The Confederation Line Ottawa LRT Project

Transcription

1 The Confederation Line Ottawa LRT Project Tom Middlebrook, P.Eng Senior Vice President, Business Development Canada Dragados Canada

2 Project Stakeholders Sponsors Project Co Equity Developers Design Build Joint Venture Maintenance Team Engineering Joint Venture 1

3 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) Yukon Northwest Territories Nunavut Newfoundland / Labrador British Columbia Alberta Manitoba Saskatchewan Ontario Quebec Prince Edward Island New Brunswick Nova Scotia 2

4 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 3

5 Initial Design Approach Running tunnel: TBM tunnel (mono tube or twin-tube) Underground stations: cutand-cover 4

6 Design Options Design Scheme Excavation Procedures Option Pros Cons Single Tunnel Twin Tunnel TBM Drill & Blast Mechanical Lower cost Flexibility in operation Multiple faces Overlapping of construction activities Speed Open mode One pass lining Speed Economy Multi face Flexibility, Geometry Multiple faces Mobilize quickly Higher risk of settlement minimized by rock quality Higher cost and longer schedule Potential impact on building basements Paleovalley (soft soil) Possible damage to building basements Coordination required with stations years TBM procurement Urban restrictions Noise Vibrations Lower speed 5

7 Tunnel and Underground Stations LYON Station PARLIAMENT Station Existing Utilities in Parliament Station 6

8 Construction Challenges Congested downtown core Mixed ground conditions Significant potential for impacts on buildings Wide span ~ 18m Low rock cover Utilities Potential obstructions: rock dowels & tie backs Rock bolts and tie backs Complex utilities Adjacent buildings 7

9 Implications Cut-and-cover or top down excavation not feasible Twin-tube tunnel not feasible High risk for TBM operation from complex and unknown utilities, and presence of tiebacks and bolts from existing structures Cut-and-cover social cost: business interruptions Flexible and adaptable tunneling method required 8

10 Selected Construction Method Sequential Excavation Method (SEM) Equipment used: Excavation: 3 roadheaders (SANDVIK MT-720) Mucking: LHD loaders Roadheader Loaders 9

11 Work Planning Three independent tunneling teams were deployed at separate access points Ottawa University Apartment complex East Portal University residential complex 10

12 Construction Challenges Lyon and Parliament Stations Challenge: Build 18m wide stations in between buildings 20m apart. Design issue: Potential horizontal load transfer onto the adjacent buildings Solution: Tension ties 11

13 Excavation Sequencing Lyon and Parliament Stations & 12

14 Excavation Sequencing Lyon and Parliament Stations LYON Station PARLIAMENT Station Without Ties 1a 2a 2b 3a 1b 3b With Ties Excavation Stages 2a 3a 2b 2b 1a 4 1b 13

15 Construction Challenges Rideau Station Proximity to existing sewer tunnels and Rideau Canal 14

16 Excavation Sequencing Rideau Station In Soil 15

17 Excavation Sequencing Rideau Station In Rock 16

18 Gallery 17

19 Running Tunnel 18

20 Excavation with Tension Ties Lower side drifts Permanent side walls With Ties 2a 3a 2b 2b Preliminary tension Side drift backfilling 1a 1b 4 19

21 Lyon Station Cavern Excavation at Lyon Station 20

22 Parliament Station 21

23 Rideau Station Rideau Station Hard and Soft Ground 22

24 Rideau Station Rideau Station Cavern Arch Concrete Work 23

25 In the 21st century, the construction of new infrastructure in urban areas should not negatively affect stakeholders Photo Credit: Giuseppe Gaspari 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 Space Photo of the Year, Tunnel Association of Canada 24

26 TAC 2017 Canadian Infrastructure Project of the Year 25