The numbers do not tell the whole story, either. At present there are only two through trains between Niagara and Aldershot, one each way..... but..... they are extremely long trains with DPU, and the switch configurations that they pass through limits them to 25 mph or less.... if, that is, the grade out of Hamilton doesn't hold them to an even lower speed.... and if the switches are lined in the two yards so they can clear the main track without having to stop. They tie up the full junction when they pass, because they must cross over all the way from one side of the main line (Hamilton) to the other (Aldershot).
Add to that 2-4 transfers each way between Aldershot and Hamilton, and to be optimistic, a dozen freights each way heading to/from Copetown. Plus one each way up the "Cowpath" from Hamilton to Copetown.
Nominally, there are three CPKC trains in each direction through the Desjardins junction.
CPKC and CN's interest will be not as much how many trains pass through today, as how many might pass through at some point in the future. And, they will want to conserve capacity so that these can pass at whatever time they need to. Few or no promises about keeping those routes clear all day long so passenger trains are not delayed. CP provides a window for the peak GO trains, but would be unlikely to extend that further.
Is there lots of idle capacity at present? Sort of. Can GO or VIA exploit that capacity? No. It belongs to the freight railways and they are conserving it for their own needs. After all, they paid to build it. A model might show the absolute amount of spare capacity, but its timing will vary from day to day....and in the daily operation VIA or GO can't afford to have their trains wait around for it.
- Paul