The administrative cost of a road toll eats away at the revenue generated and it adds a new layer of government that we don't need. 
If you want to raise funds for building roads the easiest way to do it is a gas tax. It's already in place and only drivers pay it.. the cost of implementation and collection is minimal The only problem is that we already have the tax but. Over time governments have seen fit not to spend the revenue on roads or transit. But it is worth a second chance.
Five cents a liter in Toronto and three cents a liter in the suburbs would raise hundreds of millions of dollars and it would be difficult for drivers to avoid it.