OC Transpo - Transit Service Adjustments during Confederation Line Construction
The Confederation Line Ottawa LRT Project · PARIS – 15 November 2017 Confederation Line • 12.5...
Transcript of The Confederation Line Ottawa LRT Project · PARIS – 15 November 2017 Confederation Line • 12.5...
PARIS – 15 November 2017
The Confederation LineOttawa LRT Project
Tom Middlebrook, P.EngSenior Vice President, Business Development – Canada
Dragados Canada
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Project Stakeholders
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Sponsors
Project Co
Design Build Joint Venture Maintenance Team
Equity Developers
Engineering Joint Venture
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British Columbia
Alberta
Saskatchewan
Manitoba
Ontario
Quebec
Newfoundland /
Labrador
New
Brunswick Nova Scotia
Prince Edward Island
Yukon
Northwest
Territories Nunavut
City of Ottawa
• Canada’s Capital City with population of
950,000
• Problem: saturated with buses (BRT)
• Solution: replace BRT with Light Rail
Transit (LRT)
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Confederation Line
• 12.5 km LRT line with 13 stations
• 10 km at grade in existing BRT Right-of-Way
• 2.5 km tunnel between Ottawa University (uOttawa) and Pimisi
• 3 underground stations: Lyon, Parliament and Rideau
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Initial Design Approach
• Running tunnel: TBM tunnel(mono tube or twin-tube)
• Underground stations: cut-and-cover
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Design Options
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Option Pros Cons
DesignScheme
SingleTunnel
• Lower cost• Flexibility in operation
• Higher risk of settlement minimized byrock quality
Twin Tunnel• Multiple faces• Overlapping of
construction activities
• Higher cost and longer schedule• Potential impact on building basements
ExcavationProcedures
TBM
• Speed• Open mode• One pass lining
• Paleovalley (soft soil)• Possible damage to building basements• Coordination required with stations• 1.5-2 years TBM procurement
Drill & Blast• Speed• Economy• Multi face
• Urban restrictions• Noise• Vibrations
Mechanical• Flexibility, Geometry• Multiple faces• Mobilize quickly
• Lower speed
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Tunnel andUnderground Stations
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LYON Station PARLIAMENT StationExisting Utilities inParliament Station
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Construction Challenges
• Congested downtown core
• Significant potential forimpacts on buildings
• Wide span ~ 18m
• Potential obstructions: rockdowels & tie backs
• Complex utilities
• Mixed ground conditions
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UtilitiesLow rockcover
Adjacentbuildings
Rock boltsand tie backs
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Implications
• Cut-and-cover or top downexcavation not feasible
• Twin-tube tunnel not feasible
• High risk for TBM operationfrom complex and unknownutilities, and presence oftiebacks and bolts fromexisting structures
• Flexible and adaptabletunneling method required
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Cut-and-cover social cost: businessinterruptions
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Selected ConstructionMethod
• Sequential Excavation Method(SEM)
• Equipment used:
– Excavation: 3 roadheaders
(SANDVIK MT-720)
– Mucking: LHD loaders
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Roadheader
Loaders
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Work Planning
Three independent tunneling teams were deployed at separate
access points
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East Portal
Apartmentcomplex
OttawaUniversity
Universityresidentialcomplex
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• Challenge: Build 18m widestations in between buildings20m apart.
• Design issue: Potentialhorizontal load transfer onto theadjacent buildings
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• Solution: Tension ties
Construction ChallengesLyon and Parliament Stations
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Excavation SequencingLyon and Parliament Stations
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&
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LYON Station PARLIAMENT Station
ExcavationStages
Without Ties With Ties
1a2a
2b
3b3a
1b2a
3a
2b
1b1a
2b
4
Excavation SequencingLyon and Parliament Stations
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Construction ChallengesRideau Station
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Proximity to existing sewer
tunnels and Rideau Canal
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Excavation SequencingRideau Station
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In Soil
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Excavation SequencingRideau Station
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In Rock
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Gallery
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Running Tunnel
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Excavation with Tension Ties
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With Ties
2a3a
2b
1b1a
2b
4
Lower side drifts Permanent side walls
Preliminary tensionSide driftbackfilling
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Lyon Station
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Cavern Excavation at Lyon Station
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Parliament Station
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Rideau Station
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Rideau Station – Hard and Soft Ground
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Rideau Station
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Rideau Station Cavern Arch Concrete Work
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In the 21st century, the construction of newinfrastructure in urban areas
should not negatively affect stakeholders
Innovation in Tunnelling is Key to reach this goal.
Ottawa’s Confederation Line LRT Tunnel
proves that it can be done
Confederation Line LRT Multi-Dimensional Underground SpacePhoto of the Year, Tunnel Association of Canada
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Photo Credit: Giuseppe Gaspari
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TAC 2017 Canadian Infrastructure Project of the Year
https://youtu.be/P0h0qk36mqk