Impact of Pavement Roughness on Cost and Emissions: A Network-Level Study in Oregon

ABSTRACT This research study aimed to assess the impact of pavement smoothness across the roadway network in Oregon and analyze various scenarios to identify opportunities for reducing financial expenditures and emissions via reductions in overall roadway roughness levels. An analysis of 20 years of Oregon Department of Transportation (ODOT)’s International Roughness Index (IRI) data shows that reducing pavement roughness to 40 in/mi could yield substantial benefits, an estimated $142 million in annual cost savings and a reduction of 423,462 metric tons (MT) of CO2 emissions per year. Maintaining an IRI of 65 in/mi, even if 40 in/mi is not feasible, yields major benefits, about $45 million in annual savings and a 134,927 MT CO2e reduction, nearly matching ODOT’s total yearly emissions of 182,592 MT. These benefits are influenced by the adoption of electric vehicles, which could reduce both cost and emissions savings by approximately 4–16 % and 4–10 %, respectively. Within Oregon, focusing maintenance on the highest-traffic roads and maintaining IRI at 40 in/mi could result in annual savings ranging from $49 million to $126 million and emission reductions of 262,082 to 427,829 MT of CO2, depending on whether 3 %, 6 %, or 12 % of the network is maintained. Overall, the study reflects the massive impact of pavement roughness on the road user costs and the associated emissions considering different scenarios for Oregon road network. The potential savings could be even greater if smoother pavements are combined with the use of sustainable materials in asphalt production.