A Barrier to Terrorism or the Public?

Terrorism takes many forms, but the most potent attacks come when everyday items are transformed into weapons of destruction. Cities the world over are faced with such attacks, and their responses will shape not only safety practices but the development of those cities as a whole. As more and more metropolitan areas add barricades and additional security measures, it comes at a cost. Pedestrian traffic and public enjoyment might be limited by barriers, but what is being sacrificed, and can those concerns be mitigated?