While doing some research on the 1989 Loma Prieta Earthquake, I came across a detailed report from the California Highway Patrol about the collapse of the Cypress Street Viaduct. Obviously, the collapse of the structure proved fatal to many drivers and passengers whether they were wearing seat belts or not – 35 on the lower deck and 7 on the upper deck. But one interesting and tragic aspect was the case of a Dodge van, a vanpool from UC San Francisco to Alameda, driving southbound on the upper deck. According to the report (page IV-85, listed as “Vehicle 37” in the report above), the driver and all seven passengers were wearing their seat belts. But only one of the passengers in the rear – where there were no seat belts, only lap belts – survived, and with critical injuries. The report says the van hit the collapsed structure at an estimated speed of 27 mph. But five of the passengers were killed by the internal injuries caused by the force of the crash applied through their lap belt.
The report also summarizes seat belt usage for all drivers and passengers on the structure:
The moral of the story here, though, isn’t “don’t wear your seat belt” – it’s “passenger vans from the 80s and 90s are unsafe”.