without taking out the side but we had to allow a gap for all sorts of things like wind load, asymmetric passenger loadings, mechanical defects on the trams and the occasional transit by a non-stopping vehicle (for example empty trams or maintenance vehicles). On the main line railway obviously trains can pass through stations at a higher speed, so you have to allow for a larger gap to allow for sway and movement, plus as others have said, the different widths of vehicles calling at or moving through the station.

 

I know the "KE" was given as a reason to me why we couldn't get closer to level boarding on main-line platforms and why we need ramps to access main line trains.

[Grovenor]

The Rail Vehicle Accessibility Regulations now specify maximum stepping distances and level variations which are very difficult to achieve, even in a dedicated metro environment. This is leading to new trains being provided with retracting steps/gap fillers, fairly common in Europe already and bound to turn up here eventually or new vehicles are not going to get approval.

Regards

[Compound2632]

The Rail Vehicle Accessibility Regulations now specify maximum stepping distances and level variations which are very difficult to achieve, even in a dedicated metro environment. This is leading to new trains being provided with retracting steps/gap fillers, fairly common in Europe already and bound to turn up here eventually or new vehicles are not going to get approval.

Regards

 

Joseph Locke et al. didn't have a copy of these to hand...

[Mike Storey]

But isn't that chicken & egg? Isn't the restricted width at low level a consequence of having raised platforms, even if only 1'6" above rail height - a common dimension for many stations as built. Most of the comments above cover recent practice but the early story has its points of interest too. Early platforms often sloped gently down towards the line, for drainage I presume, to that 1'6" at the edge. Around the last couple of decades of the nineteenth century there seems to have been a move towards increased platform height - up to 3'0" above rail - which led to platforms sloping away from the edge. The tragedy of the Wellingborough accident of 1898 was that the up main platform was the only one at the station that hadn't been raised, so that unattended trolley was able to roll off the platform onto the line. 

 

Goods and cattle platforms were generally higher - 3'6"-ish - to make life easier when barrowing goods or walking livestock over the drop-flap wagon door. But these platforms weren't on running lines.

 

At many stations that still have their nineteenth-century buildings, sunken or modified thresholds bear witness to increases in platform height, as do changes in the brickwork at the platform edge. Always an interesting study to while away the time waiting for your train!

 

Which is the chicken and which is the egg? The loading gauge example I have utilised emanates from the 1905 Regulations (I think that is the right date) by which time, train designs and platforms had already evolved into what they were, much higher on average than your example. I would guess that things would have been very different if engineering tolerances had been mandated at a much earlier date, but that was not the way of things in Victorian Britain. Conversely, if such restrictions had been placed too early on to innovative engineers, we may not have seen the progress that evolved quickly in those years, as the maxima regarded as tolerable for, say, an 1830's railway, would have represented the generally accepted leading edge of technology for the time. We could thus have seen train speeds restricted to, let's say, 25 mph for many decades, because there was significant medical opinion that foretold major medical disasters at speeds above that. It is noticeable that many European railways, who were restricted by codes of practice to a major extent much sooner than the UK, due to the adoption of a Napoleonic code approach across much of Europe, kept their platforms at absurdly low heights until quite recently (historically speaking).

 

We are, simply, where we are.

[BoD]

Thank you for the informative replies.

[Dagworth]

The Rail Vehicle Accessibility Regulations now specify maximum stepping distances and level variations which are very difficult to achieve, even in a dedicated metro environment. This is leading to new trains being provided with retracting steps/gap fillers, fairly common in Europe already and bound to turn up here eventually or new vehicles are not going to get approval.

Regards

Ever been on a Pendolino?

 

(and did APT have retracting steps too?)

 

Andi

[BernardTPM]

Ever been on a Pendolino?

(and did APT have retracting steps too?)

Andi

Yes. Looked very slick back in 1984.

[DCB]

The Rail Vehicle Accessibility Regulations now specify maximum stepping distances and level variations which are very difficult to achieve, even in a dedicated metro environment. This is leading to new trains being provided with retracting steps/gap fillers, fairly common in Europe already and bound to turn up here eventually or new vehicles are not going to get approval.

Regards

 

There are lots of low platforms on BR and vast numbers of too high platforms on models especially in 00 gauge.  as a rule of thumb 00 UK platforms should be at least 1 mm lower than the centre line of the buffers. Mine are too high through using 1/2" timber with approx 2mm hardboard surface and it looks and is wrong with modern RTR and RTR Hornby Dublo but was OK with Triang and re wheeled (larger wheels 26 against 24mm) Hornby Dublo .

Lots of railways outside the UK have virtually rail level platforms from which you have to climb steps into the coach and the foreigners don't seem too worried about it.

 

If modelling post 1970 ish don't forget the tracks dip down approaching platforms as the modern thickness of ballast is much greater than in steam days. Swindon is quite dramatic and some of the now disused platforms on the Gloucester Swindon line are now virtually at or below rail level.

[Compound2632]

If modelling post 1970 ish don't forget the tracks dip down approaching platforms as the modern thickness of ballast is much greater than in steam days. 

 

... which is really the wrong way round. Find a long straight section of the Paris Metro, e.g. the line 4 under Ave. Jean Jaures, and you'll notice that there's a gradient up into the platforms, designed in to help with rapid stops and starts.

[Mike Storey]

There are lots of low platforms on BR and vast numbers of too high platforms on models especially in 00 gauge.  as a rule of thumb 00 UK platforms should be at least 1 mm lower than the centre line of the buffers. Mine are too high through using 1/2" timber with approx 2mm hardboard surface and it looks and is wrong with modern RTR and RTR Hornby Dublo but was OK with Triang and re wheeled (larger wheels 26 against 24mm) Hornby Dublo .

Lots of railways outside the UK have virtually rail level platforms from which you have to climb steps into the coach and the foreigners don't seem too worried about it.

 

If modelling post 1970 ish don't forget the tracks dip down approaching platforms as the modern thickness of ballast is much greater than in steam days. Swindon is quite dramatic and some of the now disused platforms on the Gloucester Swindon line are now virtually at or below rail level.

 

That has been changing though, due to accessibility regs. Here in France, all (?) new DMU's on local and regional services now have at least one lowered floor pan and entrance in each set, designated for disabled access. In reality, these seem to be mostly used by young mums with prams/pushchairs.

[justin1985]

I was told by a friend who was very involved in rail planning at TfL in the mid-2000s that the then current Accessibility Regulations, or at least the understanding of them at the time, was that any changes to existing platforms would have to be fully compliant.

 

Existing platforms had "grandfather" rights for being too low or or too big a gap, but any attempts to improve these would have to be fully compliant. Therefore even where it was feasible to raise a platform, NR wouldn't do it, because it would lose the grandfather rights and have to be fully compliant.

 

I get the impression that a more sensible and flexible version of the rules, or perhaps just more nuanced interpretation of them, is now in force. For example platforms 1 and 2 at East Croydon have recently been "decked over" with some kind of (rather flimsy) plastic raft to raise the platforms about 6" or 1ft. This has reduced the step, but certainly not made it level (with either Electrostar or MK3 type units), and done nothing to reduce gap. Of course this was one about 6 months after the new footbridge and lifts were completed, so the nearly new lift is now submerged and accessed down a rather elaborate ramp!

 

Similarly St Pancras Thameslink platforms have now gained Victoria line humps that line up with the accessible areas on the new class 700 units. These actually have semi rigid rubbery "fins" projecting out that close the gap too. Again, these are very much an afterthought though, looking like they've been made from bog standard cheap patio slabs from Wickes, in the middle of a otherwise pleasantly finished polished stone effect platform. And why on earth the platforms weren't built to that height to start with, when presumably the new units were already specced (or the units specced to match the infrastructure ...) Is utterly beyond me. The fabled English Project Management strikes again!

 

Justin

[Trog]

 

Lots of railways outside the UK have virtually rail level platforms from which you have to climb steps into the coach and the foreigners don't seem too worried about it.

 

 

They are a funny lot these foreigners, have you ever watched the production they make of finding the door handle when they want to alight from a Mk3 coach? It never seems to occur to them that it is on the outside where they left it when they got in.

[Compound2632]

They are a funny lot these foreigners, have you ever watched the production they make of finding the door handle when they want to alight from a Mk3 coach? It never seems to occur to them that it is on the outside where they left it when they got in.

 

It has to be admitted that the whole business of having to lower the droplight* and lean out to open the door is positively antique. At least the Mk1s had a catch on the inside - but of course no central locking!

 

*and the Mk3s don't even have a stout leather strap to help with that operation.

 

I well remember my first experience of the SNCF, at Calais c. 1980 - yes, a stiff climb up into the carriage but then the announcement: attention à la fermeture automatique des portes. (Up to date version here.) "They order, said I, this matter better in France" - Laurence Sterne, A Sentimental Journey (1768).

[Jonboy]

They are a funny lot these foreigners, have you ever watched the production they make of finding the door handle when they want to alight from a Mk3 coach? It never seems to occur to them that it is on the outside where they left it when they got in.

Part of the joy of Readings new layout is that as an occasional user you never know which side the platform will be on on arrival, and invariably it will be someone that doesn’t know on the side with the platform..l

[jjb1970]

Plenty of British passengers now get into a minor panic when it comes to getting off mk.3 coaches and they can't find the door open button. Given that they vast majority of our trains now have power doors it's not surprising people assume there will be a door open button somewhere.

[Christopher125]

The Rail Vehicle Accessibility Regulations now specify maximum stepping distances and level variations which are very difficult to achieve, even in a dedicated metro environment. This is leading to new trains being provided with retracting steps/gap fillers, fairly common in Europe already and bound to turn up here eventually or new vehicles are not going to get approval.

Regards

IIRC 'gap fillers' will be fitted to the new Stadler fleets for Greater Anglia and Merseyrail.

 

Similarly St Pancras Thameslink platforms have now gained Victoria line humps that line up with the accessible areas on the new class 700 units. These actually have semi rigid rubbery "fins" projecting out that close the gap too. Again, these are very much an afterthought though, looking like they've been made from bog standard cheap patio slabs from Wickes, in the middle of a otherwise pleasantly finished polished stone effect platform. And why on earth the platforms weren't built to that height to start with, when presumably the new units were already specced (or the units specced to match the infrastructure ...) Is utterly beyond me. The fabled English Project Management strikes again!

I think the 'humps' had to wait until the core was exclusively worked by 700s.

[Edwin_m]

The logic for a "hump" rather than a full-length raised platform may be to do with directing wheelchair passengers to the doorways designated for them.  As well as placing them within reach of the accessible toilet, this ensures that platform staff know where to look for them with the portable ramp if they later alight at a station without level boarding.