switchback
US /ˈswɪtʃ.bæk/
UK /ˈswɪtʃ.bæk/

1.
a road, path, or railway with a series of sharp turns, each reversing the general direction of travel, used for climbing or descending a steep gradient
:
•
The mountain road was full of dangerous switchbacks.
•
Hikers often encounter switchbacks on steep trails.