Alas... No More!!
I'd, like to be detailing the various interesting points to be noted and connected to along this section of access road, but alas, there is no longer any access! This road section has been closed down: no cars, no bikes, no hikers nor runners. The closure area is so permanent as to be colorfully detailed on the park service map.
Effectively, all the great access routes entering close upon the Kilauea Volcano Caldera are now fully restricted, no access allowed.
Toxic off gassing is the expressed reason.
You can view most of the same areas from further out and up, but many of the great connecting loops are now out of bounds. The ever present plume of gases may be viewed from the upper Caldera's edge... or, you can skirt the lower basin at a few trail points: Ilahi Trail, far end of the Halema'uma'u Trail, Byron Ledge Trail (again, the end allowed), Waldron Ledge Trail, Crater Rim Trail, and the Devastation Trail from Pu'u Pua'i Point.
Nicely, most of these routes receive very little use... the crowds tend to hold to the upper edge. You can put together some great connecting loops and have the space to yourself. Hopefully, these maps with the big red circle of off limits area will become collector's items, and this description can be adjusted to review the points of interests so easily enjoyed in earlier days...
...but, that may be awhile. This is an active Volcano!