Staff Sgt. Carol Pacey said the downbound access was closed where it joins the Kenilworth Access at 10:30 a.m. after a car collided with two large rocks.
The vehicle sustained damage to the undercarriage and had to be towed from the scene.
Police responded to the scene as did city staff. City staff concluded there was no risk of a rock slide and the access was reopened after about 20 minutes.
Falling rock on the Mountain accesses has been a periodic problem in the past.
Last year, the city budgeted an extra $210,000 for slope stabilization measures at 17 escarpment roads and accesses from Fifty Road in Stoney Creek to Sydenham Road in Dundas.
That’s on top of the $300,000 a year spent on rock scaling, debris cleanup and inspections conducted every year.
A rock slide in April 2015 blocked a lane on the upper portion of the Kenilworth Access, and forced a weekend closure for repairs and cleanup.
That followed a three-week closure on the same access the previous May and slides on the Claremont and Sherman accesses in the two years before that.
Rock scaling — the targeted mechanical removal of loose limestone — is by far the popular measure used by the city to prevent such slides.
Source: The Hamilton Spectator