Rational Method to Determine Investment Amount for Making Roadways Resilient to a Changing Climate

Abstract

The increase in maximum air temperature and annual rainfall caused by climate change can shorten the lives of pavements and hence increase the mileage of roads that would require rehabilitation at any point in the future. Most agencies are aware of the potential of the use of better materials such as high-modulus asphalt in reducing the negative impacts, thereby making roads resilient to climate change. However, using better materials does involve higher investments; currently, the major hindrance is the inability to decide on a justifiable level of investment. This is a challenge because climate change predictions have major uncertainties associated with them, and there could be competing needs for the limited budget that is available. This paper presents a rational framework that is based on the use of system dynamics and Monte Carlo simulations to identify an appropriate level of investment for making roads resilient to climate change. The process consists of predicting the mileage of roads that will need rehabilitation because of climate change with and without the use of better materials, considering the reduction in this mileage caused by using better materials as a future “return” on a present investment on better materials, and then comparing that return with one that could be expected from a regular investment with a reasonable interest rate. The comparisons are made probabilistically, so that depending on the level of selected confidence level, one can identify the investment that would result in the same return in a certain number of years as the return from resilient pavements in the same number of years. This investment would then be used as an appropriate and justifiable number for investing in better materials for making roads resilient to climate change. A worked-out example is presented, which shows an appropriate investment (that is far greater than one would spend for a conventional pavement) of approximately $2,4 per 1.6 km (1 mi) of a roadway network to obtain the same benefit from the reduction of cost of rehabilitation as an amount that could be obtained from an interest-paying investment in 15 years. The framework allows users to utilize their preferred method of pavement analysis, costs, mileage of roads, and results of laboratory and/or field study on pavement life–enhancing ability of better materials.