That's clearly an issue that has come up only recently, especially in the movement by rail of crude oil and ethanol in larger quantities. Prior to that, while the railways have been moving dangerous goods for 100 years, this had not been considered an immediate issue. The railways have been abandoning lines for quite a long time now, certainly since the late 1950s, early 1960s. In some cases, they were branch lines that weren't handling a lot of dangerous goods. They wouldn't have been appropriate alternate routes in any case.
There are other routes that in retrospect might have been kept if there had been proper analysis, the two lines up the Ottawa Valley that you mention are a good case in point. The CPR second line west from Perth through Peterborough and Havelock, and those places, which was abandoned some years ago, is also another case where that might have been an appropriate place. It's really very difficult to answer your question definitively, but there may be some cases where that would have been appropriate.
I think one of the things that the minister's announcement dealt with last week was the fact that Canadian railway routes tend to be somewhat linear, so there aren't the same opportunities for looking at alternative routes as there are within the U.S. rail network. One of the options where there isn't is to look at speed restrictions and while the minister's announcement talked about a 50 mile an hour speed limit, there also was a provision in her announcements that there would be investigations through certain municipalities. Obviously in municipalities where there are large populations, there would and could be lower speed limits as well.