Would that not affect your sightlines?
And it should be obvious what that means; the city can't build such a structure without GO's approval. I mean they do own the land afterall. And more importantly they do provide an extremely valuable service to the city. Something people seem to be forgetting.
I'm just curious because so many cities have buried tracks but we can't even build a bridge over the tracks at the most desirable location due to these "sightlines" issues.
It's not about 'sightlines'. Its about running a commuter service as efficiently as possible. Impeding sightlines reduces system capacity. Clearly its in GO's best interest to prevent this.
Besides the bigger issue with regards to such a bridge would be where all the support pillars would go? There's just no space for them. Like Enviro noted, if money was not an issue they would do a big study and then the entire corridor would be completely rebuilt. Either way it would cost huge money, money no one currently has and a lot of time.