Gradients, LU steepest

[d7666]

Stemming from a.n.other contributor question about Elizabeth line gradents (q.v.) and subsequent chatter, I thought a list of steep grades would be of interest to all. It is to me! Should have worked this lot out long ago.

I went through a data set and decided greater than 1 in 30 a cut off point - there are really too many in the 1:30-1:40 range to list. All this lot comes from a single source and I am not going down the road of "this source says this while Fred's blog says something else" - all I am doing is relaying the gen from this one source.

This list is sorted in descending steep grade order and always means falling grade in the direction listed. Except where noted, all these grades lie immediately after the named station and are short - mostly in the 50 to 150 m range but a few are a bit longer. It covers running lines only.

The discovery - for me anyway - of a 1:19 was new - and is less than 100 m i.e. less than a train length : can any of our resident Northern line persons comment ? Typo in data ? 1:29 would appear more plausible ? I seldom use the Northern and certainly don't know it well enough to have noticed.

Predictably, Central line mostly bubbles to the top of the steepest list but then pretty well documented the line was built this way to aid acceleration - none of the upgrades running in to stations are as steep.

The list :

Northern NB 1:19 Kennington route via Bank
Northern SB 1:24 Borough
Central EB 1:25 Oxford Circus
Central WB 1:25 Holborn to TCR in section
Central WB 1:25 Notting Hill Gate
Northern NB 1:25 Oval
Central EB 1:26 Marble Arch
Central WB 1:26 Bank
Central EB 1:27 Bond Street
Central WB 1:27 Bond Street
Central WB 1:27 Queensway
Central EB 1:28 White City to Shepherds Bush in section
Central EB 1:28 Chancery Lane
Central WB 1:28 St Pauls
Central WB 1:28 Tottenham Court Road
Central WB 1:28 Oxford Circus
Northern NB 1:28 Tooting Broadway
Northern NB 1:28 Clapham North
Northern SB 1:28 Tooting Bec
District WB 1:28 Earls Court towards West Kensington
Central WB 1:29 Lancaster Gate
Central WB 1:29 Holland Park
Northern NB 1:29 Angel to Kings Cross in section
Northern NB 1:29 Balham
Northern NB 1:29 Clapham South
Northern SB 1:29 Old Street
Northern SB 1:29 Bank
Northern SB 1:29 Balham

Piccadilly all none found
Jubilee all none found
Victoria all none found
Bakerloo all none found
W & C all none found

[100andthirty]

I'm guessing that 1 in 19 is a typo. I've never seen a gradient that steep quoted as a requirement that the trains have to cope with.

Having checked just one sample specification, 1 in 30 is the steepest gradient quoted, but I expect that trains would cope with up to 1 in 25, as I expect thise aren't a train's length

The only 'teenage' gradient I'm aware of on the TfL estate is the one between the Bank branch and the viaduct on the DLR.

[Tom]

I'm certainly aware of some 1 in 28 gradients on the Northern line, but they were all 1 in 28 falling on 'humped' tube platforms, and, as my learned friend above states, of quite short duration.

There's certainly a 1 in 28 leaving Earl's Court on the WB District (to Olympia/West Kensington), but the steepest rising gradient I've come across is the 1 in 30 into Ealing Common Depot from Acton Town.

[d7666]

Nov 26, 2022 18:41:29 GMT 100andthirty said:

I'm guessing that 1 in 19 is a typo. I've never seen a gradient that steep quoted as a requirement that the trains have to cope with.

Having checked just one sample specification, 1 in 30 is the steepest gradient quoted, but I expect that trains would cope with up to 1 in 25, as I expect thise aren't a train's length

A different view is if it is 1:19, then one might have expected that fact to have been more well known - it is the sort of thing that anoraks would be citing every time the subject of gradients come up, a perpetual question in crank quizzes, and probably an entry in guiness.


Seriously, if the diagram I have is anything like to scale, this stated 1:19 is only around ~50 m long and between a shorter 1:85 fall from the end of the northbound platform and a longer level section.

Surely doing the requirements for a 1:19 grade would only apply if all of the train were on that grade at the same time - equally for motoring, for coasting, for braking and for holding a stationary train ?

Given that 1992 tube stock train is 106 m long, this stated grade somewhere around 3-4cars length, so the average grade the train is actually on is nothing like 1:19. The average is 1:52, and the most you'd have when considering wheelbase (not car length) is ~4cars on the 1:19 (if say it is a ~60 m length) and that comes out at ~1:30 hence within known guidelines.

I am not a rolling stock technical person but my engineering past has done enough basic stuff that the Newtonian mechanics would consider the average would suffice for such a short section.

Not to say I'd not apply Occams Razor - a typo is the simplest hence most plausible explanation.

[100andthirty]

d7666...all good and valid points, but I would still expect to tell any supplier about such a gradient. They can then judge how much it matters e.g. for performance or for strength of couplings.

[stapler]

How long was an Edwardian CLR train, and would have ability to cope with the original humped gradient profile have been affected when the Bo-Bo locos were replaced by EMUs?

[d7666]

Nov 28, 2022 8:20:49 GMT stapler said:

How long was an Edwardian CLR train, and would have ability to cope with the original humped gradient profile have been affected when the Bo-Bo locos were replaced by EMUs?

Interesting question.

We need a Tardis to go back 120 years in time.

The highest value grades even in the hump profile are all falls - there are no rising grades in that list they are all falling - unlike double tubes / main lines, single bore tubes take (and often forced to take) differing paths - nonetheless the same mechanical issues for braking would apply. The Edwardians must have known what the values were, so made it work, loco operated or EMU.

[alpinejohn]

The web is full of interesting if not fully verified information - does this link throw any light on the very steep incline at King William Street...

www.abandonedstations.org.uk/King_William_Street_2.html

The stated gradient of 1 in 14 seems pretty challenging but as King William street was the Northern end of the line and that extreme gradient was for the Southbound tunnel I guess trains would simply enjoy rapid accelleration gravity assist.

[ta]

Regarding the 1:19 at Kennington, I can confirm that this is the gradient value used in the Thales TBTC System data (for a 30m stretch of track shortly after departing platform 1).

[d7666]

Updated the opening post : checked data for the missing lines Bakerloo, Jubilee, Victoria and W&C : none of these show any grade in the steeper than 1:30 range.

[100andthirty]

Nov 29, 2022 16:32:50 GMT ta said:

Regarding the 1:19 at Kennington, I can confirm that this is the gradient value used in the Thales TBTC System data (for a 30m stretch of track shortly after departing platform 1).

Well, you learn something every day!

[d7666]

Nov 30, 2022 7:45:43 GMT 100andthirty said:

Nov 29, 2022 16:32:50 GMT ta said:

Regarding the 1:19 at Kennington, I can confirm that this is the gradient value used in the Thales TBTC System data (for a 30m stretch of track shortly after departing platform 1).

Well, you learn something every day!

THere is the possibility this 1:19 is a compensated gradient value and not a physical 1:19 on site although the latter would still be steep and probably still the steepest even.

If so, then all the values I list are similarly compensated gradients but then again if they are then are truer reflection of what the train encounters which is what matters.

30 m long is about two cars when you consider it is wheels on rails that count here so wheelbase matters => one third of a 6car 1995 stock train.

[jimbo]

When R stock was converted from 6 or 8 car to 7 car, they took one car from the 8 formations and put it into the 6 car trains. As a result, some equipment failures could result in only 2 cars having to move a train. Drivers didn't think this would work up the steepest bank on the line at Bow, but the engineers reassured them that they had done the calculations and there would be no problem. Drivers, being practical people, asked to see it and a demonstration took place on the bank from Acton Town into Ealing Depot, an equivalent slope. Needless to say, it wouldn't budge and regulations had to be changed to require a pushout!

[d7666]

Dec 2, 2022 18:57:02 GMT jimbo said:

When R stock was converted from 6 or 8 car to 7 car, they took one car from the 8 formations and put it into the 6 car trains. As a result, some equipment failures could result in only 2 cars having to move a train. Drivers didn't think this would work up the steepest bank on the line at Bow, but the engineers reassured them that they had done the calculations and there would be no problem. Drivers, being practical people, asked to see it and a demonstration took place on the bank from Acton Town into Ealing Depot, an equivalent slope. Needless to say, it wouldn't budge and regulations had to be changed to require a pushout!

I continue to be puzzled by this Bow gradient alleged to be the steepest enough on the District and a big issue.

It is marked as 1:38 or 1:39 (about half and half) for about ~350 m between Bow Road platforms and around about "dismantled rail bridge D130 and D129". This grade is equalled west of Whitechapel.

It is true there are no steeper District grades I can find apart from the short 1:28 already listed for Earls Court - so while this Bow 1:38/1:39 is "steepest on the District" it must either be myth and legend that it is problematical - or that every District line train that preceded S-stock was underpowered - or some misinformation about it has been put out, internally or externally.

1:38 is nothing for an electric train with at least 50% axles motored (e.g. R stock) and more in later stocks (66% D; 100% S) so IMHO dismiss underpowered as a consideration.

If one considers traction equipment failures well OK but that is a non standard case - while a part failed train should be able to perform to a minimum spec, then you may as well go down the road of considering 8/7car trains with 1 or 2 or 3 or 4 or 5 or 6 failed csars and then wonder why it staggers or stall when a certain cuot out proportion is reached.And maybe such an event has made its way into mythology ?

Perhaps by being the steepest on the District, canteen gossip does not consider anything outside the world of the District ignoring the whole line is itself more or less free from many of the gradient constraints on every other line.

[stapler]

Surely this depends not only on the % axles motored, but on the gearing and power of each motor?

[d7666]

Dec 3, 2022 8:20:10 GMT stapler said:

Surely this depends not only on the % axles motored, but on the gearing and power of each motor?

Installed motor power is inversely propotional to number of motored axles - in probably over simplified terms if you half the number of motors in a train set the remaining motors needed to be around twice the power you'd need if all axles were motored.

Then there is tractive effort that is a function of weight - you may well (although I doubt it) double the motor weight for bigger power motor, but you won't double the weight of the car - and it is tractive effort you need to put down.

[Dstock7080]

I remember there were strict regulations for working defective R and CO/CP Stock up Bow bank.
The references i could find were for 1974 and 1983, after the CO/CPs had been withdrawn:
1974:


1983:

[theblackferret]

I can't comment on the technical issues here,but one of the reasons King William Street closed as early as 1900 was the gradient problem at the station site.

It apparently meant,on more than one occasion,trains had to take a 2nd or 3rd run at entering the station! Either that,or two locos could be needed.

This was simply because the approach to it was amongst the first parts of the City & South London Railway to be built & so it was built for the traction power that had initially been planned for working the line-and that wasn't electric locos, it was planned & first built,though never operated, as a cable-hauled system.

Luckily for the future of the Tube, the cable-equipment manufacturers went bankrupt & the CSLR big cheeses saw a couple of electrically-driven railways in action(including Volks in Brighton) & decided to take a chance on the electric.

[t697]

A couple of points about Bow;
1. Starting from the bottom a train assisting one stalled on the bank is partly still on the fairly tight curve in the platform and leaving it, which adds to the train resistance (to movement) a bit.
2. The climb is rather longer than most of the others listed in the thread. So the restrictions cited about R stock even for 3 cars pushing/pulling 4 might also have been to avoid very slow progress with only a small number of cars motoring, which might have caused the traction starting resistors to overheat and melt since the speed would probably balance below Full Series.
I recall being on the type test for D78 stock where half the train (empty) pushed the other half (loaded) to simulate a worst case pushout at Bow. The test succeeded in starting and completing the climb trouble free but the starting resistors were a bit hot and smelly by then.
These days with modern traction drives we tend to forget about those limitations of older systems with starting resistances.

[Tom]

Dec 3, 2022 11:29:02 GMT Dstock7080 said:

I remember there were strict regulations for working defective R and CO/CP Stock up Bow bank.
The references i could find were for 1974 and 1983, after the CO/CPs had been withdrawn:
1974:

What was so special about 21146 and 21147?

[Dstock7080]

Dec 3, 2022 22:47:46 GMT Tom said:

What was so special about 21146 and 21147?

I seem to recall that being proper built R Stock these had an improved cab handbrake, possibly applying to more wheels, therefore not having a Guards position handbrake as on R38.

[d7666]

Dec 3, 2022 22:47:46 GMT Tom said:

Dec 3, 2022 11:29:02 GMT Dstock7080 said:

What was so special about 21146 and 21147?

You beat me to that, and i see it's been answered.

Ta for the gen Dstock7080

Notwithstanding all that, it does not answer the specific point that started this sub-topic - which was this :

Nov 24, 2022 18:53:02 GMT Chris M said:

tubeprune notes on his website that (at least as of 2003) the steepest gradient on LU is 1 in 28 or 3.57% - between Bow Road and Bromley By Bow, District Line.

How did they cope with that under steam traction for the first 5 years of the Whitechapel & Bow - and from a standing start?!

To which I responded :

I can only comment as I posted just above the data I have shows that as 1:38/1:39 not 1:28.
Repeat I can't further comment which is correct, only relay the data I have from current source.

It was the 2 bits to the statement -

(1) steepest grade on LU 1:28

(2) and is between Bow Road amd Bromley By Bow that led on.

Think we have resolved point (1).

For (2) so far no-one else has been able to come with a steeper value than the 1:38/1:39 - the one I have - for this District grade. It does look like it is the steepest extended running line grade on the District, but is by no means as steep as was alleged; except for the sohort one listed west of Earls Court.

The interesting gen you posted in the images concerns defective trains. But any train anywhere defective with more than half it's motors cut out (R 2 live + 5 dead) or (R 4 live + 3 dead) is somewhere going to result in special handling. This is atypical and not representative of normal operation, which seemed to be the gist of other's comments, e.g. when asking about steam.

I mentioned the steepest main line grade as those used for 700s on Thameslink route as determining traction performance - yes it does, but that too is with the provision of at least 50% of the motors cut in (more than 50% cut out the train - even a 700 - not permitted to climb from City to Blackfriars).

A.n.other poster mentioned resistances (applicable here to anything before S-stock). That is a good point. I'd guess it is likely that available kW or kN is not the issue but the balancing speed of those defective trains on that grade causes notching up to not occur so too resistances stay in circuit for way to long. I had not thought of that point.

[jimbo]

The tech.spec. for the deep tube upgrade project trains gives the steepest gradients as 1 in 26 on the Central Line, 1 in 29 on the Waterloo & City, and 1 in 30 on both the Piccadilly and Bakerloo lines. The Central Line has the tightest radius curves of 63 metres with cant and 45 metres without. They also have the tightest reverse curve with cant, although the Waterloo & City features the tightest reverse curve without cant at 50 metres both ways. The Central line also features the tightest vertical hog and sag curves.

[stapler]

The GER, faced with 1 in 70 and extended dwell time at LV, on the Bethnal Green Bank, always worked with locos smokebox first up the bank. Did the District (or LT&S) locos also always work chimney first up the Bow bank?

[roythebus]

A lot of railways prefer steam locos smokebox first where at all possible. This is all to do with the water level in the boiler. Going uphill smokebox leading, it will be almost impossible for the water at the firebox to drop to such a level as to expose the fusible plug and uncover the boiler tubes. Tender first there is a danger that this could happen with possible catastrophic results. The Kent& East Sussex is a prime example with Tenterden Bank being about 1 in 36 for the last mile into Tenterden. Most locos face towards Tenterden for this reason. If a loco is on loan from elsewhere special authority has to be granted for running the "wrong way round".

It's nothing to do with filling up with water, it's all to do with how long the loco is ikely to be working up hill on a regular basis.

[philthetube]

It surprises me that the section between East Finchley and Camden does not get a mention, particularly the bet from East Finchley to the tunnel mouth, as a n ex Northern line driver I would have thought that this was much steeper than anything at the south end of the line

[d7666]

Sept 22, 2023 16:00:19 GMT philthetube said:

It surprises me that the section between East Finchley and Camden does not get a mention, particularly the bet from East Finchley to the tunnel mouth, as a n ex Northern line driver I would have thought that this was much steeper than anything at the south end of the line

From the same source I used for the opening post, there is nothing worse than a long 1:50 anywhere from Camden Town to East Finchley (and that is actually between Archway and Highgate), and a short (~100 m) 1:48 and shorter (~40 m) 1:46 approaching East Finchley both within the last ~300 m of approaching East Finchley.

[melikepie]

Arnos Grove to Bounds Green or even just north of Southgate feel steep

[rincew1nd]

I seem to remember from discussion on here, that the steepest gradient was part of a crossover somewhere that was a drop of about four inches due to cant over around four feet, giving 1 in 12.

Can't remember where it was though.

[Chris M]

I also have very vague memories of something like 1 in a single digit over a distance of a few inches to get wheels over the running rail as part of trap points somewhere. I want to say Tower Hill/Minories sort of area but could be completely wrong.