TF1884: Arbutus LRT Thurlow Alignment?

TF#1551. 2019-01-15. 

A lot of talk has been going on around the routing of the Arbutus LRT in the downtown core with most of the conversation focused towards the Downtown Eastside. The below is an alternate, more direct connection to the Commercial Business District while additionally providing new RRT coverage for the West End.

Arbutus LRT Thurlow Alignment Option.

The alignment follows the existing Arbutus ROW to Burrard Street after which it will cut and cover under Fir St. and 4th Ave. This is necessary because it will likely be a conventional motor LRT and it will need a longer approach to dive underground because of the lower maximum grade for a conventional motor (4%).

Profile of the Route beginning at Burrard Street and Ending at Waterfront.

Comments

scryer: Could the LRT be grade separated at Broadway or 41st?
In my fantasy, if the Arbutus Greenway was going to be LRT, it would dip into short little tunnels underneath those major intersections. It wouldn't be a full tunnel; just a few convenient dips underneath some major intersections (like Broadway and 41st).

waves: Probably not with the constraint of a 4% grade maximum.
This might not be very practical with a conventional motor train set that can only get max 5% grade. The depths would need to be great enough to go under existing utilities in the street and deep enough for the overhead wires (8.5-10m). So at a 4% grade plus vertical curves, you would need 200-300m of distance minimum for each crossing. To go under Broadway, you would essentially need to start descending at 12th.

fredinno: Would they be less tall for road over rail rather than rail over road?
The entire Hastings St overpass over the rail there is that long. And it’s over an active freight line. These overpasses would be much less tall, if road going over rail. So maybe overpasses (of the road by the rail or the rail by the road) would work better than underpasses. I don’t even think you’d need 10m depth to get under the utilities on an underpass, but regardless.

waves: No. But the approach distance would be shorter for rail over road.
Roads and vehicles can climb steeper grades than train vehicles so a road overpass would be much shorter than a rail underpass, but practically, an overpass wouldn't really work for a developed intersection such as Arbutus and Broadway. 2-3m depth on utilities plus 6m depth on the train row is right in that 8-10m range. 6m is the Canada Line tunnel depth. 3-4m is a typical LRT vehicle height. Add tracks and overhead wires and you quickly use up that 6m of space.

scottN: Moving utilities may be possible to reduce height requirements.
Moving the utilities is also a possibility, and could be less expensive especially if they can accommodate a steeper grade than the train.

I recall during Canada line construction along Cambie (between Broadway and 6th) that they first the dug up the street to rebuild some sort of sewer pipe, then they dug up the street again again for the canada line tunnel. In that case I think the train tunnel crossed over top of the sewer as the train shifts from the east side of Cambie (At Broadway) to the west side (at 6th)