Time-Cost-Quality Tradeoff Modeling based on Resource Allocation
Decision Variables and Assumptions
Relationship among Equipment Productivity, Quality, and Cost
Construction equipment is a crucial factor of construction techniques to increase construction quality, to reduce cost, and to shorten time. In order to calculate construction time variation impacted by equipment, a modified factor to labor productivity caused by equipment is introduced:
where is the actual productivity in activity is a modified factor to labor productivity by changes of construction equipment parameters; is labor productivity in activity .
A better equipment quality performance will improve construction productivity, so the modified factor could be derived from the equipment quality :
Construction equipment quality and equipment cost is also assumed as an approximate linear function just like construction material:
where actual quality level of construction equipment in activity , minimum quality level of construction equipment (i) in activity maximum quality level of construction equipment in activity minimum cost of construction equipment in activity maximum cost of construction equipment in activity actual cost of construction equipment in activity (i), .
Work overtime usually decreases construction productivity and increases hourly cost rate. Then construction equipment cost will be modified by factor :
where construction equipment cost modification factor during overtime because of extra or additional construction equipment, ; productivity decreased rate during overtime per unit time (e.g., hour), normally .