leo carse and ashok kothari - parsons brinckerhoff inc - los angeles county mta - westside purple...
TRANSCRIPT
Westside Purple Line ExtensionLos Angeles, California. USA
October 13, 2015
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Los Angeles Metro Existing Fixed Guideway System
n Metro Blue LRT 35.4 kmn Metro Green LRT 32.2 kmn Metro Gold Pasadena LRT 22.0 kmn Metro Gold Eastside LRT 9.7 kmn Metro Expo LRT 13.8 kmn Metro Red & Purple HRT 28.0 km
Total 141.1 kmn Metro Orange BRT (Busway)20.9 km
Current LA Metro Underground Rail Projects in Construction
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Measure R Westside Transit Program• ½ cent sales
tax for Los Angeles County passed in 2009
• projected to raise $40 B over 30 years
• 35% to new rail and bus projects
• 20% for new car pool lanes
• 20% for bus operations
• 15% for local city sponsored improvements
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Westside Subway Extension
• 8.9 mile extension of Metro Purple line• 7 new stations • 78,000 New Daily Trips• 25 minutes travel time Downtown –
Westwood
Section1 – Wilshire Western to Wilshire La Cienega• FTA Record of Decision
for all three sections – August 9, 2012
• FTA Full Funding Grant Agreement for Section 1 – May 21, 2014
• Delivery– 3 Advance Utility
Relocation Contracts– A single design-build
contract for the twin –bored tunnels and 3 new underground stations. Contract NTP issued on
• Revenue Service Date: – FFGA – October 31,
2024– Forecast – November
2023
Section 2 – Wilshire La Cienega to Century City
• FTA Full Finding Grant Application is in process
• Delivery– One advance utility
relocation contract– One design build
contract for twin bore tunnels and two underground stations
• RFP / RFQ contract solicitation documents for the design build contract were issued on 14-Sep-15
Section 3 - Century City to Westwood VA Hospital
• Originally scheduled for completion in 2036
• Completion date may be brought forward to 2024 in support of Los Angeles Bid for 2024 Summer Olympics
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BIM Modeling
• Design– 3-D design on one
platform– Coordination and
Integration• Construction
– QA / QC data base• Operation and
Maintenance– Asset
Management
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BIM Modeling – Underground Utilities
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BIM Modeling – Interfaces with Existing Properties
Tunnels
Geology
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Geology
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Tunnel Section
5750 mm ID300 mm Precast Segment150 mm Secondary linerHCR membrane
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Cross Passage
Cross Passages at 800 ft (245
m) max.
38’-10” (11,838
mm)
Tunnelling Challenges
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Seismic
• Omega Seals and/or Steel liners provide flexibility at tunnel /station interface
• Steel liners and/or oversize tunnel through fault zones
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Seismic
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Oil Fields
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Oil Fields
• Active oil field adjacent to alignment at Century City
• Locating abandoned oil wells is a challenge
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Methane Zones
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Tunnelling through Gassy Ground
Closed Face TechniquesIsolation and VentilationA closed face Slurry Machine isolates
tunnel interior and construction crews from contact with the tunnel muck and ground water.
EPB machines do not normally contain muck beyond the end of the screw conveyor , but ……….
EPB muck can be diluted to make a pumpable slurry
Gas neutralizing agents can be mixed with soil in front of the EPB machine to reduce off-gassing of soil and ground water
Tunnel segments that seal out water and gas
Ventilation to deal with gases that do
enter the tunnel
Double Gasket Segments
• Double gasket liners have been used successfully on Metro Gold Line
Tunneling Operations from Below the Street
Stations
Typical Metro Underground Station
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Cut and Cover Construction
Modular Subway Station
Unity between Sections of the Project
1. Identity and public awareness2. Simplifies Design &
Construction3. Systemwide Operation and
Maintenance
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Station Water / Gas Proofing Concept
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Station Construction
Steel soldier piles, wood lagging and struts Slurry walls / secant piles may be used where
groundwater or gas and tar are concerns Concrete deck panels are placed on deck beams
over the excavation during construction. Excavation occurs from beneath the deck.
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Station Cut-and-Cover Construction Planning
The tunnel access shaft and staging area located at the station site ultimately becomes the underground subway station.
Off-Street Construction Staging Area
Station construction under temporary concrete deck panels
Traffic is maintained above the excavation
during station construction
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Soldier Piles and Deck Beams
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Deck Beams and Temporary Street Concrete Panels
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Earth Backfill and Final Street Restoration
StationChallenges
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Utility Relocation
Third party coordination has begun with the City, County, State agencies and utility companies. 3-D CADD modeling is being used to determine utility conflicts.
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Utility Relocation and Temporary Support
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Naturally-occurring Tar Pits
Fossils are boxed and removed from the excavation
Fossils are then separated from the tar sand matrix
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Fossil Removal
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Exploratory Shaft
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Building Protection
THE END
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