Isolated ped/bike grade crossing is a really bad idea. If it works like the ones I've seen on light rail lines, after the first death there, trains will be required to slow to restricted speed and make a lot of noise (cue the lawsuits from nearby residents) until clear of the crossing. Regardless of the lights, bells, and gates. Also, the gates and fences will be a continuous maintenance nightmare (normal issues, plus damage from people pushing through and just plain vandalism), and people will jump them anyway unless the fences and gates are prison-level height. Just.A.Bad.Idea (should trademark that).