San Diego State University

CON E 340

Problem 1: (30 pts) A contractor wants to investigate the production and cost differences of using a 7S blade on a D7H) dozer or an S blade on an 824 dozer. The material is a dry sand, and it is to be moved a distance of 250 ft from the beginning of the cut. The dozing is uphill on a 5% grade. The operator will have average skill, the dozers have power-shift transmissions, and traction is assumed to be satisfactory. The operating technique is slot dozing. The site will be dusty with some visibility loss. The material weighs 103 pcf in the bank state and has a swell percent of 15%. Job efficiency is assumed to be equivalent to a 50-min hour. Calculate the direct cost of the proposed earthmoving operation in dollars per bcy. Assume that the O&O cost for the D7 dozer is $116.00 per hour and $127.00 per hour for the 824. The operator's wage is $45.00 per hour plus 35% for fringes, workman's compensation, and other benefits. Complete the following for each dozer D7H-7S 824-S 1- Ideal production rate. 2- Material-weight correction factor 3- Operator correction factor 4- Material-type correction factor 5- Operating-technique correction factor 6- Visibility correction factor 7- Job Efficiency factor 8- Machine transmission factor 9- Blade adjustment factor 10- Grade correction factor