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Comment by AnthonyMouse | Hacker News Reader

> 50 km/h to 30 km/h on a city commute doesn't make a substantial difference.

This seems like a weird argument. If your commute is an hour at 50 km/h then it's an hour and 40 minutes at 30 km/h, every day, each way. That seems like... quite a lot?

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That's not how it works. It's a 30km/h speed limit for one kilometer in your local neighbourhood until you hit the first through road, then it'll be 50km/h / 60km/h / 80 km/h / 120 km/h as usual, and another one kilometer at 30 km/h at your destination.

In other words, it's 2km at 30km/h plus 48km at 80km/h, versus 2km at 50km/h plus 48km at 80km/h. That's a difference of 1 minute 36 seconds.

Here for example is a map of Amsterdam (click on Wegcategorie en snelheid). Inside the block it's 15 km/h, on blue roads are 30, red roads are 50. The map doesn't color-code the highways, as they don't belong to municipality, but they are 100. https://maps.amsterdam.nl/30km/

It's like that since last December and was somewhat controversial when introduced (expanded), because muh freedoms, but not the kind of enduring controversy.

That map seems like the thing not to do. They have one section of the city where nearly the whole thing is blue and another section where nearly the whole thing is red, whereas what you would presumably want is to make every other road the alternate speed so that cars can prefer the faster roads and pedestrians can prefer the slower roads, thereby not just lowering speeds near pedestrians but also separating most of the cars from them whatsoever, and meanwhile allowing the cars to travel at higher speeds on the roads where most of the pedestrians aren't.

Amsterdam is an old city. The "everything is slow" part has extremely narrow roads, which were never designed for significant amounts of through traffic and realistically can never be made safe. Ideally they would indeed have a bunch of faster access roads, but that's just not physically possible.

The everything is red part is only red for throughroads and has different density compared to everytging is blue part.

The separating part is already done, so what you see is lowering the speed from 50 tp 30 even on the roads where the cars were funnelef into.

2017 Helsinki speed map for reference: https://www.hel.fi/hel2/ksv/Aineistot/Liikennesuunnittelu/Au...

(in support of the above thesis)

This is about driving in a city: you spend most of your time accelerating, decelerating, and waiting at intersections. 30 vs 50 km/h doesn't make much of a difference - travel time does not scale linearly with it.

Whether you can hold the maximum as the average doesn't mean there is no proportionality. If you're traveling at 50 km/h and then have to come to a stop and accelerate again your average speed might be 25, but if the maximum speed is 30 then your average speed might be 15.

Which city is an hour long drive at 50km/h?

It’s city centre driving that the article talks about.

You can drive through London for an hour in mostly 20mph (~30km/h) zones. Thing is, you're unlikely to be averaging anything even like 20. Even when the limit used to be 30 you weren't either. My old car averaged 16mph, & that included trips out of town at motorway speeds.

When the 20 limits were first introduced, lots of people would speed & overtake, but then you'd catch them up at the next traffic light & the one after etc.

I know London's quite an extreme case, but all a 20 limit means in a lot of stop/start urban areas is that you travel to the next stop at a speed which is less hazardous should you hit something/someone, with far more time to react to all the unpredictable things which happen in busy urban areas, thus decreasing the chances of hitting anything in the first place.

Yeah, it's mildly boring, but driving in cities pretty much always is. Just put on some music or a podcast and take it easy.

See, the real problem is that people cover too much distances daily. 50km is more than Luxembourg is wide where it's narrowest. They probably don't commute internationally every day there.

Actually a lot of people do, because it's cheaper to live and shop on the other side of the border.

I think people allocate themselves an hour or what their comfortable time is to commute and travel whatever distance they can cover in that time. If something is too far, they either move closer or pass on it. The exact mode, distance and speed can all vary, but what's budgeted for is time.

> See, the real problem is that people cover too much distances daily.

Which is why most of this is really a housing problem. If you make it too difficult to add new housing in and around cities, people have to live farther away, and in turn show up to the city in cars.

That's true, but people will willingly sacrifice time for a rather small career step up; moving house is hard once you have a family in schools and so on; so in a conurbation you end up with 1hr+ commutes anyway.

I don't think most are math-minded enough to factor commute time and cost into any salary calculation, if there's a 10% pay bump they'll take it even if all the gains get eaten up travel.

The speed limit is not 30km/h for the entire trip.

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