Why not, in the interim, institute a rush-hour only commuter train, like the West Coast Express (WCE), but using diesel multiple units (DMUs) from Waterfront to Langley via Cloverdale over the CPR, BNSF/CN, and the Interurban?
Because the commuter rail would operate only in rush hours, there does not need to be heavy investment in additional tracks, and it can be up and running relatively quickly and affordably. And because the DMU trains are short, the stations can stay small. The DMU commuter rail can readily be extended to Abbotsford and Chilliwack.
Here is an example of a new DMU commuter rail in Texas:
The WCE provides a useful precedent. It enabled improved mass transit to Port Moody, Coquitlam, and Port Coquitlam, and beyond, for over 20 years before the Evergreen Extension was built. And both the WCE and the Evergreen Extension complement each other.
Brendan Read, Ontario