Anecdata, but I regularly see people exceed the speed limit by 30mph in Houston without much intervention by police.
The city has (imo) a psychotic driving culture, but is still roughly middle-of-the-road in us news and world report's ranking of most dangerous US cities to drive in.
Large speed deltas are (conjecture I haven't bothered to research) probably unsafe under any conditions. Exceeding safe speeds for the conditions is obviously dangerous, but the size and design of the road and it's lanes are some of those conditions.
I don't particularly care which, but in order to minimize speed deltas I do think it should be incumbent on the state to either set low speed limits and fastidiously police them or else set speed limits that are close to the natural speeds a given road supports to cut down the gap between people who drive the road as it feels and those who drive the signage.
Not Just Bikes has a great set of videos on Youtube about how road design and driver psychology help to tame speeds much more than simple road signs.
By now the evidence is clear: people will drive at the speeds they feel comfortable at given their environment (sight lines, spaciousness, density, etc.). Just putting a sign on the side of a wide and spacious road is not going to do much to affect driving speeds.
The most interesting one to me was how tree-lined streets encourage slower driving without any speed limit signs, because it feels more like a tunnel and less like an open road.
> tree-lined streets encourage slower driving without any speed limit signs
Somewhere near me (south UK) has a dual carriageway that approaches a roundabout. There is a fence on the side of the road as you approach the roundabout, so that you cannot see what traffic on the adjacent road is doing, forcing you to slow down on the approach, rather than maintaining a higher speed when it appears you might get away with it. Seems to work quite well.
The city has (imo) a psychotic driving culture, but is still roughly middle-of-the-road in us news and world report's ranking of most dangerous US cities to drive in.
Large speed deltas are (conjecture I haven't bothered to research) probably unsafe under any conditions. Exceeding safe speeds for the conditions is obviously dangerous, but the size and design of the road and it's lanes are some of those conditions.
I don't particularly care which, but in order to minimize speed deltas I do think it should be incumbent on the state to either set low speed limits and fastidiously police them or else set speed limits that are close to the natural speeds a given road supports to cut down the gap between people who drive the road as it feels and those who drive the signage.