Before revision: Five types of horizontal curves on roads and railways: Simple curve Compound curve Opposite or serpentine curve Deviation curve Two types of vertical curves on roads: Valley curve Summit curve Horizontal Curve Simple curve Diagram of simple curve A simple curve has the same radius throughout and is a single arc of a circle, with two tangents meeting at the intersection (B in this diagram).
After revision: Five types of horizontal curves on roads and railways: Simple curve Compound curve Transition curve Reverse curve Deviation curve Two types of vertical curves on roads: Valley curve Summit curve Horizontal Curve Simple curve Diagram of simple curve A simple curve has the same radius throughout and is a single arc of a circle, with two tangents meeting at the intersection (B in this diagram).