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I think a better solution would be to re-evaluate how we set speed limits. Clearly, the design of the road has an incredible influence over what speeds drivers

I think a better solution would be to re-evaluate how we set speed limits. Clearly, the design of the road has an incredible influence over what speeds drivers feel comfortable - and uncomfortable - going. There is a road near me (SWFL) where everyone routinely goes about 50 MPH, despite a 35MPH limit. The road has three lanes on each side, ditches on either side, a wide median, and dedicated turn lanes to get on and off. It's uncomfortable - and often dangerous - to follow the posted speed. For any major road, it seems like the best approach would be to build it, then test what speed the majority of traffic goes on it before setting the limit. Get the average speed, add 5, and post the sign. If the speed is too high for the type of road, it should be redesigned. Surely it'd only take a couple of tries at the process before we figured out how to make a road where most people would drive the speed we intend. -- As for electronic speed monitoring, there is another nearby road that's posted at 50 MPH that google maps insists is still 35 MPH. If electronic speed monitoring goes to its natural extent, that sort of mistake could result in hefty, unjustified fines or even jail time. In any case, I have a feeling that this is a band-aid solution that will further discourage the average consumer from purchasing new cars.

acdha 2y ago
The problem with that approach is that it only considers drivers, and it lets the aggressive drivers influence the speed limit by bullying safer drivers. Outside of freeways, we shouldn’t dedicate millions of dollars in public space to private car drivers, so we should be looking at the rest of the community and ensuring that cities aren’t built around the idea that everyone needs a private vehicle. That’s a financial hardship for many people (where I live, cars are neck and neck with food as a household expense, behind only housing) and it freezes out the roughly ⅓ of the population who can’t drive. It also locks in significant health and environmental costs and we don’t tax driving to pay for those.
- LeftHandPath 2y ago
  See the Solomon Curve - https://en.wikipedia.org/wiki/Solomon_curve https://en.wikipedia.org/wiki/Solomon_curve We absolutely should consider the entirety of drivers and their existing behaviors when we design roads, instead of wishing they would behave differently. Moreover, reducing accommodation for motor vehicles in cities leaves the non-urban population behind - and neglects that private vehicles aren't the only users of the roadway. Truck deliveries, garbage collection, and mail become a lot more difficult if roadways are reduced.
  - squidgyhead 2y ago
    Differences in speed matter, but so does absolute speed. "Inappropriate speed is responsible for 20 to 30% of all fatal road crashes." from https://www.itf-oecd.org/speed-crash-risk https://www.itf-oecd.org/speed-crash-risk Also, due to kinetic energy increasing with speed, collisions are worse, in addition to being more likely.
  - acdha 2y ago
    Note that I’m not saying we don’t consider drivers at all - only that we look at the needs of the entire city rather than saying anyone who doesn’t drive doesn’t matter or, especially, that people who live there are less important than faster commutes for non-residents as was the case for much of the 20th century. > Moreover, reducing accommodation for motor vehicles in cities leaves the non-urban population behind - and neglects that private vehicles aren't the only users of the roadway. Truck deliveries, garbage collection, and mail become a lot more difficult if roadways are reduced. Non-urban drivers shouldn’t have primacy over residents just because they chose to live further away and refuse to use transit. Moreover, there’s a fundamental flaw in the assumption that speed limits are the primary limiting factor there: we actually know from decades of studies that they’re slowed by other cars, and adding lanes tends to make things worse by incentivizing more car trips. Boston famously spent enormous amounts of money on the Big Dig - which the MBTA is still struggling to pay off - and the net impact was a slight time savings for suburban commuters for about six months, after which traffic was worse than before because more people were driving. Getting those people onto trains would be far more effective and cheaper. Similarly, delivery and garbage trucks aren’t affected at all by calming measures because those drivers aren’t flooring it all the way downtown - they’re stopping too often. What does help is reducing congestion and simplifying roads because that makes their routes more predictable (they don’t have the option of picking an alternate route) – if we wanted to help them, we’d ban unprotected left turns or reserve one parking spot per block for deliveries.
    - LeftHandPath 2y ago
      It sounds like you're working with a base assumption that increasing usage of cars is bad. My base assumption is that moving people around is good. Freedom of movement and time-efficient movement. The car reigns supreme over trains, planes, and buses in those terms. > the net impact was a slight time savings for suburban commuters for about six months, after which traffic was worse than before because more people were driving. By the sound of it, more people were able to get where they were going because of the the Big Dig. > Getting those people onto trains would be far more effective and cheaper A breakdown of the numbers here would be great, but I'm not sure how much more time either of us want to spend lol. I like trains, but I'm cautious about them because they generally can't take people directly to an end destination the way an independent vehicle can. The US has also generally failed to use rail in a way that could replace cars in a meaningful way, despite rail having a decades-long head-start over the automobile. > Similarly, delivery and garbage trucks aren’t affected at all by calming measures I was under the (perhaps mistaken) impression that you wanted to remove or replace roads in cities to make way for alternative transportation. That's based on the statement in your original comment: > Outside of freeways, we shouldn’t dedicate millions of dollars in public space to private car drivers, I was not referring to traffic calming measures when I said that would be a logistical nightmare. I more meant that private cars share common infrastructure with a number of critical services; reducing their share of public space would harm those other services.
beached_whale 2y ago
Rust/deterioration will take care of that.
hyrix 2y ago
Optimistically, this rule could create tighter feedback loops due to increased community engagement with planners so that databases get updated more quickly and speed limits are perhaps dialed in to match real conditions--the mismatched limits that you mention might have been established with expectation of a neighborhood buildout that never happened, or may be an oversight in low population areas--or they may be there for good reasons. As it stands, speed limits are not usually enforced and are basically ignored by drivers, so (optimistically) this may encourage communities to make them more realistic limits, as opposed to suggestions.
Zak 2y ago
> Get the average speed, add 5, and post the sign. A common method for setting speed limits in the past was the 85th percentile speed. I agree that changes to road design are a good idea when a significant number of people drive too fast, with "too fast" being determined by risk factors that are not necessarily obvious to drivers. Adding curb extensions, chicanes, or narrowing lanes by painting new lines are some inexpensive options for encouraging slower driving. I'm against nannies built into cars or heavy punitive enforcement.
scruple 2y ago
> There is a road near me (SWFL) where everyone routinely goes about 50 MPH, despite a 35MPH limit. You say this but in SoCal I see vastly many more people driving 35 in a 50 than 50 in a 35. Which is... Probably what causes a lot of the speeding problems in the first place and is, frankly, vastly more dangerous because people set expectations around the signs.

acdha 2y ago

The problem with that approach is that it only considers drivers, and it lets the aggressive drivers influence the speed limit by bullying safer drivers. Outside of freeways, we shouldn’t dedicate millions of dollars in public space to private car drivers, so we should be looking at the rest of the community and ensuring that cities aren’t built around the idea that everyone needs a private vehicle. That’s a financial hardship for many people (where I live, cars are neck and neck with food as a household expense, behind only housing) and it freezes out the roughly ⅓ of the population who can’t drive. It also locks in significant health and environmental costs and we don’t tax driving to pay for those.

LeftHandPath 2y ago
See the Solomon Curve - https://en.wikipedia.org/wiki/Solomon_curve https://en.wikipedia.org/wiki/Solomon_curve We absolutely should consider the entirety of drivers and their existing behaviors when we design roads, instead of wishing they would behave differently. Moreover, reducing accommodation for motor vehicles in cities leaves the non-urban population behind - and neglects that private vehicles aren't the only users of the roadway. Truck deliveries, garbage collection, and mail become a lot more difficult if roadways are reduced.
- squidgyhead 2y ago
  Differences in speed matter, but so does absolute speed. "Inappropriate speed is responsible for 20 to 30% of all fatal road crashes." from https://www.itf-oecd.org/speed-crash-risk https://www.itf-oecd.org/speed-crash-risk Also, due to kinetic energy increasing with speed, collisions are worse, in addition to being more likely.
- acdha 2y ago
  Note that I’m not saying we don’t consider drivers at all - only that we look at the needs of the entire city rather than saying anyone who doesn’t drive doesn’t matter or, especially, that people who live there are less important than faster commutes for non-residents as was the case for much of the 20th century. > Moreover, reducing accommodation for motor vehicles in cities leaves the non-urban population behind - and neglects that private vehicles aren't the only users of the roadway. Truck deliveries, garbage collection, and mail become a lot more difficult if roadways are reduced. Non-urban drivers shouldn’t have primacy over residents just because they chose to live further away and refuse to use transit. Moreover, there’s a fundamental flaw in the assumption that speed limits are the primary limiting factor there: we actually know from decades of studies that they’re slowed by other cars, and adding lanes tends to make things worse by incentivizing more car trips. Boston famously spent enormous amounts of money on the Big Dig - which the MBTA is still struggling to pay off - and the net impact was a slight time savings for suburban commuters for about six months, after which traffic was worse than before because more people were driving. Getting those people onto trains would be far more effective and cheaper. Similarly, delivery and garbage trucks aren’t affected at all by calming measures because those drivers aren’t flooring it all the way downtown - they’re stopping too often. What does help is reducing congestion and simplifying roads because that makes their routes more predictable (they don’t have the option of picking an alternate route) – if we wanted to help them, we’d ban unprotected left turns or reserve one parking spot per block for deliveries.
  - LeftHandPath 2y ago
    It sounds like you're working with a base assumption that increasing usage of cars is bad. My base assumption is that moving people around is good. Freedom of movement and time-efficient movement. The car reigns supreme over trains, planes, and buses in those terms. > the net impact was a slight time savings for suburban commuters for about six months, after which traffic was worse than before because more people were driving. By the sound of it, more people were able to get where they were going because of the the Big Dig. > Getting those people onto trains would be far more effective and cheaper A breakdown of the numbers here would be great, but I'm not sure how much more time either of us want to spend lol. I like trains, but I'm cautious about them because they generally can't take people directly to an end destination the way an independent vehicle can. The US has also generally failed to use rail in a way that could replace cars in a meaningful way, despite rail having a decades-long head-start over the automobile. > Similarly, delivery and garbage trucks aren’t affected at all by calming measures I was under the (perhaps mistaken) impression that you wanted to remove or replace roads in cities to make way for alternative transportation. That's based on the statement in your original comment: > Outside of freeways, we shouldn’t dedicate millions of dollars in public space to private car drivers, I was not referring to traffic calming measures when I said that would be a logistical nightmare. I more meant that private cars share common infrastructure with a number of critical services; reducing their share of public space would harm those other services.

beached_whale 2y ago

Rust/deterioration will take care of that.

hyrix 2y ago

Optimistically, this rule could create tighter feedback loops due to increased community engagement with planners so that databases get updated more quickly and speed limits are perhaps dialed in to match real conditions--the mismatched limits that you mention might have been established with expectation of a neighborhood buildout that never happened, or may be an oversight in low population areas--or they may be there for good reasons. As it stands, speed limits are not usually enforced and are basically ignored by drivers, so (optimistically) this may encourage communities to make them more realistic limits, as opposed to suggestions.

Zak 2y ago

> Get the average speed, add 5, and post the sign. A common method for setting speed limits in the past was the 85th percentile speed. I agree that changes to road design are a good idea when a significant number of people drive too fast, with "too fast" being determined by risk factors that are not necessarily obvious to drivers. Adding curb extensions, chicanes, or narrowing lanes by painting new lines are some inexpensive options for encouraging slower driving. I'm against nannies built into cars or heavy punitive enforcement.

scruple 2y ago

> There is a road near me (SWFL) where everyone routinely goes about 50 MPH, despite a 35MPH limit. You say this but in SoCal I see vastly many more people driving 35 in a 50 than 50 in a 35. Which is... Probably what causes a lot of the speeding problems in the first place and is, frankly, vastly more dangerous because people set expectations around the signs.