Speed limit arithmetic
9 February 2026 03:53 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
igenlode"It took an average of three minutes and 38 seconds to drive one kilometre (0.6 miles) in the centre of London last year... This was partly blamed on widespread 20mph speed limits" -- *what*?
20mph is 32km/h (using the rule-of-thumb conversion ratio of 5:8). So if you were travelling at 32 kilometres per hour it would take (60/32)=1.875 minutes to cover one kilometre: 1 minute 52 seconds. Clearly the majority of the time spent driving in central London is already spent travelling at speeds far *lower* than 20mph; probably spent stationary in traffic jams consisting of other cars. So just how fast are they expecting drivers to sprint between traffic jams in order that increasing the maximum speed limit will reduce journey times?
20mph is 32km/h (using the rule-of-thumb conversion ratio of 5:8). So if you were travelling at 32 kilometres per hour it would take (60/32)=1.875 minutes to cover one kilometre: 1 minute 52 seconds. Clearly the majority of the time spent driving in central London is already spent travelling at speeds far *lower* than 20mph; probably spent stationary in traffic jams consisting of other cars. So just how fast are they expecting drivers to sprint between traffic jams in order that increasing the maximum speed limit will reduce journey times?
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Date: 2026-02-19 03:57 pm (UTC)Thanks for all the new information, as I really didn't know that before now, and it's certainly good to learn more! For some specifics:
London consisting of multiple city centres makes more sense of its structure; I knew that the outer suburbs were once separate villages, but I hadn't considered it for the core, so I did find it weirdly large... and now I know what's causing that.
Yeah, I didn't even need to read the article to guess that it dominates its entire environment. Good to hear it might be replaced with a tunnel, though.
Nice that some of those streets have survived to the present day, even if they aren't obvious now; it's still a bit of history in a relatively accessible place.