There was talk of making State Hwy 1 a freeway where it branched off from 101 at Manzanita, but that never got beyond lines on a map as I recall. However, there was more serious talk of a direct road across the marsh to Mill Valley, bypassing the traffic at Tamalpais Valley Junction. Maybe the filled areas in the photos were part of that effort. The channel of Coyote Creek was improved as part of a flood control project in the early 1960's. Most filling of bay marshlands stopped in 1965 when the Bay Conservation and Development Commission was created.

The NWP's route from Manzanita to Corte Madera via Almonte and Tunnel 1 did not cross navigable waterways so did not need a drawbridge. However, floodwaters did short out the third rail a few times over the years in the area between Manzanita and Almonte.