What's the more common way to refer to a road with 180° curves?

A hairpin road is a road with hairpin turns or bends.

According to Wikipedia:

• A hairpin bend , named for its resemblance to a hairpin/bobby pin, is a bend in a road with a very acute inner angle, making it necessary for an oncoming vehicle to turn almost 180° to continue on the road.

• Such turns in ramps and trails may be called switchbacks in American English.

I've always thought, as it appears from the article above, that the common expression to refer to such a curvy road is "hairpin road" and that "switchback road" is a less common AmE variant.

But checking with Ngram "switchback road" turns out to be the more common expression both in BrE and AmE.

Question:

What is the the above described road more commonly called in BrE and AmE?

Are there alternative expressions to refer to it?

A serpentine road seems to fit the bill.

Here's something actually called Serpentine Road:

A switchback is a section of trail or road that switches back: turns back on itself, but typically while also ascending or descending.

There are typically many switchbacks in a switchback trail (or road). Some of them might be hairpin turns - those curves that are really quite tight corners. A curve can be qualified as hairpin if it is a tight curve, but you would never refer to the trail or road itself as a hairpin. The turn of a switchback is often a hairpin turn, but it need not be.