How are you going to implement elevated crossings in a suburban neighborhood, where the soccer moms in their monster SUVs can't see squat, and routinely speed? Kids are crossing multiple places; we can barely get ADA type curb cuts at the crossings.

Oh, and "pedestrian airbags" only help you avoid hitting the windshield. On most trucks and SUVs you don't even make it that far. You're just squashed like roadkill on their grills.