Economically and environmentally informed policy for road resurfacing: tradeoffs between costs and greenhouse gas emissions

Abstract

As road conditions worsen, users experience an increase in fuel consumption and vehicle wear and tear. This increases the costs incurred by the drivers, and also increases the amount of greenhouse gases (GHGs) that vehicles emit. Pavement condition can be improved through rehabilitation activities (resurfacing) to reduce the effects on users, but these activities also have significant cost and GHG emission impacts. The objective of pavement management is to minimize total societal (user and agency) costs. However, the environmental impacts associated with the cost-minimizing policy are not currently accounted for. We show that there exists a range of potentially optimal decisions, known as the Pareto frontier, in which it is not possible to decrease total emissions without increasing total costs and vice versa. This research explores these tradeoffs for a system of pavement segments. For a case study, a network was created from a subset of California's highways using available traffic data. It was shown that the current resurfacing strategy used by the state's transportation agency, Caltrans, does not fall on the Pareto frontier, meaning that significant savings in both total costs and total emissions can be achieved by switching to one of the optimal policies. The methods presented in this paper also allow the decision maker to evaluate the impact of other policies, such as reduced vehicle kilometers traveled or better construction standards.

Optimal policies for greenhouse gas emission minimization under multiple agency budget constraints in pavement management

“…At the pavement system level, research has focused on both minimizing GHG emissions (Wang et al, 2014) and minimizing lifecycle societal costs under a constraint of total GHG emissions (from users and agencies). Examples of the latter include Reger et al (2014), who solved for the optimal 4 rehabilitation policy, and Lee et al (2016), who solved for the optimal mix of rehabilitation and reconstruction strategies. One limitation of this line of work is that the objective function, minimizing societal costs under an emissions budget, may not be a realistic representation of a highway agency's problem.…”

The effect of agency budgets on minimizing greenhouse gas emissions from road rehabilitation policies

“…As in Reger et al (2014), we use a continuous time, continuous state, infinite-horizon optimization formulation. The problem is formulated as an objective function subject to two constraints, as shown in equations (1)-(3).…”

“…While effective in reducing user emissions, rehabilitation actions result in large quantities of GHG emissions being released into the atmosphere from the manufacturing and transporting of the materials and the construction stage (Santero and Horvath 2009). There is optimal timing to perform rehabilitation where the combined user and agency emissions for that segment are minimized (Reger et al 2014). In theory, an agency would always choose to rehabilitate at that timing, but in practice, there are other factors that can interfere.…”

“…In Reger et al (2014), we solved a multi-facility, continuous time, continuous state, infinite horizon problem for a heterogeneous pavement network. We sought to minimize total societal costs (user and agency combined) subject to an emissions constraint, giving a range of potentially optimal policies that could be applied by the agency.…”

“…The methodology used in Reger et al (2014) is modified to become more applicable for real-life scenarios. That paper considered a single type of rehabilitation activity, but state agencies have many options at their disposal.…”