DPW has a limited number of vehicles that can vacuum yard waste directly off of the terrace to keep yard waste off the street during collection. However, vacuum collection is a slow process, and vacuum trucks cannot pick up brush and larger yard waste. Anything other than grass and leaves clogs the vacuum tube and vacuum mechanism. Depending on conditions, grass and leaves sometimes also clog the vacuum truck. So multiple types of equipment must be used for yard waste collection.
The most effective and least time-consuming method for yard waste collection is to sweep it off the terrace into large piles and bulk load it into trucks. Of course this method leaves a mess on the road. So shortly after the yard waste is loaded, DPW sweeps the street. Using this method, yard waste sits on the street for a short time during the collection process compared to yard waste sitting in the street for longer periods of time before DPW can collect it.