Topographical (depth) maps of the Underground

[stuartroy]

My good friend Daniel has created a number of line diagrams providing a visualisation of the platform depth data which is publicly available.  The diagrams show how the depth (relative to sea level) of the lines changes between stations, and how this relates to the ground level at that point.  What they don't show is how line depths and gradients vary between stations, so they don't indicate, for example, the "sawtooth" profile of rising gradients on the approach to stations and falling gradients on departure which is found in several places on the network.  They do show, for instance, how the Central Line "stacked" lines change position between Chancery Lane and St Paul's, but don't indicate the exact point at which the change happens, nor the dip in both running lines where they have to navigate under the Fleet.  I think they're nevertheless very interesting diagrams in their own right.

Dan is not a member of this group, although he's every bit as much a tube fan/geek as I am, but I've promised to pass on any feedback about his diagrams which members would like to post here.  He does stress that both the diagrams and the website itself are "works in progress".

The full set of diagrams can be downloaded as a pdf from the main site:

www.dansilva.co.uk/underground-diagrams/

[class411]

Those are absolutely fascinating.

Thanks to Daniel for producing them, and yourself for bringing them to our attention.

[rapidtransitman]

Jun 19, 2018 15:06:14 GMT stuartroy said:

My good friend Daniel has created a number of line diagrams providing a visualisation of the platform depth data which is publicly available.  The diagrams show how the depth (relative to sea level) of the lines changes between stations, and how this relates to the ground level at that point.  What they don't show is how line depths and gradients vary between stations, so they don't indicate, for example, the "sawtooth" profile of rising gradients on the approach to stations and falling gradients on departure which is found in several places on the network.  They do show, for instance, how the Central Line "stacked" lines change position between Chancery Lane and St Paul's, but don't indicate the exact point at which the change happens, nor the dip in both running lines where they have to navigate under the Fleet.  I think they're nevertheless very interesting diagrams in their own right.

Great maps, but I was really confused by the numbers in the station circles. It's not clear at all that they are actually negative numbers, for the depth below ground level. Only by seeing the +8 on the Bakerloo map at Stonebridge Park did I realise that most of the numbers in the station circles are negative.

All negative numbers should be prefixed with '-'.

[35b]

Jun 19, 2018 15:06:14 GMT stuartroy said:

My good friend Daniel has created a number of line diagrams providing a visualisation of the platform depth data which is publicly available.  The diagrams show how the depth (relative to sea level) of the lines changes between stations, and how this relates to the ground level at that point.  What they don't show is how line depths and gradients vary between stations, so they don't indicate, for example, the "sawtooth" profile of rising gradients on the approach to stations and falling gradients on departure which is found in several places on the network.  They do show, for instance, how the Central Line "stacked" lines change position between Chancery Lane and St Paul's, but don't indicate the exact point at which the change happens, nor the dip in both running lines where they have to navigate under the Fleet.  I think they're nevertheless very interesting diagrams in their own right.

Dan is not a member of this group, although he's every bit as much a tube fan/geek as I am, but I've promised to pass on any feedback about his diagrams which members would like to post here.  He does stress that both the diagrams and the website itself are "works in progress".

The full set of diagrams can be downloaded as a pdf from the main site:

www.dansilva.co.uk/underground-diagrams/

They’re superb. I’d be interested to know where he’s taken the datum points for the stations, as the figure for Southfields didn’t seem entirely right, which set me wondering about the other “open” stations.

[whistlekiller2000]

Jun 19, 2018 19:54:41 GMT rapidtransitman said:

Jun 19, 2018 15:06:14 GMT stuartroy said:

My good friend Daniel has created a number of line diagrams providing a visualisation of the platform depth data which is publicly available.  The diagrams show how the depth (relative to sea level) of the lines changes between stations, and how this relates to the ground level at that point.  What they don't show is how line depths and gradients vary between stations, so they don't indicate, for example, the "sawtooth" profile of rising gradients on the approach to stations and falling gradients on departure which is found in several places on the network.  They do show, for instance, how the Central Line "stacked" lines change position between Chancery Lane and St Paul's, but don't indicate the exact point at which the change happens, nor the dip in both running lines where they have to navigate under the Fleet.  I think they're nevertheless very interesting diagrams in their own right.

Great maps, but I was really confused by the numbers in the station circles. It's not clear at all that they are actually negative numbers, for the depth below ground level. Only by seeing the +8 on the Bakerloo map at Stonebridge Park did I realise that most of the numbers in the station circles are negative.

All negative numbers should be prefixed with '-'.

The dotted ground level line makes it fairly clear though really. I hadn't even noticed the '+' until you mentioned it! 

[rapidtransitman]

Jun 20, 2018 10:06:50 GMT whistlekiller2000 said:

The dotted ground level line makes it fairly clear though really. I hadn't even noticed the '+' until you mentioned it! 

The dotted ground level line has (positive) values for height above ground. But the Underground line values, generally underground, also appear as positive numbers. So there are two sets of values, the top one assumed to be positive, and the lower (Underground) set assumed to be negative.

There's the rub. The graphics are brilliantly clear. The values aren't.

[rincew1nd]

However rooms/structures underground are labelled with "floor/room", IIRC the floor numbers count up the deeper you go.

[norbitonflyer]

I agree it might have been helpful to have a note indicating what the numbers signified, but it is only convention that says that vertical distances are positive if measured upwards (just as it is only the history of European colonialism and the genetic disposition to right-handedness that have led to the Southern and Western hemispheres having negative values for latitude and longitude respectively). The mining industry, for one, goes against this convention in identifying its structures. Nor do people usually have much difficulty when the Ordnance Survey do it.

If you must have positive numbers being "up", the numbers can be thought of as the distance the ground is above the tracks.

The modern metric temperature scale differs from that originally developed by Anders Celsius in 1742 - he had water boiling at 0 and freezing at 100.

[Chris M]

Jun 20, 2018 12:53:59 GMT rincew1nd said:

However rooms/structures underground are labelled with "floor/room", IIRC the floor numbers count up the deeper you go.

They do. 1 is the ground floor, 2 is the first floor below ground level, 3 the floor below that, etc. The first floor above ground level is A, the one above that B, etc. There was a thread on this years ago.

[stuartroy]

Thank you all for your comments and feedback, which I have shared with Dan and for which he is also most grateful.

In answer to one of the specific points made, the original data came from a FOI request which is linked here:
www.whatdotheyknow.com/request/depth_of_tube_lines
If anyone spots any mistakes, I'm sure Dan would be pleased to hear about them.

There was some concern about positive and negative numbers - this is something which Dan and I discussed, and we came to the conclusion that as the majority of stations were underground, it was cleaner to show the depths as plain numbers, rather than cluttering the place up with - signs. Then the question arose as to how to show stations above ground. Of course 8 is the same, mathematically, as +8, but perhaps ^8 or *8 (with a key) might have been clearer. However, point taken, and once again thank you. It's really just a matter of finding the right balance between convention, clarity of presentation, and readability.

As forum members may have seen, interest has now been taken by the Evening Standard and Londonist.

[banana99]

Nice. Some observations. Central Line map Oxford Circus and Holborn are both 26m BUT shown at different levels. Might also be good if the distance between stations was proportionate so the gradient was relative between stations.

Very good idea though. Love it.

Also the Jubilee and Bakerloo line platforms (paired NB and SB) are at the same level at Baker Street, but not according to the map.r

<<superteacher: posts merged.>>

[Deleted]

Jun 28, 2018 20:40:40 GMT banana99 said:

Also the Jubilee and Bakerloo line platforms (paired NB and SB) are at the same level at Baker Street, but not according to the map.

There's slight incline in the cross-platform passageways - so I guess some minor depth difference is present.

[Deleted]

These are fascinating, I usually lose all sense of depth underground. I would point out that the TfL-supplied data relates to rail level (platforms are up to about 0.8 metre above that). There is also a red herring at Gants Hill: both platforms there are at the same level, from where the escalator rise is 9.83 m to the ticket hall floor (per Underground News No.495, March 2004, page 119). The station is something of a showpiece, and illustrations including cross-sections etc. have been published over many years (recently in Anthony Badsey-Ellis’s Building London’s Underground).