North tunnel was the longest of the two tunnels heading to Tiburon, extending a quarter of a mile under a mountain between Bel Aire subdivision and Corte Madera, straight and pitch black in its middle. The south tunnel was shorter, and built the same way.
My father predicted my brother and I would explore inner reaches of both tunnels, so he taught us how to scrunch our backs and push hard against the beam foundation, in case of emergency. He didn’t want me sucked into a train. We played in those tunnels for years and years without a train in sight. I felt safer thinking I wouldn’t die by train, and felt grateful that my father understood his children.