How do they do that? Dig a subway tunnel

How do they do that? is a series for The Source that explores the technology that helps keep Metro running and passengers and other commuters moving. Some of it applies directly to the trains, buses and freeways and some of it runs in the background — invisible to nearly everyone but essential to mobility in our region.

Lowering tunnel boring machine into the ground — Dec. 15, 2005 — for construction of Metro Gold Line Eastside Extension.

With the Crenshaw/LAX line, the Metro Regional Connector and the Purple Line Extension readying for construction, there will be plenty of digging going on in L.A.County. But how do you dig a subway tunnel? Dynamite? Giant corkscrew? Spoon?

In the U.S. we’ve been mining subway tunnels for more than a century. At first there were men and shovels and dynamite and excruciating physical labor. (Think Holland Tunnel under the Hudson River between New York and New Jersey. Think pressurized compartments holding workers who had to be depressurized at the end of a shift to avoid getting the “bends.”) Fortunately, we now have machines to do the heavy work.

During the past 20 years Metro has constructed three sets of tunnels: one for the Metro Red and Purple lines, another for two stations of the Metro Gold Line Eastside Extension and a third to carry the Expo Line under the busy Figueroa-Exposition Boulevard intersection.

Tunnel boring machine

Tunnel boring machine

For the Gold Line Eastside Extension, two tunnel boring machines nicknamed Lola and Vicki (see video above) were lowered into the ground in Boyle Heights to bore twin subway tunnels from First and Boyle to First and Lorena streets at a depth of 50 to 60 feet. Each TBM weighed more than two million pounds and was 344 feet long. Each built a tunnel that was 21 feet in diameter.

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How do they do that? Unlatch the gates automatically for wheelchair patrons

How do they do that? is a series for The Source that explores the technology that helps keep Metro running and passengers and other commuters moving. Some of it applies directly to the trains, buses and freeways and some of it runs in the background — invisible to nearly everyone but essential to mobility in our region.

Hands-free intercom for wheelchair patrons.

Hands-free intercom for wheelchair patrons.

The subway gates are being latched one station at a time and given that we are an advanced civilization, Los Angeles seems to have survived. (The Red and Purple lines are on schedule for latching completion Aug. 5.) For most of us the gate latching has turned out to be no big deal. We pull out our TAP cards — either plastic TAP or TAP-enabled paper tickets — and we march on through.

But what if we were commuting in a wheelchair?

A new hands-free intercom system developed by Metro for ADA patrons opens the gates automatically upon verbal request by a wheelchair patron or silently, if the patron cannot speak.

How do the subway gates unlatch for customers in wheelchairs?

Attendants on duty 24/7 monitor the wheelchair-accessible gates on closed circuit TV. As passengers in wheelchairs approach the special hands-free intercom (a silver box with a blue wheelchair sign next to it) a round camera above the hands-free intercom transmits the image to attendants standing by to help. Or, if they are able, patrons can press a red button to call for help with the gate. The attendants also are alerted to the presence of a wheelchair by a small sensor posted below on the same column.

The attendant verbally greets the wheelchair patron and, if possible, the patron confirms verbally that assistance is required. If the patron cannot speak, the attendant can see that and respond by triggering the ADA gate to unlatch. When it does, the patron can proceed through the opened gate.

The technology required for this innovation is not unusual or particularly high tech — camera, telephone, speaker, lights and an electrical connection to the gate that facilitates the opening of it remotely. Yet used in partnership in this particular combination, it is a simple but innovative way to make travel a little easier for patrons in wheelchairs.

How do they do that? Measure sound levels in stations

How do they do that? is a series for The Source that explores the technology that helps keep Metro running and passengers and other commuters moving. Some of it applies directly to the trains, buses and freeways and some of it runs in the background — invisible to nearly everyone but essential to mobility in our region.

Sound monitoring microphone.

Sound monitoring microphone.

Buses, trains, cars and construction all make noise. That’s why Metro monitors sound levels at Metro properties and projects.

How do they do that?

Sound level measurements are taken throughout the Metro system … but not everywhere. The measuring can be part of routine maintenance. It can be in preparation for a construction project. Or it can be the result of a question or complaint from a patron or someone who lives or works near a Metro project or facility. Whatever the reason, the analysis is done pretty much the same way.

Typically an acoustical engineer measures noise levels with a microphone connected to a sound level meter or other sound recording device that collects the sounds for later analysis.

Sound level meter.

Sound level meter.

Noise levels measured at a moderately busy downtown bus stop generally are about 70 decibels. The highest noise levels collected at Metro stations are found at trains running down of the middle of a freeway. Those could be 85 to 90 decibels — by far the noisiest places in the system because of the surrounding vehicle traffic but still safe for human ears in part because the sound exposure doesn’t last long.

By comparison, the humming of a refrigerator is 45 decibels; normal conversation is approximately 60 decibels. Noise-induced hearing loss can result from short bursts of sound from firecrackers or small firearms emitting sounds of 120 to 150 decibels. But sounds of less than 75 decibels, even after long exposure, are unlikely to cause hearing loss, according to the National Institutes of Health. Since bus and train noise is brief and noise level takes into consideration duration as well as intensity, stops and stations are well below what would be considered harmful to the human ear. And that, of course, is what’s important. 

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How do they do that? Repair the seats on the buses

How do they do that? is a series for The Source that explores the technology that helps keep Metro running and passengers and other commuters moving. Some of it applies directly to the trains, buses and freeways and some of it runs in the background — invisible to nearly everyone but essential to mobility in our region.

Photo by Kim Upton/Metro

Photo by Kim Upton/Metro

How much does Metro spend each year to repair and recover bus seats ruined by food, drink, gum and graffiti? In 2012, the cost was $865,000 in taxpayer dollars to replace stained, carved, graffitied or torn seat inserts. The covered inserts that fit into the back and bottom of Metro bus seats range in price from $10.44 to $23.46 each. In addition to the cost of the inserts, Metro bus divisions expended $1.5 million in labor, replacing both window guards and seat inserts.

The most common reason that a seat insert is changed? Graffiti.

Last year was not unusual. More than 55,000 seat inserts were replaced … or about one every nine minutes. Bus maintenance works constantly to keep up with seat damage so that the buses look good and we don’t have to sit on dirty or destroyed seats. It’s not easy to keep up.

Each bus has between 40 and 57 seats, depending on the size and the style. And with just over 2,200 buses in the Metro system, that’s 88,000 and 125,400 seats that are targets for graffiti.

It takes less than 10 minutes to replace a bus seat insert but 1 1/2 hours to replace an entire seat section. An insert, which looks something like a seat float (see photo above), can be unscrewed from their metal supports, pulled out and the new insert pretty quickly added and screwed back in. But a seat section installation — replacement of the entire seat — is more complicated, requiring assembly of the seat supports and inserts before the whole thing can be carefully fastened back into the bus. Replacement of the entire seat is only done as a result of severe damage. In 2012 there were 79 seat installations — the whole seat including metal supports for the 2-to-3-passenger covered seats — on Metro buses. The cost, not including labor, was an additional $220,000.

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How do they do that? Provide real-time updates on Go511

How do they do that? is a series for The Source that explores the technology that helps keep Metro running and passengers and other commuters moving. Some of it applies directly to the trains, buses and freeways and some of it runs in the background — invisible to nearly everyone but essential to mobility in our region.

How does Go511, the automated phone and web service, know when freeways are jammed? How does it know what we're saying when we ply it with questions about traffic? Can it tell from our voices when we're starting to panic?

Go511 is the five-county, toll-free phone and web service that provides verbal and digital 24/7 updates on traffic and public transit. It's updated constantly so the answers are there when we need them and they change every minute with the flow of traffic.

If you're driving to the airport and running late for your plane you can call 511 on your hands-free phone and the service will verbally deliver estimated travel times including accidents, bottlenecks or potentially dangerous road conditions between you and the airport.

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How do they do that? Change a flat on a steel train wheel

150 cutters "re-profile" a Red Line wheel/Metro photo

150 cutters “re-profile” a Red Line wheel/Metro photo

‘How do they do that?’ is a series for The Source that explores the technology that helps keep Metro running and passengers and other commuters moving. Some of it applies directly to the trains, buses and freeways and some of it runs in the background — invisible to nearly everyone but essential to mobility in our region.

How do they change the steel wheels on the trains? And why? It’s not like they can get a flat. Or can they?

There are 2,884 wheels in the Metro Rail fleet: 2,052 on light rail and 832 on the subway.  At some point in their working lives, many of those wheels will need to be “re-profiled”  or replaced.

What would cause a steel wheel to wear out? Many of the same things that damage car tires: Sudden stops. Sweeping curves. Lots of miles. While many of us change our car tires every 50,000 miles or so, Metro rail wheels can travel as far as 700,000 miles before they need to be replaced. Good thing because changing the wheels on a single rail car can take more than a week, depending on the design of the car.

Re-profiling a steel wheel is the process of removing a thin layer of the wheel tread and flange with a large “wheel truing” machine (see photo). The truing machine restores the wheel’s roundness, tread taper and flange thickness to create good ride quality and steering.

And yes, steel wheels can get flats … although not the kind you’re thinking of. Flat spots are caused by the wheel locking up during an emergency stop, usually because it has come in contact with grease or oil that has dripped off automobiles crossing the tracks. This slippery spot can cause the metal wheel to slide on the metal rail and this can generate a flat spot on a wheel. The flat is removed by taking a layer of steel off the wheel, using a lathe or a milling machine. Metro’s “wheel truing” machines have 150 cutters on each side that can re-profile two wheels at the same time. When the steel tires are too small to “wheel true” any more, they are replaced.

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How do they do that? Hire and train rail operators

A train operator navigates the Expo Line through the Exposition Park area during testing in 2011. Photo by Steve Hymon/Metro.

A train operator navigates the Expo Line through the Exposition Park area during testing in 2011. Photo by Steve Hymon/Metro.

How do they do that? is a series for The Source that explores the technology that helps keep Metro running and passengers and other commuters moving. Some of it applies directly to the trains, buses and freeways and some of it runs in the background — invisible to nearly everyone but essential to mobility in our region.

There’s not much traffic to deal with on the Metro Red and Purple line subways but there are customers who do the craziest things. From pulling the red ball emergency handle to open the doors on a departing train to jumping down on to the tracks to retrieve a lost hat, there’s plenty for Metro Rail subway operators to handle from the cab of a train.

Above ground on L.A. streets, where the light-rail Gold, Blue and Expo trains run, there are unpredictable cars and pedestrians and bicyclists and running pets. One line passes a skateboard park and you never can tell what kids on skateboards are going to do so the train operators must be hyper vigilant when they approach the park.

A bus can swerve (although it would rather not need to) but a six-car train weighing 80,000 pounds per car — not including passengers — can take quite a while to come to a stop. And it can never ever swerve away from a problem, no matter what.

Those are a few of the reasons rail operators live by dozens of what-to-do-if rules and work closely with voices constantly streaming into the train cab from the Rail Operations Center (ROC), where men and women carefully monitor what’s going on at all times on all parts of the rail system, both above ground and below.

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