Silver Bridge - Design Loads

Design Loads

At the time of the bridge construction, a typical family automobile was the Ford Model T, with a weight of about 1,500 lb (680 kg). The maximum permitted truck gross weight was about 20,000 lb (9,072 kg). By contrast, at the time of the collapse, a typical family automobile weighed about 4,000 lb (1,814 kg) and the large truck limit was 60,000 lb (27,216 kg) or more. Bumper-to-bumper traffic jams on the bridge were also much more common, occurring several times a day, five days each week, thus causing more stress to the bridge elements.