ORINDA -- There was almost no way to escape the Caldecott Tunnel on April 7, 1982, when a drunk driver crashed inside, touching off a chain reaction that turned the third bore into a 2,000-degree tomb and killed seven people.
There were no emergency passages, and the narrow tunnel had no shoulder. There were no traffic lights, emergency gates or message signs to warn motorists of the fireball inside, caused when a gasoline tanker burst into flames.
Three decades later, lessons from one of the worst tunnel fires in American history have inspired many safety features built into the new $417 million Caldecott Tunnel fourth bore, which opens Nov. 16 or 17.
On Friday, a smoky car fire in the first bore injured eight people, reawakening memories of the 1982 disaster. The incident brought home the need for greater safety improvements in all the older tunnels.
Some upgrades already have been added to the first three tunnels, including surveillance cameras and external warning signs. The new fourth bore will definitely be the safest of the four.
"Drivers of the 160,000 vehicles a day that use the Caldecott Tunnel will have a safer environment to travel through," said Byron Lim, a Caltrans engineer working on the project. "The 1982 fire caused people to rethink tunnel safety throughout the country and change the standards for tunnels."
But the fire Friday underscores the need for increased safety and better lighting in the original two Caldecott tunnels opened in 1937, said Amy Worth, chairwoman of the Metropolitan Transportation Commission.
"This is an urgent project that we should move on as soon as it's feasible," Worth said. "There are physical restraints with the older, smaller tunnels, but we need to make them as safe as we can."
As part of the Highway 24 project, traffic lights and a traffic gate that swings down in emergencies have been added to the third and fourth bores.
The third and fourth bores also will be the first to have an extensive network of electronic message signs and traffic signals inside.
And unlike the original two bores, the third and fourth will be connected by seven lighted, 12-foot-wide escape passages. Fleeing motorists can escape on foot and get out of harm's way rather than face a chaotic trek through the tunnel like the one that confronted motorists in 1982.
"The cross passages are huge for public safety," said Steve Healy, chief of the Moraga-Orinda Fire District. "It gives you more access points for people to get out and for emergency responders to get in to help them."
The Moraga-Orinda and Oakland fire departments were among many safety agencies that helped shape the planned operation and design of the new bore.
The new bore also has some safety features either missing or not as well developed in the other bores.
Only the fourth bore has a shoulder, a 10-foot wide swath to stash damaged vehicles or for fire trucks, ambulances or law enforcement to access accidents.
The escape passages are air pressurized to keep smoke and toxic gases away from fleeing travelers.
Safety wasn't an afterthought, but it wasn't the driving force behind construction of the fourth bore.
Caltrans, the Contra Costa Transportation Authority and the federal government put up the bulk of the funds for the project to cut traffic congestion during the reverse commute.
A fourth bore lets Caltrans have two bores for traffic in each direction at all times, ending the daily switch in direction of the middle bore that slows the reverse commute.
"We used the most modern technology to excavate the new bore, and now we're using it to operate it to enhance safety for the driving public," said Ivy Morrision, a spokeswoman for the project.
The Caldecott Tunnel also is safer than it was in 1982 because of a ban on trucking gasoline and other flammable liquids or poison gases through the tunnel, except between 3 and 5 a.m. That ban was enacted shortly after the tunnel disaster.
Not all new safety features are evident because they are tucked inside the 3,339-foot-long fourth bore that has been off limits to the public during construction.
Even when the new bore opens, some safety features will be hidden, such as water lines. Some will be too small to see, like heat sensors.
Most obvious will be 19 ceiling-mounted fans, all capable of churning up 20 mph breezes to sweep away smoke and gases. The fans are more powerful than those in the other bores.
One new safety feature common to all four bores is a radio override system that allows tunnel operators to broadcast emergency messages on car radios, regardless of the station to which they are tuned.
"We only override car radios for important communications inside the tunnel, not outside of it," said Lim, the Caltrans engineer.
Last month, Lim helped train tunnel control operators to use computers that display a large video wall to flash messages, check monitors and use zoom cameras to keep an eye on traffic and conditions inside the third and fourth bores.
Operators also prepared for drills to simulate crashes, explosions and the troubling possibility that a deer could wander inside, which could be a disaster, Lim said.
"We want to be prepared for anything," he said.
Contact Denis Cuff at 925-943-8267. Follow him at Twitter.com/deniscuff.
Access: Ten-foot-wide shoulder for stalled vehicles or for emergency use. Other bores have no shoulders.
Water: Fire pumps will deliver 500 gallons per minute at 100 pounds per square inch. (Upgrades will be done later to pumps in existing bores.)
Ventilation: The bore has 19 jet fans, each with 200-horsepower motors that can generate 20 mph winds to sweep out smoke and gases.
Heat: Five linear detectors run its length.
Gates: The third and fourth bores have one-arm gates that swing down in emergencies, like at railroad crossings.
Cross passages: The third and fourth bores are connected by 12-foot-wide escape passages. The doors can be pushed open during emergencies. The first and second bores have smaller maintenance passages unsuitable for moving lots of people.
Lights: The third and fourth bores have high-pressure sodium lights on both sides. The narrower first and second bores have just one set.
Warning signs: The third and fourth bores have five variable message signs and 10 traffic lights inside. There also is one message sign and two traffic signals at openings to each tunnel. The older first and second bores have message signs at tunnel opening approaches.
Air quality monitors: The fourth bore has four carbon monoxide and four nitrous oxide monitors. Other bores have three.