What is the maximum length of trench that can excavated by hand economically rather than by a trenching machine. it cost 900.00 to transport a trenching machine to the job and back to the storage yard. the trenching machine can excavate 265 linear feet per hour. the trench is 3 ft wide and 4 feet deep.
Use hand excavation data from table 7-3 to obtain the production rates to loosen earth with a pick, shovel earth from the trench, and shovel earth back from the edge of the trench. assume that 4 laborers plus a foreman will be used. assume a 40-min hour for the hand labor operation and a 45-min hour for the trenching machine.
the following cost information applies
trenching machine $42.82/hr
trencher operator $20.45/hr
laborers each $16.65/hr
foreman $28.30/hr
loosen earth with pick= 1/4 - 1 cy/hr
shoveling earth from trenches = 1/2 - 1cy/hr
shoveling earth into truck= 1/2 - 1 cy/hr