Network ring design for maximum resilience?

I'm designing a network for new train system and the stations are arranged in a ring of about 20 stations. Each station has 72 strands of dark fiber between them, and the plan is to run eigrp (we are a heavy cisco shop) with two switches at each station for HA. Assuming that under normal circumstances we only lose one switch at a station during a failure situation, what would be the most dependable layout for fast convergence and maximum uptime? A simple ring? Triangles? What other design options are there?

Thanks for any suggestions!