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Lovat TBM Breaks Through First LRT Extension Tunnel in Edmonton

Lovat TBM Breaks Through First LRT Extension Tunnel in EdmontonA Lovat EPB TBM broke through to the University LRT station on 8th November, completing the 293 m-long southbound tunnel of Edmonton's Light Rail Transit system. The project is built by a JV of Aecon and McNally for $100.1 million. The southbound tunnel was driven downward to the University station from an open cut section at the Jubilee Auditorium Parking Lot. Further south of this portal is where the future Health Sciences station will be built. The TBM is being removed at the University station through a TBM removal shaft which was constructed as part of the original contract. It will then be trucked back to the Health Sciences station open cut and reinstalled to drive the northbound tunnel. When this second tunnel is completed, the TBM will be removed from the shaft and shipped back to Lovat in Ontario.The 676-tonne machine is equipped with a 6.2 m-diameter cutting head. It is owned by Lovat and was rented to the JV for this project. This TBM was originally utilised on a project in Singapore. Lovat shipped the machine to Edmonton and rehabilitated it on the project site. The machine averaged six metres of digging per day. The tunnel runs through a layer of fine sand. Water and a foaming agent have been sprayed into the dry sand to stiffen it, then the TBM advanced 1.2 m before stopping. Then seven precast concrete segments have been assembled to form a 5.4 m-inner diameter tunnel ring. Each ring has six segments plus one key. The segments are being cast by the Aecon/McNally JV with management services provided by A.J Hart & Associates. The designer of the segments is Hatch Mott MacDonald. The actual casting of the segments was subcontracted to Con-Force Structures, based in Calgary. The segments forms are inherited from the Puerto Rico 'tren urbano' project. Visit www.aecon.com, www.mcnallycorp.com, www.hatchmott.com and www.con-force.com From the lower face of the TBM, the material is lifted through a screw conveyor and discharged onto a conveyor belt supplied by Lovat with the TBM. The material will then travel approximately 55 m along the conveyor before being discharged into a muck car on rail. There are six muck cars (8 m3/car) for one push of 1.2 m liner. The muck car is pulled out of the tunnel by a locomotive. The muck car is then lifted by a crane, approximately 12 m to grade and dumped into the holding bin. The material is then loaded into trucks and hauled off site. All of the rail equipment was provided by a previous JV of Aecon and McNally that constructed the Sheppard tunnels in Toronto. Since both the northbound and southbound tunnels are driven down grade from the portal at 6%, modifications had to be made to all rail equipment to suit this steep grade. These modifications included the coupling of two 35-tonne Brookville diesel locomotives which can be operated by one operator, adding or enhancing braking devices for all muck cars, segment cars and grout cars. The rail equipment re-builds and modifications were performed by McNally Tunneling at their shop in Hamilton.Drilling of the northbound tunnel, 283 m in length, will begin just before Christmas. The tunnels should be done by mid-March. Construction of the new Health Sciences station west of 114th Street will be tendered before mid-2004 and LRT tracks and signals will be installed. The LRT will begin carrying passengers in January 2006. Visit www.lovat.com, www.edmontonslrt.com and www.gov.edmonton.ab.ca/transit/lrt 48/03.