This also came up recently in a thread about speed governors: https://news.ycombinator.com/item?id=43812856 Just a few governor-equipped vehicles (e.g. from public fleets or prior speeding offenders) can reduce speeding on the whole road.
On most roads, speeding isn’t a safety issue and shouldn’t be discouraged, as road throughput is important. Speed limits are usually set too low due to standardized inflexible policies or desire for revenue.
On some roads, however, it is a massive safety issue, and everyone is driving unsafely because the road is designed badly for its intended purpose. (So-called “stroads” are the canonical example.)
Yeah and we should definitely leave deciding the appropriate speed to the drivers. Because, uh, throughput is important, got it. Is safety important? Who knows, but throughput definitely is!
Speed is always a contributing cause to a collision. It's pretty simple to understand, if colliding parties are going slower, they would have more time to prevent collision.
The speed limits on most residential roads are too low from a variety of factors, including tradition, policies, and desire for revenue or to generate PC to pull over drivers.
You don't drive 25 on residential roads, because you know this to be true. Neither do I, nor does anyone else.
The above comment is getting downvoted, and I suspect it's due to a misunderstanding of their intent. Yes, high speeds can make collisions (especially, as another commenter points out, to pedestrians and cyclists) more dangerous. However, just as human drivers subconsciously speed up when part of a group of cars, they are not often conscious of the environmental queues informing the speed at which they drive. Given the poster's allusion to 'stroads', I suspect that they're in favor of traffic engineering patterns that encourage speed reduction based on safe context queues without solely relying on an unenforced and often unobeyed traffic speed.
Lane narrowing, raised walkways, curves in the road (chicanes), etc. are all environmental queues that enforce safe traffic speed based on context, without relying on conscious human compliance.