At-grade circulators or small-scale monorails are effective at moving people within a dense area, usually the downtown core. These types of vehicles are typically small, with constant service and many stops in a small area. Circulators reduce the number of short trips, allowing the urban core to remain walkable, with as little traffic as possible. Vehicles are continually arriving, leading to short wait times for riders, and a greater number of passengers served. Downtown Miami has the most successful circulator in the US, with over 8 million rides annually. The connections between other forms of transit and the rapid turnover make circulators a more appealing option than waiting in traffic. Under the right circumstances, circulators can be an effective investment for cities.