Semicircles and spiral

Geometry Level 2

A spiral is made up of successive semicircles, with centres alternately at A and B, starting with centre at A, of radii 0.5 cm, 1.0 cm, 1.5 cm, 2.0 cm, . . . as shown in the image.
What is the total length of such a spiral made up of thirteen consecutive semicircles?

Details and Assumptions:
☻Take π = 22/7