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A key challenge facing cities of today is the persistent and growing urban congestion that has significant adverse effects on economic productivity, emissions, driver frustration, and quality of life. The concept of smart cities, which can revolutionize the management of metropolitan transportation operations and infrastructure, shows great promise in mitigating this problem. Specifically, the automation and connectedness (A&C) of smart city entities such as its infrastructure, services, and vehicles, can be helpful. In this regard, this paper focuses on the potential of autonomous vehicles (AVs) and AV infrastructure, particularly during prospective transition era where there will be mixed streams of AVs and human driven vehicles (HDVs). The paper considers two aspects of this potential: connectivity-enabled travel demand management and travel infrastructure supply through lane management. To demonstrate the opportunity associated with this potential, this paper first presents an AV-enabled tradable credit scheme (TCS) to manage travel demand. Here, the transportation authority distributes travel credits to travelers directly and instantaneously using the AV's A&C features. Travelers use their A&C features to pay these credits for travel at specific locations or times-of-day according to their choices of lane types and links. With regard to supply, this paper considers that the road network consists of two lane types: AV-dedicated, and mixed traffic lanes, and develops a scheme for travel demand and lane management strategies in the AV transition era (TLMAV). Firstly, the paper models the expected travel choices based on user equilibrium concepts, at different levels of AV market penetration. Then, the existence of the optimal solution in terms of link flows and the prevailing travel credit price is demonstrated. Then the paper establishes the optimal TLMAV that minimizes total travel time subject to user equity constraints. The results demonstrate the extent to which HDV users will suffer an increase in travel cost if equity is not considered in the model. The results also show how the transportation agency can use TLMAV to keep HDV travel costs to acceptable levels, particularly during the early stages of the AV transition period. Further, the paper shows how TLMAV could be designed to gradually diminish inequity effects so that travelers, in the long term, are motivated to shift to AVs.

This study set out to evaluate the influence of carbon black (CB) on the rheological properties and activation energy of asphalt binder at high service temperatures. The rheological performance of virgin and modified asphalt binders are investigated using three evaluation approaches: (1) Superpave specification parameter (G*/sinδ), (2) multiple stress creep recovery (MSCR) test, and (3) interaction model for computing zero shear viscosity (ZSV). Moreover, the Arrhenius model was used to quantify the activation energy (Ef) of virgin and CB-modified asphalt binders. The result of this study reveals that modifying asphalt binder with up to 10% of CB, by weight of the total asphalt binder, enhances the elastic behavior (R%) and decreases the non-recoverable creep compliance (Jnr) of asphalt binder at high temperatures. Moreover, according to this study, the ZSV index can describe successfully rutting resistance of asphalt binder when compared with MSCR and Superpave rutting specification parameter. Besides, it was indicated that CB-modified asphalt binder has a high fluid resistance as more thermal energy was required for overcoming intermolecular force between molecules.

Introducing crumb rubber (CR) into asphalt binder can both provide environmental benefits such as conservation of natural resources and conservation of landfill space and significantly improve rheological and mechanical performance characteristics of asphalt binders. Incorporation of CR into asphalt binder demands some amount of kinematic energy to make modified asphalt binder sufficiently fluid for mixing and compaction purposes that liberates some greenhouse and fume emissions. By taking advantage of warm mix additives (WMA), it is possible to effectively reduce the production temperature of hot-mix asphalt mixtures to mitigate such environmental concerns. This study, Firstly, aims to investigate the CR dosage effect on the properties of asphalt binder containing different non-foaming warm mix additives: Sasobit and Evotherm M1. Secondly, the environmental concerns regarding CR inclusion into asphalt binder are evaluated by implementing gas chromatography-mass spectrometry (GC–MS) test. Rheological and mechanical tests have provided deep insight into the effects of such combinations of WMA and CR in asphalt binders and results indicated that a crumb rubber modified (CRM) asphalt binder with 15–20% CR yielded optimum performance concerning rutting, fatigue, and cracking performance. Furthermore, while both WMA additives can significantly improve the workability and enhance the rutting performance of CRM asphalt binders, they have a slightly negative effect concerning fatigue and cracking performance of CRM asphalt binders. From the environmental aspect, application of WMA additives also could potentially result in a 63–75% reduction in total emission of CRM asphalt mixtures containing 10–25% CR. Relationship between temperature and the total emission of CRM binders is not linear and it is more than likely a second-order polynomial relationship. Moreover, the results of emission analysis showed that CRM binders deliberate some hazardous fumes due to high temperature, which can be alleviated by incorporating WMA additives into the modified blend.