Bottom Dump Truck

Bottom dump trucks, most often used for HMA in more rural settings, (Figure 1) unload their payload by opening gates on the bottom of the bed. Internal bed walls are sloped to direct the entire payload out through the opened gates. Discharge rates can be controlled by the degree of gate opening and the speed of the truck during discharge. The discharge is usually placed in an elongated pile, called a windrow (Figure 2), in front of the paver by driving the truck forward during discharge.

A windrow elevator is used to pick up HMA from the windrow and feed it into the paver hopper. Windrow elevators do not have any method of regulating material flow, which makes it necessary to place the correct amount of HMA in the windrow to match the paving width and depth being placed without allowing the paver hopper to run out of mix or become overloaded (TRB, 2000[1]).

Figure 1. Bottom dump truck used in an urban setting in Salt Lake City.

Figure 2. Paving windrow made by emptying a bottom dump truck.

Footnotes    (↵ returns to text)
  1. Transportation Research Board (TRB).  (2000).  Hot-Mix Asphalt Paving Handbook 2000.  Transportation Research Board, National Research Council.  Washington, D.C.