Second in a three-part series. Click here for the first part.
SACRAMENTO, Calif. -- Where Highway 99 meets the state capital here, a motorist has choices. He can pivot toward the San Francisco Bay, veer inland to the Nevada border, or ride the flatlands south toward Los Angeles.
It's an important junction for any California driver -- and, in a sense, a symbol of California's climate choices.
The state already has plans to widen Highway 99 to deal with increased traffic in the coming decades. But boosters of high-speed rail for the state say no amount of road expansion will be able to serve a larger population.
Build the train, supporters say, and the state will cause far less greenhouse gas emissions than if Californians took all their trips by car and plane instead.
Skip it, they say, and get ready for highway and airport paralysis.
Dan Leavitt is deputy director for the California High-Speed Rail Authority, the state agency in charge of the project. He said the train's strongest argument on climate is that it keeps the sprawl-driven past from becoming the future.
"What is California going to look like in our future, with or without high-speed rail?" he said. "We believe that the argument of 'with high-speed rail,' in terms of not just climate change but sustainability as a whole, is far greater with high-speed rail."
Roughly 38 million people live in California today; by 2050, that's projected to reach 60 million. Leavitt believes that the state can't continue its development pattern of recent decades: what he called "market-driven sprawl."
If it does, he said, the state will sink deeper into a world of emissions and traffic, with jobs and land getting constantly scarcer.
The planners' solution to sprawl and emissions
What's the alternative? To the authority and its supporters, it's a 200-plus-mph train whose backbone would run along much of Highway 99.
Its major endpoints would be San Francisco and Los Angeles, but cities like Sacramento and San Diego would eventually be included, even though they're not in the middle.
The idea is to link the city's biggest population centers so when Californians want to travel, they have options other than plane and car.
The authority estimates that by 2030, the system would annually save nearly 6 million gallons of oil and 7 billion pounds of carbon dioxide. If the system reaches its goal of getting all its power from renewable energy, those figures would be roughly double.
From a basic engineering standpoint, it's easy to see why. Electric trains, which run on motors, are more energy-efficient than cars and planes, whose engines use fossil fuels.
But from a policy standpoint, things get more tricky. It's not always clear what mode saves the most energy.
An empty train, after all, expends great energy moving nothing but seats; even a single-occupancy car, or low-occupancy plane, comes close. A packed train, on the other hand, moves its riders more efficiently than a car or plane can.
And the authority is counting on its trains to be packed.
By 2030, it projects, 88 million to 117 million passengers will ride the system each year. If a high-speed train didn't exist, Californians would take 33 million flights that year; with the train available, they would take 21 million.
Critics assailed these numbers, calling them rosy estimates of Californians' interest. As the public protest rose, the authority put together an independent panel to review them.
Gregg Albright, a vice president at Parsons Brinckerhoff who is consulting on the project, said the authority has received input from the panel and is "enhancing" its studies appropriately.
But for the study's current purpose -- getting a broad sense of how many people can be diverted to trains from other modes -- he said it's workable.
Whatever number they arrive at, Leavitt is standing by this conclusion: that millions of Californians want an alternative to sprawl.
State lawmakers have begun the process with bills like S.B. 375, which requires metropolitan areas to consider their future development in terms of greenhouse gases.
Can Californians reorient themselves?
Leavitt and high-speed rail supporters believe that laying down infrastructure will give communities something permanent to cluster around. Their transit systems will have renewed value as people realize they can cross the state without ever getting in a car.
If a city can reorient itself around a subway line, the argument goes, the state can reorient itself around a high-speed train.
Leavitt said towns along California's interior want to begin developing in a way that manages their growth -- and just happens to reduce their carbon footprints. They just need a catalyst.
"The problem is, we don't really have the infrastructure to take care of all the smart growth that they want to do," he said. "They all have downtowns that are really starving for development. And they all have cities that want to develop downtown, but they have not had the market there to bring downtown development."
But in the research world, experts are divided as to whether high-speed rail can cut CO2 emissions. They've asked these questions: Will people ride the trains? And if they do, will they offset enough car and air travel to make a difference to the climate?
Some have come to Leavitt's conclusion: that once Americans have the high-speed rail option, they will change travel modes.
Others have come to different conclusions.
In January of last year, two researchers at the University of California, Berkeley, asked this question: With all the emissions that go into building the California train, how many people would have to ride before it was "worth it" to the climate?
The researchers did a "life-cycle assessment" accounting for all the energy used to build and power those trains, cars and planes.
'Ridership is uncertain'
When that was counted, the energy appetite of California's high-speed project rose by 40 percent, and its carbon footprint swelled by 15 percent. Much of that was driven by the use of energy-intensive materials like concrete and steel.
The authors, Mikhail Chester and Arpad Horvath of UC Berkeley's civil and environmental engineering department, said there might be other reasons to build a high-speed train. It could reduce strain on highways and airports or rein in sprawl, for example. But whether it reduces energy use hinges on how many people ride it.
In a high-ridership scenario, they found, all the energy that went into powering, building and operating the train could be "paid back" in eight years, as Californians chose the train over planes and cars.
In other words, it would take at least eight years to achieve a net reduction of greenhouse gases.
With fewer riders, it would take 30 years. And in the lowest-ridership scenario, only one rider for every 10 seats, the energy that went into building the train would never be paid back. The train would always have caused more emissions than it saved.
Chester and Horvath also said the increased electricity use would increase sulfur dioxide emissions, since car and plane fuels face stricter regulations for that pollutant.
"Ridership is uncertain, and for an entirely new mode it is very uncertain," the authors wrote in a December summary. "Thus the California high-speed rail system can reduce greenhouse gas emissions, but may do so only over a very long period, and will do so in exchange for other air emissions."
Will cities save the plan?
High-speed rail supporters often argue that systems in France, Japan and elsewhere have achieved high ridership. But researchers dispute whether the United States, with its sprawled-out development and low gas prices, will follow suit.
In a 2009 study, the Congressional Research Service doubted it: "To extrapolate from the adoption of HSR in other countries to the conclusion that the United States should follow a similar path may not be warranted," it said.
If cars get more fuel-efficient, and passengers fly even when they have the option of the train, high-speed rail won't meaningfully cut CO2 emissions, CRS said.
That's why advocates like Petra Todorovich, director of America 2050, believes high-speed trains have to market themselves differently.
Trains only save energy if they have high ridership, she admitted. The key to that is making sure trains go from the center of one city to the center of another -- from one intense locus of activity to another.
That's a different model than aircraft, since airports tend to pave over a large parcel of land on the city outskirts. And it's different from cars, too, since entering a downtown usually means traffic.
"When high-speed rail does provide that center-city-to-center-city connection, it's more attractive than air travel or driving," she said.
Todorovich, like many other rail advocates, will be closely watching how the authority negotiates with towns that want a stop. It may allow the stations to sit far from downtown, where land is cheap and parking is easy, or in the city center, where the opposite holds true.