A broken-down big rig forced a lengthy closure Monday morning of the northbound Lakeville Highway onramp onto Highway 101.

The CHP issued an alert to the problem, advising drivers wanting to get to Highway 101 northbound to take South McDowell Boulevard to East Washington Street and get on the highway there.

The big rig apparently had a broken hitch, causing the huge vehicle to stop, blocking the busy route.

The incident started at about 8:20 a.m.

As of 10 a.m. efforts continued to get it towed away and there was no estimated time the ramp would be reopened, said CHP Officer Jon Sloat.