As we get set to mark the 30th anniversary of the earthquake that massively shook the Bay Area on October 17, 1989, we're taking a moment to retell the history of the biggest tragedy of that day, via CHP footage and interviews with those who witnessed it.

That tragedy was the collapse of a huge section of the double-decker Cypress Street Viaduct, better known as the Cypress Freeway in West Oakland. Hundreds of cars on the lower deck of the viaduct were trapped and/or crushed in the earthquake, and while many of the trapped and injured were rescued — some out of a gap of just a few feet between two concrete roadways — 42 people died there, mostly in the cars.

The viaduct was constructed in 1956 and opened to traffic on June 11, 1957, where Mandela Parkway now runs in West Oakland. The road connected I-880 with I-80 and the Bay Bridge, and has now been replaced by surface freeway that does the same. "At the time of its design, such structures were not analyzed as a whole, and it appears that large structure motion contributed to the collapse," as Wikipedia explains. "It was built on filled land on top of bay clay; filled land is highly susceptible to soil settlement during an earthquake, and Bay clay exhibits larger ground motion."

Chronicle photographer Michael Macor describes the horrific, chaotic scene that he came upon that October evening, when he was sent on assignment after working in the photo lab at the Oakland Tribune. "It looked like a movie set," he says. "It didn't look real." (See some of his images in the 2014 video below.)

Even more dramatic is the 23-minute CHP documentary seen below, which was made for FEMA training purposes for emergency responders, and for documentation of the day's events following the earthquake — and a separate rescue operation that took place on the Bay Bridge when a panicked driver attempted to jump over the collapsed segment of the upper deck of the bridge, resulting in one death.

Starting at the 9:50 mark in the video, you'll see the story of a 1980 Mercury Zephyr traveling from San Francisco, being driven by a 23-year-old woman at 5:35 p.m., 31 minutes after the quake. The woman managed to get onto the upper, westbound deck of the bridge, and she sped east in an apparently urgent effort to get back to Oakland. Upon seeing that a piece of the deck on the eastern span was missing, she hit the gas in an ill-fated attempt to leap the 50-foot gap, going 49 miles per hour. The car made it almost across, crashing into the break in the upper deck on the opposite side, with the front of the car getting lodged there, suspended. The driver and her brother, the passenger, were medivac'd out, and the driver was pronounced dead on arrival. The brother survived because he'd been wearing a seatbelt.

The video also contains harrowing footage and live CHP tape of the rescue at the Cypress Freeway.

Below is a KPIX interview with one of the survivors who had been in his car on the Cypress Freeway when it collapsed. He said he felt the front end of his car vibrating and thought he had a flat tire. "I just happened to be between two cross-members [of the roadway structure] and there was enough space for me to live."

Related: Loma Prieta at 30: Watch the Minutes After the Quake Live