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Are road speed limits based on safety?

cricetuscricetus.co.uk

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Re: Are road speed limits based on safety?

#2
The implicit point here is that speed limits should be based upon safety, or they should be abolished. This article fails to mention that there are important reasons for speed limits other than safety. For example, noise, pollution and climate. Mobility and freedom of those without a car, especially the young and very old. Speed limits are a tool that can be used to help boost the health, fitness and quality of life for people who live and work near roads (that's pretty much all of us).

Re: Are road speed limits based on safety?

#3
They can't be just based on safety. If they were, then 5 mph is safer than 10 mph, and 2mph is safer than 5 mph.

Road speeds need to be a tradeoff between safety and convenience. Unfortunately, in our mind safety and convenience are not just quantitative things, they carry moral connotations. Safety is good, convenience is at best neutral.

Until people develop a good framework to express this tradeoff, speed limits will be more or less arbitrary.

Re: Are road speed limits based on safety?

#4

They can't be just based on safety. If they were, then 5 mph is safer than 10 mph, and 2mph is safer than 5 mph. Road speeds need to be a tradeoff between safety and convenience. Unfortunately, in our mind safety and convenience are not just quantitative things, they carry moral connotations. Safety is good, convenience is at best neutral. Until people develop a good framework to express this tradeoff, speed limits w…

One of the things I think you are labeling under convenience is efficiency/productivity.

Until we can all work from home and use replicators to create our stuff, transportation will be a huge part of the production side of society. Speed limits affect that directly.

Re: Are road speed limits based on safety?

#5
post #2

The implicit point here is that speed limits should be based upon safety, or they should be abolished. This article fails to mention that there are important reasons for speed limits other than safety. For example, noise, pollution and climate. Mobility and freedom of those without a car, especially the young and very old. Speed limits are a tool that can be used to help boost the health, fitness and quality of life…

The point of all of these arguments is always that speed limits should be increased when all evidence suggests they should be lowered.

Evidence, in this case, being number of deaths.

Re: Are road speed limits based on safety?

#6
This article bakes in some false assumptions about compliance.

You can't just set a 40mph speedway on a limited access highway because "tHaT's WhAt'S sAfE gUyZ". Drivers will ignore it. Except that one guy with a dead hooker or brick of cocaine in the trunk or some other specific reason to be very cautious about complying with the law. He'll do 40. And safety will have been reduced because you have increased the variance in speed of traffic on the road.

There's a reason that current civil engineering doctrine is to set speed limits based on traffic speed and not the other way around.

Re: Are road speed limits based on safety?

#7
> In the UK the 60mph country roads in particular shouldn't be trusted to provide a safe speed at all times.

Especially on country roads, you shouldn't view the 60 mph speed limit as a speed target - drive at the speed appropriate to the road and conditions.

Re: Are road speed limits based on safety?

#8

They can't be just based on safety. If they were, then 5 mph is safer than 10 mph, and 2mph is safer than 5 mph. Road speeds need to be a tradeoff between safety and convenience. Unfortunately, in our mind safety and convenience are not just quantitative things, they carry moral connotations. Safety is good, convenience is at best neutral. Until people develop a good framework to express this tradeoff, speed limits w…

There is a road on my route home that switches from 50mph to 30mph for no other apparent reason than it is slightly residential. Fair enough, but there are many similar examples where this isn't the case - the limit is uniform regardless.

What people miss about this is that there is also a slightly awkward bend at mid-way point and it isn't unusual to see a car lodged into the fence that runs alongside.

Sometimes the speed limit is based on statistical information that may not be obvious until one day you are the fool who thinks he knows better.

Re: Are road speed limits based on safety?

#9

This article bakes in some false assumptions about compliance. You can't just set a 40mph speedway on a limited access highway because "tHaT's WhAt'S sAfE gUyZ". Drivers will ignore it. Except that one guy with a dead hooker or brick of cocaine in the trunk or some other specific reason to be very cautious about complying with the law. He'll do 40. And safety will have been reduced because you have increased the vari…

People who obey speed restrictions have a dead hooker in the trunk, who knew?

Re: Are road speed limits based on safety?

#10

This article bakes in some false assumptions about compliance. You can't just set a 40mph speedway on a limited access highway because "tHaT's WhAt'S sAfE gUyZ". Drivers will ignore it. Except that one guy with a dead hooker or brick of cocaine in the trunk or some other specific reason to be very cautious about complying with the law. He'll do 40. And safety will have been reduced because you have increased the vari…

Roads do a surprisingly good job of making clear how fast is safe to drive on them. I'm sure there must be places where people think, "Oh wow, going with the flow of the rest of these drivers feels really unsafe," but much more common is the experience where people are comfortably driving 10-20mph over the speed limit and there is no higher incidence of accidents there than anywhere else.

I think in general setting a speed limit to try to regulate speed for the sake of safety is one of the least effective ways to bring about the desired change.

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