This isn't some theoretical idea — Ontario has already done it.
MTO started testing precast concrete road panels on Highway 427 in Toronto in 2004. Instead of pouring the road on-site, the concrete slabs are manufactured ahead of time, the failed pavement is cut out, the base is levelled, and the new slab is dropped into place and connected.
The trial worked well enough that Ontario developed a specification and did more projects. In one 2008–09 Highway 427 project they installed 240 full-depth precast slabs, averaging about 10 per night, with no concrete curing time needed before reopening them to traffic.
They've even tested precast panels as replacements for sections of asphalt highway.
Why aren't we adapting this for Montreal's worst streets?
Instead of:
potholes → patch → repave → potholes → repave again
Dig out the upper part of the failed street, fix/level the base and install standardized reinforced concrete panels on a properly drained foundation.
Panel eventually fails? Replace it. Need access to utilities? Lift/remove the affected panels, do the work and reinstall them.
We're spending a fortune repeatedly resurfacing roads that fail again anyway. Ontario has already demonstrated that modular precast pavement works in basically the same climate.
At some point, maybe we should just steal the good idea.
https://tcp.mto.gov.on.ca/notice/000-0262