Life cycle cost analysis (LCCA) is one of the well-established methods to determine the cost-effective alternative between different transportation infrastructure projects. Life cycle cost of a roadway alternative consists of agency and user costs over an analysis period appropriately selected. Agency costs include initial construction costs, and maintenance and rehabilitation costs incurred within the analysis period. User costs incur when there is a work zone present and also during normal operating conditions. In traditional LCCA, adopted by many agencies around the United States, it is assumed that the difference in user cost between alternatives mainly arise from work zone costs. The costs that arise during normal operating conditions (mainly vehicle operating costs) are not dependent on project alternatives and thus are traditionally considered to be negligible. This paper introduces a methodology to test the sensitivity of vehicle operating costs to roughness and texture profile quantitatively and evaluate its contribution to LCCA calculations. It was hypothesized that even the slight changes in surface profile between various alternatives may result in different user costs between the alternatives. A case study is presented to illustrate the effect of user costs of normal operating conditions on LCCA analysis results. Case study showed that vehicle operating costs that arise during normal operation may greatly affect the results of LCCA and should be considered, especially for low-volume traffic projects.

Truck platooning with autonomous and connected vehicles has several advantages compared with traditional trucking. Platooning improves overall road safety and reduces fuel consumption by up to 15%. This is a result of the advanced control systems and high steering accuracy of autonomous vehicles. These advanced control systems present an opportunity to pavement design engineers, as the lateral positions of the vehicles could be altered to create less damaging loading scenarios. This study introduces an expected response framework to quantify the impact of lateral position on pavement performance. Using the expected response framework, any mixture of human-driven and autonomous vehicles can be analyzed by characterizing lane position as a mixture probability distribution instead of point loads. Pavement damage can subsequently be computed by using the expectation of the responses. This approach requires little computational effort and is easily incorporated in any mechanistic–empirical design or optimization framework. The approach is illustrated by analyzing four flexible pavement sections using the expected response framework. Compared with human-driven trucks, optimized lateral position could decrease pavement damage by 40%. Channelized traffic on the other hand could increase pavement damage by 60%. A simplified approach is introduced alongside a reliability analysis and fragility curves for various pavement structures. Distributed traffic was found to have the lowest probability of failure among all traffic scenarios.

Truck platooning has many benefits over traditional truck mobility. Literature shows that platooning improves safety and reduces fuel consumption between 5% and 15% based on platoon configuration. In Illinois, trucks carry more than 50% of freight tonnage and constitute 25% of the traffic on interstates. Deployment of truck platooning within interstate highways would result in significant fuel savings, but may have a direct impact on flexible pavement performance. The channelization of the platoon and reduced rest time between consecutive loads would accelerate the damage accumulation at the channelized position. Ultimately, this would lead to pavement service life reduction and a subsequent increase in maintenance and rehabilitation costs. Therefore, the main objective of this project is to quantify the effects of platooning on flexible pavements and provide guidelines for the state of Illinois by considering the aforementioned factors. Although the benefits of platooning are quantifiable, not every truck route is platoonable. For efficient platooning, trucks need to travel at a constant high speed for extended distances. The integrity of the platoon should be preserved because interfering vehicles would compromise the platooning benefits and road safety. An introduced high-level approach considers the volume/capacity of a roadway and the expected number of highway exit and entry conflicts. Using these parameters, each roadway section is assigned a level of platoonability, ranging from one to five—with five being the highest. A framework was developed to analyze the Illinois highway network. It was found that 89% of the network highway is platoonable under average capacity conditions.

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