Paddington Cant

[Morpethcurve]

Is it some sort of optical illusion or do some of the (terminus) tracks at Paddington have extreme cant as the alignment turns left (down direction) near the platform ends? Surely nothing is going fast enough at that point to require such banking?

http://lowres-picturecabinet.com.s3-eu-west-1.amazonaws.com/43/main/52/131906.jpg

http://www.bbc.co.uk/blogs/pm/images/trainaf.JPG

Thanks for your patience - Morpethcurve

 

[cambsy]

Could be due to re modelling etc, station works in the past, but definitely not due to speed, don't know exact reason, but probably historical.

 

[DarloRich]

It isnt an illusion

 

[MarkyT]

The rear of a departing train can be going quite fast by the time it reaches the end of the platform.

 

[Ironside]

I thought they were canted to reduce the difference between platform height and floor height. That's an opinion that I have no evidence to back up with.

 

[RichmondCommu]

Is it some sort of optical illusion or do some of the (terminus) tracks at Paddington have extreme cant as the alignment turns left (down direction) near the platform ends? Surely nothing is going fast enough at that point to require such banking?

http://lowres-picturecabinet.com.s3-eu-west-1.amazonaws.com/43/main/52/131906.jpg

http://www.bbc.co.uk/blogs/pm/images/trainaf.JPG

Thanks for your patience - Morpethcurve

Don't be so rude!

 

[JN114]

Linespeed in and out of most platforms is 40mph, and the Turbos, 332s and 360s are almost certainly capable of attaining that on departure

 

[heart-of-wessex]

Yes quite unusual, but as mentioned compared to most London termini, it has a fast exit. It's quite something boarding Coach A from, say, Platform 2. You can tell it's on a cant as you can feel the forces as you open the door, and climb on board.

 

[Morpethcurve]

Don't be so rude!

Didn't want to flamed for ignorance!

Morpethcurve

 

[asylumxl]

Linespeed in and out of most platforms is 40mph, and the Turbos, 332s and 360s are almost certainly capable of attaining that on departure

40mph in to the platform does not seem like a rather good idea.

 

[455driver]

40mph in to the platform does not seem like a rather good idea.

And is completely against any companies defensive driving policy.
The driver would up in the office with tea and no biscuits before his feet touched the floor.

Now leaving the platform is a different thing!

 

[asylumxl]

And is completely against any companies defensive driving policy.
The driver would up in the office with tea and no biscuits before his feet touched the floor.

Now leaving the platform is a different thing!

The driver would probably be through the windscreen and on the concourse first to be fair.

In my experience of trains out of Paddington you'd still be pretty lucky to get a nice clear run out of the station throat.

 

[heart-of-wessex]

compare that to a few years ago before black boxes etc.

On a VHS tape I have with footage at Paddington in the NSE era, there's some 117 nutter driver who comes into the station, I'd say around 20-25mph, who then applies the throttle (with clag of course) and just throws into the station, proceeded then by a sharp but neat stop at the blocks.

Probably beat any timing record set by a 165/166

 

[Rich McLean]

Padd is 40mph going into the Platforms, until the H+C footbridge where it drops down to 10mph towards the buffers.

 

[JN114]

Lowest speed limit anywhere at Paddington is 25, for platforms 11-14, and the crossovers to/from lines 5 and 6 - as publicised in the sectional appendix. Note that while both professional/defensive driving policies and common sense will likely see a driven speed that is lower than these, the infrastructure (and thus the cant at the country end of the platforms) has to be designed for the linespeed as that's the theoretical maximum, and track geometry should be maintained to maximum theoretical.

 

[1018509]

..........The driver would up in the office with tea and no biscuits before his feet touched the floor...........

Along with his train, at that speed!!

 

[455driver]

At a 12 coach platform a train can be doing 55+ at the ramp and still stop smoothly at the end, it wouldnt work at a terminal line though as the TPWS will trip you up.

Defensive driving policies are a good thing but they can be a bit restrictive at times.

 

[Kentish Paul]

At a 12 coach platform a train can be doing 55+ at the ramp and still stop smoothly at the end, it wouldnt work at a terminal line though as the TPWS will trip you up.

Defensive driving policies are a good thing but they can be a bit restrictive at times.

I remember reading that when the GWR introdused AWS (or was it ATC) tests proved they could have stopped before the buffers at Paddinton if hitting a warning ramp at the outer platform end doing 40mph with the regulator left fully open.

A full emergency stop is something to experience. Happened to me twice over 40 years as a passenger (I will not say why), both times it made you realise how gentle normal service braking is.

 

[YorkshireBear]

I remember reading that when the GWR introdused AWS (or was it ATC) tests proved they could have stopped before the buffers at Paddinton if hitting a warning ramp at the outer platform end doing 40mph with the regulator left fully open.

A full emergency stop is something to experience. Happened to me twice over 40 years as a passenger (I will not say why), both times it made you realise how gentle normal service braking is.

It certainly is, i have had one in a Pacer when some kids were playing on a foot crossing and even on the KWVR when someone stood on a foot crossing in the four foot taking a photo of the approaching train. Said well its a slow train.... My pint had to be saved and i nearly lost it. Fortunately I didn't and the day could proceed as planned.

 

[D1009]

At a 12 coach platform a train can be doing 55+ at the ramp and still stop smoothly at the end, it wouldnt work at a terminal line though as the TPWS will trip you up.

Defensive driving policies are a good thing but they can be a bit restrictive at times.

After the current layout at Paddington was implemented, trains regularly passed the platform ramp at 40 mph and stopped without any problem. However we must not forget that it was the accident at nearby Ladbroke Grove which was the turning point that caused the implementation of many of the safety measures we see in place today.

I'm sure there are better examples of lines canted for higher speeds than trains ever regularly achieve.

 

[Bald Rick]

compare that to a few years ago before black boxes etc.

On a VHS tape I have with footage at Paddington in the NSE era, there's some 117 nutter driver who comes into the station, I'd say around 20-25mph, who then applies the throttle (with clag of course) and just throws into the station, proceeded then by a sharp but neat stop at the blocks.

Probably beat any timing record set by a 165/166

In the early days of TPWS and Voyagers in 2003 I was on one into Paddington late one evening. We came in at about 40, and not long after going past the ramp end the anchors were dropped and we stopped on a sixpence. After peeling myself of the seat in front, and realising that the conductor had released the doors, I got off at the front door, to hear the driver explaining with a chuckle to the platform staff he had tripped the TPWS. Then we all had to walk about 120 metres to the buffers!

 

[bronzeonion]

40mph in to the platform does not seem like a rather good idea.

Should see some of the 332's come in!

 

[edwin_m]

track geometry should be maintained to maximum theoretical.

Agreed the cant deficiency shouldn't exceed the limit for a train passing at line speed, but I think within this the engineers have some discretion to set the actual amount of cant to minimise passenger discomfort and rail wear, in the light of the sort of speeds the trains are actually doing.

 

[TheKnightWho]

Agreed the cant deficiency shouldn't exceed the limit for a train passing at line speed, but I think within this the engineers have some discretion to set the actual amount of cant to minimise passenger discomfort and rail wear, in the light of the sort of speeds the trains are actually doing.

Yeah - I'm not sure why they don't reduce the maximum to account for this. (To 25mph, say?)

 

[455driver]

Yeah - I'm not sure why they don't reduce the maximum to account for this. (To 25mph, say?)

Because that would be far too sensible!

Having the track canted so the wheels are pressing hard against the inner rail doesnt do either the track or wheels any good because the inner wheel will be running on its biggest diameter part and leaning on the flange and the outer wheel will be running on its smaller diameter part, this will cause the wheelsets to bind and one wheel will have to slip slightly as it goes around the curve causing wear and possibly noise depending on whether there are flange greasers there.

 

[Nippy]

Yup the 332s don't have TPWS to worry about!

 

[RPM]

Yup the 332s don't have TPWS to worry about!

I didn't realise that. Presumably they are exempt because they never stray from NR ATP-fitted infrastructure?

 

[Joseph_Locke]

I have never (in my 25+ years of design) ever come across a terminal platform that was deliberately canted, nor any need to ever do so. If it was done at Paddington to fix a clearance problem it was a cludge in the extreme.

Cant is applied to reduce lateral forces on passengers, as in A=(V^2)/R; it can be seen that for any terminal platform V will be at or near zero, so no cant required at all for most of it. In fact, at (say) 25mph, cant would not be mandatory until you got down to 210 metres radius.

 

[edwin_m]

Depending on the exact distance from the stops to the canted part, for the tail of a train starting away from the stops to be doing 40mph requires an average acceleration of about 1m/s/s, which isn't that much more than something like a 333 or an IEP will be capable of at low speeds.

Any lower limit in the platforms would effectively apply for a train length out into the throat, meaning that the work that has gone into designing a throat for 40mph would be mostly wasted (given that defensive driving will impose a lower speed for arriving trains). The occupancy of the throat would also be that much more, along with an increase in journey times. So I would guess it is worth applying the minimum cant needed to keep cant deficiency within the limits at 40mph, and thus allowing departing trains to accelerate unhindered up to that speed.