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.
The Colorado Street Bridge, with the San Gabriel mountains in the background, around 1920. The Colorado Street Bridge was designed and built in 1912 at a total cost of $191,000 (equivalent to $4,566,867 in 2016). The bridge was designed by the firm of Waddell & Harrington, based in Kansas City, Missouri.