Completed Hydroshield tunnel with precast segmental liner
Edmonton light rail transit,
a tunnelling laboratory for North America CASE STUDY: Construction of Edmonton’s light rail transit system saw the first application of NATM in soft ground and the first use of bentonite slurry TBM excavation in North America. The organisation and management of the project, as well as the contractual arrangements for the execution of TBM and SEM observational excavation methods, marked the Edmonton experience as a test case from which other urban metro authorities learned a great deal.
SITE VISIT REPORT: MARCH 1992
E
dmonton, the capital of Canada’s oil-rich province of Alberta, is to open a new section of its light rail system in late August 1992. Inauguration of the new 2.4km section will extend the existing 10.3km line and will provide a vital bridge connection over the North Saskatchewan River to link the city’s commercial centre with the University of Alberta campus. Of this length, 7.7km is on the surface and 3.4km is in twin-tube tunnel with five stations on the surface and seven underground (Fig 1). Construction of the system started in 1975, with the first 7.2km length from Central Station to Belvedere opened in 1978. The 2.2km surface extension from Belevedere to Clareview Station opened in 1981. The third phase, a 900m underground extension, included two underground stations, opened in 1983. The next phase, the 900m underground section between Corona and Grandin (Government Centre) Stations started in September 1986 and opened in September 1989. Work on the last leg, from Grandin across the river to University Station, began in late 1988 and will open at the end of August 1992.
the good-quality till, a favourable medium for costeffective tunnelling. 2. Experience gained by the city’s Water and Sanitation Department during excavation of deep-level sewer tunnels using full face TBMs inspired confidence • Owner: City of Edmonton, Transportation Department • Project administrators: City of Edmonton, Public Works Department • Managing consultant: Stanley Associates Engineering Ltd • Geotechnical adviser: Professor Dan Z Eisenstein, University of Alberta, Edmonton • Contractors: Several on different contract packages
From here, the masterplan is to extend this one line further south past Crawford Centre to Southgate Mall with a branch going ultimately to the famous West Edmonton Mall (Fig 1). Another line is proposed to serve the Northgate area. Design of the next phase, the 2.5km section from University Station to Crawford Centre Station with an additional station at the Health Sciences, is in the preliminary phase and is scheduled to be constructed by the year 2000. About 1km of this 2.5km length will be underground, with the Crawford Centre Station being located on the surface. A debate continues as to whether the proposed Health Sciences Station will be underground or on the surface. Four major factors influenced the decision to take the LRT services underground in the downtown area of Edmonton: 1. Tunnelling costs would be relatively inexpensive in
Fig 1. Existing and planned routes of the LRT network 15
