The primary issue affecting the transportation system is the maintenance crisis (compounded by climate change). The maintenance crisis has three elements: a) the growing stock of assets to be maintained; b) deferral of maintenance in preference for expansion, and c) the resulting deferral of maintenance accelerating deterioration.
As state populations continue to grow, so does demand on the state transportation system. To keep pace with vehicle congestion, state transportation agencies constantly increase road capacity. Increasing capacity means additional lane-miles are being constructed, which then require ongoing maintenance. The ongoing demand for road capacity and increasing stock of maintenance results in maintenance being deferred []. Politically, road construction provides immediate benefits, while maintenance provides long-term but time-distant benefits. However, in much the same way that failure to patch a roof increases repairs, delayed maintenance accelerates deterioration of roads, such that a constant amount of funding has less effect when applied later []. Consequently, over time, share of funding devoted to maintenance remains insufficient to maintenance needs []. Efforts to overcome the maintenance backlog by making critical repairs (a ‘filling pot-holes’) approach is a sub-optimal maintenance regime, as it fails to stop the deterioration of the broader system.
Climate change also acts as an accelerant to this dynamic by inducing more climate extremes in heat, cold, and precipitation. Extremely hot days vaporize asphalt thus increasing the rate of wear. Increased freezing increases frost-heaving (damaging roadbeds beneath pavements). Extreme precipitation results in large sudden floods of water which generates washouts along and beneath the edge of paving.
Current performance measures do a good job regarding these issues, providing an incentive to maintain pavements in the low-maintenance good category and out of the poor category. Problematically, they may incentivize states to engage in ‘pot-hole filling’ by doing the minimum to boost roads into the fair category, which characterizes the phase of most-rapid deterioration on the pavement maintenance curve. In a worse case scenario, decades of such a program result in a road system consisting of marginally good category roads and marginally fair category roads, both high deterioration contexts.
The second most important trend facing pavements is the decline in the gas tax and accompanying decline in available Federal Funding. The per-gallon rather than per dollar pricing means inflation recurringly eats away at the spending power of the gas tax, requiring iterative increases to the headline rate to provide the same amount of funding. Further, vehicle electrification represents an existential threat to this funding mechanism, by removing the nexus between the impacts of automobile travel and the funding derived from that travel. It undermines the fundamental equity argument for funding roads: roads are paid for by road users. Suggestions include a per-mile vehicle fee, and if such a fee is enacted, given the maintenance impacts of large trucks and the prevalence of weight stations, vehicle mass multiplier to the fee might not be far behind. As an alternate to such ‘soft tolls’, federal funding programs might include a rebate reimbursing states proportionately to the road damage caused by large trucks.