The effect of varying the elevation change from to and is also analyzed. The lowest cost is achieved with a highest precision () because more alternatives are evaluated. In this experiment, the same costs are found using and , but for the cost increases in all the instances. Table 7 presents the relative gap between the cost of the solutions obtained with and . For example, the cost of a series of 20 pipes on steep ground using PVC pipes and is $53,738.8, but using the cost rises to$61,813.4. Thus, the relative gap is 15% and is due to the accuracy reached with each elevation change .

Table 7

Relative gap between the solutions obtained with and

Number of pipesRelative gap
Steep ground
Flat ground
ConcretePVCConcretePVC
1% 4% 3% 3%
10 6% 8% 5% 8%
15 12% 13% 13% 13%
20 16% 15% – –
Number of pipesRelative gap
Steep ground
Flat ground
ConcretePVCConcretePVC
1% 4% 3% 3%
10 6% 8% 5% 8%
15 12% 13% 13% 13%
20 16% 15% – –

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