Semicircle Road Trip #2

If you figured out Semicircle road trip problem #1, you will find this second problem easy. The challenge is setting-up the solution/ explanation and not really in figuring out which road is longer. If you have an explanation, share them in the comment section.

Problem

There are two ways to get from Town A to Town B. The blue road goes directly to B and the red one has a few side trips. The routes are semicircular. Which road is longer? Explain your choice.

View the solution.

Your thoughts?