In my experience, American roads are built to support much higher speeds than the speed limit is set. Going 10-20mph over the limit doesn’t feel particularly unsafe on the wide, straight roads.
On the other side, it felt crazy to drive the speed limit on (for example) the narrow, windy roads in Ireland. The limit there felt like a literal maximum, whereas in the US it feels like the minimum.
As noted car enthusiast NotJustBikes has said, driving is not a conscious activity. We drive to what feels right, to a degree. A road built to support 100kph will always have speeder problems until layers of traffic calming are put in place.
UK B road limits are in fact limits, often being little more than millennia old cart paths with asphalt applied
If you look at the design documents for the roads in your area, usually available in plain old PDF files at your State DOT website… it usually states both the designed speed, and what the posted speed will be.
If it’s a modern road, it is almost certainly designed for 5-10mph over what the posted limit will be. Because they know most traffic will speed, and that is accounted for in the road design, regardless of the posted limit sign.
It’s wild to me that someone heard this logic and said “makes sense”.
Like, I get it from an engineering perspective. You find out the maximum capacity of a bridge, account for extremes like multiple heavy loads, find the point of failure, and then engineer in a safety factor. Making sure your bridge can handle your theoretical maximum several times over.
But, we aren’t dealing with people seeing a strong bridge and thinking “nice, I can carry more stuff in my car” and encourage a larger capacity. The capacity they carry is already limited by their vehicle. They aren’t even thinking about the bridges capacity.
With road design. The road controls the capacity (speed) directly to the user of the road. There is a physical speed that if their car reaches they will crash. They interact with it directly.
Designing a road that increases that speed at which a guaranteed crash will happen is primarily just increasing the lethality of said crash. That’s the primary part of “safety” that the design guideline is controlling.
It’s saying. “Hey, if you go too fast for the road conditions, don’t worry. We made sure that the road was designed so that when you reach that speed you’ll have less time to react and more chance of dying”.
Also, “everyone speeds” is bull shit. Every speeds down a zero intersection straight road with a posted speed limit 15 MPH under what the road was designed for. It’s a fucking self fulfilling prophecy.
It’s saying. “Hey, if you go too fast for the road conditions, don’t worry. We made sure that the road was designed so that when you reach that speed you’ll have less time to react and more chance of dying”.
That’s not at all what’s being said. Knowing the speed people will want to drive with a specific design, doesn’t make it inherently “too fast”, its the exact opposite. The road designers are literally designing what the road condition will feel like to drivers, then taking the human factor into account to set a sensible limit instead of an arbitrary one.
If they know the road design will make people drive 50mph, and that most people drive 5mph over the posted limit, they post a 45mph limit. Driving at 50mph down that road is not “too fast”, that’s literally what was designed to feel correct.
There have been several studies over the years about posted versus real world speeds. Including studies of the same road with the posted speed being changed and monitoring driver behavior. They found that regardless of what the posted sign says, people usually drove about the same speed on that road. The minimum and maximum speeds varied with different signs as some people used that number directly, but the average of all traffic stayed the same regardless of the signage because that’s the speed that felt correct for that roadway. In some cases that was under the posted limit, in others that average was up to 10 over the posted limit.
Every speeds down a zero intersection straight road with a posted speed limit 15 MPH under what the road was designed for. It’s a fucking self fulfilling prophecy.
Most roads do not have posted speed limits that vary dramatically from the speed that feels right on that road, because they’re designed for a specific speed and posted with that consideration. Artificially low speed limits are not common. They’re usually from a speed being changed years after the road was designed and built, so it wasn’t intended to have drivers at that speed and also wasn’t physically changed to help reinforce that speed subconsciously, or from a town trying to boost ticket revenue.
When I was in Appalachia, on the mountain roads, many are very narrow, and winding. Speed limits often like 40, and you can’t go more than that without crashing unless you have a motorcycle or something. It’s not a suggestion, it’s the maximum you can do on the curves.
In my experience, American roads are built to support much higher speeds than the speed limit is set. Going 10-20mph over the limit doesn’t feel particularly unsafe on the wide, straight roads.
On the other side, it felt crazy to drive the speed limit on (for example) the narrow, windy roads in Ireland. The limit there felt like a literal maximum, whereas in the US it feels like the minimum.
this is often not thought about when talking about this but even the spacing in the lines drawn on the road influences your perception of speed.
the solution isn’t trying to enforce lower limits, it’s having roads enforce them.
As noted car enthusiast NotJustBikes has said, driving is not a conscious activity. We drive to what feels right, to a degree. A road built to support 100kph will always have speeder problems until layers of traffic calming are put in place.
UK B road limits are in fact limits, often being little more than millennia old cart paths with asphalt applied
If you look at the design documents for the roads in your area, usually available in plain old PDF files at your State DOT website… it usually states both the designed speed, and what the posted speed will be.
If it’s a modern road, it is almost certainly designed for 5-10mph over what the posted limit will be. Because they know most traffic will speed, and that is accounted for in the road design, regardless of the posted limit sign.
It’s wild to me that someone heard this logic and said “makes sense”.
Like, I get it from an engineering perspective. You find out the maximum capacity of a bridge, account for extremes like multiple heavy loads, find the point of failure, and then engineer in a safety factor. Making sure your bridge can handle your theoretical maximum several times over.
But, we aren’t dealing with people seeing a strong bridge and thinking “nice, I can carry more stuff in my car” and encourage a larger capacity. The capacity they carry is already limited by their vehicle. They aren’t even thinking about the bridges capacity.
With road design. The road controls the capacity (speed) directly to the user of the road. There is a physical speed that if their car reaches they will crash. They interact with it directly.
Designing a road that increases that speed at which a guaranteed crash will happen is primarily just increasing the lethality of said crash. That’s the primary part of “safety” that the design guideline is controlling.
It’s saying. “Hey, if you go too fast for the road conditions, don’t worry. We made sure that the road was designed so that when you reach that speed you’ll have less time to react and more chance of dying”.
Also, “everyone speeds” is bull shit. Every speeds down a zero intersection straight road with a posted speed limit 15 MPH under what the road was designed for. It’s a fucking self fulfilling prophecy.
That’s not at all what’s being said. Knowing the speed people will want to drive with a specific design, doesn’t make it inherently “too fast”, its the exact opposite. The road designers are literally designing what the road condition will feel like to drivers, then taking the human factor into account to set a sensible limit instead of an arbitrary one.
If they know the road design will make people drive 50mph, and that most people drive 5mph over the posted limit, they post a 45mph limit. Driving at 50mph down that road is not “too fast”, that’s literally what was designed to feel correct.
There have been several studies over the years about posted versus real world speeds. Including studies of the same road with the posted speed being changed and monitoring driver behavior. They found that regardless of what the posted sign says, people usually drove about the same speed on that road. The minimum and maximum speeds varied with different signs as some people used that number directly, but the average of all traffic stayed the same regardless of the signage because that’s the speed that felt correct for that roadway. In some cases that was under the posted limit, in others that average was up to 10 over the posted limit.
Most roads do not have posted speed limits that vary dramatically from the speed that feels right on that road, because they’re designed for a specific speed and posted with that consideration. Artificially low speed limits are not common. They’re usually from a speed being changed years after the road was designed and built, so it wasn’t intended to have drivers at that speed and also wasn’t physically changed to help reinforce that speed subconsciously, or from a town trying to boost ticket revenue.
When I was in Appalachia, on the mountain roads, many are very narrow, and winding. Speed limits often like 40, and you can’t go more than that without crashing unless you have a motorcycle or something. It’s not a suggestion, it’s the maximum you can do on the curves.