Part of it is historical lack of investment, which is thankfully improving. But I think there are three major factors at play:
1) Low quality road asphalt. There was a report that came out a few years back showing the city paid for new asphalt but contractors installed recycled lower quality asphalt.
2) Lack of maintenance, unlike nearby municipalities, Hamilton doesn't fill cracked in asphalt allowing water to penetrate and destroy the roads.
3) Another report showed that the city is really bad at auditing and prioritizing road reconstruction. Basically doing it where citizens complained the most, which means Ancaster and Waterdown and Stoney Creek get fixed the most because people living downtown have historically been disadvantaged and are not always capable of being in constant contact with the city.
My road was repaved in 2012, and is a disaster. Compare that to Upper Middle in Burlington which was repaved earlier that 2007 and looks in better shape and is in better shape despite more traffic and more truck traffic.
I had heard the city was to start maintaining roads by filling in cracks, I'm curious what happened to that.