Concrete versus Tailpipes

Abstract

The methodology and the results pertain to developing a carbon footprint from a feasibility study for the addition of dedicated truck lanes to I-70 in Illinois, Indiana, Missouri, and Ohio. A complete method is provided for carbon accounting in roadway infrastructure projects by integrating both greenhouse gases from vehicle emissions and embodied carbon from the construction and maintenance of the facility. The U.S. Environmental Protection Agency's MOVES model was used to estimate vehicle emissions, with off-model adjustments for hypothetical higher-productivity vehicles (HPVs) (longer or heavier trucks). Embodied carbon was estimated per unit of construction activity and material based on the quantities in the construction cost estimates. The results confirmed the importance of a holistic approach that incorporated both vehicle emissions and construction and maintenance. For some scenarios, embodied carbon from construction and maintenance offset operational benefits from congestion relief. In other scenarios, especially those with allowances for HPVs (such as longer double-trailer or triple-trailer trucks), decreases in vehicle emissions far outweighed emissions from construction and maintenance. Under the proper circumstances, dedicated truck lanes could be an infrastructure solution that would decrease the carbon footprint of freight transportation, but a true reckoning of their net carbon impact can be given only by incorporating embodied carbon.