L.A.’s 4-Level: A Deathtrap Like the Nimitz?

The Cypress viaduct is one link in a spider web of freeways that cross west Oakland. Last week, if you had gone shopping in downtown Oakland and headed home to Berkeley, the thing that got you there was the Cypress viaduct, part of the Nimitz Freeway. You would never have been aware of that, of course. The viaduct was as invisible as the hard neighborhoods that sprawled underneath it.

Now we all are aware of the Cypress. In large disasters, there is often a single image that emerges and imprints itself in the memory. These images are chosen, I think, because they evoke the deepest fears, they threaten us in the most visceral way. And for the Bay Area earthquake of October, 1989, that image surely is the upper deck of the Cypress viaduct torn loose, collapsed, pressing with such unimaginable weight on those cars trapped within.

They still don’t know how many. So tightly are the cars squeezed, with those thousands of tons bearing down, that the autos themselves have disappeared from view. The Cypress viaduct collapse is so powerful because it is the image of death by crushing, death that could not be foreseen or forestalled and, most important of all, death to which we are all vulnerable.

Let me put it this way. Each morning when I drive to work in downtown Los Angeles I pass through the famous four-level interchange. Three elevated decks flying over the Pasadena Freeway. If you notice the little signs stuck on the freeway pillars, you will see those upper levels are also called viaducts.

So we’ve all been there, and could easily have been those people pinned under the Cypress. We will be there again tomorrow, passing through some anonymous labyrinth. Except now, for most of us, the image of the Cypress will be there with us, and we may glance upward, very quickly, at those gray strips of concrete just over our heads. That’s the kind of legacy these images leave.

Just what happened along that strip of freeway is interesting, if you can separate it from the results. The Cypress viaduct portion of the Nimitz Freeway was completed in 1957, the first two-tiered structure built in California. As you may have read in news reports, the columns supporting the structure were bundles of steel rods encased in hardened concrete. They were the pieces that failed.

In one of those capricious acts of any disaster, the waves of the earthquake just happened to be traveling in the same direction as the freeway. Some eyewitnesses recall seeing those waves move down the upper deck, saying it looked like the deck was floating on a heavy sea. As the waves passed the columns they twisted them in an undulating motion. The steel rods bent with this motion but the concrete did not. Within seconds the columns were exfoliating themselves of their concrete, leaving only the bare steel. The rods then gave out what is described as a grating wail and succumbed to their burden. More than a mile of upper deck fell neatly onto the stream of rush-hour traffic below.

In the aftermath, the accusation was made that the Cypress columns were antiquated and lacked a layer of spiraling steel rods now built into freeway supports. That spiral design might have prevented some of the concrete from exploding off the columns and enabled them to hold their weight. It has also been suggested that the viaduct rests on bay fill, which likely amplified the power of the waves.

Perhaps so. We know there will be investigations, and someone may pay with their career, or worse. If there are engineers or administrators at Caltrans who ignored warnings, fine. Let them pay.

But I think the meaning of the Cypress goes beyond that. Earthquakes have peculiar and terrorizing powers that make them unlike most other natural disasters. Some of these can be prepared for, and some cannot. The Cypress is a reminder of the second category, a reminder of the most haunting sort.

For example, I have always imagined myself as one of those who would dodge the ceiling panels as they fell, or look upward just as the high tension wire was about to wrap itself around me. This notion has just enough plausibility to afford some psychic protection.

With the Cypress, though, there is no psychic protection. Those people could not dodge, and they had no warning. This was not a hurricane. They could not choose to stay off the viaduct because Tuesday was an earthquake day. They felt the steering wheel wiggle, and then nothing.

That is the truth about the danger that we live with. Does anyone believe anymore that a strong enough earthquake in Southern California would not pull down overpasses and viaducts, spiral design or not? I doubt it. It’s the lesson of the Cypress and its image will not leave us soon.