Finding park staging areas in Maps

My local park district working with its non-profit and a local health care provider pulls together an annual "trails challenge." The notion is that each year, they map out trails in various parks in the system and encourage participants to walk enough of them over the year that the total distance covered is more than 26 miles. This is a great way to visit parks in the system that you wouldn't otherwise get to, you can take along a camera and take nice pix, and you get some exercise.

My problem is that Siri can't manage to find the staging areas where the trail heads are and the walks begin. S/he can find the parks just fine and while the directions will get me to the park, it usually ends up taking me to some fire trail that is behind a locked gate and would lead, I guess, to the middle of the park because that's where the pin is on the map. There seems no way to get to designated park staging areas where I can park and find the trail head. Something of a frustration.

Any ideas?