Test air leakage rate: With a fully-charged air system (typically 125 psi), turn off the engine, release the service brake, and time the air pressure drop. The loss rate should be less than 2 psi in 1 minute for single vehicles and less than 3 psi in 1 minute for combination vehicles.
Construction on the Coronado Bridge began in 1967. Almost 500 prestressed concrete piles were fastened to the sea floor of the bay to provide the foundations for the bridge. The steel and concrete components were largely built offsite, then assembled together from marine construction barges over the bay.
In 1928 a tunnell was completed beneath the pass, and the rails over it were no longer used, and the town of Corona was abandoned. The rails over the pass were left in place as an emergency route in case of a cave in in the tunnel until 1936, when they were finally picked up. What was left of the town was dismanted and burned by the U.S.forestery sevice, as were the snow sheds, and the brick hotel.