Aren't their tunnels low diameter? Self driving seems an absolute necessity. If someone clips the tunnel wall that's an enormous traffic jam just waiting to happen.
Unless they've pivoted again since the last time it was discussed/demonstrated, the cars don't steer themselves through the tunnel like a car on open road, but instead are steered by the tunnel itself, more like a roller coaster on a track.
How does that work with rubber tires? I'm just having trouble visualizing it.