Caterpillar Performance Handbook, January 2017, SEBD0351-47

Production Estimating ● Single Drum

Vibratory Compactors

Adjusting the Production Estimate If the assumed conditions are not close to the actual construction conditions, the production estimates should be corrected. The production estimate from the table can be adjusted for ‘actual’ construction conditions by applying adjustment factors: Q (actual) = Q (assumed) × Fs × Ft × Fp Where: Q (actual) = adjusted productivity Q (assumed) = productivity from table based on assumed conditions Fs = adjustment for machine speed Ft = adjustment for layer thickness Fp= adjustment for no. of passes The adjustment factors are determined by compar- ing the ‘actual’ conditions to the ‘assumed’ ones: Fs = actual speed/assumed speed Ft = actual thickness/assumed thickness Fp = assumed passes/actual passes Metric example Actual Conditions — An 9.15-meter (full road width) base aggregate job is being completed with a compacted thickness of 15 cm. A CS44B is being used, operating at 4.0 km/h, and making 6 passes to achieve the desired com- paction. The roller is overlapping its passes 6 inches. For a 9.15-meter road base the table gives a CS44B productivity of 249 m 3 /hr. Since the speed, thickness, and passes are different from the assumed conditions, we should adjust this estimate:

English example Actual Conditions — An wide area commercial site development job is being compacted in lifts of 8 inches. A CP56B is being used, operating at 4.0 mph, and mak- ing 4 passes to achieve the target density. First, the table gives a CP56B productivity of 847 yds 3 /hr. Since lift thickness and passes required are different from the assumed conditions, we should adjust this estimate:

Assumed 4.0 mph 12 inches 6 passes

Actual

4.0 mph 8 inches 4 passes

Speed

Thickness

Passes

Fs = no correction necessary Ft = 8 inches/12 inches = 0.7 Fp = 6 passes/4 passes = 1.5 The estimated production is adjusted using these factors: Q (actual) = 847 yds 3 /hr × 0.7 × 1.5 = 890 yds 3 /hr (680 m 3 /hr) Notes on Productivity: ● For jobs that are relatively narrow, especially road construction jobs, it is important to understand that certain widths of construction will be more produc- tive than others for a given compactor. A productive construction width will make the most use of each side by side pass required by the compactor in order to cover the width. ● Production estimates should be adjusted further if the length of the compaction cycles are shorter than 75 m (250 ft). Refer to the Travel Speed Efficiency chart to determine efficiency E TS . For example, a compactor traveling at 6.4 km/h (4 mph) operating at cycle lengths of 150 ft has an E TS of 0.91. Multiply Q (actual) by E TS .

Assumed 6.4 km/h 10.2 cm 4 passes

Actual

4.0 km/h

Speed

15 cm

Thickness

6 passes

Passes

Fs = 4.0 km/h/6.4 km/h = 0.6 Ft = 15 cm/10.2 cm = 1.5 Fp = 4 passes/6 passes = 0.7 The estimated production is adjusted using these factors: Q (actual) = 249 m 3 /hr × 0.6 × 1.7 × 0.7 = 178 m 3 /hr (233 yds 3 /hr)

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