ADKJeff,
Good precise description of the trailhead. Thanks!
The trail is marked, which also helps.
It should be noted that the trail crosses the auto road once, about .5 miles up, and then comes out onto the auto road again near the summit. When the trail comes out onto the auto road near the summit, that's the end of the trail. To reach the actual summit, cross the road and scramble up the bank and through the picnic area.
A couple watchouts:
When crossing the road, watch for traffic. Cars are common during the day in the summer. In the evening, there can be bike traffic, and the downhill bikes can be coming silently at 50+ mph. Look carefully!
A place where people commonly get off the trail is just after it crosses the auto road the first time. The trail steps up the rock bank, then swings left for about 100 feet, then back right for a couple hundred feet, then goes straight up hill for a couple hundred feet, and then swings back abruptly left. Pay attention to the markers in this section.
I used to use the Prospect trail for race training. Years ago, I had a pretty large group of co-workers who would run the trail as a time trial. We would start at the round clearing on the left, just up the sand hill and inside the woods after you cross the Northway bridge. Our finish point was where the trail came out onto the auto road near the top. Just thinking about it gets me motivated to go back and run it again!
TCD