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Purple Line Extension Tunnel Boring Machines (TBM)

The two Tunnel Boring Machines (TBMs) for the Purple Line Extension Transit Project Section 1 will be used to dig two parallel tunnels that will connect three new stations betwen Koreatown and Beverly Hills.

The TBMs will dig side by side starting at Wilshire/La Brea in the Miracle Mile section of Los Angeles and continue towards Wilshire/Western in Koreatown. Then they will be disassembled for transporting back to Wilshire/La Brea and then reassembled for the last leg of their journey through Wilshire/Fairfax and finishing at Wilshire/La Cienega in Beverly Hills.

When will they start work?

The TBMs will start work in Summer 2018 after they have been assembled and tested.

For more information about the TBMs check out this factsheet .

Follow The Twins on Twitter for weekly updates on their progress and more.


Tunnel mining on Wilshire Bl

The Purple Line Extension Transit Project will construct two parallel tunnels to create a seamless connection from the current Purple Line Wilshire/Western Station in Koreatown to three new stations located at Wilshire/La Brea, Wilshire/Fairfax, and Wilshire/La Cienega.

The new 3.4 mile railway will be constructed using a combination of tunnel boring machine and an “open-cut” methods. The Twins will be responsible for approximately 17,845 linear feet of tunneling, as they travel under Wilshire Bl. Each tunnel will take approximately 24 months to complete.

Along the way, The Twins will encounter different soil conditions. The tunnel crown will always be at least 20 feet or more under the subsurface water table.

In terms of geology, tunnels will be bored through two types of geological formations: San Pedro and Fernando.

The following ground conditions may be encountered during tunneling:

  • Full face San Pedro
  • Mixed face ~ Top San Pedro and bottom Fernando
  • Full face Fernando
  • Between STA~490+00 (Dunsmuir Av) and 540+00 (Crescent Heights Bl) equals~ 5,000 linear feet. These three ground types will also be saturated with tar (with various percentages of saturation/presence).

Tunneling Statistics

Progress is measured in total linear feet traveled and the number of rings they build.

Reach

Linear Feet

Location

1

9,570

La Brea Bl to Western Av

2

4,440

La Brea Bl to Fairfax Av

3

3,280

Fairfax Av to La Cienega Bl

4

555

La Cienega Bl to tail track west of La Cienega Bl

Totals: approximately 17,845 linear feet or 3.4 miles; two tunnels equal approximately 35,690 linear feet or approximately 6.8 miles.

Follow The Twins on Twitter for weekly updates on their progress and more.


Thank you to all the Los Angeles students who entered the Purple Line Extension Tunnel Boring Machine (TBM) Art Contest.  The 5 finalists were selected by a panel of five judges composed of community stakeholders. These original entries best explains the significance of the proposed names and how it relates to the community, transportation or engineering.

Vote for your favorite names!

Vote below and help us choose the names to display on the #PurpleLineTBMs. The winning names will be announced at the Purple Line Extension TBM Unveiling Ceremony! If you have trouble viewing the poll, please visit the polling page .

The winning contestant will receive:

  • A commemorative Metro TAP card with the winning names pre-loaded with a fare value of $100
  • Award Presentation
  • Invitation and recognition at the TBM Unveiling Ceremony
  • Photo with Purple Line Extension Project Management Team at TBM Unveiling Ceremony
  • Behind the scenes tour of the project
  • Recognized in the Purple Line TBM Contest press release
  • Included in a feature story on Metro’s The Source and El Pasajero blogs
  • A prize bundle worth over $350

Follow The Twins on Twitter for weekly updates on their progress and more.

Disclaimer: These essays have been submitted and published in their original form.

Names for Tunnel Boring Machines: Castor & Pollux

Submitted by Ryan and Amanda Walker
School: New Patchway Middle School
Grade: 7

In Greek and Roman mythology, Castor and Pollux, were twin brothers. In Latin the twins are also known as the Gemini twins.

Castor and Pollux are also the brightest stars in the constellation Gemini. Castor is actually sextuple star system 52 light-years from Earth, which appears as a magnitude 1.6 blue-white star to the unaided eye. Pollux is an orange-hued giant star of magnitude 1.2, 34 light-years from Earth. Pollux has a recently discovered planet revolving around it.

Ancient Greek authors tell a number of versions of the story of Castor and Pollux. In both the Odyssey and in Hesiod, they are described as the sons of mother Leda and father Zeus or Jupiter. The Gemini twins were regarded as helpers of humankind and believed to be patrons of travelers and of sailors in particular. Castor was a skilled horse-tamer, while Pollux possessed great boxing skills.

In their role as horsemen and boxers in Greek Mythology, the Gemini twins are regarded as the patrons of athletes and athletic contests. In 2028 Olympic athletes and fans will travel to their sporting events in the Metro Purple Line tunnels bored by Castor and Pollux.

The Gemini twins would be great names for the twin purple line extension boring machines.

Names for Tunnel Boring Machines: Elsie & Soyeon

Submitted by Marianne Gutierrez
School: Fairfax High School
Grade: 9

I believe the twin TBMs that will be digging the tunnels for the Purple Line Extension should be named Elsie and Soyeon, both names of important female figures in engineering and/or space travel. I chose Elsie for the female civil engineer Elsie Eavers, who was the first female to be elected as a member of the American Society of Civil Engineers. Eavers was also the first female member of the American Association of Cost Engineers and the first female to receive an honorary lifetime membership in the association. Elsie is known to mean “noble” in its American and German meaning. Similarly, I chose Soyeon for the other TBM name for the female astronaut & mechanical engineer Yi Soyeon. Yi was the first Korean to fly in space. In Korean, Soyeon means “bright” and “beautiful.” I also think Soyeon should be used because it is a Korean name and I find it fitting since the TBMs will be digging the parallel tunnels that will allow trains to travel from Koreatown to Beverly Hills. In conclusion, the TBMs should be named Elsie and Soyeon because of the people they represent and the significance of the names themselves.

Names for Tunnel Boring Machines: Abeona & Adiona

Submitted by Tiffany Pamilar
School: Fairfax High School
Grade: 9

I believe that the TBMs/Tunnel Boring Machine should be named after Abeona and Adiona. The reason on why I would think a proper name for the TBMs would be Abeona and Adiona is because of what these names represent. Abeona in Roman mythology is the Goddess of Outward Journeys. She protects travelers and her name comes from the Latin verb abeo , which means “to depart, go away, or go forth.” On the other hand, Adiona is Abeona partner in Roman mythology where she is the Goddess of Safe Return. Of course, these two travel goddesses watch over travelers. Abeona making sure of safety on departure while Adiona making it safe on the return of the traveler. Since these two TBMs are going to be built as subways, workers/future passengers need to be safe by outward journeys from Koreatown to Beverly Hills which is what Goddess Abeona does. Adiona will then make sure that these future passengers of the subway will make it back safe on their return back to the area they live in. In other words, I believe that the TBMs should be named after the Roman Goddesses Abeona and Adiona for travelers being safe on departure and also return

The 2nd name i have chosen is “Athena”. She is the goddess of wisdeom, poetry, and art. When riding the metro you must be very alert. Athena can bestow wisdom into you. god forbid something really bad happens and all the emergency exits are crowded, you would have to become articulate. You know it. Athena has your back!! She will protect you from any harm put in your way. It’s good to know someone as our back

Names for Tunnel Boring Machines: Rosa & Milagros

Submitted by Kenny Uong
School: Herbert Hoover High School
Grade: 12

To commence, the name I would like to propose for the first T.B.M. is Rosa. First, Rosa comes from Rosa Parks, an important African American civil rights activist who started a bus boycott and fought to terminate the legal segregation on
public transportation and at public facilities. On December 1, 1955, she was arrested for refusing to give up her seat to a white passenger on a bus in Montgomery, Alabama. In addition, Rosa is also Spanish for rose. A purple rose, corresponding with the color of this Metro Rail line, is primarily a symbol of enchantment. Riders will definitely fall in love with the Metro Purple Line Extension at first sight.

Furthermore, the name I would like to propose for the second T.B.M. is Milagros. Milagros is Spanish for miracles. The Metro Purple Line will serve the Miracle Mile neighborhood, which is well known for their museums. In addition, the Metro Purple Line Extension will symbolically represent a miracle on Wilshire Boulevard. At last, one will finally be able to breeze under the thoroughfare without experiencing any traffic congestion. A public transportation miracle is indeed taking place along this main corridor. Go west, young subway!

Names for Tunnel Boring Machines: Genesis & Nova

Submitted by Valerie Castro
School: Fairfax High School
Grade: 12

Genesis represents the emergence and the beginning of something new, which suits the production of the subway tunnels. The name Genesis is perfect because it embodies the Purple Line Extension, which will extend the subway from its current terminus on Wilshire/Western and extend it to Westwood, which is about nine miles. This new line is something that has not been done before and it will be known because it would provide high capacity, high-speed, and dependable alternatives for people and connect through cities such as Westwood, Century City, Beverly Hills, etc.

The name Nova means new and represents something that is different and out of this world which symbolizes the new tunnels since its magnitude and speed would help provide citizens an easier and speedy transportation to and fro and reduce the traffic in LA. Nova in astronomy means a star that releases an immense amount of energy and is extremely bright. I thought of this name because the image of the fast-pace subway reminded me of a bright star in the sky traveling at a high velocity just like a stellar nova.


Thank you to all the Los Angeles students who entered the Purple Line Extension Tunnel Boring Machine (TBM) Art Contest.  The 5 finalists were selected by a panel of five judges composed of community stakeholders. The top entries were original, artistic and presented a vision of the ideal community with the Purple Line Extension.

Vote for your favorite artwork!

Vote below and help us choose the artwork to display on the #PurpleLineTBMs. The winning artwork will be announced at the Purple Line Extension TBM Unveiling Ceremony! If you have trouble viewing the poll, please visit the polling page .

The winning contestant will receive:

  • A commemorative Metro TAP card with the winning art pre-loaded with a fare value of $100
  • Award Presentation
  • Invitation and recognition at the TBM Unveiling Ceremony
  • Photo with Purple Line Extension Project Management Team at TBM Unveiling Ceremony
  • Behind the scenes tour of the project
  • Recognized in the Purple Line TBM Contest press release
  • Included in a feature story on Metro’s The Source and El Pasajero blogs
  • A prize bundle worth over $350

Follow The Twins on Twitter for weekly updates on their progress and more.


Please use the materials below to learn more about the Regional Connector Tunnel Boring Machine (TBM).

Follow The Twins on Twitter for weekly updates on their progress and more.


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