This series works through the three-part presentation of the proposed Eglinton LRT design that appears on the project’s website. Part 1 brought us east from the Airport to Black Creek, and Part 2 covered most of the remainder east to Warden.
Part 3 of the presentation deals with the short section from Warden to Kennedy as well as various construction issues, notably an alternative scheme for tunnelling.
Birchmount Stop: Like many others, this intersection gets the left turn relocation treatment, but with farside stops that allow the retention of right turn lanes.
Kennedy Station: This station will be a complex project in its own right linking the existing subway and GO services to the Eglinton LRT, the Scarborough-Malvern LRT and the S(L)RT. This station and its surroundings have always been rather sad as a major transit terminal both because it hides beside the Eglinton overpass, and because Scarborough Council, in its wisdom, chose to downplay the importance of this location for development to avoid competition with the Town Centre.
Three options are given for the Eglinton LRT’s route into the station, two on the surface and one underground. All appear to be designed to use the existing passageway from the kiss-and-ride into the mezzanine level of Kennedy Station, and it is unclear how this structure would be affected. It is also the unused loop from the Scarborough RT above.
An alignment is also shown for a Scarborough-Malvern loop around the existing bus platform, although how exactly this line would get across the rail corridor is unclear.
From other discussions, we already know that the SRT station will move underground as part of the line’s reconstruction with a connection at the mezzanine level.
Various layouts are possible, but we need to see more details including provision for transfer moves between buses, LRT and subway. Demand on the bus loop itself will not be significantly changed until both Eglinton LRT lines open and replace east-west bus services.
Depending on the technology choice for the SRT, there may a requirement for tracks linking this route with the east-west Eglinton lines. Also, if the SRT through-routes with Eglinton (not a good idea to my mind because Eglinton is long enough already, and has a different service level requirement from the SRT), the track connection would have to include the station. If this were only a service connection for carhouse moves, then there would be more flexibility in the design.
Construction Methods: Three basic types of construction are introduced on Panel 57 (Page 3 of the PDF) — surface construction in the manner of streetcar lines, twin tunnels such as are used on Yonge north of Eglinton and on the Sheppard line, and cut-and-cover construction with a box tunnel commonly seen on much of the Yonge and B-D subways.
Twin bored tunnels reduce the construction effects at street level, except at stations, but can be more expensive because they tend to lie deeper underground.
Station construction for this line may be a bit less intrusive than conventional subways, but this depends on whether provision is made for eventual expansion to 500-foot platforms. If so, then the station structures would need to be built out to that size even though it may never be used. Moreover, at that eventual length, all stations would need provision for two separate exits to meet fire code.
Tunnelled lines tend to be deeper, and this affects station structures both for cost of construction and for the facilities (elevators and escalators) needed to get passengers between surface and platform levels.
Panel 62 shows an alternative construction with a single large tunnel 13m in diameter. This technique has certain advantages:
- A single tunnel is cheaper to build than two small ones.
- For street sections where space between building foundations is at a premium, there may not be enough space for twin tunnels plus the clearance needed between them for structural stability (the “column” of earth separating them).
- As shown on the display, stations can be accommodated within the tunnel itself and do not require separate construction except for the vertical access paths. One disadvantage is that the lower platform is further under the street than would be the case with a common centre platform.
- Lengthening a station would not require additional pre-construction provisions.
This tunnelling method has been used for part of the new Line 9 in Barcelona, and is proposed for an extension of the Washington DC system.
The project is now accepting public comments on the proposed designs, and will return with another round of meetings in November. These will include design details for complex locations such as the junctions with other lines, and the alignments at Weston and at the airport.