I've had a go at walking round the Circle line. That's the original loopy Circle line, not the extra spiral arm added in 2009.
It was a very interesting walk.
I wonder if you can guess how long it took?
n.b. I started at Aldgate, and walked clockwise.
n.b. I passed the 'main entrance' of all 27 stations on my circuit.
n.b. I attempted to follow the quickest walking route between stations.
n.b. I didn't run.
n.b. My walking speed is on the fast side of average.
n.b. I'm not averse to crossing a road on a red light.
I don't know if any of that changes your guess.
I thought I'd be able to walk it in one go. But somewhere around Notting Hill Gate I realised I'd been walking for ages without stopping and was quite tired, so I gave up and went home. I came back to walk the second half from Notting Hill Gate to Aldgate another day. This should mean my timings are more accurate, because I wasn't knackered and slower on the return journey. But blimey, it's a lot further round the Circle line than you think. Turns out it's a fifteen mile walk altogether. I wonder if that changes your guess again.
Here's a map showing how many minutes it took me to walk between each station. Times are in minutes.
You may be surprised how irregular all the timings are. Most of the gaps look roughly equal on the tube map, but real life turns out to be very different. Cannon Street, for example, is only three minutes away from the Circle line stations on either side. Meanwhile Sloane Square and High Street Kensington are about quarter of an hour away from their neighbours. The longest hike is from King's Cross St Pancras to Farringdon, which is well over a mile and took me 22 minutes. The average walking time between Circle line stations is nine minutes. Distances in the City and along the Embankment are generally shorter than elsewhere.
This geographical map gives a good idea of how irregular the Circle line actually is, and why the timings vary so much.
The Circle line is anything but a circle. Paddington isn't really the 'top left' station. Victoria is a lot further south than Embankment. Notting Hill Gate is actually the furthest station west, and King's Cross the furthest north. Walking from Farringdon to Blackfriars would be a lot quicker than catching a Circle line train. The long gap between King's Cross and Farringdon really ought to be filled by another station, if only TfL had an unlimited supply of money. The loop is really an amorphous wiggle. No wonder my Circle line orbit took so long.
Altogether my walk around the Circle line took me four hours and ten minutes.
That gives me a walking speed of about 3½ miles per hour.
A Circle line train completes the loop in approximately fifty-seven minutes.
I wouldn't get exactly the same results if I walked it again. The traffic would be different, and a long wait at a pedestrian crossing can really slow the timings down. Also, I was only recording the times between stations to the nearest minute, so some of them might round up a bit. I'd allow a margin of error of plus or minus a minute on all the individual figures. But four hours and ten minutes is probably about right overall.
You probably wouldn't get these timings if you walked it. You probably walk at a different speed to me. You'd probably follow a different route. Even crossing a road junction one way rather than another can add a minute on. There's no such thing as an absolute value.
But there are definitive walking times for how long it's supposed to take. TfL have a walking map they're very proud of, to encourage us all not to take the tube but to walk between neighbouring stations instead. How, I wondered, do TfL's official walking times vary to mine. The figures on this map provide the answer. The red numbers are TfL's times, and the blue numbers are my own.
Four of the times are identical, but generally TfL took a couple of minutes longer than me to walk between each station. Perhaps they were slower, or took a less direct route, or had worse luck with traffic and traffic lights than I did. Indeed, who even knows how they worked their figures out?
One of the more significant differences is between Embankment and Westminster, where I managed the simple Thames-side walk four minutes quicker than they did. Another yawning gap is Euston Square to King's Cross St Pancras, where TfL took a full five minutes longer than me (although that may be because I timed myself to the Circle line portal rather than to the centre of the complex).
Three of the larger discrepancies (Gloucester Road to High Street Kensington, Bayswater to Paddington and King's Cross to Farringdon) occur where I took a shortcut through the backstreets rather than sticking to the main roads. Meanwhile the only walk TfL managed quicker than me was Victoria to Sloane Square, which isn't the easiest of cut-throughs, so maybe they know a more direct route than I do.
TfL's figures suggest that a complete walk round the Circle line takes five hours two minutes.
That's a walking speed of approximately bang on three miles an hour.
My circuit was almost an hour faster.
Just know, it's a heck of a long way round.
And if you ever fancy a fifteen mile walk without leaving central London, follow the Circle line.