Speaking from a land acquisition perspective, it's generally easier to widen an existing ROW than it is to create an entirely new one. The Planning Act states that the government can't create a ROW through someone's property, and leave them with a second, un-usable piece of land. Using the 401 as the ROW to piggy-back onto makes sense for some of the routes, but the problem with that is a lot of highway-dependent businesses have sprung up directly beside the highway, making the widening of the ROW difficult in some instances. Also, building right beside the highway creates the risk of driver distraction, etc. Also, it would mean that basically every overpass would need to be rebuilt to accommodate HSR.
This would lead me to believe that using the existing rail ROWs would be the better solution. Although it may require land acquisition around curves (to smooth them out), overall I think it would be easier than running beside a highway.
This would lead me to believe that using the existing rail ROWs would be the better solution. Although it may require land acquisition around curves (to smooth them out), overall I think it would be easier than running beside a highway.