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.

Truck platoons have many benefits over traditional truck mobility. Truck platoons have the potential to improve safety and reduce 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. Therefore, expected fuel savings would be significant for trucks. Deployment of truck platoons within interstate highways may have a direct effect on flexible pavement performance, as the time between consecutive axle loads (i.e., resting time) is expected to decrease significantly. Moreover, platoons could potentially accelerate pavement damage accumulation due to trucks’ channelized position, decreasing pavement service life and increasing maintenance and rehabilitation costs. The main objective of this project was to quantify the effects of truck platoons on pavements and to provide guidelines to control corresponding potential pavement damage. Finite-element models were utilized to quantify the impact of rest period on pavement damage. Recovered and accumulated strains were predicted by fitting exponential functions to the calculated strain profiles. The results suggested that strain accumulation was negligible at a truck spacing greater that 10 ft. A new methodology to control pavement damage due to truck platoons was introduced. The method optimizes trucks’ lateral positions on the pavements, and an increase in pavement service life could be achieved if all platoons follow this optimization method. Life cycle assessment and life cycle cost analysis were conducted for fully autonomous, human-driven, and mixed-traffic regimes. For example, for an analysis period of 45 years, channelized truck platoons could save life cycle costs and environmental impacts by 28% and 21% compared with human-driven trucks, respectively. Furthermore, optimum truck platoon configuration could reduce life cycle costs and environmental impacts by 48% and 36%, respectively, compared with human-driven trucks. In contrast, channelized traffic could increase pavement roughness, increasing fuel consumption by 15%, even though platooning vehicles still benefit from reduction in air drag forces. Given that truck platoons are expected to be connected only in the first phase, no actions are required by the agency. However, in the second phase when truck platoons are also expected to be autonomous, a protocol for driving trends should be established per the recommendation of this study.

Since 1970, the U.S. National Highway Traffic Safety Administration (NHTSA) has been responsible for setting and monitoring traffic and safety standards for all motor vehicles on U.S. roads. Authorized by the National Traffic and Motor Vehicle Safety Act of 1966, the agency can investigate and recall any vehicle that contains a safety-related defect or is in violation of a federal motor vehicle safety standard. This paper describes the role of the NHTSA in assessing automotive electronics reliability and safety. We discuss the definition of "safety defect," and how it has been applied. In a number of defect investigations, automakers had initially led the NHTSA to believe that their vehicles were safe and complied with safety standards, although they contained potentially fatal defects. As a result, NHTSA had difficulty in taking effective action against rollovers, stalling problems, and fire hazards in some of the nation's popular vehicles, even though evidence pointed to a safety defect. This article then describes a juridical process that may improve road safety. Examples are given as to how regulations could be manipulated to stymie federal investigations, followed by an explanation of how the Transportation Recall Enhancement, Accountability, and Documentation Act, passed in 2000, could facilitate more effective investigations. Finally, we discuss the economics of defect recalls, and provide some recommendations.

Researchers conducted eight large-scale laboratory tests to assess the combined impact of hot-mix asphalt (HMA) overlay mix and thickness on its performance to control reflective cracking. Bonding efficiency, flexibility, and stiffness of the HMA mix as well as overlay thickness significantly affect an overlay’s performance against reflective cracking. Researchers developed a generalized 3D finite-element model to predict an overlay’s reflective cracking potential and generated a database of 128 cases. They also developed a data-driven surrogate model to predict reflective cracking potential that engineers can easily use. Life-cycle cost analysis of overlay alternatives was performed using Illinois Department of Transportation’s unit prices from contracts between 2018 and 2019. The researchers identified optimal overlay configurations to control reflective cracking. An overlay composed of a 1.5 in (38.1 mm) SMA-9.5 or 1.25 in (31.8 mm) IL-9.5FG surface course and a 0.75 in (19.1 mm) IL-4.75 binder course had the lowest annual cost per mile among non-interstate projects. For interstate projects, an overlay composed of a 2 in (50.8 mm) SMA-12.5 surface course and a 2.25 in (57.2 mm) IL-19.0 binder course was the most cost-effective. The study concluded that to control reflective cracking and to reduce life-cycle cost, an overlay composed of an SMA-9.5 surface course and an IL-4.75 binder course is recommended for non-interstate projects. An IL-9.5FG surface course and an IL-4.75 binder course are suggested for low-volume and low-speed roads. For interstate projects, an overlay comprised of an SMA-12.5 surface course and an IL-19.0 binder course is recommended. A data-driven surrogate model may be used to design overlay thicknesses.

Truck platoons are expected to improve safety and reduce fuel consumption. However, their use is projected to accelerate pavement damage due to channelized-load application (lack of wander) and potentially reduced duration between truck-loading applications (reduced rest period). The effect of wander on pavement damage is well documented, while relatively few studies are available on the effect of rest period on pavement permanent deformation. Therefore, the main objective of this study was to quantify the impact of rest period theoretically, using a numerical method, and experimentally, using laboratory testing. A 3-D finite-element (FE) pavement model was developed and run to quantify the effect of rest period. Strain recovery and accumulation were predicted by fitting Gaussian mixture models to the strain values computed from the FE model. The effect of rest period was found to be insignificant for truck spacing greater than 10 ft. An experimental program was conducted, and several asphalt concrete (AC) mixes were considered at various stress levels, temperatures, and rest periods. Test results showed that AC deformation increased with rest period, irrespective of AC-mix type, stress level, and/or temperature. This observation was attributed to a well-documented hardening–relaxation mechanism, which occurs during AC plastic deformation. Hence, experimental and FE-model results are conflicting due to modeling AC as a viscoelastic and the difference in the loading mechanism. A shift model was developed by extending the time–temperature superposition concept to incorporate rest period, using the experimental data. The shift factors were used to compute the equivalent number of cycles for various platoon scenarios (truck spacings or rest period). The shift model was implemented in AASHTOware pavement mechanic–empirical design (PMED) guidelines for the calculation of rutting using equivalent number of cycles.