The Wrong Way to Set Speed Limits [ST06]
Why Hacker News recommends it
Recommended again and again in traffic-safety threads as an eye-opener on road design versus posted limits and driver behavior.
What it is
Not Just Bikes explains how North American speed limits are set and why posted limits matter far less than street design. It argues that drivers follow the road's cues, so safe speeds have to be built into the street.
Recommended by 9 HN commenters across 9 different months, 2021 to 2025.
What Hacker News said
Strong rec gregmac · 2022-03 · on “New speed camera ‘detect’ vehicles braking as they approach”
I think my first intro to this was from a Not Just Bikes video on speed limits [1], and that profoundly affected my opinion on this stuff. I now think a lot of road design is just utterly broken, and it includes speed limits, what that channel (and other related) refer to as "stroads", and intersections (roundabouts vs traffic lights). That video in particular is highly relevant to the speed camera thing. [1] [this video]
Strong rec noirdujour · 2023-01 · on “America’s roads and highways have a big, fat style guide”
> MUTCD designs streets similarly to rural highways, and this can create conditions where people speed when they need to be driving slowly, because the design of the street doesn't reflect the speed the sign says you need to be driving. Not Just Bikes covers this shortfall in a video on speed limits[1], and it really opened my eyes on the relationship between rules and actual behavior. Essentially, speed limit signs affect driving speeds slightly, but the street design is important. Wide, open, straight roads naturally prompt drivers to drive to highway speeds, even in more suburb areas. It's amazing how often I check the speedometer and find that I'm driving much more than the posted speed
Strong rec gregmac · 2024-05 · on “Bollards: Why and What”
Europe has a lot more roads with a lower design speed. Curves, narrow lanes, on-street parking, trees/poles/etc close to the road. These things cause people to drive slower, because it doesn't feel safe to go fast. In North America, roads are usually built in the complete opposite way, with long straight roads and wide lanes, so the design speed is actually quite high -- even if that wasn't the intent. People go fast, because it feels safe to go that speed, but isn't, because there are pedestrians and turns. We then "fix" that shit road design by having low speed limits. This video is all I think of when this discussion comes up now: [this video]
Strong rec CalRobert · 2024-05 · on “California Senate Passes Bill Requiring Passive Speed Limiters”
Not much but it’s a start. Unfortunately the US treats every street and road like it’s a country road when it comes to speed limits, with a lot of deaths as a result. Great video on this at [this video]
Recommends xputer · 2021-10 · on “Car accidents cause death, injury and trauma. Why do we shrug them off?”
Sorry but this is just so wrong. American road design is super predicated on personal responsibility. We design roads that are as wide as freeways and then put a little sign on the side that says 35mph speed limit. What we need is less focus on personal responsibility and accept that people make mistakes, we're all human after all. Our roads should be designed with human error in mind. The road design itself should make it natural for drivers to slow down near dangerous areas. See this video for example: [this video]
Recommends xputer · 2021-10 · on “Car accidents cause death, injury and trauma. Why do we shrug them off?”
It's not about making the roads more narrow or winding per se. It's about deliberately slowing cars down where they need to, through the road design. See this video for example: [this video] Besides that, roads in the US are generally poorly classified. They're often trying to both function as both high throughput roads and destination serving streets. Such hybrid roads are known as "stroads" and they're bad for everyone involved. Stroads are bad for moving cars fast due to the many conflict points (driveways, intersections, etc.) that force drivers to constantly slow down. They are also bad at serving destinations because the many conflict points make stroads very dangerous, especially if you're
Recommends occz · 2022-09 · on “Heavier cars are safer for their drivers, but far deadlier for everyone else”
People don't follow speed limits, regardless of how literate they are. Relevant Not Just Bikes-video on the subject: [this video]
Recommends ben-schaaf · 2022-09 · on “Heavier cars are safer for their drivers, but far deadlier for everyone else”
Not Just Bikes has a great video covering this: [this video] TLDW: People don't obsessively check their speedometer and thus changing the speed limit largely doesn't affect the speed people drive at. To effectively change that you need to change the road design.