The Vancouver SkyTrain was the first fully-automated light rail system built in Canada. The completion of the Millennium Line in August 2002 extended its elevated guideway system by 16 km.
The Millennium Line uses a single-cell, precast concrete segmental box girder. The cross section of the segment was designed to be torsionally stiff, allowing the construction of long spans through curved sections of the alignment. Each guideway beam was typically 37 m long, 2.1 m deep, and consisted of twelve 25-ton concrete segments.
About 5,700 concrete segments were cast at a special facility constructed for the Millennium Line. The segments were stored at the facility and moved to their erection sites using flatbed trucks. Each segment was unique to fit the horizontal and vertical geometry of the guideway rails in the section for which it was destined. Each segment took one day to form and cast, using about 9.9 m3 of concrete. The job was a massive undertaking, requiring about 99,392 m3 of concrete. Even so, construction of approximately 16 km of standard elevated guideway was finished in only 16 months.
Most of the guideway, designed for a 100-year lifespan, was built along existing rail and highway corridors and represents a unique application of truss-erected precast concrete segmental box girder construction, that was unprecedented in the area. Four massive 200-ton overhead erection trusses with lengths in excess of 100 m were used to build the guideway. Standing on the guideway's support columns, these launching girders raised precast guideway segments into place. Crews then threaded steel post-tensioning tendons through the concrete segments to form self-supporting beams wide enough to carry the two SkyTrain tracks.
The inserts for rail fasteners were cast into the segments at the plant, and then the trackwork was laid directly on the structural concrete. After the spans were erected, the elevations were surveyed, the profile grade was adjusted, and shims were introduced beneath fasteners as required. The average shim thickness for the entire project was less than 6 mm. This is the first application of direct fixation rail onto a segmental constructed guideway without the use of plinths.
More than 500 cast-in-place concrete columns support the Millennium Line elevated guideway. The support columns are eight-sided and either 1.6 or 2.1 m wide (wider at SkyTrain stations and some other locations). The columns flare out at the top to meet the inward angle of the guideway segments placed above them. About 20 m3 of concrete was required to build an average column. The foundations that hold the columns were typically created using drilled pier technology: steel casings with a diameter of 2 m were vibrated into the ground, the earth was then augured from the center of the casing, a reinforcing steel cage was lowered into the casing, and concrete was placed. In areas where it was appropriate, spread footing foundations were used instead of drilled piers.
Unique Station Designs
The Millennium Line's 13 stations are key to the success of the expanded rapid transit system. Each station is unique and was designed by British Columbia's prominent architects and structural engineers, with input from an extensive public consultation process. Designed to be futuristic while complementing the communities in which they are located, the stations are built with provisions for public amenities and security features to ensure that commuters of all abilities and ages can use the line safely and efficiently. Stations are constructed primarily with concrete elements up to the platform level. Columns and foundations are constructed with cast-in-place concrete, and the platforms are supported with precast concrete beams. The station ancillary cores utilize architectural concrete blocks.
The first section of the Millennium Line was turned over to the operating authority in December of 2001, with the balance of the line completing operational testing in August of 2002, less than three years after groundbreaking. The project was completed on budget and within the established construction schedule. The Millennium Line is used by approximately 20 million riders annually. The total project cost was $1.1 billion dollars.
|Contractor||SAR Transit JV
||Lafarge Canada Inc.
|Precaster||SAR Transit JV