Down in the "H" part of the "GTHA", a series of rail infrastructure improvements are being made that will enable more frequent GO Train service to Hamilton, and eventually to Niagara Region. One of the most visible is the expansion of the CN rail bridge over the Desjardins Canal.

The Desjardins Canal has an infamous place in Canadian rail history. On March 12, 1857, 59 people were killed when the timbers of the original bridge collapsed and the train plunged onto the ice-covered canal below, breaking the ice on impact and filling the engine and first car with the freezing water of the canal. Only 31 of the 90 passengers survived. It remains one of the worst rail disasters in Canadian history, second only to the St-Hilaire disaster in terms of loss of life.

Rebuilt more sturdily and reopened with two tracks, the bridge evolved again when a new span was lifted into place on November 28th, 2016. The photo below, taken on January 5th, shows the new span in place beside the existing span. The closer track at the bottom of the photo is the CP track leading to the Hunter St Tunnel and the downtown Hamilton GO Centre. (It crosses the canal on a separate bridge.)

New span of the Desjardins Canal Bridge (January 5, 2017) 

This new span will allow for a third track over the canal and into Hamilton's West Harbour GO station, which had its own second track started late last year. The track work and retaining walls adjacent to York Boulevard will continue in the spring. While the second platform track is completed, existing GO train service is being accommodated on the north platform at West Harbour.

The new tracks, coupled with reconfiguration of the Bayview Junction—which Metrolinx CEO Bruce McCuaig once called "the most complex corner of railway infrastructure in Canada"—will enable more frequent GO Train service into Hamilton. It will remove many of the conflicts currently experienced between CN freight (and to a certain extent CP freight) and GO service that exists between Aldershot station and Hamilton.

Map showing the locations of relevant sites in Hamilton

The current official RER plan, which dates back to 2014, calls for 30 minute rush hour service through West Harbour to the new Confederation GO station in Stoney Creek on Hamilton's east side. It is slated to open in 2019. The older Hamilton GO Centre located downtown is expected to receive 15 minute rush hour service and 60 minute all-day two-way service.

This however could potentially change with last summer's announcement of GO Train service to Niagara Region. The announcement calls for service extended east to Grimsby by 2021, and on to St. Catharines and Niagara Falls by 2023. This means that Niagara-bound trains will be either passing through or terminating at West Harbour, depending on which operational configuration is chosen. Niagara Region's Business Case for the GO expansion prefers a "shuttle service" for the Niagara Region, operationally independent from the Lakeshore West line, and meeting it at West Harbour. This would make it the first GO Train line that does not begin or end at Toronto's Union Station.

The details of how this new span and track will fit into GO's broader RER and Niagara Region service plans remains to be seen publicly. In any event, the addition of the third track over the Desjardins Canal will significantly improve service reliability and remove some of the infrastructure barriers to greater GO Train frequency for Hamilton and Niagara Region.