A project requires $692,500$ CY$,$ bank measure, of rock$-$earth mixture, which will be excavated by a $2-$CY front shovel. The material will be loaded into $15-$CY$,$ loose measure truck, and hauled $4$ miles to the project. The trucks will average $25$ mile$/$hour loaded and $30$ mile$/$hour empty. Assume $5$ minutes to dump a truck load.

The front shovel can excavate the rock$-$earth mixture at the optimum depth of cut and at a $120$ average angle of swing. It will cost $$2,400$ to transport the shovel to the Job, set it up to operate, and return it to the storage yard.

Assuming the rock$-$soil mixture has a swell factor of $45\%.$ Use TABLE $7\mathrm{.}11,7\mathrm{.}12,$ and $7\mathrm{.}13$ as needed.

Estimate the total cost and the cost per cubic yard, bank measure, for excavating and hauling the earth. Assume that the shovel and trucks will operate at a $45-$minute per hour efficiency. Determine the economical number of trucks to balance the production rate of the backhoe with the hauling rate of the trucks. The following cost

information applies:

Front Shovel $$105\mathrm{.}00/$hour

Trucks, each $$34\mathrm{.}85/$hour

Shovel operator $$23\mathrm{.}50/$hour

Truck drivers, each $$19,75/$hour

Foreman $$29\mathrm{.}80/$hour

TABLE $7\mathrm{.}11$ I Fill factors for front shovel buckets.

Source: Caterpillar, Inc.

TABLE $7\mathrm{.}12|$ Time for elements in a shovel

production cycle.

Note: These values are for shovels with $3-$ to $5-$cy buckets. TABLE $7\mathrm{.}13$ I Conversion factors for depth of cut and angle of swing for a power

shovel.

Source: Power Crane and Shovel Association.