How Hot Is The Tube?

[@ziggydamaestro]

Two more facts for your Central line video! 1) Central line trains run on a slick of magma. 2) Between Holborn and Tottenham Court Road, you might think you've seen the British Museum ghost station - but it's not! It's actually where Hell used to be situated, before Satan moved out because it was too hot.

[@ohok734]

Where did you get these information 🤔

[@Trainsteddy]

I’m a LU expert aswell

[@kingfinley-cs1wc]

@@hdy8792 Your Weird Bruh

[@kingfinley-cs1wc]

@@ohok734 yea

[@kingfinley-cs1wc]

@ModernHarry 🤣

[@googleboughtmee]

To be fair to the tube, it's bloody hot everywhere else too

[@silvus3491]

For next time: Could also measure humidity somehow, too, makes an enormous difference to how it feels

[@chriswitmer9754]

Came down to suggest the same thing. Where I live the humidity is what makes it nasty in the summer. Also as I type this at 6:02 some does say the problem is the humidity.

[@Computer895]

Here in egypt it is 37 c but it feels like 43 because of humduity

[@Ryan-dx8ry]

Interesting video Geoff. I actually work on the Underground and some of the temps in rooms, track and areas behind-the-scenes are much hotter than this. You've inspired me to buy a thermometer and see the various temps I can record when I'm out and about.

[@k.r.baylor8825]

Let us know what you find out. That 91F (33C) on the Bakerloo line is awful, even with the end windows down underway. I can't imagine what it must feel like if is just 9F (4C) hotter in the enclosed non-public spaces of the Underground.

[@edwardjoynes7961]

So nice of you to give out free water!!

[@DoubleDeckerAnton]

I always carry 2 small bottles of cold water...an ice pack in a 'cooler bag' helps throughout the day!

[@NextSound170]

DDA compliance is with us! LOL big up Anton

[@dawndoherty1]

Hello DoubleDeckerAnton

[@autistic2wheelrider72]

Didn't expect to see you here Anton. How's the new bus going ?

[@SBS2827U]

that bag would be of no use in Singapore since its 32-37 degrees c this few weeks

[@bigbabylons]

Anton, in summer, those tube trains are saunas inside.

[@teags3474]

Haha love the Aussie! She'd know about heat, here in Aus during the summer's we often reach low 40s and one or two days per summer we reach 45'C. But our trains (in Sydney anyway) are air conditioned.

[@PavithSVK]

Can we just appreciate how he's giving everyone water

[@cppricemac5217]

What a nice human being the fact that he was giving out free water to people on a hot day inspires me MR MARSHALL RESPECT FOR YOU SIR !!!💗👌👍👏

[@thomaswhitcomb624]

I am looking forward to ‘how cold is the tube?’ In 6 months

[@patricescattolin43]

I think he did that one already?

[@BenTheMiner]

Why is there a 1½ year long time gap between the two videos? Should be ½ year, considering it could've been done on the summer of 2017

[@unknown-im2bh]

BenTheMiner / MTA Railfanner wasn't as hit last year we got rain

[@diluteduk]

I've never been too cold on the central line

[@donyahosseini1132]

Thomas Whitcomb o

[@rjfaber1991]

I'm positively surprised to be watching this before the "It's always 50°C where I live, what are you complaining about?" comments start rolling in...

[@lmaoroflcopter]

Robert Faber like the Aussie lady said in the video. It's the humidity that's the issue. I've been in Vegas in 48c and it's been more comfortable than 25c in the UK due to it being an incredibly dry heat.

[@DanielsPolitics1]

Also, obviously no one lives outside air conditioned structures in 48 c. That would be a fatal fever if it was a body temperature (and humans need to lose heat to their surroundings to shed the heat we produce), as you were more or less slow cooked.

[@lmaoroflcopter]

DanielsPolitics1 eh... I think you've got things confused with how warm blooded mammals regulate heat but regardless you don't spend 100% of your time in air-conditioned luxury either and people lived there long before Air conditioning was a thing. The wonders of evaporative cooling. High humidity means your sweat doesn't evaporate, so you don't cool down. Low humidity is fantastic, your body can maintain its core temperature much easier.

[@bubblyizzy7723]

where do u live like 50 degrees?!?

The thing with air conditioning though... it heats up the tunnels and stations. Was in Barcelona last summer where the trains felt almost arctic inside, while the stations were unbearably hot.

[@Polschinski]

Same in NYC in summer

[@MaDxStArZv]

you spend way more time on the train in london than on the platform ill take that everyday of the week

[@eyeofthetiger6002]

Not if the stations themselves are air-conditioned as well.

[@CommunistLenin]

How ironic, when the British built us the MTR in Hong Kong, they have installed air-con in every trains and stations since day one. But the British themselves don't have air-con on their tubes until today😅😅

[@gonetea4081]

CommunistLenin cos London don’t go above 30 normally Sidenote hk underground is lush ac is brilliant

[@Lauren-dz9fq]

There is air condition on the met, circle, district and H&C

[@artsed08]

You're welcome. And they say we treated our colonies badly.

[@Fiddling_while_Rome_burns]

The London train have heating though, I bet the Hong Kong ones don;t.

[@DanielsPolitics1]

The Central was literally the first deep/tube railway in the world, so it is very, very narrow, and predates AC by, in common use, about 100 years. I think refrigeration at the time was literally based on towing ice from the arctic circle. No one though to include the facilities for it, and at first it was notably chilly, and marketed itself as such in summer. Then over 100-150 years the heat of brakes and traction motors literally heated the surrounding clay up.

[@todayonthebench]

At 8:08 we can here the fact that the London Underground should look into regenerative breaking for their trains. This means that the train dumps it's kinetic energy back into the third rail instead of dumping the energy into break pads or more often into resistor banks on the train itself. Another advantage of regenerative breaking is that it also reduces the power demand of the train network as a whole as the overall power efficiency has increased. Another thing one can do is drive heatpipes into the surrounding rock to provide a larger thermal mass for heat to sink into. And during winter one can use said thermal mass to keep the tube a bit warmer. (or even draw in extra cold air to preemptively cool the tunnel for summer season, people after all wear winter clothing so won't really mind if the tube is 5-10 C during winter.)

[@ianmcclavin]

Yes, although I miss the A, C and D Stock, those S Stock trains really come into their own on hot days in the summer, with their powerful air-conditioning!! For a stark comparison, try changing from a District or H&C train to a Central Line one at Mile End on a hot day!

[@smdhomeworkhelp]

Good to see Andy and Geoff reuniting for another video - you two make brilliant videos!

[@priestpilot]

I was in London during this time after a two week holiday across England. It barely rained! It was my first time in England and I got to experience it without any rain. I dreamed of visiting London and ride the Tube for so long, but because of the heatwave and my exhaustion from my walking-filled holiday, I didn't even want to use the Tube! I will maybe return to London sometime in the wintertime and take a few days off work to explore it myself.

[@itsrenderman]

He is like the London Underground version of Casey Neistat.

[@heinrichb]

I wouldn't insult Geoff like that.

[@benjammin2020]

The music at the beginning had nothing to do with that, huh?

[@hazptmedia]

lol

[@hazptmedia]

Emporio Alniño Really? Well hello then!

[@Lol5967]

Agreed

[@OltonHall]

I don't miss the two times I've been in London during a proper heat wave. It was good seeing Andy again.

[@felixw19]

You should have gone to the overground parts of the not-air conditioned liens, where the sun directly heats up the air in the train.

[@pgchase4578043026]

Bring back Calling All Stations. Been gone too long.

[@radders1963]

I used the Bakerloo Line recently and it was pretty hot between Elephant & Castle and Waterloo. Still Loved that the old 1973 Stock Tubes were still running.

[@wta1518]

Ha, you were incorrect on the internet 4 years ago. You see, the 1973 stock doesn't run on the Bakerloo line, it runs on the Piccadilly line. The Bakerloo has the slightly older 1972 stock.

[@k1an24]

Lets Make a petition to the government and TFL to rename Cross rail/Elizabeth line to Cross Elizabeth Purple rail.

[@superdresser]

I just got back from a week in London,and must say that i ADMIRE you guys spending all that time in that heat on the tube. I found myself getting off the trains one station earlier just to get out in the open air...

[@VulcanTrekkie45]

We get heat like this quite regularly in Boston, so most of our subway lines are air conditioned. But as someone who lives in an old house (built about a century before the proliferation of AC), here's some advice. Cold showers. Shower with cold water rather than the normal temperature and then don't towel off. It works wonders for staying cool. And according to my weather app, it looks like there's rain forecast in London for Sunday. Hang in there Geoff!

[@neilbain8736]

Interesting video! Clay must have a really high specific heat capacity- heats up slowly, cools down slowly. A full air conditioned train may that's hotter than an empty one might be partly because of the constant opening and closing of doors. You'll get the same thing with a fridge that's being opened all the time such as in a busy hostel. It doesn't get a chance to cool down much. The train is effectively a fridge.

[@emilysamanthataylor]

I've been in London on two separate occasions within the past two weeks and it's been fairly cold outside, especially yesterday. But the tube was just so HUMID, it's hard to escape the heat. We literally felt this astonishing air current coming up from inside when coming out of 4 degree heat outside. Can't begin to imagine how it is to take in the summer.

[@peteri8924]

If you had filmed this at rush hour it would have been much hotter. The Northern line yesterday when packed was unbearable.

[@roryonabike5863]

In New York, we have air conditioned subway cars. But guess where all the heat goes from the cars. The platforms, where the temperature can easily hit over 100F/38C.

[@stanpatterson5033]

Yeah, but New Yorkers are a tough bunch. They can handle it :)

[@paulthomas8262]

That is the issue, Our stations have had some cooling since the beginning through large scale convection including water cooling from water than needs to be pupped out anyway. However we didn't bother with AC for years. NY stations can indeed get very hot partly becuase of road heat many of them are just under the road. I remember in fact road falling in and the steel slabs an pin being used as a temporary solution (around 2001), which I though was a bit rough and ready. Most NY line are dig an cover, where as we have more tunnelling. We don't have the grid system, it was our FU to the Romans. Beside London clay is perfect for tunnels.

[@bobwbarnes]

Very useful video - but have you also measured the noise? Some underground trains are very loud - even dangerously so.

[@iurope4834]

which one

[@BomberFletch31]

I visited London for the very first time two months ago, and had the misguided impression that the Tube would be similar to the MTR in Hong Kong, with air conditioned, modern trains. I couldn't have been more wrong!

[@oisin_smith]

Tfl, please officially name it Cross Elizabeth Purple Rail

[@anthonychrisbradley]

I was on the Toronto Subway in 2011. Official air temperature was 38 Celsius. Have to think it was about 45 C on the subway. Probably the hottest you’ll feel in Canada!

[@davidanderson1639]

This is one thing I don’t miss about living in London. I worked in Oxford St for 8 years & during summer I always walked to Charing Cross, rather than get the Bakerloo line.

[@aa67216ify]

Hi Geoff, can we have a video about the temperature on different types of buses, including where best to sit/stand. Loved this one though.

[@dertseha]

And there I was, hoping to get a slight cool-down next week when I'll visit London - and you're telling me it's both hot AND the tubes are hot, too. Thank you for the heads-up!

[@ColinsTravels]

I was on the Bakerloo Line when I was in London for the first time last month. It was autumn and it felt like it was 105F in the train.

[@nxhb]

1 very memorable trip to London i have is 2 years ago in early Sept. Staying out in Essex as my partner was working and I spent the day wandering the tube in central London. My partner returned to our hotel to find me fully clothed in a bath of cold water eating a chinatown bakery bun and ill with heatstroke! i honestly never expected it to be that hot!

[@Fs3i]

The problem is that you can't create cold - you can only move heat away. That is a very annoying and fundamental law of thermodynamics. If you're in the underground, far away from the surface, where are you gonna put the heat to? Giant, long valves all throughout the tunnels, that go all the way back to the surface? You could cool down water at the surface and pump it down and back up once it's warm... that ought to be cheap, especially the plumbing! London's underground is (basically) impossible to cool, because it's so far below the surface.

[@rjfaber1991]

True. You could air-condition individual trains, but because of some other fundamental laws of physics, that would only increase the total amount of thermal energy in the system, even if the interior of the trains would be cooler, so you'd end up with pleasantly cool trains but absolutely sweltering platforms.

[@williamthebutcherssonprodu227]

They have started pumping cool ground water around the stations to help cool them, and also on cross rail they have extractor fans under the platforms to try and take away hot air away from the ac system to above ground.

[@GregRobsonUK]

At the time of construction the Central Line was not that hot, unfortunately as it's in the densest built part of London, getting any kind of pipe/duct between the existing pipes/roads/buildings/power cables etc is near to impossible. There's hardly any space to run anything between tube and surface. Other lines were built later and/or there has been (limited) room to fit some kind of solution, even if it's only partial.

[@BenTheMiner]

Basically it's heat in the tunnel then

[@stewartbrodie1720]

Robert Faber, that is exactly my experience of the main NYC subway lines running up through Manhattan - it's a relief to get onto a train even if it's packed, because you get out of the heat of the platform areas.

[@brian9731]

Had to go from Canons Park to Fulham Broadway this evening - all but 3 stops on air conditioned sub-surface - bliss!

[@TheEPROM9]

I took my thermal camera out today as I work in London, did not go on the tube as I like being alive. But in the shade the ambiant temp was 29*C -30*C 36*C - 37*C in the sun. Temperture serfaces in direct sunlight were 40*C -50*C. A black car was 58*C at its hottest point, other colour cars were around 45*C. These were all parked, bit hard to mesure the moving ones.

[@themalfoy979]

The Bakerloo at rush hour in the summer, always a pleasure.

[@stefanocoppo3949]

3:50 you just broke the challenge 'to carry and not to drink' Geoff! Tut, tut:P

[@FarlandHowe]

Let’s not forget that air conditioning in the trains will make the stations hotter than they are now.

[@jur4x]

that is why they are not installing them now. Once they figure out how to drive the heat away from stations and tunnels, trains can be upgraded to having an a/c unit

[@normdeplume6133]

Air condition the stations and send the heat up and out to the rest of London. Really, given the typical temperatures, would it make financial sense to add A/C all over?

[@ASLEFshrugged]

Rob McCain - the new Deep Tube trains will have air cooling not air conditioning

[@ASLEFshrugged]

jur4x - they can't install air con or air cooling on the existing trains, there simply isn't anywhere to put it as all space is already filled up. There's equipment under every seat, passengers just don't know its there.

[@jur4x]

ASLEF shrugged I know. What I meant is even if there was possibility to fit them in the train, it doesn't matter, since there are no means to get the air out of the tunnels and stations. Not yet, at least.

[@ZLDSmogless]

This helps me take my mind off the fact I live in Scotland and it is (obviously) raining right now

[@goneutt]

Humidity is an important aspect. It's 100FREEDOM (37 Commie) in Dallas, but the humidity is only 27% so it's easy to stay cool, as long as you have some air movement and stay out of the sun.

[@droguk1]

it would be good to repeat this again with a humidity sensor - luckily I have only been on the tube in the middle of summer a few times, but always think of the air feeling quick thick

[@greatportlandstreetmodelra6513]

When I visited London the last time in 2019, there also was immense heat. Around 35-40 degrees. But it was a dry heat, so one could deal with it.

[@BriannaButterfly333]

The last day it rained was May 2nd, Geoff. I know this because it was the day after I arrived in London for my 10 day trip, after which the first heat wave hit on May 3rd. Just so you know!

[@lumpyfishgravy]

Cooler than the Kent coast where it's been up to 34 outdoors. We've been shutting the windows to keep indoors below 30. Fans don't even help - just blow hot air!

[@blueish4]

Most important is the "feels like" temperature that takes into account humidity and wind chill. Hot tube trains are like steaming in a small pot.

[@RaymondCalloway]

I'm from New York City in the States and from July 2008 and October 2011 I lived and worked in the UK. With 2 of those years I lived in Harrow and took either the Bakerloo or Met Line into London. I had assumed, as with the NY City subway, the London Underground trains would have air conditioning. Boy was I wrong and it wasn't until near the end of my stay when the Metropolitan Line and the Overground got those newer cars did I feel relief.

[@DC4444]

The heat on the tube was on the news in New Zealand a few days ago. Also, CrossLizabethPurpleRail (I called it Crossrail Elizabeth Line before Geoff did) was on the news in 2014. I thought it was going to be a tube line because I didn't know the Overground, DLR, Trams & TfL Rail existed until last year.

[@mr51406]

When Parisian engineers were helping plan Montreal’s Metro, the Frenchies assumed “it’s always cold in Canada” (🤪), so they actually planned *heating* in the trains! As Andy correctly states, that the heat from the brakes is MORE than enough to keep the Metro *very* warm! Even in February. The original 1966 cars didn’t even have ventilators. They were installed in the roof of the cars later... causing some clearance problems! But tunnel ventilation shafts were built. Montreal is almost all deep tube and not subsurface like Paris. It’s limestone not clay but still...

[@IM35461]

Humidity readings would have been useful as Aircon typically reduces that and thus it can be comfortable but still quite hot.

[@Riggers6805]

I went on the Bakerloo, Northern & District lines on Sunday (29-7-18). I can agree that Bakerloo was the worst but I was fortunate enough to stand next to a window. I only went one stop on District so I didn't have time to appreciate it. Anyway, great video Geoff

[@michaeljames8531]

That the new Cross Betty Purple Rail Line carriages will have A/C will likely make matters worse. NYC subway trains have aircon and the stations become unbearable hotboxes in summer because of the heat thrown off the trains, then you have 4mins of cool in the carriage before you step back into the sauna.

[@01276]

But on crossrail the platforms are separated from the tunnel by platform screen doors so this should help stop that happening

[@jur4x]

Also on some crossrail stations they are going to have extractors under the platforms to take excess heat outside

[@beneliastrains]

Geoff, you need to do this again with a more accurate device. Your thermometer is designed to be kept in one place so the temperature will change very slowly. I expect on the A/C trains, the temperature will be closer to 21 or 22 degrees.

[@Mergatroid]

I'm watching this in a week where the heat indices here in Chicago are hitting 44C.

[@avantgauche]

should compare them with the buses too.

[@benkolya]

Just want to say props to you guys for handing out water, really nice gesture ❤️

[@benkolya]

It means the same as 'Kudos', apparently it comes from a shortening of 'proper respects'

[@roarwilhelmseersholm2358]

I visited London in that period. IT Was indeed bloody hot... We had the same weather here in Denmark.

[@alex-vd4vm]

As a person who has all air-conditioned trains, getting out of the train at above-ground stations is very hot, and where I live it's currently around 33°C-35°C, I can't imagine how much hotter it would be to exit from an air-conditioned train to a hot underground station (The ones in my country has had platform edge doors since opening.)

[@Crazytrain2015]

In Stockholm Metro [Underground] even if it is the hottest day in Stockholm it is kinda cold at the stations. Which is good

[@naomismith4933]

Geoff - can you do the same on the top deck on the new buses that HAVE NO WINDOWS?!

[@Mo.Jo.]

I'm visiting london/Birmingham next week, from Toronto. This helps, thank you!

[@TG_Trains]

I'm gonna call crossrail the "Cross Elizabeth Purple Rail" now.

[@edwardjoynes7961]

As you put the temperature thing in your hand it would make it show a higher number

[@MrJezza31]

I went on the Piccadilly line, and travelled to South Kensington the other day on the way to the royal albert hall, and I measured 43 degrees between Green Park and South Kensington.

[@ukgeographer]

I travelled on the Circle Line on the 9th July 2018 (My first time in 20 years) from Liverpool Street to Euston and was very surprised how cool it was and it was very hot outside on the surface

[@cigmorfil4101]

The cooling effect of the emptier trains is the same reason you should not tightly pack your fridge - the coolness comes from the circulation air (convection). A freezer however uses conduction more to transfer the heat so you should pack it tightly.

[@danellis-jones1591]

I live in Perth Australia. We don’t have an underground but air conned trains. 80%+ drive to work, as I do. In the summer the car is in the sun and reads in the mid to high-40s most days when I get in at the end of the day. Instant sweat. Literally instant. It’s weird when the train doors open in summer. It’s like someone is poking a massive hairdryer in the door! I remember the tube in summer. It’s awful.

[@T_vEg]

I've almost passed out on the The Central Line last year in the Summer

[@tomsmith5584]

The easiest way to cool off in London is to take a train to Heathrow, Gatwick, Stansted or Luton and catch a plane to Reykjavik, Iceland. One thing to consider with your temperature experiment is that your body is 37°C +/- 1°C, and holding the thermometer will transfer some of that heat into the thermometer causing a false high reading. Finally, one suggestion for a future video is to see how loud trains are. You should be able to download a free decibel meter onto your phone, which would tell you how loud the trains are.

[@rafaelgamma07]

I am so jealous that I am not experiencing the REALLY hot weather in the UK right now, I am on holiday!

[@themerryrose]

Our trains have AC and I freeze in summer but boil at the platform ... then again I am currently freezing on the platform and warm in the train but it’s winter and today will be a nice and sunny 18C after a very wet and windy 12-14 for this week. Hi from Melbourne.

[@conorspencer5411]

Geoff ALWAYS travels to train stations that I frequently use and yet I never see him, whether be where I live or work or commute through, I feel I let myself down with my travel times

[@TheEarthHistorysConfusing]

lol @ 9:02 That's our normal daily morning temps. last sat it was 44 degs @11 am. kept going up!. too hot!. @ least we have air-con , lots of people use trains to cool down, head into shopping centers.

My room in Helsinki is now at 20:40 nearly as hot as the Central Line. Our Metro tunnels are quite cool but the 100-series trainsets do not have AC and they are hot because they travel also partially overground.

[@ThomasJM]

All of our subways here in Toronto have air conditioning systems on them. However we do have ventalation fans and ducts around the system plus there are a number of open areas too.

[@ayush1ism]

it gets upto 45 degrees in delhi!! but luckily all metro trains have great air conditioning!!

[@sarahjoyholden7856]

Be interesting to do the same again this week with the new trains and stations

[@nemianyamele2265]

Ahhhh you should have done it on the Thursday!! It was boillling today!

[@LinxFox]

The subway in Toronto got soo hut one summer, the AC units on our 90s Bombardier T1 trains failed. And most of our stations are underground and they get really hot too. Our stations are fairly shallow though except the ones in the new TYSSE extension and on upper Younge street.

[@The682Media]

I used the Jubilee back in April and was surprised at how hot it was, especially the JLE bit. Now that map confirms no air-conditioning on that line.

[@sahonsarma8384]

And its one of the coolest deep level tube lines

[@malcolm4672]

Watching this in Christchurch, New Zealand where it is minus 1. with Frost on the ground.

[@davidcollins9512]

Minus 2 on my garden thermometer in Dallington, Chch, Malcolm.

[@AndreiTupolev]

You get a nice breeze with the droplight in the doors at the coach ends. But typically they chose a driving car.

[@famoterlhh4993]

In Singapore we have air conditioning but as for the above-ground stations the heat from the engines of the train is practically negligible and in the underground stations there are platform edge doors to help keep the heat in the tunnels and air conditioning in the stations

[@mariosavva999]

I'm obsessed with watching your videos. Also big up to me Loughton girl!

[@just_aiden16]

I liked how cold the tube gets that was my favourite :D

[@imogentait5744]

it is currently 41* C outside in Adelaide. can't imagine how hot it would be if we had an underground system!

[@chrisporter7872]

Think you needed a better temperature detector. I have a Garmin Tempe an ANT+. Which works with my Garmin GPS and it also works with an app on my phone. So you can put the detection on the roof of the train where the heat rises and read the temperature on your phone.

[@johnwhitehouse5244]

Really happy I don't have to use tube. Only winter times great video again thanks. ( John Whitehouse )

[@varun009]

In Delhi, we have air conditioners in our metro. Pretty good ones at that. In the winter, they just switch them off and we rely on the one advantage our population density affords us.

[@w0033944]

I''m in rural South Norfolk, and it was 31C here...

[@macstyle2012]

I find it amusing that when it gets into the high 20s in England, people think it is too hot. That is winter temperatures where I live.

[@harveydee9115]

Wow! Hot trains. I got the train from London and we wear delayed by 40 mins. But thankfully we were one of the few trains with air con! Southeastern commuter trains have no air con but our express one did we did have to run for it though but it was worth it

[@AndreiTupolev]

I thought they were about to be run over by that New Routemaster at 1:40. "Carry a bottle of water with you" is like "Dogs must be carried on the escalator".

[@Cadwaladr]

It's usually way hotter where I live than anywhere in Europe or the UK, but currently it's only about 20 degrees here.

[@SL-kz5dk]

Cadwaladr where’d you live

[@johncrwarner]

The coolest place on the U-Bahn in Bielefeld is the Hauptbahnhof station platform at level -3 (their deepest platform and the one I use). But there aren't that many sweaty bodies on the trams at these places and the brakes are designed to recharge the system or at least that is the advertising the city council have on the trams.

[@XalphYT]

Bielefeld has a U-Bahn? I'm not joking, I thought it was a small town.

[@johncrwarner]

They put the tram system underground in the city centre and to the west of the city of 350 000 inhabitants - about 27 years ago. The longest underground stretch is (I think) from the concert hall (Rudolf-Oetker-Halle) to City Hall (Rathaus) which is only 5 stops but it is labelled U-Bahn.