GO Transit - Davenport Diamond Guideway Project

GO Trains and VIA's Canadian have begun operating over the recently constructed Davenport Diamond Guideway. The new structure carries a portion of GO Transit's Newmarket Subdivision over the Canadian Pacific's North Toronto Subdivision. The guideway is part of the work to expand GO's Barrie line with frequent two-way, all-day service.

First GO Trains Operate Over the Davenport Diamond Guideway | UrbanToronto

Metrolinx GO Trains Now Using Elevated Davenport Diamond Guideway - Railway Track and Structures

First Canadian

Does the Canadian still operate via Richmond Hill and Markham? I know that was the main route for some time.

Yes - for its westbound route out of the city the train takes the Metrolinx-owned part of the Newmarket sub up to Richmond Hill where it reverses into the CN York sub. From there it travels a few miles east before switching NB to the CN Bala sub.

The eastbound train does not follow this route - it approaches on the Bala sub, but instead of switching to the York sub it continues straight through into the city all the way to where the Bala sub meets the Kingston sub about a mile from Union.