Approach to assessing tradeoffs between construction equipment fleet emissions and cost

The environmental effects of construction equipment emissions have been studied in previous research. Total emissions for construction activities and projects were previously calculated for various transportation projects as well as for other project types. This paper focuses on how contractors can use different equipment combinations and make project schedule adjustments to reduce total emissions from construction projects. It presents a newly developed optimization model that companies can use to select a fleet for a particular project to achieve the reductions. The model can be used to minimize total equipment cost and total emissions, or to minimize total equipment cost while limiting (capping) emissions for one or more of six pollutants. When the model was applied to example construction projects, the predicted reductions in emissions were significant, ranging from 25 to 85% depending on the pollutant. When the model was used to minimize cost, a reduction of 63% of the total equipment cost was achieved from the minimum-emissions solution. The lower-cost solution also resulted in a 43% reduction in project duration from the minimum-emission solution. The major contribution of this paper is the development of a decision model that can be used to select construction equipment fleets to reduce emissions production or equipment cost. The model can be customized to take into consideration the equipment fleet available for each activity and can be developed in concert with preliminary activity scheduling to look at daily emissions.