Yellowstone National Park - Old Chittenden Road Trail Q?

I am wondering if anyone knows anything about the Old Chittenden Road trail to the top of Mount Washburn. According to all the guidebooks, there was once a wagon/vehicular road to the top of Mount Washburn, which has been closed to vehicles and is now a trail used by both hikers and bikers. However, when you drive to the current parking lot/turnaround to access the trail, just before the parking area there is an obvious road that is totally closed off, and the marked trail does not look at all like a former road, as well as being labeled as over 5 miles. When I asked a ranger what the blocked off road was, she said it was a maintenance road - but I found it curious that anyone would construct a separate maintenance road in that terrain, when there was already a former vehicular trail in existence. Plus, I couldn't explain the discrepancy in the trail length.

If anyone can explain that blocked-off road - maybe the ranger is correct and that "maintenance road" just stubs off somewhere? I would appreciate it. I'd also appreciate an explanation of how a 3 mile trail suddenly becomes more than 5 miles - unless that continues to Dunraven Pass?