A contractor has a contract for the construction of a shopping center and adjacent parking lot. The site plans for the project indicate that 35,000 compacted cubic yards of fill are required to bring the site up to the desired grade or elevation. The contractor has selected 18-cubic-yard dump trucks to haul the fill material. To load the trucks, the contractor has selected 2 hydraulic front shovels with 5-cubic-yard buckets. The fill material is a rock-earth mixture weighing 3,165 pounds per bank cubic yard with a swell of 18%. The shrinkage of the soil is estimated to be 9% when compacted to the specified density. The ideal cycle time for each front shovel is estimated to be 0.4 minute. What is the estimated productivity of the front shovels in compacted cubic yards per hour if the contractor plans to excavate the material at 80% of the shovels optimal digging depth and the average angle of swing will be 120o ? Assume an operational efficiency of 45 minutes per hour.