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.
Mackinac Bridge. The Mackinac Bridge is one of the world's most beautiful bridges and truly something to see! The bridge was designed by the great engineer David B. Steinman and opened on November 1, 1957. The structure took 48 months to complete with over 3, 500 workers and $99,800,000 dollars. Also know as the Big Mac or the Mighty Mac, the bridge stretches 8,614 feet making it the fourth longest suspension bridge in the world.