I would identify and address all of the various infrastructure, logic, and fail safe issues as well as design systems to handle caching, redundancy, and customer experience handling in case of failures.

To build a BART system, you first secure an exclusive right-of-way using underground tunnels and elevated viaducts to lay a stable, broad-gauge track network. You then energize the route by installing a 1000V DC third-rail traction power system alongside the tracks. Safety and routing are managed by an Automatic Train Control (ATC) network that completely automates train speeds, spacing, and station stops. Finally, you deploy lightweight, electric train cars equipped with regenerative braking to operate seamlessly across the integrated infrastructure.