May I make a suggestion. I would invest in some really good motion activated IP cameras and a subscription to a data storage service. Point one camera from the window at one end of your building facing one way and another camera from the other end facing the opposite way.

This will capture every car, person, etc.. that goes up and down the street, and allow you to review it later, to post here, or on Youtube, or to give to the police, as needed.

I do this, and it gives me piece of mind. I can review an entire days worth of activity in about 30 minutes, and it gives me the plate numbers, as well as the actual people and vehicles, so identification is easy