D-1510 is a tiny dirt road that takes you to the back side of Fuzzy Top Mountain. There is no access to the hiking trail from this road, and while the road does technically continue, the logical end to this road is a larger section with a campfire ring and an unofficial dirt backstop that has been used as a short firing range. If you continue past the fire ring, the road deteriorates quickly, and high clearance with a good approach/departure angle will be needed to get you turned around.
Capitol State Forest can have active logging operations, so be sure to pay attention and watch for heavy machinery and trucks while exploring the forest. There is no dispersed camping allowed in Capitol State Forest; the only camping permitted within the forest is in official campgrounds, so please ensure that you have a plan for that if you need a place to stay for the night.
Capitol State Forest is an 11,000-acre forest packed with roads and trails and specific opportunities for recreational purposes. Please see https://www.dnr.wa.gov/Capitol for up-to-date info and closures relating to this location and any restrictions on activities.