Impact of Pavement Roughness on User Costs and Carbon Emissions: A Review of Insights and Challenges

The use phase of the pavement life cycle assessment (LCA) contributes significantly to both economic and environmental burdens. However, its role is often overlooked when making decisions for pavement construction, maintenance, and rehabilitation. Pavement roughness is among the key factors influencing these burdens, and understanding its effect is crucial. This paper presents comprehensive insights into the impact of pavement roughness on road user costs and carbon emissions, while also highlighting associated challenges. The literature review clearly defines pavement roughness and distinguishes it from surface texture, a common source of confusion. Additionally, it outlines the impact of pavement roughness on climate change, energy use, user cost, and carbon emissions. Reported impacts include a 15 to 20% increase in fuel consumption under high-roughness conditions and user cost increases from $84 to $629 per vehicle annually as the International Roughness Index (IRI) rises from 1.58 to 3.95 m/km (100 to 250 inches/mile), with optimized rehabilitation triggers capable of cutting CO2eq emissions by up to 44%. Moreover, this review shows that vehicle electrification directly mitigates roughness-related impacts, with the transition to EVs capable of lowering roughness-induced emissions, with studies reporting reductions of 25% and 54% under different conditions. As a whole, it can be stated that the impact of pavement roughness is inevitably affected by pavement type, vehicle type and speed, vehicle tire condition, traffic load, and environmental factors. Although vehicle electrification offers potential for combating the consequences associated with pavement roughness, it introduces new challenges, including the high initial costs, limited charging ports, battery capacity, heavy load on the grid, and safety concerns. Overall, the current review improves the understanding of pavement roughness as a critical factor in sustainable transportation systems, consequently supporting the decision-making that reduces the effects of climate change and promotes sustainability.