But TfL said no. They didn't have a problem with Underground stations because they've already published data for the depth of Underground stations, they did that in 2022 (and indeed in 2011). If you want confirmation that the platforms at Pinner are 53m above sea level and at Covent Garden 14m below, they're perfectly happy to tell you. As obscure spreadsheets go, that one's nerd level. But they won't add the Overground or Crossrail to the list, they point blank refuse.
TfL are quite within their rights to restrict this under Section 38(1)(b) of the Freedom of Information Act, and they're doing it because Crossrail is regulated differently to London Underground.
They say they don't believe the purpose of the FoI was in any way terrorist-related, but minimising risk takes precedence over "the interests of a select few individuals or transport enthusiast groups".
But this is hardly top secret information, the data must be out there somewhere. So I asked myself "OK, how deep are all the Crossrail stations? I'm sure I can work this out."
I started by going for a ride on a purple train. I started at Stratford where the station is above ground, and used an app on my phone to display the height above sea level. It told me the Crossrail platforms were 8.8m above sea level, then 8.9m, then 8.6m - the number never really settled down. Also I was holding my phone in my hand which technically wasn't at platform level, maybe almost a metre above, so the actual result was more like 8m. Then I realised I could check in the official TfL Underground spreadsheet because Central line trains stop immediately alongside, and that said 7.2m instead. So my app wasn't very accurate.
Also once my train entered the tunnel at Pudding Mill my phone stopped being able to register heights and just stuck on the number it had said when we entered the portal. This continued all the way through to Paddington and beyond, even when I managed to get 4G or a wifi signal, so I realised measuring it myself wasn't going to work. No GPS, no data.
So I searched on Google instead. Things were a lot less secretive during Crossrail's construction process, back when press coverage was all about amplifying how amazing the engineering was. But TfL have summarily deleted the Crossrail website since, every last page of it, so I had to rely on other websites and how they reported things during the years of construction. It proved surprisingly difficult.
The most useful webpage I found was an opinion piece from the Architects Journal published in May 2016. The author was mostly unimpressed by the station architecture but ended with a list of facts including the depth of every central station below ground level. So this sounds definitive.
Severalwebsitesconfirm that Liverpool Street is indeed the deepest Crossrail station below ground level, because superlatives are more widely publicised than individual figures. Woolwich is the subterranean station closest to the surface, and yes those escalators at Whitechapel and Bond Street really are really long.
But that isn't the data the FoI petitioners requested. They didn't want distances below ground level because these are very much at the mercy of contours on the surface which may have no correlation to the tunnels below. What they actually asked for was distance below sea level, and that's even harder to Google for. You can't even calculate it from the depth below ground level without knowing the elevation of the station with some degree of precision.
I didn't manage to find a table or a list of distances below sea level, or even a convincing individual statistic. I did find a good cross section of the route showing all the ups and downs, but it didn't have a vertical scale so it was no use for measurement. Eventually I found a proper schematic cross section on the learninglegacy.crossrail.co.uk site, which is a massive info dump left behind in the hope future civil engineers would find it useful. Here's a jpg of the cross section and here's an enormous pdf.
This cross section shows the tunnel passing through the bedrock, plus the various station boxes and a vertical scale measuring mATD, or 'metres Above Tunnel Datum'. Crossrail (and TfL) set sea level as 100 mATD, because this helps avoid working with negative numbers. Using this scale 120 mATD is 20 metres above sea level and 80 mATD is 20 metres below. No official platform measurements are given on the diagram so all I could do with the map was get a virtual ruler out. I measured the vertical distance between 100 mATD and the station platform and these are the results I got.
Distance above or below sea level
Paddington: 5m above
Bond Street: 3m below
Tottenham Court Road: 2m above
Farringdon: 15m below
Liverpool Street: 23m below
Whitechapel: 14m below
Canary Wharf: 19m below
Woolwich: 7m below
This confirms Liverpool Street is the deepest Crossrail station below sea level, as well as the deepest below ground level. Canary Wharf is unexpectedly second. Meanwhile Tottenham Court Road turns out to be just above sea level, not below, because the West End is quite a lot higher than the Thames. Only six Crossrail stations are in fact below sea level, assuming I've got this right. None of this materially affects national security.
The smallprint on the cross section says "Do not scale off these drawings. The information shown is only indicative and should not be relied upon." Also there's no guarantee my measuring or calculations are correct, so don't take this as gospel. But it looks right, unless you tell me different, and in the absence of a successful FoI it's the best data we've got. If TfL won't tell you something, work it out for yourself.
