Confederation Line West LRT Extension (Stage 2) [Tunney's to Baseline/Moodie] | U/C

[Richard Eade]

This will be a very expensive ‘extra kilometre’ if they build it to the standards of a finished, revenue LRT line. Think about the delay in extending the Transitway trench south of the Baseline Station and under Tallwood; it keeps getting delayed because of the cost. It turns out that there are ‘challenging’ ground conditions in the area between Baseline Station and the rail line. For example, I have heard that there is ‘running sand’ where the cut would be in the area of Tallwood. This would probably need to be de-watered. Unfortunately, I believe that the senior’s residence is built on a ‘floating slab’ foundation. If the neighbouring ground is de-watered for a trench, there would likely be differential ground subsidence under that slab; potentially causing cracking. This is an expensive option.

An alternative, of course, is to take the LRT tracks up, over, Tallwood. The run would be about 500 metres between the below-grade Baseline Station and the crossing of Tallwood, so a rise of, say, 15 metres would be practical (3% grade). Once up, the LRT could be left elevated to curve and pass over Woodroffe to get to the proposed M&S area. The LRT might need to cross over Woodroffe at a higher elevation than the VIA tracks since the LRT crossing is north of the VIA crossing, where Woodroffe is not yet at its lowest point. This option, however, is also not inexpensive because of all the support structure that would be necessary. [There might be an option to ‘float’ the Tallwood overpass embankments, but I don’t know if that is possible here. I suspect that City Staff are looking into this as it could drastically reduce the support structure needed; and, thus, the cost.]

As for a future extension of the tracks further south, having the M&S to the east would ensure that there is a service track fly-over of any south-bound tracks and Woodroffe. This needs to be designed in from the start so that the link does not need to be broken for future construction. This will also add to the cost.

There is already about 550 metres of tunnel at the Baseline Station that was originally planned for Transitway; that could house ten 50 metres long vehicles. Because the announcement mentioned two recommended sites, I am assuming that there will be another M&S site in the east end. Given that the southwest line will (eventually) be extended to Barrhaven, perhaps the M&S facility at Woodroffe could be a minimal site configuration. The storage could be in the existing tunnel (remaining vehicles stored in the east and central facilities), and a small, inexpensive, temporary, maintenance yard could be at the end of the line north-west of the Woodroffe/VIA crossing (south of the new City Archives). When the line is extended south, a final M&S facility can be built south of the Greenbelt, where the land is cheaper.