Why are they 60mph? Well, the symbol they display doesn't say 60mph, it's basically just a slash symbol - it should be read "National Limit Applies" or perhaps "Derestricted" and it so happens that the law in the UK says that if there's no other rule in place that limit is 60mph and on these tiny roads nobody has put in place a more specific limit so that's the law.
[If there is carriageway separation, e.g. a larger road on which traffic flowing in the opposite direction isn't sharing the same tarmac, this global rule says 70mph, but no tiny roads have multiple carriageways, actually sometimes it feels like there's barely room for one let alone two]
However, just because there isn't a lower limit doesn't mean it's appropriate to drive at 60mph and people who do are generally maniacs. Where I grew up there are lots of these roads, steep, winding, narrow tracks paved in the 19th or 20th centuries for access to a farm here or a cottage there, and maintained by the public. You absolutely might turn a corner and find an entire flock of sheep in the road going "Baa!". If you're doing 60mph after you've killed a bunch of sheep and the bodies start smashing through your windscreen you're probably dead. Sheep don't have lights, don't know about jaywalking laws (which Britain doesn't have anyway) and aren't smart enough to have considered this risk, they're just there and now you're dead. So you drive at maybe 30-40mph on the straight parts, slower on curves and always pay a lot of attention 'cos things can go very bad, very quickly.
Roundabouts are a bit different. The UK has a lot of what are called "mini roundabouts". As a pedestrian, or perhaps on a bicycle these do just look like they're small roundabouts, too small for the island in the middle to have any purpose so it's just paint. But in a vehicle it's apparent that the island can't exist because you'd crash into it, perhaps not in a Mini but certainly in a bin truck or a bus. The mini roundabout isn't a roundabout except in the sense that the same rules apply as if it was, which means if I can see you can't enter before I do then I know you mustn't enter, I have right of way, which means I needn't slow down - you won't be in my way, you're not entering.
Triangular signs with a red outline are warning signs.
Just because legally you can drive at 60 doesn't mean you're legally allowed to drive recklessly. National speed limit is basically, "you're permitted to drive as fast as you like so long as you do so in a safe manner".
https://www.nps.gov/features/yell/slidefile/gatewaycommuniti...
Instead of having a speed limit sign after each and every intersection, they're placed periodically. If you enter a road and there's no sign, that's the speed limit. If there's a different speed limit than the default, and you cross through an intersection and there's not another sign after it, that means the speed limit reverted to the default.
It can be a bit confusing (MN has 35 in city roads, WI 25) but also handy (wide open plains states often have much much higher freeway speeds).
But the tiny roads are usually where there is no housing - hardly anybody lives there so even the single lane of tarmac is a great expense considering average traffic. The "No housing => faster" is part of why there aren't signs limiting them. It's still a terrible idea to do 60mph though, just not necessarily illegal.
I've heard before about setting speed limits using percentile studies of people driving on the road, which in the absence of some specific safety concern (which then needs engineering like narrowing the road or adding turns) makes the most sense.
I also wish there was more of a culture of pulling over if you don't want to drive at the flow speed. If I want a leisurely drive and see someone rapidly coming up behind me, I'll happily pull over and let them pass. There seem to be these sociopaths or self-righteous jerks who will happily drive 5km/h under the speed limit with 20 cars behind them. This is way more dangerous than speeding and should be treated as such. If you just want to drive slowly, why would you want the stress or a bunch of angry drivers behind you.
Visibility is poor and you cannot safely go through a bend at 50+ mph when you cannot see what's beyond it. There might be a stationary vehicle, a horse, a cyclists, even a pedestrian and you wouldn't know or be able to stop in time. This is how lethal collisions happen in those roads.
Yeah you know THE ROAD not what might be in it this morning.
In practice there seems to be a ton of correlation between people who say things like that and people who think their Fiat 500 stops like a garbage truck.
D: "Dad why does everyone honk at mom when she drive's us to school?"
F: "Because she drives too slow sometimes."
D: "Why doesn't she speed up?"
F: "I don't know. She's always been like that."
D: "I tried saying people are waiting for us to go [referring to a pretty benign yield right-on-red near their house]."
F: "How'd that go?"
D: "She didn't listen!"
I don't know why but it was absolutely hysterical to me. Kids are precious.
You are supposed to drive 60mph where appropriate, e.g. on straight stretches with good visibility and no junctions. It's very possible to fail your driving test for not going fast enough on a single carriageway.
What you’re supposed to do is drive at a speed that gives you chance to react to dangers given your visibility and road surface conditions.
For country roads, they’re typically winding rather than straight. So more often than not, that means you shouldn’t be travelling much past 30mph.
But you are right that straight stretches do exist. They’re just not as common on such roads.
Indeed, I always think of my instructor's words "can you stop within the distance you can see". As that distance decreases, you should be slowing down; potentially there's a cyclist or horse right around the corner.
I’m constantly amazed that some idiot hasn’t hit him.
What matters more is the far stricter driver licensing and “Scarlet L” (my words) that the learners have to display.
That and the fact that it is bloody impossible to conduct 2 way traffic down country roads thanks to all the hedgerows and so everyone is extra careful and courteous (usually).
However some back roads aren't even B roads, the classification keeps going through C and D but it's local numbering, the numbers are just for local maintenance crews - so a C-1234 could be duplicated a few miles away in another local government territory and that would be confusing for drivers so they won't write C-1234 on a sign, they'll just say what's in that direction or maybe a local name for the road.
The best case scenario then, is that you write off your car with a deer shaped hole in the front. The worst case scenario is you have a death on your conscience for the rest of your life.
When I started driving I preferred the dark for these roads because the lights let you 'see' hazard around a corner.
Headlights were worse then - and I hadn't seen a crash into a deer.