3 ms·

It's apparently not in the interest of traffic engineers in the U.S. to care for pedestrian (or cyclist) safety. It's been this way since the post-war area wher

by slhck 4y ago

It's apparently not in the interest of traffic engineers in the U.S. to care for pedestrian (or cyclist) safety. It's been this way since the post-war area where everything was built for cars, and this seems to have manifested in peoples' minds like the concrete they built. Hard to remove this. People seem to fight over minor improvements (like adding a protected bike lane or making safer crosswalks) while a drastic change would be necessary (like building completely different roads or changing underlying laws). I'd recommend checking out the "Not Just Bikes" YouTube channel for some interesting observations on the differences between the U.S. and Europe when it comes to traffic safety. Also, Strong Towns is a resource you might want to check out: https://www.strongtowns.org/ https://www.strongtowns.org/

oblio 4y ago
> It's apparently not in the interest of traffic engineers in the U.S. to care for pedestrian (or cyclist) safety. Knowing the average engineer, traffic engineers probably care about a lot of things. What usually happens is that someone higher up (politicians, city administrators, etc) set up an incentive system that forces the engineers' hand. Stuff like: "Increase car traffic speed in region X by Y% in 2023".
- consp 4y ago
  Funny you mention that metric since it happens often and is irrelevant since throughput would be way more interesting since it is often chosen as a metric to "solve" congestion, especially total throughput (including not cars) would most likely increase the total speed (in general) for all commuters due to limiting congestion. Don't mention to car-centric politicians the most effective speed for safe throughput is about 40kph/25mph and not 120/75.
  - eru 4y ago
    > Don't mention to car-centric politicians the most effective speed for safe throughput is about 40kph/25mph and not 120/75. I would assume that depends on the road in question? Eg Autobahn vs dirt road? If not, that would be a very interesting result!
    - consp 4y ago
      Throughput is mostly independent of road as distances between cars increase more than you can speed up to compensate (you reaction time stays the same or get's worse). Type of road can make a difference, obviously dirt makes the distance requirements worse. If people also exit/enter the road it's even worse. I was assuming an ideal road though with everyone sticking to the same speed. Cross lane movement and speed difference in traffic also places limits and slower speeds limit both of those afaik.
    - wiredfool 4y ago
      It's pretty well known graph in traffic engineering -- Max throughput isn't free flowing traffic. (Though I remember it at 35-40 mph on interstate/motorway). The basic reason is that free flowing traffic requires bigger gaps between vehicles. (safe anyway, but practically the way people drive generally follows the safe spacing function, but with a 'bit' of y offset). At the minimum latency (the free flow speed (ffs)) the spacing between cars is x seconds, so you get 3600/x cars per hour. At maximum flow rate, ~1/2 the ffs, the spacing is more like 1-2 seconds, so you get closer to 2k cars per hour. Even slower, the cars can be packed closer, but you don't clear the road nearly as quickly so the throughput is lower. See https://courses.washington.edu/cee320ag/Lecture/Freeway_LOSd1.pdf https://courses.washington.edu/cee320ag/Lecture/Freeway_LOSd... (page 13) and https://courses.washington.edu/cee320ag/Lecture/Freeway_LOSd2.pdf https://courses.washington.edu/cee320ag/Lecture/Freeway_LOSd... (page 9) It's a little bit like the tradeoff between latency and throughput in servers.
- andrepd 4y ago
  Traffic engineers routinely make design choices that prioritise minor driver convenience (think 5 seconds saved) over pedestrian life-or-death.
Tade0 4y ago
I've become disillusioned with the Not Just Bikes guy. He tends to omit key disadvantages of the lifestyle he's advertising.
- slhck 4y ago
  Which are?
  - Tade0 4y ago
    Costs mostly. He's talking from a privileged position of someone who can afford living in Amsterdam with his lifestyle. Take for example buying groceries in your corner shop daily on your way back from work. Easily 50% more expensive than taking a longer, less frequent trip to a larger supermarket further away. But what upset me the most was showcasing a building built somewhere in Canada that was, in his view, great because it didn't have parking spaces. What actually happened is that the building rented-out parking spots from a nearby multi-level parking lot and was only allowed to be built as an exception, because it was too tall according to the zoning. And it shows, because it stands out like a buck tooth. I live in a country essentially taken over by construction companies' interests and this is the kind of bullshit they peddle to improve their margins.
    - andrepd 4y ago
      I don't follow. One of the things he rallies against the most in his videos is precisely laws — like zoning regulations and parking minimums — which make it illegal to build walkable neighbourhoods and encourage car-dependent sprawl. As for buying for the corner shop being 50% more expensive, why? What are you basing yourself on to make that assertion?
      - Tade0 4y ago
        > One of the things he rallies against the most in his videos is precisely laws — like zoning regulations and parking minimums — which make it illegal to build walkable neighbourhoods and encourage car-dependent sprawl. I see this as a perspective of someone who never lived in a walkable city that has both zoning and parking minimums. It's not a case of either-or. The type of construction he's proposing is a net negative to how a city functions - specifically it was a particularly tall building in an area where four floors + ground level buildings were already allowed - that's an already appropriate density for a city. > What are you basing yourself on to make that assertion? That's my experience from just about every European city I spent any appreciable time in(meaning - at least a few months) - especially the one I grew up in. And no wonder - grocery stores scale exceedingly well so far as there's cheap land to build on. That's not the case in city centres.

by slhck 4y ago

oblio 4y ago

> It's apparently not in the interest of traffic engineers in the U.S. to care for pedestrian (or cyclist) safety. Knowing the average engineer, traffic engineers probably care about a lot of things. What usually happens is that someone higher up (politicians, city administrators, etc) set up an incentive system that forces the engineers' hand. Stuff like: "Increase car traffic speed in region X by Y% in 2023".

consp 4y ago
Funny you mention that metric since it happens often and is irrelevant since throughput would be way more interesting since it is often chosen as a metric to "solve" congestion, especially total throughput (including not cars) would most likely increase the total speed (in general) for all commuters due to limiting congestion. Don't mention to car-centric politicians the most effective speed for safe throughput is about 40kph/25mph and not 120/75.
- eru 4y ago
  > Don't mention to car-centric politicians the most effective speed for safe throughput is about 40kph/25mph and not 120/75. I would assume that depends on the road in question? Eg Autobahn vs dirt road? If not, that would be a very interesting result!
  - consp 4y ago
    Throughput is mostly independent of road as distances between cars increase more than you can speed up to compensate (you reaction time stays the same or get's worse). Type of road can make a difference, obviously dirt makes the distance requirements worse. If people also exit/enter the road it's even worse. I was assuming an ideal road though with everyone sticking to the same speed. Cross lane movement and speed difference in traffic also places limits and slower speeds limit both of those afaik.
  - wiredfool 4y ago
    It's pretty well known graph in traffic engineering -- Max throughput isn't free flowing traffic. (Though I remember it at 35-40 mph on interstate/motorway). The basic reason is that free flowing traffic requires bigger gaps between vehicles. (safe anyway, but practically the way people drive generally follows the safe spacing function, but with a 'bit' of y offset). At the minimum latency (the free flow speed (ffs)) the spacing between cars is x seconds, so you get 3600/x cars per hour. At maximum flow rate, ~1/2 the ffs, the spacing is more like 1-2 seconds, so you get closer to 2k cars per hour. Even slower, the cars can be packed closer, but you don't clear the road nearly as quickly so the throughput is lower. See https://courses.washington.edu/cee320ag/Lecture/Freeway_LOSd1.pdf https://courses.washington.edu/cee320ag/Lecture/Freeway_LOSd... (page 13) and https://courses.washington.edu/cee320ag/Lecture/Freeway_LOSd2.pdf https://courses.washington.edu/cee320ag/Lecture/Freeway_LOSd... (page 9) It's a little bit like the tradeoff between latency and throughput in servers.
andrepd 4y ago
Traffic engineers routinely make design choices that prioritise minor driver convenience (think 5 seconds saved) over pedestrian life-or-death.

Tade0 4y ago

I've become disillusioned with the Not Just Bikes guy. He tends to omit key disadvantages of the lifestyle he's advertising.

slhck 4y ago
Which are?
- Tade0 4y ago
  Costs mostly. He's talking from a privileged position of someone who can afford living in Amsterdam with his lifestyle. Take for example buying groceries in your corner shop daily on your way back from work. Easily 50% more expensive than taking a longer, less frequent trip to a larger supermarket further away. But what upset me the most was showcasing a building built somewhere in Canada that was, in his view, great because it didn't have parking spaces. What actually happened is that the building rented-out parking spots from a nearby multi-level parking lot and was only allowed to be built as an exception, because it was too tall according to the zoning. And it shows, because it stands out like a buck tooth. I live in a country essentially taken over by construction companies' interests and this is the kind of bullshit they peddle to improve their margins.
  - andrepd 4y ago
    I don't follow. One of the things he rallies against the most in his videos is precisely laws — like zoning regulations and parking minimums — which make it illegal to build walkable neighbourhoods and encourage car-dependent sprawl. As for buying for the corner shop being 50% more expensive, why? What are you basing yourself on to make that assertion?
    - Tade0 4y ago
      > One of the things he rallies against the most in his videos is precisely laws — like zoning regulations and parking minimums — which make it illegal to build walkable neighbourhoods and encourage car-dependent sprawl. I see this as a perspective of someone who never lived in a walkable city that has both zoning and parking minimums. It's not a case of either-or. The type of construction he's proposing is a net negative to how a city functions - specifically it was a particularly tall building in an area where four floors + ground level buildings were already allowed - that's an already appropriate density for a city. > What are you basing yourself on to make that assertion? That's my experience from just about every European city I spent any appreciable time in(meaning - at least a few months) - especially the one I grew up in. And no wonder - grocery stores scale exceedingly well so far as there's cheap land to build on. That's not the case in city centres.