The current focus of research attention on reclaimed asphalt pavement (RAP) utilization is expanding the applications of RAP. This study aims to analyze the road performance of recycled permeable asphalt mixtures (RPAMs), which represents a novel direction for utilizing RAP. Firstly, the Marshall design method was used to carry out the material composition design of the RPAM with varying RAP contents (10%, 20%, and 30%). Subsequently, the performance of the RPAM with different RAP contents (10%, 20%, and 30%) and preheating temperatures (120 °C, 130 °C, 140 °C, 150 °C, and 160 °C) was tested with a permeable asphalt mixture containing 12% high-viscosity asphalt as the control group. The mixture’s performance included high-temperature stability, low-temperature crack resistance, water stability, anti-raveling performance, and dynamic mechanical properties. The results indicate that the higher the RAP content, the better the high-temperature performance of the RPAM, while the low-temperature performance, water stability, and anti-raveling performance deteriorate. At 30% RAP content, its pavement performance is comparable to that of the control group mixture. However, increasing RAP preheating temperature can improve low-temperature and water stability but may reduce high-temperature performance. The optimal RAP preheating temperature for pavement performance is between 140 and 150 °C. The dynamic modulus test showed that the higher the RAP content, the greater the dynamic modulus of the RPAM, leading to better high-temperature stability but reduced low-temperature crack resistance. The influence of RAP preheating temperature is the opposite. These test results demonstrate the feasibility of utilizing RAP for paving permeable asphalt pavement under controlled RAP content and preheating temperature conditions.

With the increasing demand for improved road performance and sustainable development, modified asphalt is increasingly being used in pavement construction. This study investigates the preparation and properties of a novel high-viscosity modified asphalt. Firstly, different contents of novel thermoplastic rubber (NTPR) were mixed with neat asphalt to prepare high-viscosity modified asphalt (HVA). Then, the basic physical properties containing penetration, a softening point, ductility, and viscosity were conducted. Moreover, the rheological properties of the HVA before and after aging were analyzed via a dynamic shear rheometer test and a bending beam rheometer test. Finally, the dispersity of the modifier in HVA was analyzed via fluorescence microscopy. The results show that adding the NTPR restricts the flow of asphalt to a certain extent and improves the high temperature performance of asphalt. Furthermore, the apparent viscosity of HVA with various contents increases less and is always less than 3 Pa·s. Although adding NTPR makes the asphalt brittle, the HVA can meet the requirements when the NTPR is from 6% to 11%. With the increase in the NTPR, the modifier forms a mesh structure in the asphalt, enhancing its stability. Considering the above results, HVA with 10~11% of NTPR is recommended because it has better comprehensive properties.

In order to explore the feasibility of a renewable hybrid energy system in highway tunnels, a scenario-coupled construction method for a highway tunnel renewable hybrid energy system is proposed. Based on this method, a tunnel on a highway in southern China serves as an example, and a renewable hybrid energy system for the highway tunnel is constructed. Using HOMER, the hybrid energy system is simulated, optimized, and analyzed, studying the characteristics of the operation of the highway tunnel hybrid renewable energy system in an off-grid mode. The optimal configuration for the hybrid energy system is proposed. The research results indicate the feasibility of constructing a highway tunnel renewable hybrid energy system by utilizing natural resources within the road area (solar energy, wind energy). The hybrid renewable energy system for this tunnel can provide 1112392 kWh of electrical energy annually, with the lowest energy cost being $0.17/kW. Furthermore, the hybrid energy system can reduce greenhouse gas emissions, contributing to the sustainable development of the environment.

China’s expressways generate substantial carbon emissions annually. To mitigate these emissions, this study explores the deployment of photovoltaic (PV) modules in the available areas of expressway service areas. As critical energy consumption nodes along the expressway network, service areas offer notable advantages for PV deployment compared to other highway segments, including ease of management, cost-effectiveness, and reduced transmission losses. However, the scattered distribution of service areas—many of which are located in mountainous and complex terrains—poses significant challenges to accurately assessing their PV potential. To address this issue, this study develops a spatiotemporal model to evaluate the solar photovoltaic power generation potential of expressway service areas across China. First, national service area coverage is determined using highway network data. Second, digital elevation model (DEM) data are used to estimate hourly shadow areas caused by surrounding terrain; solar radiation within these shadowed regions is assumed to be zero. Finally, by integrating ground-based solar radiation data with a radiation estimation model, the PV potential of service areas in each province is calculated. The model integrates expressway service area data, high-resolution digital elevation models, and ground-based solar radiation datasets to simulate spatially and temporally resolved irradiance conditions, enabling accurate estimation of photovoltaic potential at the provincial and national scales. Based on data from approximately 3225 expressway service areas as of the end of 2022, the results indicate an annual photovoltaic potential of 1400.72 TW, with an estimated installable capacity of 51.85 GW, yielding an annual electricity generation of 66.37 TWh. The southeastern regions, particularly Guangdong Province, exhibit greater PV potential due to their higher density of service areas, compared to the northwestern regions. Nationwide adoption of PV systems in expressway service areas is projected to reduce carbon emissions by 48.85 million tons. This study provides a valuable reference for regional planning and suitability assessment of PV expressway infrastructure development in China. Moreover, this study provides a novel spatiotemporal assessment framework and the first national-scale case study of PV potential in expressway service areas, offering valuable guidance for highway energy planning and low-carbon infrastructure development in China.

Highways consume a significant amount of electrical energy annually, especially in remote desert regions where the cost of electricity is high. This research explores the utilization of natural resources along desert highways to establish hybrid energy generation systems for service areas. Three service areas along the desert highway in northern Xinjiang, China, serve as case studies. To assess the feasibility of hybrid energy generation systems in these service areas, meteorological data for the three locations were obtained from the NASA platform. The HOMER Pro software was employed for technical, economic, and environmental analyses of the systems. The results indicate the feasibility of Photovoltaic (PV)/Wind/Battery hybrid energy systems in the Huanghuagou, Kelameili, and Wujiaqu service areas. The application of these hybrid energy generation systems across the three service areas could provide 3,349,557 kWh of electrical energy annually for the desert highway. Sensitivity analysis reveals that the Net Present Cost (NPC) and Cost of Energy (COE) values decrease with increasing radiation levels, while NPC shows an increasing trend with growing load demand, and COE exhibits a decreasing trend. Among the three regions, Wujiaqu demonstrates the highest economic viability, with a COE of $0.34/kWh and an NPC of $3,141,641/kWh. Furthermore, Wujiaqu exhibits the lowest environmental impact, with CO₂ emissions of 198,387 kg/yr, SO₂ emissions of 493 kg/yr, and NO_x emissions of 1,711 kg/yr.

To explore the feasibility of renewable hybrid energy systems for expressway infrastructure, this study proposes a scenario-based design methodology integrating solar, wind, and hydropower resources within the expressway corridor. A case study was conducted on a highway service area located in southern China, where a solar/wind/hydro hybrid energy system was developed based on the proposed approach. Using the HOMER Pro 3.14 software platform, the system was simulated and optimized under off-grid conditions, and a sensitivity analysis was conducted to evaluate performance variability. The results demonstrate that the strategic integration of corridor-based natural resources—solar irradiance, wind energy, and hydrodynamic potential—enables the construction of a technically and economically viable hybrid energy system. The system includes 382 kW of PV, 210 kW of wind, 80 kW of hydrokinetic power, a 500 kW diesel generator, and 180 kWh of battery storage, forming a hybrid configuration for a stable and reliable energy supply. The optimized configuration can supply up to 1,095,920 kWh of electricity annually at a minimum levelized cost of energy of USD 0.22/kWh. This system reduces CO₂ emissions by 23.2 tons/year and NO_x emissions by 23 kg/year. demonstrating strong environmental performance and long-term sustainability potential.