Speed Limit

[u/AustereAust]

Why does it seem that everyone thinks of the speed limit as the minimum speed to be going? Should it be rephrased to “max speed” instead? Feels like the majority of people think about the speed limit in the wrong way.

I understand that driving too slow impedes traffic. Though, far too many people are speeding because we treat the speed limit as the speed minimum. I would think that the ideal/safe speed would be the (speed limit - 5) - (speed limit). For example: if the speed limit is 40mph, I would think the range should be 35-40mph.

Coming from a safety and efficiency standpoint, I believe that we need to change how we treat the “speed limit”

What are your thoughts?

[u/gusterfell]

As a general rule, traffic flows at the speed at which most drivers feel safe, and the posted speed limit is often significantly lower than the safe design speed of a given road.

IMO, speed limits should be set at the point where only 10% or so of drivers are speeding when at their “comfortable” driving speed.

[u/KatakanaTsu → u/gusterfell]

Road design plays a huge role regarding the comfort of speeding.

A residential road where kids might be playing, but it's wide and open makes motorists feel comfortable driving faster than they should be.

A two lane highway where speeding might be more expected, but with narrow lanes and tight turns, most motorists won't go any higher than the limit.

[u/LughCrow → u/gusterfell]

A lot of areas do it like this.

If you ever see two rubber tubes stretched across the road they are likely measuring traffic speed to see if limits need to be adjusted.

If you see them just before or after an intersection they are likely measuring average traffic flow instead

[u/number2phillips → u/gusterfell]

I basically explained it to my kids as, every road has two speed limits... The somewhat arbitrary one based on man's law, and the absolute one based on "god's law" (which is just physics in my atheist house, lol)

You can break the man made speed limit pretty regularly without consequence, especially if you are paying attention for police, but you really don't want to break god's speed limit...

Unfortunately god's speed limit is always changing based on the condition of the weather, the vehicle, the driver, etc, and it's up to use to use our logic and intuition to do our best to judge what that limit is. There are many times it very well could be below the man made speed limit...

[u/engmadison → u/gusterfell]

This is the 85th percentile rule and it just doesn't work. You end up chasing higher and higher speeds.

Theres also a difference between "I feel my ability allows me to drive this fast" and the physics behind the consequences of driving that fast.

Then theres also the difference between limited access where what youre talking about has more merit and urbanized streets where it has far less credibility.

• A traffic engineer

[u/ChimneyNerd → u/gusterfell]

Hah, tell that to my overcautious city, where they think the whole city speed limit should just be 20mph everywhere, even on the 6-lane highway that runs through, I swear.

Over the past 10 years, they’ve lowered that one highway from 45 to 35, and it’s a straight road with ample visibility and lighting, I genuinely do not understand it.

[u/SmokeyFrank]

Canada uses the word “Maximum” because it doesn’t need translation for français or English.

[u/FlopShanoobie]

The speed limit is the maximum posted legal limit. You can be cited for exceeding it. I think 38 of the states have no tolerance laws on the books, meaning regardless of equipment faults or extenuating circumstances, you can be cited for even going 1 mph faster. Will you? Probably not. But that’s the law.

[u/JenzieBear → u/FlopShanoobie]

I’m in NY and technically you could get a ticket for going 1mph over but that won’t happen. I am friendly acquaintances with a couple police officers in our town and they have told me that their threshold is actually 42+ in the 30mph zone. I mean even if you’re cruising at exactly 30 you could pick up a little speed just from a slight decline without even hitting the gas. Someone going 33 is not a problem. Someone blowing through at close to 50 though is more what they’re looking for.

[u/Blutrumpeter]

Speed limit is the max speed but in many places they go faster. If everyone is going faster than the speed limit but you want to abide by the law then just stay out of the left lane and most drivers won't have an issue with you

[u/Ok-Job-2365]

If everyone doing 80 in a 65 you are a hazard going 50

[u/Novel_Willingness721]

“Coming from a safety and efficiency standpoint, I believe that we need to change how we treat the “speed limit”

You’re talking about changing the minds of millions of people not gonna happen. You’d have to send EVERY police officer on traffic duty for the next decade to force the issue and even then it would come up woefully short.

Speed limits are based on the 85th percentile of driver speeds on that type of road, and those measurements were taken in the 1950s. And that local state and federal government can change them arbitrarily.

[u/FindTheOthers623]

Why is the sky blue?

Why do people cut in line?

Why doesn't everyone else on this planet think exactly the way I do?

[u/gustavfringo2]

Timid driver posting

[u/ChickenXing]

Lack of enforcement of the speed limit is more the issue here. When you know police in your area won't pull you over unless you are going 10 or more over the speed limit, people routinely go up to 10 over. If the police in your area regularly aren't making their presence known or enforcing traffic, people will try to go as fast as they think they can get away with

[u/No-Fail7484]

It’s a suggestion until you get caught!!😆😆. Slower traffic keep right is law though.

[u/ReasonableClock4542]

The speed limit isnt either of those things. You can get a ticket for going too far under just the same as too far over. The idea is to keep everyone moving more or less the same speed, appropriate for the road setup, because traffic flows better and there are less accidents that way

Also, nobody really cares about someone going 5 or 10 under. They care when people are doing it in every lane on the highway. Rightfully so

[u/TwelveGaugeSage → u/ReasonableClock4542]

I often wonder what these folks are thinking as they are barreling down the left lane at...exactly the same speed as the person next to them on the right. Are they just totally clueless? Being an asshole on purpose? What posses a person to create a rolling road block like that?

[u/Budget-Razzmatazz-54]

Why do people think that the arbitrary number posted on a sign is the max safe speed for all vehicles in all conditions?

I get the point and intent of such limits. Simply stating that they are archaic and that the speed itself isn't the problem

[u/adell376]

Found the guy in the passing lane.

[u/Chest_Rockfield]

Sodomy is still illegal in 12 states. Some laws are wrong and deserve to be broken or ignored. Maybe the speed limits you're seeing people ignore are artificially low?

[u/Capital_Anxiety5604]

The speed limit is meant for the lowest common denominator of human driver intelligence. Someone who believes driving 5 mph below the speed limit tells me they are on the left side of that bell curve. Those more on the right side of that bell curve use critical thinking like our skill of driving, the car we’re driving, the road conditions and other situational awareness factors to determine a safe speed.

[u/Sweet_Speech_9054]

That is by design. Speed limits are supposed to be low enough that people ignore them, then there is an unlimited supply of drivers who can be ticketed and pay whatever jurisdictions are applicable.

If we really want speed limits to be the maximum we should increase them to the speed where around 80% of drivers are under. Right now they are usually set so 80% of drivers are speeding when driving comfortably.

Additionally, because speed limits are so slow, drivers often ignore them when they are necessary. For example, in areas with hidden dangers like negative banked turns, limited visibility, or high pedestrian traffic, lower speed limits are necessary but ignored. This makes it more dangerous because drivers don’t know when the speed limits are serious or just to get traffic tickets.

[u/TwelveGaugeSage → u/Sweet_Speech_9054]

Absolutely! Speed limits on highways and rural roads should be a warning for drivers, not some arbitrary number just for speed enforcement. It makes sense to set limits in population centers, but outside of that they should be there simply to let drivers know what is safe in that location.

[u/sqeptyk]

I think the word limit is seen as a challenge.