The impact of transportation construction projects and activities on emissions

Construction equipment is an important contributor to emissions from construction projects. EPA develops emissions regulations that are followed by equipment manufacturers when producing new equipment. However, there are no national regulations that address emissions related to equipment use or fleet management. The objective of this research is to model emissions from construction projects and to analyze and understand the impact of equipment and activity characteristics in the total emissions. The study will focus on the exhaust pollutants that are included in the EPA NONROAD model for equipment used on construction sites. The first part of the study included the estimation of construction equipment emissions for various transportation construction projects. The projects included road and utility projects, and highway projects. The calculations included emissions per day, emissions per construction activity, and emissions per equipment. Total project emissions were used to determine emissions metrics including emissions per dollar of bid cost, emissions per day of construction, and emissions per unit of work, that for the transportation projects was emissions per foot of road length. The results were compared to the total emissions and the emissions metrics for a commercial building project that was completed previously. The data needed to complete these calculations was collected from different sources. Actual construction data was collected from the contractors for all projects. Data collected during construction vary between projects. The contractor’s data was supplemented with data from the RS Means Construction Data publication. Basic equipment characteristics were collected from the Caterpillar Performance Manual. Emissions factors for all the equipment were collected from the EPA NONROAD model. The second part of the study included the development of an optimization model to select equipment fleet composition to minimize emissions or cost. This part also included a sensitivity analysis that was used to identify the effect of equipment characteristics and schedule changes on construction emissions. The model was developed with multiple objectives: minimize emissions, minimize cost, or minimize cost with a cap on emissions. The results showed that equipment cost increase if the emissions are minimized. The minimum cost solution includes all Tier 1 equipment while the minimum emissions solution requires all the equipment to be Tier 3. Changing the emissions limit results on a mixed fleet that includes items of different tiers. The last part of the study included the identification and assessment of the emissions regulations and the incentive programs that are in use currently. Future and possible policies were also identified. Current and future policies were assessed based on the lessons learned from the first two sections of this study and the unique construction industry characteristics.