In the Sixties, Sacramento even then was a "quiet zone". The engine bell was rung constantly while going through all those grade crossing in downtown. However, WP also had what was known by train crews as the "Iron Curtain," which was a more or less "rule" (I don't recall seeing it in writing) that no trains would go through that area during the weekday morning and afternoon rush hours. I imagine the city put quite a bit of pressure, formal or not, on the WP to not run through there at rush hour.