I have a 1,000,000 SF building in NYC that does not own sidewalk that surrounds the building on one of the four sides. This side has a rear entrance. How can the building enforce a no smoking within 25 feet of the door policy when they do not own anything more than 1 foot from the perimeter of the building. Note that this sidewalk will not be included in the site area plan.

We are willing to put up signs and work with the owners of the sidewalk to enforce the smoking policy, but if the owners do not allow it, what can we do to meet this prerequisite's requirements?