Thanks, that was fast!
I'll try to figure this out this evening (I'm out of pocket most of today), including a look at the Transports Quebec website. OSM/Mapnik indicates the extension routing, but I'm not yet sure about how much of that is now open, or whether it accurately shows the tie-in to QC 170. mapcat, any thoughts?
The article indicates yet another A-70 extension is in the works, but not for a few more years.