[xefer]

I noticed they mentioned the speed reduction "Boston, for example, has reduced the city speed limit from 30 miles per hour to 25 mph." Cambridge across the river followed suit soon afterward, but having lived there for decades I can't say I've noticed one iota of difference in the speed cars travel. 25 mph is still ridiculously fast in most of the tight neighborhood streets. Really the speed limit should be reduced even further to 20 mph and even 15 in some areas accompanied by much stricter enforcement. It's not uncommon to see cars hitting 40+ going down some of the straighter roads that emanate out of the major squares.

I am a daily all-weather bike commuter and to be honest have not had a problem with cars. I don't really mind the concept of SOVs- we use one ourselves; it's just that they need to be much more tightly controlled at least in these neighborhoods.

[zanny]

I live in a town here the main street has a posted speed limit of 25 that absolutely nobody obeys and the average speed of traffic is always around 40.

If you take a road with a "natural" speed and try to artificially restrict with a speed limit, unless you are prepared to have officers posted on that road at all times ticketing people will ignore the limit entirely and go the "natural" speed of the road.

I see it all the time, all over, especially since I live in PA where the state thinks its a really sensible idea to keep almost every highway at 55 mph no matter what. When you try to heavily constrain car speed well below the natural speed of the road people simply stop trying to obey the limit at all and go whatever speed they want.

[clairity]

i wish this were more common knowledge. narrowing lanes is among the best ways to slow cars down, if that's the goal.

but in many cases, that goal is missapplied to reduce accidents. accidents are typically not caused by speed, but rather distraction or anger. it hard to enforce attention and mindfulness, so we regulate speed as a (poor) proxy (partially for harm reduction, as speed increases severity of accidents), which directly leads people to wrongly associate speed as the cause of accidents.

it makes sense, for example, to reduce vehicle speeds around schools to reduce harm in case of accidents with small people. but rather than an artificial speed limit that depends on police enforcement, narrow the lanes to 8 feet and people will naturally drive 15-20 mph in those school zones without the added enforcement burden (and use the remaining road space for bike lanes).

[emj]

Lower speed leads to fewer deaths; at ~18 mph almost no one dies, compared to 80% of pedestrians who are hit at 30 mph die. Your reasoning comes from another angle it might be correct but you can never assume people are attentive in traffic, neither pedestrians nor drivers, that's why you need rules and infrastructure that makes it possible to share the roads.

[ryantgtg]

In California (and I believe many other states), what you describe would be considered a speed trap, and it isn't allowed. Speed limits are supposed to be set by measuring how fast people drive on the roads. If 85% of drivers go 40, then that's the speed limit. If a city/county hasn't surveyed a street recently, then an officer cannot park their vehicle and hand out tickets for speeding (though they can give a ticket if they are driving their vehicle and see someone speeding) - because that could be a speed trap.

In 2016, the speed limit was enforceable on only 19% of streets in Los Angeles due to the speed trap law. The city has made great efforts recently to update their speed surveys, resulting, in most cases, in an increase in speed limits.

[amanaplanacanal]

The roads are engineered wrong. If you design a road for 40, then set the speed limit at 25, it's not going to work. You have to re-design the road for the 25 MPH speed limit. There are several ways to do this, and they are well known.

Of course cities are chronically underfunded for infrastructure, so this is really hard to do in practice.

[dsfyu404ed]

The city wide speed limit was irrelevant in both cities to begin with because in 99.99% of places you couldn't get up to that speed or if you could it would be uncomfortable (narrow streets, poor visibility, etc).

Conditions where one can even go 25+ for more than a couple hundred yards are rare and basically limited to main roads in low traffic conditions (i.e. late at night). These roads already had good bike lanes and the one cyclist riding in said lane at 1am is unlikely to be bothered by the one car that's also around going 30-40 in a separate lane (or I'm not at least).

[jnty]

In the UK, people against 20mph limits often oppose them while claiming that they're never able to get above that speed anyway. Why are they opposing it then? The answer is simple - it's not true and on many streets you're able to drive at 30 or over (if you disregard other people's safety). I would sincerely doubt this was any less the case in the US where traffic lanes even on 'tight' streets seem to be stupidly wide. Many drivers also seem perfectly happy to break the speed limit in their desperate rush to get the back of a queue or to a red traffic light.

It's all very well having cars going at 40mph past you on a bike until the driver of one of them gets distracted or makes a simple mistake and hits you. Then you'll wish they were doing 20!

[dsfyu404ed]

You can't just slap a 25 sign on a stretch of road where 90% of people feel like 30 is reasonable 90% of the time and expect people to go 25. Without Orwellian enforcement that does not work, not enough people will comply with the new limit. You need to make people actually feel like 25 is the right speed to go. Allowing on street parking on one side (less space for lanes) planting trees on the sidewalk (visually narrower), tuning traffic lights to create congestion , narrower lane markings and all sorts of other things can do that. You can try Orwellian enforcement but that will not fly in any American city (though it may take longer to crash and burn in some cities than others).

[ryantgtg]

In California, you literally can't "slap a 25 sign on a stretch of road where 90% of people feel like 30 is reasonable 90% of the time." That would be a violation of the vehicle code, which states that speeds are determined by the 85th percentile of operating speeds.

[dsfyu404ed]

As far as "laws CA has that most places don't have" that seems like one of the few reasonable ones. (and I say that as someone who has spent way to much time reading up on traffic and vehicle speed related things). In addition to delivering reasonable speed limits in most places it prevents towns from lowering speed limits in key areas to enable law enforcement rent seeking and probably saves countless hours of arguing over speed limits in local government.

[ryantgtg]

Another perspective is that "speeding leads to increased speed limit."

Generally, many streets are not designed in a context-sensitive way, but instead designed to fit the standards of a limited functional roadway classification system (arterial, collector, local). The passive safety approach of the '60s, as championed by the NHTSA, assumed that crashes are inevitable, and so the safety focus was put on preventing injury after a crash. Thus arterials, for example, have a similar design in which many roadside objects (trees, signs, lights, bollards, etc) were removed, with a "soft landing" on the side. And now we have big wide straight streets that, in their design, encourage us to drive faster.

There are extensive efforts to revise this CA law because of the unintended consequence that it makes roads more dangerous for non-vehicular travelers.

[mbrameld]

Once thing I've noticed is that for the large majority of US drivers, the speed limit is a very weak signal for how fast they should drive. I think the strongest signals are the driver's perceived safeness and the "flow of traffic", although the 2nd might actually just be a corollary of the 1st. If it "feels safe" to be driving 35mph, then most drivers are going to drive 35mph regardless of the speed limit.

[afcwebdesign]

Yeah, it's this exactly. We basically need to make our roads feel more dangerous to go fast on.

[dfxm12]

accompanied by much stricter enforcement

This is the crux of the matter. If people really thought they'd get a speeding ticket, perhaps they wouldn't speed. I live in a big city similar to Boston and I've never seen someone pulled over for speeding though. After all, what are the odds that:

1. A car speeds

2. In front of a cop

3. The cop can safely pursue the speeding vehicle in city traffic

[afcwebdesign]

Roads need to be redesigned so that going fast feels dangerous. Until then, there's no way to enforce it enough to actually change driver behavior. The US loves its wide roads that you can feel comfortable doing 80 on... until it starts to build narrow little shared streets people won't slow down.

[randcraw]

That's why in my area (outside Philly) speedtraps require at least two cops: one to gun you down and a second 100 feet down the road to wave you over.

[bluntfang]

>much stricter enforcement.

I believe enforcement of moving violations in the Boston metro is impossible. It is impossible because there is not enough room for an officer in a car to pull a vehicle over while simultaneously keep traffic moving at a reasonable speed. The police have purposely chosen to not enforce moving violations in order to prioritize traffic.

[alexlrobertson]

In Chicago they've reduced the speed limit on one of the most frequented bike routes to 20 mph in some areas but its had perceivably no effect. My perception is that cars still average 25 to 35 mph through these areas and I've yet to ever see someone pulled over for speeding.