It defines and groups a project's discrete work elements in a way that helps organize and define the total work scope of the project. Worker - a person engaged in the accomplishment of work. In cost estimating, the hands-on workers contribute to the production and are counted in calculations of the production rate.
Crossbowman cocking an arbalest. The arbalest (also arblast) was a late variation of the crossbow coming into use in Europe during the 12th century. A large weapon, the arbalest had a steel prod (bow). Since the arbalest was much larger than earlier crossbows, and because of the greater tensile strength of steel, it had a greater force. The strongest windlass-pulled arbalests could have up to 22 kN (5000 lbf) of force and be accurate up to 100 m.
This distinctive form of the arbalest shaft is carefully kept in view in the illumination from Add. He then lay down beside him, with one hand on his arbalest, and drew the bear-skin over them, hair inward. The cross-bow, or arbalest, does not appear to have been used in war until the close of the twelfth century.