Dave Roberts has worked in heavy construction for over 40 years, starting as a laborer/pipe layer and heavy-equipment operator, then moving into positions as estimator and superintendent. He currently operates his own heavy construction contracting company in the northwestern states. An acknowledged expert on heavy equipment operation, his reviews of new construction equipment and articles on excavation work have been widely publisher in trage magazines. Dan Atcheson who revised this book in 2011, also started young, and worked in all areas of construction, settling on earthwork and earthwork estimating. Now a consultant to the construction industry, he has published several construction manuals.