Well, yes and no. The number of trains per day is definitely lower, yes. And due to the dimensions of the Detroit tunnel, a certain amount of traffic that used to run through Windsor now detours through Buffalo so that it can be handled as a double stack container train(s).
But in terms of tonnage, it's still very busy.... just fewer trains that are much longer. And run to more demanding schedules that could be messed up if there were too many passenger trains in the way. With different yarding and switching needs and locations.
The challenge for running these longer trains is how to keep them moving so they don't block crossings, or have awkward meets with other trains given that both may be over siding length. In Halton and Peel especially, what used to be possible in having trains stop and cross over to pass each other and weave around GO trains is much more difficult.
So a route that looked like an easy path for GO when it was overhauled back in the 1980's is not necessarily just as easy a path today, even though fewer trains a day pass over it.
- Paul