TOareaFan
Superstar
This discussion is occurring in 2 threads simultaneously...
Currently the Georgetown to Kitchener segment is the capacity constraint on the line, even if you consider that most trains will turn back before Georgetown. The capacity is pretty much zero as far as all-day service is concerned because it currently takes an hour in each direction from Georgetown to Kitchener. Given that it's a single track, the best possible frequency with the current configuration would be every 2 hours, though that's unrealistically low because it does not include any layover or padding time.
Building a second platform at Guelph Central station to allow trains to cross there would cut that roughly in half, to a roughly 1h15 minimum headway. But the elephant in the room is peak-hour service. We currently have 1h headways in the peak direction, likely to drop as low as 30 min in 2016. With only a single track, counter-peak service is simply impossible, which is not acceptable given the importance of Kitchener-Waterloo as an employment hub. Furthermore the upgrade is not only in capacity, but also in speed (read: reduced operating costs and increased revenue).
Yes, in order to get "proper" regional rail (i.e. 4+ suburban trains per hour from Union to Mount Pleasant, and an additional 1+ regional trains per hour to Kitchener) very significant investment is needed in Brampton, in the form of either a new freight bypass line or a GTS-level upgrade of the existing railway. But in the meantime, double tracking the line west of Georgetown means that we can enjoy 1 train per hour from Toronto to Kitchener along with as many trains as we like from Union to Bramalea.
That is the point....GO/Metrolinx have advised me that service is not possible without a third track