I'm talking about regional rail that could carry trains at up to 200 km/h, which isn't much faster than current VIA Rail trains. 300 km/h HSR is much more expensive. As for highways, the first phase of the 407 cost $1.6 billion not including land acquisition. The 407 East through Durham is going to cost about $2 billion for 68 km of highway - that's almost $30 million/km.Rail lines are cheaper? Maybe existing ones. Building new ones is surely more expensive than roads, hence the high price tag of HSR.
In contrast, the completely rebuilt rail line to Peterborough was budgeted at somewhere between $150-300 million for about 120 km. The not as extensively rebuilt GO line to Barrie cost $25 million, and it included 20 km of completely new track. Even if you double or triple those numbers for a brand new rail line in a new right of way it would still be cheaper than a new highway.