When Bertha, a giant tunnel-boring machine, stalled and nearly caught fire beneath downtown Seattle, opponents of a similar tunnel proposed for the 710 Freeway between Alhambra and Pasadena would point to the drill’s troubles and say if they can’t do it there, they can’t do it here.
But after a two-year delay, Bertha is back in business as of March 7, churning out a roadway tunnel that will replace the Alaskan Way Viaduct (SR-99), an old freeway with structural problems.
• Graphic: The Tunnel Boring Machine
Besides Seattle’s renewed tunneling success, the Los Angeles County Metropolitan Transportation Authority this month placed its own machine, nicknamed Harriet, under Crenshaw Boulevard, where tunneling for three new underground rail stations will take place during the next 15 months. In addition, Metro will soon tunnel under Wilshire Boulevard at La Brea, Fairfax and La Cienega to complete the first section of the Purple Line subway extension, and will tunnel beneath downtown Los Angeles for the Regional Connector rail project between Little Tokyo and Bunker Hill.
All this digging beneath different neighborhoods of Los Angeles, plus the resurrection of Bertha in Seattle, has buoyed those in favor of extending the 710 Freeway underground for cars, possibly trucks, as part of a long-awaited extension from the freeway’s end at Valley Boulevard in Alhambra, through El Sereno and South Pasadena to the 134/210 interchange in west Pasadena.
“Yes, its doable,” said the leading 710 Freeway tunnel proponent, Alhambra Councilwoman Barbara Messina. “It was doable when they tunneled under the English Channel. Plus, look at all the subway tunnels (in L.A.) we’ve built successfully.”
Metro’s next three rail projects are tunnel-ready. In mid-Wilshire, the large transit agency is prepared to move forward no matter what the obstacles may be.
“We will be tunneling through the La Brea Tar Pits. Talk about complex,” said Dave Sotero, Metro spokesman. “There you may have gassy grounds and oil deposits.”
710 tunnel options
With the 710, two freeway tunnel options have been explored in a 26,000-page draft environmental impact report released in March 2015. Twin-bore tunnels would be excavated side by side — one northbound, one southbound — and each tunnel would have two levels, with two lanes of traffic per level, for a total of four lanes in each tunnel. A single-bore, double-decker tunnel would be one tunnel with two levels: northbound traffic would use the upper level and southbound traffic the lower level, amounting to two lanes in each direction for a total of four lanes.
Caltrans and Metro estimate the cost of the tunnels between $3.2 billion and $5.6 billion.
Alhambra is a leading force in the 710 Coalition, which calls for “closing the gap” of the freeway that starts in Long Beach and is considered the missing link in the 14 Southern California freeways. Caltrans first proposed the extension in 1959. Other cities in the group include San Marino, Monterey Park, Rosemead and San Gabriel. They say the congestion raises the level of air pollution in their cities and that a tunnel would ease gridlock and air pollution.
Opponents include the cities of South Pasadena, La Cañada Flintridge, Glendale, Sierra Madre and Pasadena, which say tunnels are unfeasible, dangerous, too costly and not a solution to local traffic. Two analyses, one by the South Coast Air Quality Management District and one by the U.S. Environmental Protection Agency, say the tunnel option would adversely affect air quality. The AQMD analysis says the tunnel would raise the cancer risk to unacceptable levels. The EPA said that a dual-bore tunnel carrying 180,000 vehicles a day would add to the load of PM2.5 particles, which are fine particles that can reach the lungs and cause disease.
With groups entrenched on both sides, neither the EIR nor the project itself has received approval from Metro or Caltrans. Some say the vote, expected this spring by the Metro board, will be postponed until after the November election.
But until then, can anti-710 groups still say tunnels are not possible?
Tunnel size matters
Opponent Anthony Portantino, a former member of the state Assembly and a La Cañada Flintridge resident, says transit tunnels are smaller than roadway tunnels and therefore easier to complete. In short, with tunneling, size matters.
“Are any of those tunnels (being dug by Metro in L.A.) this size? That is the key difference,” he said.
Engineering consultant and civil engineer Thom Neff, who worked on the Big Dig project in Boston and wrote a feasibility study for Seattle’s Highway 99 project, agreed. Neff, president of his own firm OckhamKonsult, said the larger a tunnel’s diameter, the more difficult it is to build. The size of Seattle’s tunnel is one reason for the delays, he said.
L.A.’s Harriet is 21.5 feet in diameter, compared with Bertha’s 57 feet. “(It’s) big, but not as big as Bertha,” says Metro in its tunnel graphic of the Crenshaw project.
Either tunnel option for closing the 710 Freeway gap would require a tunnel of an excavated diameter of about 60 feet, according to the EIR. Both the single-bore and dual-bore variations would be about 6.3 miles long, with 4.2 miles of bored tunnel, 0.7 miles of cut-and-cover tunnel and 1.4 miles of at-grade portions, according to the EIR. The interior diameter would be 52.5 feet and the outside diameter would be 58.5 feet. The extra width is required so the machine can maneuver. The 710 EIR cites the Highway 99 project in Seattle as similar in terms of size of tunnels needed for freeway tunnels.
Twin tunnels would require cross passages to allow first responders to reach each tunnel in an emergency, the EIR states. A single-bore tunnel would need emergency exits and ventilation pipes throughout, something Neff says adds to the cost.
Underground variables
“No tunnel is easy, first of all,” said Neff, who spent 15 years with Parsons Brinckerhoff, one of the largest engineering firms in the world. “You have to deal with Mother Nature, and she is unpredictable. Any work underground has a higher level of uncertainty than any kind of civil engineering structure.”
Neff said Los Angeles has other soil-related issues.
“You have two additional problems: earthquakes, and you have a lot of deposits of oil and gas. Those pose problems in tunneling,” said Neff, who has examined project specs for the 710 tunnel.
In Seattle, Bertha only moved 1,000 feet when on Dec. 6, 2013, it stopped when the machine overheated and reached high temperatures, said the Washington State Department of Transportation. The damaged machine was repaired by its manufacturer, Hitachi Zosen, between March and August 2015. In December, tunnelling restarted but was stopped when a giant sinkhole opened up in the middle of the street. Also, excavated dirt placed on a barge caused the boat to crash into the pier. The transportation department suspended the work, then lifted the suspension March 7 and declared Bertha to be working.
The 1.7-mile Seattle tunnel was not finished by December 2015 as promised. A report from an independent panel said the two years the machine stopped working caused the delay. The earliest completion is set for April 2018. The transportation department filed a lawsuit against the developers and estimated it is costing the state $78 million in overruns.
Too big to succeed?
Oxford University researcher Bent Flyvbjerg studied so-called megaprojects that include bridges, tunnels and skyscrapers. In his research paper from April 2014, he concluded that nine of 10 projects produce cost overruns and some “of up to 50 percent in real terms are common.”
The Boston Dig, the Channel Tunnel connecting the United Kingdom and France and the Denver International Airport all saw costs rise 80 percent to 220 percent, for example.
One theory is called the “lock-in” or “capture,” whereby commitment to large multiyear projects continue despite obvious problems, “leaving analyses of alternatives weak or absent,” he concluded. A similar phenomenon is known as “optimism bias,” in which managers of megaprojects proceed despite massive, negative events he calls “black swans.”
“As a consequence, misinformation about costs, schedules, benefits and risks is the norm throughout project development and the decision-making process,” he concluded.
Companies bring cash
Metro and Caltrans have called for private investors. If private money is obtained, the 710 tunnel portion would be a toll road.
In February, Metro hosted its first forum soliciting banks, engineering firms and high-tech companies to come forward and suggest how they can help. About 400 companies showed up at the J.W. Marriott in L.A. Live.
Messina says two private investors inquired about the 710 tunnel project but were told to wait and see due to the project’s hot political environment.
Metro would neither confirm nor deny any interest in the 710 tunnel project, so far.
Joshua Schank, Metro’s chief innovation officer, spoke in general terms about the benefits of private investors in public transit and roadway projects. He said adding private investment can speed up projects and can also reduce the cost.
Also, private companies may shield Metro and the taxpayer from paying cost overruns. But Schank said financiers usually want something in return.
“Some projects are toll based, such as a highway project where you pay back investors,” he said. “In the private sector, when there is a toll involved, the private sector is attracted because that toll can go up.”
New CEO Phil Washington has opened the door for private dollars. That door remains open for short-term and long-term projects, Schank said.
“I’m seeing three or four different ideas (from private investors) a day,” he said. “Most so far have not been about major capital projects, but we are expecting to see that later on.”
High costs, delays and even conflicting environmental benefits have not stopped the popularity of transit and roadway tunnels. Experts say they are more popular than ever.
“Tunnels are being built all over the world,” Neff said. “Everybody wants a tunnel. Around urban areas, they are becoming more desirable because they are environmentally friendly.”
