this post was submitted on 03 Jun 2024
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Fuck Cars

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Part of an event called Sternfahrt where cyclists protest for policy changes by taking over the city on 20 routes covering 2000 km of public roads.

some infos in german: https://berlin.adfc.de/pressemitteilung/adfc-sternfahrt-medienkit

translation to english: https://berlin-adfc-de.translate.goog/pressemitteilung/adfc-sternfahrt-medienkit?_x_tr_sl=de&_x_tr_tl=en&_x_tr_hl=en-US&_x_tr_pto=wapp

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[–] [email protected] 14 points 5 months ago (5 children)

Looks to be an average of 2 ppl per lane with 3m ahead & behind. An average biking speed for commuters is 18-29kph, so let's do the calculus for 20, 25, & 30. This gives a throughput of 2x3x(20 or 25 or 30)/(3.6x6) ≈ (5.5 or 7 or 8.3) ppl/second

Car occupancy is ~1.5ppl/car in the EU. Given that this is a german highway Average distance between cars ~3 lengths meaning 4x4.5m=18m/car. For a long time these roads had "no speed limit", but the recommendation was ~130kph. Let's conservatively use 120 & 100kph. This gives 1.5x3x(100 or 120)/(3.6x18) ≈ (7 or 8.3) ppl/second.

Various things fudge the numbers in either direction, but that's actually shockingly close between the two.

[–] [email protected] 8 points 5 months ago (1 children)

You don't enter or exit at 120kph so throughput is cut by the bottle neck of exiting/entering (also the reason why there's traffic no matter the number of lanes, bottleneck is the throughput of entry exit creates the traffic stall

[–] [email protected] 3 points 5 months ago

Yeah I was trying to estimate the max throughput this highway has ever seen with cars, not the average. Nowadays they've even reduced the speed limit to a measly 80kph.

[–] [email protected] 5 points 5 months ago (1 children)

Here is some data to get more accurate numbers:

  • max speed on that highway for cars is 80km/h
  • the bicycles had an average speed of ~18km/h
[–] [email protected] 3 points 5 months ago (1 children)

The speed limit used to be higher though, originally it was nonexistent. Point was to estimate what the highest throughput of people in cars that highway has ever seen.

[–] [email protected] 3 points 5 months ago

Point taken, you’re correct.

[–] [email protected] 6 points 5 months ago (1 children)

I gotta take issue with those numbers. A car moving at 130kph covers 18 meters in about half a second. According to the numbers I found online, experts estimate the perception-reaction time for braking at 1.5 seconds, which is up from the value of 0.75 seconds that they used to use. Thirteen and a half meters is an unrealistically-close following distance, even for German super-humans.

I have not driven on the Autobahn, but the videos I can find show scenes much more consistent with a ~55 meter (1.5 seconds) gap between cars, or much-slower traffic speeds. That drops the estimated human-throughput way, way down.

[–] [email protected] 4 points 5 months ago

You assume people are driving safely - in my experience, during rush-hour at 90-100kph (Stockholm) someone will file in ahead of you if you leave more than 2 car lengths of space.

Is it safe? No.

Is it reality? Yes.

Furthermore, this is an estimate of a feasible max throughput that may have occurred.

[–] [email protected] 5 points 5 months ago (1 children)

Ok, but still healthier for all.

And you can savely take half of car throughput on average. Or far less in congestion.

[–] [email protected] 4 points 5 months ago

Just a fun calculation, aiming at comparing the video to a reasonable max throughput of people in cars that may have ocurred, not the average :)