What does the National Rail symbol on the tube map mean?
Obviously it means 'National Rail interchange', it says so in the key.
But what does 'National Rail interchange' actually mean?
I ask because several stations with a National Rail service don't have the symbol, for example here in the northwest corner of the map.
Crossrail's fine. Reading, Twyford and Maidenhead are also served by GWR and Taplow isn't.
The Central line's fine. West Ruislip and South Ruislip are also served by Chiltern and the other stations aren't.
But the Metropolitan line's not fine. Five of its stations are served by Chiltern but only three have symbols.
What's going on?
The two symbol-less Metropolitan line stations are Rickmansworth and Chorleywood. Both have a half-hourly Chiltern service from trains operating between Marylebone and Aylesbury but there's no symbol. All the trains that stop at Chalfont & Latimer also stop at Chorleywood, and yet one has a symbol and the other doesn't. Outside the peaks Rickmansworth gets exactly the same number of trains as Amersham and Harrow on the Hill, and yet it's symbol-free and they're not. Why might this be?
This Metropolitan omission is nothing new, it's been the case on tube maps since the British Rail symbol was first introduced in 1970. This is a longstanding designation, nothing the map's latest designers have introduced. But it's still the case that three places where you can change trains have a symbol and two don't. n.b. Back in 1970 Moor Park also had the symbol because BR trains stopped there too, but when the stop was withdrawn in 1993 the symbol was removed.
Rather than assume that someone has made a mistake, I prefer to think there's a rule in play which I haven't fully figured out. Maybe Rickmansworth and Chorleywood don't have a symbol because they're deemed less important. Maybe Rickmansworth and Chorleywood don't have a symbol because they're neither an interchange nor a terminus. Maybe Chalfont & Latimer does have a symbol because it's where trains to Chesham diverge. Maybe xxxxxxxxxxxx (I don't know, I'm not sure what the rule is, hence my mystification).
So I've scoured the map for other places where red-symbol-less-ness also happens.
If we can somehow spot a pattern, maybe it'll tell us what the rule is.
And I think I've found 26 more discrepancies.
Only three of these are on the tube and they're the three stations at Heathrow. All three are additionally served by the Heathrow Express, indeed they share the same Crossrail platforms, but they don't have NR symbols. Maybe TfL are just trying to keep quiet about their greatest competitors.
Only four are on the Overground.
• Imperial Wharf is served by Southern but doesn't have a symbol, whereas just up the line Kensington (Olympia) and Shepherd's Bush do.
• Brockley, Honor Oak Park and Forest Hill don't have symbols, despite being served by Southern trains to Victoria, but Sydenham does. n.b. Technically the Overground and Crossrail are National Rail services but the map doesn't have red symbols for those interchanges because that would be silly.
All the other discrepancies are on Thameslink.
Here are ten of them.
The tube map has shown Thameslink services to Rainham, Sevenoaks and Orpington since 2020. Every station where Thameslink stops Southeastern do too, but for some reason only some have red symbols. Maze Hill and Westcombe Park don't, Woolwich Arsenal does. Plumstead doesn't, Abbey Wood does. Bellingham, Beckenham Hill and Ravensbourne don't but Shortlands does. Busy important Bromley South somehow doesn't but little Bickley does. Petts Wood doesn't, St Mary Cray doesn't and Swanley doesn't, even though it's the last station shown.
If the intention was to show National Rail connections all 17 of these Thameslink stations would have symbols, but instead only seven do. The map's designers must have applied a rule but I'm not sure what it is. My best guess is that it's something to do with where lines join or diverge, but even that doesn't match what's on the map.
The other symbol-less Thameslink stations on the tube map are as follows...
• At Oakleigh Park it's possible to change between Thameslink and Great Northern in the peaks, just as it is at New Barnet and New Southgate either side, but they have NR symbols and Oakleigh Park doesn't.
• City Thameslink is served by the same National Rail trains as Farringdon, but it doesn't have a symbol whereas Farringdon does.
• Loughborough Junction gets peak time Southeastern services but it doesn't have a symbol.
• Mitcham Junction, Hackbridge and Carshalton don't have symbols, despite being served by Southern trains, but Mitcham Eastfields and Sutton to either side do.
• Coulsdon South is symbol-free even though you can change to Southern services there.
• Deptford doesn't get a symbol but the next stop Greenwich does.
• Crofton Park hasn't got a symbol but Nunhead and Catford either side do.
Altogether I've identified 28 stations on the tube map which have a National Rail service but no symbol. And it seems these discrepancies got a lot more plentiful when Thameslink was added to the map, or at least more inconsistent, or more precisely seemingly inconsistent because somebody's applying a rule I don't fully understand.
Which begs the question are there any National Rail symbols on the tube map that shouldn't be there, and I think the answer is yes.
Seven Sisters is a real peculiarity. It has a symbol because it's served by Greater Anglia trains but they're exceptionally rare and only stop at the station before 6am or after midnight. Anyone using the tube map to plan their journey would find the symbol at Seven Sisters wildly unhelpful because it's untrue almost all of the time, but technically correct. n.b. Edmonton Green was also served by rare Greater Anglia trains but they ceased last year, so on the latest version of the tube map Edmonton Green is now symbol-free.
One National Rail symbol that shouldn't be there, I'd argue, is Kentish Town. Yes you can change from the tube to a train, or at least you can normally, but it's a Thameslink train and that's shown as an interchange on the map already. The red symbol made sense until 2020 but now it's no longer needed. One less bit of clutter on the map would be nice.
And another superfluous symbol is at Farringdon. It's only served by Crossrail and Thameslink, railwise, but both of these are shown on the map and you can't change onto any other National Rail service here.
No NR symbol: Chorleywood, Rickmansworth, Heathrow T2&3, Heathrow T4, Heathrow T5, Imperial Wharf, Brockley, Honor Oak Park, Forest Hill, Oakleigh Park, City Thameslink, Loughborough Junction, Mitcham Junction, Hackbridge, Carshalton, Coulsdon South, Deptford, Maze Hill, Westcombe Park, Plumstead, Crofton Park, Bellingham, Beckenham Hill, Ravensbourne, Bromley South, Petts Wood, St Mary Cray, Swanley Superfluous NR symbol: Kentish Town, Farringdon
I'm not suggesting that all these unmarked stations get additional symbols, heaven forbid, because the last thing the tube map needs is a virulent outbreak of double-arrow measles in the bottom right-hand corner. It's over-overcrowded enough as it is. But I would love to know what the rule is which explains why some National Rail interchanges get a symbol and some don't, because at the moment it all looks utterly mysteriously inconsistent.
