The Fall and Rise of the LA Metro
With gasoline prices sky-high, Los Angeles is falling back in love with public transportation, and has just opened the latest branch of its best kept secret: the LA Metro.
Los Angeles is well known for its love affair with the car and the frustrating two-to-three-hour drive to leave the city during rush hour. It is less well known for its metro-train system, which plies both underground and overground routes from one end of greater Los Angeles to the other.
Clearly, the system is still a work in progress - the latest 'Expo Line', designed to link the Downtown area with Culver City in the west, opened as recently as April 2012 - but usage figures suggest that it is becoming increasingly popular. As the eight- and ten-lane arteries that form the LA freeway system shudder to a halt, the city metro - in combination with other local transit initiatives - has the potential to relieve some of the blockage. And in a nation not exactly renowned for its public transport systems, that is a secret worth sharing.
Decline to gridlock
Greater Los Angeles is a conurbation spreading some 50 miles in each direction across five counties of southern California. This classic example of urban sprawl is a function of the landscape: a nominally flat coastal plane bordered by mountains and a propensity for earthquakes which, historically, favoured low-rise construction. However, its population density is surprisingly high. According to the US Census Bureau, the Los Angeles-Long Beach-Santa Ana "urbanized area" is the most densely populated in the US, with more than 7,000 inhabitants per square mile (beating the "New York-Newark Urbanized Area" by nearly 1,800). Of course, it all depends on definitions, as visitors to Manhattan would soon agree!
Nevertheless, there are lots of people in LA who need to move from one part of the city to another, so the need for a modern, efficient transit system is a no-brainer. It is also required because Los Angeles has a decentralised structure, based on a dozen or so areas, such as Downtown, Long Beach, Century City, Pasadena and Hollywood. Following a common development pattern, rail systems helped to extend and link these nodes, and later road networks completed the urban infill.
One of the most famous railroad magnates in LA was Henry E Huntington, who purchased the narrow-gauge Los Angeles Railway in 1898 and formed the standard-gauge Pacific Electric Railway in 1901. Having an eye towards booming real estate development, Huntington extended the transit system into new and thus poorly served housing areas. He even sponsored a development in Orange County known as Huntington Beach, which was linked to Downtown by Huntington's own streetcars.
In fact, although the latest incarnation of LA's integrated bus and train system dates to 1990, it has a long history of public transportation, dating back to 1873. Since then, according to Metro (the entity currently responsible for public transit in Los Angeles County), "at least 220 private and public companies have operated transit systems that have included horse cars, cable cars, incline railways, steam trains, electric streetcars, interurban cars, trolley buses, and gas- or diesel-powered buses". Indeed, prior to the Second World War, LA is said to have had the world's largest electric rail system.
Sadly, in common with many other cities, Los Angeles systematically dismantled its metropolitan rail network, as passenger numbers dwindled in the face of increasing car ownership. The last line of the Pacific Electric Subway closed in 1955 and was converted to a bus route. In 1963, a similar fate befell the remaining streetcar lines and LA began the short decline into gridlock.
The light at the end of the tunnel appeared in 1990, when Metro opened the first new line of what is generally called a metro (after the Parisian Metro, or metropolitan railway). The 22-mile-long Blue Line runs north-south from Downtown LA to Long Beach and is largely a surface railway integrated with the existing street system. Another five lines incorporating 65 miles of track have been added since then, extending tree-like coverage mainly east and west from the Blue Line's trunk.
In common with most metro systems, the LA metro comprises both surface and underground routes, some constructed using cut-and-cover techniques, others requiring sophisticated tunnel boring machinery. While retrofitting a metro to a city's road infrastructure can be problematic, it is once you go below the surface that the challenge really begins.
The geology beneath LA is a mixture of rock, sand and loose soil with the 'added spice' of methane gas pockets and tar pits not to mention a number of major fault lines. Matthew Crow, project engineering director, describes this as "a variety of technically challenging conditions", the solutions to which are based on pragmatic scientific and engineering principles: "identify the issues by extensive study, develop mitigation measures and implement them in accordance with rigorous procedures."
While tunnelling in an earthquake zone may not be everyone's ideal occupation - and Crow admits that "all of Metro's rail projects are within a seismically active region" - a detailed "geotechnical investigation" to locate faults is a key part of any plan. In fact, adds Crow, "building structures for human occupancy on active faults is prohibited in the state of California". Nevertheless, by necessity, tunnels are required to cross faults in accordance with the "guiding philosophy of earthquake design", he says, which in a nutshell is "to accommodate the movement of the fault while maintaining public safety".
Most tunnels in the Los Angeles Basin are classified as "Gassy" or "Potentially Gassy" by the state of California, primarily due to methane, says Crow, "but also other hazardous gases such as hydrogen sulphide associated with the oil-producing formations underlying the area". Unsurprisingly, Metro's tunnel designs have measures to exclude gas and water, including precast concrete linings with a double gasket system for redundancy. The asphalt-infused sands of the La Brea tar pits area are another noxious material to exclude from the tunnels.
Asked if Metro felt able, whatever the obstacles and challenges, to just 'go ahead and tunnel', Crow was positive: "Metro gained a lot of experience with the successful completion of the Gold Line Eastside Extension in 2009, and we feel this allows us to confidently meet the challenges of tunnelling in the Los Angeles Basin area."
Vote for Metro
The visitor's experience of using the metro is mostly good. Trains are clean and comfortably air-conditioned (certainly compared to the waves of heat emanating from buses as their doors open onto the street!) and reasonably frequent. They are also cheap at $1.50/trip or $5/day.
The key drawback for visitors (though possibly not for commuters) is the lack of interconnection between lines: it is largely a hub and spoke network with all but the Green Line passing through 7th Street/Metro Center. Other surprises are that until the Expo Line opened in April there was no link to the central university and museum area, and there is still no direct link to Los Angeles International Airport (LAX).
According to Marc Littman, a 20-year veteran at Metro: "Funding is the big issue: no matter how badly they were needed, we had to build one line at a time". The money for public transit, he explained, has to come from local taxes. "We currently have three half-cent sales taxes for transit, which has to cover highways, bikeways, pothole mending and so on." So far, Metro has spent $9bn, but hopes to spend much more in the future.
Indeed, what Littman characterises as "a miraculous event" occurred in November 2008. "In the midst of the deepest recession, voters agreed to an additional half cent in tax," he explains, which means that plans to extend respective lines both west to Santa Monica and east to Claremont (and hopefully that link to LAX) may come to fruition.
Why did two-thirds of voters agree to donate more of their hard-earned income to Metro? "They were fed up with the traffic," says Littman, "and the situation reached a tipping point. In rush hour, it can take two to three hours to go from Downtown to the west side [Culver City and the coast], which itself is a centre for about 600,000 jobs." And then there is pollution: "Along with Houston, we have the worst smog in the US."
Park the car?
So, has the rise of the LA metro succeeded in separating drivers from their cars? Anecdotal evidence suggests not yet: asked whether he used the metro much, one Boeing employee said "I remember using it once'". On the other hand, he has no love of the freeway: the local concrete ribbon cut his community in half, forcing children to negotiate a busy intersection on their way to school.
Other professionals, while married to their cars because the metro doesn't go where they need, certainly recognise its advantages. For example, an engineer at NASA's Jet Propulsion Laboratory, Pasadena, chooses to live in a less than classy neighbourhood to reduce his drive to work and gets there by 6am to miss the traffic!
But was it really the aim of the metro to get people out of their cars? Isn't city public transit more of a social programme, offering the poorer, car-less local residents a cheap and comfortable alternative to the crowded, sweaty buses that cross the city each day?
Littman confirms that many of today's metro passengers are "poor and transit-dependent", but is passionate in his belief that "public transit can't do one thing alone: it's about getting people out of cars, reducing air pollution and keeping the economy moving. Mobility is the lynchpin of the economy!". Moreover, he adds, it involves giving people more transport options, including ride-share lanes on the freeways and even bikes. "Putting all your transit eggs in one basket will only get you scrambled eggs," he concludes graphically.
Interestingly, Metro has set its sights beyond transit per se, and is involved in the development of areas around rail stations. Metro bought the historic Union Station in 2011 with an eye to housing developments, and has already invested in a new hotel at Hollywood/Vine on the metro's Red Line. Shades of Henry E Huntington, no less.
So how is Metro doing in terms of attracting passengers? "We have not quite met our goal," admits Littman, "but rail ridership is growing exponentially, considering that we had zero riders in 1990 and now count 320,000 per day - that's more than 100 million rides per year!"
Realistically, it's unlikely that a train system can entice more than a small proportion of drivers to leave their cars at home, but a combination of new line developments, creative promotions and word of mouth would certainly help change the mindset that favours the car above all else.
One of the key factors in a place where citizens are always in a hurry, is the disparity in speed between rail and road: the metro train travels at about 32mph, while buses average 10-11mph, close to that achieved by horse-drawn trams a century ago.
The Los Angeles Basin is an elongated structural depression that has been filled with sediments up to 4,000m thick since the middle Miocene period:
* Fernando Formation, a weak sedimentary bedrock
* San Pedro Formation, marine deposits comprising an interbedded mixture of sand, silt and clay
* Lakewood Formation, shallow marine deposits of sand, silt and gravel
* Alluvium, interbedded silts, clays sands and silty sands
* Artificial Fill.
Thus, depending on location, tunnels are driven through weak rock, sands, silts, gravels and clays above and below the water table. Add the potential for gas pockets, tar pits and geological faults and you have the ultimate in tunnel-boring challenges.
Tunnels beneath urban Los Angeles are bored using pressurised-face soft-ground tunnelling techniques, in which a pressurised tunnel boring machine (TBM) supports the ground at the face of the machine using a pressurised slurry. While rotating cutter-heads excavate the soil in front, the cylindrical TBM pushes off the completed tunnel lining, which is laid behind, and a cement grout is injected into the gap between the ground and the lining. A screw conveyor removes the excavated soil in a manner controlled to maintain the face pressure.
Underground sections are either bored with pressurised-face TBMs or by cut-and-cover construction. Stations are built using cut-and-cover techniques and city streets are temporary covered with decking to minimise disruption.
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