OAKLAND -- How many ways is the sleek new Bay Bridge better than the old, clunky 1936 truss span?

Caltrans principal bridge engineer Brian Maroney is counting the ways in preparation for project status briefings set with legislators, county and city officials on Monday and Wednesday.

While much of the talk will center on whether construction setbacks -- chiefly, broken bolts in seismic stabilizers -- will delay the planned Sept. 3 opening, officials also asked for a side-by-side comparison between the two bridges.

Maroney, the lanky, high-octane engineer assigned to the Bay Bridge in one form or another since 1994, described the assignment as both intriguing and mind-boggling.

"It's like comparing the safety features of a 1930s Model A Ford to a 2000 Volvo," said Maroney earlier this week during a two-hour preview. "The Model A was the first car in the U.S. to have safety glass in the windows. It had windshield wipers. A rearview mirror was optional."

As critics correctly note, the most glaring difference is time and money.

The state and contractors designed and built the entire original bridge -- west span, tunnel and eastern side -- in just under seven years at a cost of $1.3 billion in today's dollars. It was on time and under budget.

The eastern replacement bridge has taken 16 years to design and build and cost $6.4 billion. It is years late and substantially over budget, depending on which estimates one uses for comparison.

Whether the new bridge is worth the money is a matter of opinion.

But for most travelers, the clearest difference will be the roomy 12-foot-wide standard travel lanes. The original narrow lanes handled automobiles of the 1930s but squeezed modern SUVs.

The new bridge also has shoulders -- two in each direction -- where drivers who run out of gas or smack into each other can pull over. A stall or accident on the shoulderless old bridge can snarl traffic for hours.

Motorists won't see the fundamental difference between the old and new bridges until they know whether it withstands the next Big One. The new bridge was designed to meet the most stringent earthquake standards in California: Open to traffic within a day or two after the strongest ground motions engineers expect in a 1,500-year period.

In contrast, nearly every engineer who has examined the existing 77-year-old bridge predicts it will collapse if the next temblor is bigger or closer than the 1989 Loma Prieta earthquake.

Despite an epicenter 60 miles away, Loma Prieta's shaking sheared bolts on the old bridge and sent a piece of the upper deck plunging like a trap door onto the lower deck.

What few may know is that a second deck piece almost separated and connections were damaged at six additional piers, according to the Governor's Board of Inquiry in 1990.

The new span has no hinged connections of this type, one of the most common trouble-spots on bridges, Maroney said.

Instead, large steel pipes straddle the bridge joints beneath the travel deck, keeping the segments aligned while allowing the span to expand and contract with the temperature or an earthquake. The pipes are among a number of seismic safety features of the new span.

Like the automobile, bridges have come a long way in the past eight decades.

Maroney pulled out Bay Bridge engineering reports from the 1930s dotted with handwritten calculations and conclusions that sound absurd today.

"The piers and anchorage from Goat Island (Yerba Buena Island) to San Francisco are all founded on rock and will stay where put till the crack of doom," one engineer wrote. "The piers between the island and Oakland are founded on piles driven in stiff sandy clays, and their support of the bridge is entirely adequate."

The piers are far from safe, as the 1989 Loma Prieta earthquake demonstrated.

But the 1930s experts' conclusions illustrate another chief difference -- engineers' exponentially greater geotechnical knowledge about how earthquake waves impact structures and the computer power to apply that knowledge to new construction.

It wasn't until after Loma Prieta that bridge engineers began to seriously factor how seismic waves move multidimensionally and resonate simultaneously on multiple frequencies with varying effects based on the type of soil or rock, Maroney said.

"Eighty years ago, engineers didn't understand the lateral forces from an earthquake, which is understandable, because the data didn't exist," Maroney said. "And even if they had the data, they didn't have the computers to make the tens of thousands of simultaneous calculations required to run modeling software."

Researchers didn't even record the first California earthquake until the 1933 Long Beach temblor.

As a result, when engineers designed the original Bay Bridge in 1931 to 1933, they had no seismic data specific to San Francisco Bay. They based their calculations on six marine borings, the results presented in a 1-inch-thick geotechnical report.

The modern bridge team, in comparison, had reams of site-specific seismic data and a 30-volume geotechnical report with analysis of 44 marine borings, nearly 100 soil composition tests and unprecedented three-dimensional sonar mapping of the bay bottom.

The data allowed engineers to design each segment of the new bridge -- connector structures, concrete box girder viaduct and self-anchored suspension span -- to withstand specific forces unique to the bridge's precise location.

For example, the pier where the deck section failed in the 1989 earthquake sits on timbered piles hammered a maximum of 120 feet into the bay mud.

The new piers, in comparison, are supported by massive concrete and rebar-filled steel piles driven more than 300 feet into bedrock.

In another example, expansion joints between segments on the old bridge accommodate up to 2 to 3 inches of movement during an earthquake, while the new bridge can handle 3 feet, Maroney said.

Among other key differences:

  • Steel -- Old: Steel lacked sufficient carbon to allow welding, so engineers relied on rivets. Also, steel toughness ratings range from 4 to 10 foot-pounds, a measure of resistance to cracking. New: No rivets were used and high-strength steel tests at 30 foot-pounds and higher.

  • Concrete -- Old: Concrete was rated 5,000 pounds per square inch, a measure of its strength. New: Concrete is rated 8,000 psi¿, and additives were used that increased its ability to flow in and around the rebar, reducing the potential for air pockets that could weaken its strength.

    Contact Lisa Vorderbrueggen at 925-945-4773, lvorderbrueggen@bayareanewsgroup.com, politicswithlisav.blogspot.com or Twitter.com/lvorderbrueggen.

    bay bridge briefing
    The new Bay Bridge management team will brief Bay Area legislators on Monday and the Bay Area Toll Authority on Wednesday about whether bolt snafus will delay the planned Sept. 3 opening. The legislators' briefing is closed to the public, but the Bay Area Toll Authority meeting is open. Here's how you can learn or listen for yourself:
    n The Bay Area Toll Authority will post its bolt failure report and related documents by noon Monday at www.mtc.ca.gov.
    n Attend Wednesday's meeting in person at the Joseph P. Bort MetroCenter, 101 Eighth St., in Oakland or listen to live stream audio at www.mtc.ca.gov/meetings/schedule/index.htm