Warm mix property of warm mix bitumen was quantitatively researched by applying the viscosity-temperature curve method, and a practical test method and corresponding technical indices were provided. 3 types of ACMP warm mix bitumen and 2 kinds of hot mix bitumen (modified and not) were chosen to measure the bitumen viscosity by applying Brookfield test, the rheological behaviour was analyzed by drawing the rheogram of those five chosen bitumens under different temperatures, and the mix temperature change of warm and hot mix bitumen was compared with the viscosity-temperature curve method. The results show that Brookfield's viscosity is the dynamic viscosity, and rheological behaviour of bitumen obeys the Newton's law of viscosity; the viscosity-temperature curve which describes the temperature variation of different bitumens in the same viscosity can be used to evaluate the warm mix property of bitumen; the mix temperature of ACMP warm mix bitumen is 10 ℃ to 20 ℃ lower than that of hot mix bitumen, so it presents a certain warm mix property.

To promote the development of traffic engineering disciplines in China, the progress, hot topics, existing problems and its countermeasures and development prospects of traffic engineering in academic researches at home and abroad were systematically summarized in 11 aspects including traffic flow theory, traffic planning, road traffic safety, traffic control and intelligent transportation system, traffic management, traffic design, traffic service facilities and electrical facilities, ground public transit, urban parking transportation, traffic big data, and traffic evaluation. In the aspect of traffic flow theory, fundamental diagram model of traffic flow, microscopic and mesoscopic traffic flow theories and their simulations, macroscopic traffic flow theory, and network theory of traffic flow were reviewed. As for traffic planning, traffic and land utilization, traffic and sustainable development, characteristics of traffic travelling behaviors, traffic survey methods and demand forecasting were summarized. Reviews of road traffic safety included traffic safety planning, facility safety, traffic safety management, traffic behavior, vehicle active safety, technical standards and norms of traffic safety, etc. Reviews of traffic control and intelligent transportation systems included traffic signal control,corridor control,traffic control and traffic assignment,cooperative vehicle-infrastructure system and intelligent vehicle system,etc. As for traffic management, traffic laws and order management, traffic system management, traffic demand management, and abnormal traffic management were reviewed. In terms of traffic design, traffic network design, node traffic design, traffic design of urban road, the bus traffic design, and traffic language design were summed up. The review on the aspect of ground public transit involved transit industry regulation and service evaluation, planning and optimization of public transit network, transit operation management and intelligent technology, and the new transit system. As for urban parking transportation, urban parking demand, planning and design of parking facilities, parking management and policies, and intelligentization and informatization of parking were expounded comprehensively. As for traffic big data, the researches on the application of mobile phone data, transit IC card, GPS track and license plate recognition, and social media data to traffic system analysis, especially the research progress in investigation of individual travelling behavior were reviewed. In the aspect of traffic evaluation, the assessments of social and economic impact and traffic impact on traffic construction projects were analyzed.

Autonomous vehicles often need to predict the trajectories of surrounding vehicles for planning and decision making. In this paper, a model for intention recognition and trajectory prediction based on long short-term memory (LSTM) network is proposed. The proposed model comprises an intention recognition module and a trajectory output module. The intention recognition module was employed for identifying the driving intention. The Softmax function was incorporated in the intention recognition module for calculating the probabilities of left lane change, lane-keeping, and right lane change. An encoder-decoder structure and a mixture density network (MDN) layer were included in the trajectory output module. The encoder converted the past trajectory information into the context vector. Subsequently, the decoder combined the context vector and the intention recognition information for predicting future trajectories. The MDN layer was employed for representing the future position of a vehicle with its probability distribution rather than with a particular trajectory, which improved the reliability of prediction results and the robustness of the proposed model. Additionally, the compositions of a predicted vehicle and its surroundings were both taken into account, which aided the proposed model in analyzing the interactions among vehicles. Hence, the proposed model can dynamically predict vehicle trajectories according to variations in traffic conditions. The NGSIM data set based on the information of actual road conditions was employed for training, validating, and testing the proposed model. Experimental results indicate that the proposed method based on LSTM network has several advantages over conventional model-based methods with respect to trajectory prediction, especially in a long prediction horizon. Interactive information can ensure that the intention recognition module has high anticipative ability and accuracy. Furthermore, trajectory prediction based on intention recognition can significantly reduce the root-mean-square errors in predicted trajectories with respect to the ground truth, thereby leading to significant improvement in trajectory prediction accuracy.

In the past six years, China has made a tremendous number of achievements in tunnel engineering, which will greatly help China shift dramatically to achieve the great leap from a large tunneling country to a strong tunneling power of the world. In order to promote the sustainable and high quality development of tunnel engineering, the state of the art in tunneling was systematically analyzed in this review paper, including the construction status quo , design technology, survey and forward prospecting technology, excavation and support technology, green approach with Eco-friendly construction and operation technology, mechanized and intelligent construction, lining structure anti-seismic technology, operation support facilities, maintenance and operation technology, and typical tunnel engineering cases of traffic tunnels. Overall, this review paper provides references and insights for researchers and engineers in the field of tunnel engineering.

In order to promote the development of China's bridge engineering subject, the academic research status, hot issues, existing problems, corresponding countermeasures and development prospects about bridge engineering at home and abroad (including bridge structural design, new bridge construction technology, bridge disaster prevention and mitigation) were studied systematically. Firstly, the progress of bridge engineering in academic researches were summarized in five aspects including high performance materials and structural systems, industrial and intelligent construction technology, disaster-resistant capability and deep water foundation. Secondly, all aspects of the above filed in bridge engineering were summarized systematically: steel bridge, composite bridge and deep water foundation in bridge structural design; new construction technology of steel bridges and accelerated bridge construction technology of RC bridges; seismic resistance, wind resistance, fire resistance and anti-collision in bridge disaster prevention and mitigation, as well as the corresponding development prospects. Hopefully, this paper is supposed to provide new perspectives and basic data for academic researches and engineering practice on bridge engineering subject.

With the continuous and rapid development of highway tunnels in terms of scale, quantity, and construction speed, China has made considerable technological breakthroughs in tunnel construction over the past decade, and has shifted from a large nation of tunnels to power tunnels. This paper presents a macroscopic study and analysis of the construction of highway tunnels in China over the past decade, and comparatively describes the major development characteristics, trends, and relevant recommendations regarding highway tunnels in mountainous regions, underwater areas, and cities. Changes in the concept of highway tunnel construction are presented in terms of tunnel construction requirement orientation, geological advance forecast, energy conservation, environmental protection, and emergency rescue. Further, a comparative summary is presented on the application and future development trends of common highway tunnel construction methods, including the drilling and blasting, shield, immersed tube, and TBM methods. On this basis, the paper presents studies and views to address some problems that will be encountered in future during the construction of highway tunnels in China. Specifically, the tunnel design concept focusing on the support parameter design should be changed, the tunnel structure design method with the medium field as the main body should be established, and the tunnel field deconstruction and reconstruction theory and technology system should be further developed. To reduce the number of long and deep inclined shafts and improve the construction speed, a combination of the drilling and blasting method + expansion-tunneling method with a small TBM heading should be employed for long highway tunnels with the twin-tube layout mode. Additionally, as more highway tunnels enter the post-operation period, a technical approach for intelligent monitoring and rapid repair of tunnels is proposed to minimize the impacts of tunnel repair. Highway tunnel construction in China should integrate advanced technologies such as big data, intelligent equipment, and 5 G technology; additionally, relevant supporting standards should be developed as soon as possible.

With More than 40 years of reform and opening, the highway construction in China has made remarkable achievements, which strongly supports the rapid development of the country's social economy. In the recent years, new theories, new methods, new technologies, new processes, new structures, and new materials related to pavement engineering are emerging. Based on the typical problems encountered in pavement construction, the technical innovation contents of the China's National Science and Technology Award, the projects of the Ministry of Science and Technology (MOST) and the National Natural Science Foundation of China (NSFC), the excellent Chinese authoritative journals, and the highly cited papers in Web of Science (WoS), this review paper systematically analyzes the research status and future development direction of 7 major fields of pavement engineering in China and abroad. The content includes intelligent and environment-friendly pavement, advanced pavement materials, advanced construction technology, pavement maintenance technology, pavement structure and mechanical properties, solid waste comprehensive utilization technology, and pavement recycling technology. Overall, this review paper is able to provide references and insights for researchers and engineers in the field of pavement engineering.

To promote the development of automotive engineering disciplines in China, the research progress, hot topics, existing problems, specific countermeasures and development prospects of academic research in automotive engineering at home and abroad were systematically summarized from five aspects, including automobile noise-vibration-harshness (NVH) control, electrification and low-carbon, electronization, intellectualization & connection, and collision safety technologies. In the aspect of NVH control of vehicles, the sound quality from silence, the NVH control technique of new energy automobile, the NVH control technology of the car body and chassis, the initiative vibration control technology and so on were reviewed. As for the automotive electrification and low-carbon, the traditional automotive powertrain energy-saving technology hybrid power electric vehicle technology and so forth were summarized. Reviews of the automotive electronization included the electronic control technology of automobile engines, the electronic control technology of motor steering, the electronic control technology of automobile brake and the electronic control technology of automotive suspension, etc. Reviews of the intellectualization & connection of vehicles included summaries of intelligent and connected vehicles (ICV) studies in China and America, complex traffic environment perception, high precision map as well as vehicle navigation and location, self-organization character and trajectory planning of vehicles, lateral control and longitudinal dynamics control of vehicles, and ICV test, etc. Meanwhile, practical examples of advanced driver assistance systems (ADAS), vehicle to X (V2X), human-machine copilot, and so on were analyzed as well. In light of automobile collision safety technologies, the vehicles collision, occupant protection, pedestrian protection, crash safety and protection of children, the crash safety of new energy automobile and so forth were summed up. It is supposed to provide new perspectives and basic data for academic researches on automotive engineering discipline.

As the foundation of the pavement structure, a stable, strong and durable subgrade plays a key role in the quality protection of pavement. However, the phenomenon of paying attention to road surface but neglecting subgrade has existed in China for a long time, and makes it very common that the subgrade diseases lead to the destruction of pavement structure. Based on the subgrade engineering in recent years related the technical innovation contents of the China's National Science and Technology Award, the projects of the Ministry of Science and Technology (MOST) and the National Natural Science Foundation of China (NSFC), the excellent Chinese authoritative journals, and the highly cited papers in Web of Science (WoS), this review paper systematically analyzes the research status and future development direction of 5 major fields of pavement engineering in China and abroad. This content includes advanced foundation treatment technology, embankment filling engineering properties, embankment structural performance evolution under multi-field coupling action, cutting slope stability analysis, subgrade retaining and protection. Overall, this review paper is able to provide references and insights for researchers and engineers in the field of subgrade engineering.

To reveal driver-vehicle-road interaction mechanism and their influence laws on driving safety and to predict dynamic change trend of driving risk,a unified model on driving risk field of driver-vehicle-road closed-loop system was constructed.Starting from field theory,a new concept,driving risk field was proposed,which was used to represent the driving risks caused by drivers,vehicles and roads.A kinetic field,which was determined by moving objects on roads,such as motor vehicles and non-motor vehicles,a potential field,which was determined by road environment factors,and a behavior field,which was determined by the driver's individual characteristics were included in the model.Moreover,the model's application in a typical car-following scenario was illustrated,which evaluated the risks caused by traffic factors.The results show that compared with the existing driving risk evaluation methods,the driving risk field can consider the synthetic influences of driver-vehicle-road on driving safety.In addition,the model can provide a new foundation for driving risk evaluation and active vehicle control under complex traffic environment.

In order to promote the development of China's tunnel engineering subject, the academic research status, hot issues, existing problems, correspondent countermeasures and development prospects about tunnel engineering at home and abroad were analyzed systematically. Firstly, China's tunnel engineering construction history and status quo, technology development and innovation were summarized and the development trend of tunnel engineering in the future was introduced. Secondly, tunnel engineering design theory and method were investigated systematically: drilling and blasting method, shield method, immersed method, cut and cover method, and anti-seismic and shock absorption design. Then from the aspect of different methods (including drilling and blasting method, shield method, TBM, immersed method, and cut and cover method), tunnel construction technology was dissected in detail. Finally, based on operation ventilation, operation lighting, disaster prevention and rescue, disease, maintenance and reinforcement, tunnel operation environment and security management were elaborated. This paper is supposed to provide new perspectives and basic data for academic researches on tunnel engineering subject.

The structural health monitoring (SHM) technique has been adopted for use with many large span bridges. However, massive SHM data have not been well interpreted to support structural maintenance and management. In this study, to introduce big data techniques into bridge SHM for data processing and analysis, the concepts and components of big data were first summarized, and data properties and research directions of SHM were then analyzed. Big data techniques applied to bridge SHM were then reviewed according to computing techniques and data analysis methods, based on which the requirements and application scenarios for SHM were presented in a big data analysis pipeline consisting of data preprocessing, data fusion, feature engineering, pattern recognition, and data visualization. Finally, the prospects and motivations of big data techniques in bridge SHM were generalized. The results demonstrate that structural condition assessment should be the primary application scenario for employing big data techniques in SHM. Computing techniques are not the priorities of big data research in SHM even though they do have some applications. Data fusion that aims to fuse multisource and heterogeneous data from SHM system and bridge management system urgently requires support from big data analysis methods. Ensemble learning and deep learning provide new methods to extract features that are sensitive to structural conditions and enable new prospects for SHM research. Supervised and unsupervised learning methods combined with massive monitoring data enable a more comprehensive understanding of pattern recognition problems in SHM than with a small amount of data. Novelty detection, correlation analysis, and transfer learning can be verified in damage detection problems and further developed to support their applications in real bridges. This study is expected to provide a reference for big data research in bridge SHM.

Owing to the advancement in autonomous driving technology, testing tools and testing methods for conventional automobiles cannot meet the validation requirements of autonomous vehicles. Scenario-based virtual validation methods have technical superiority with respect to testing efficiency and time consumption. Such methods can aid in conducting autopilot test verification in the future and have thus drawn significant research interest. In this study, through the systematic analysis of a large number of related literature, the developmental history of scenario-based virtual testing associated with autonomous vehicles is reviewed. The differences among scenario definitions were compared and the connotation of a test scenario was defined. Various types of elements, data sources, and processing methods associated with scenarios were specified, based on which, various virtual testing methods for autonomous vehicles were identified and listed. Typical virtual testing methods, test platforms, and virtual test points were subsequently analyzed, and key technologies corresponding to software-in-the-loop testing, hardware-in-the-loop testing, and vehicle-in-the-loop testing were outlined. To address the issue of inadequate testing efficiency associated with the virtual testing process, scenario-based automated driving acceleration test technology was studied. Typical random scenario test generation methods and crucial scenario reinforcement generation methods were thereby determined and listed. Furthermore, issues and future development trends associated with scenario-based virtual validation of autonomous vehicles were also analyzed. The obtained results indicate that scenario-based virtual testing is essential for promoting the development of autopilot technology. Additionally, further research needs to be conducted on aspects, such as the development of test scenario database based on deconstruction and automatic reconfiguration, high-confidence models for human-vehicle-environment integration system, primary technologies for supporting virtual testing of automated vehicle driving through standard tool chains, mixed traffic simulation with testing under different autonomous vehicle penetration rates, iterative optimization and adaptive acceleration testing of automated driving, and establishment of standard systems for virtual testing of autonomous vehicles.

Because of the complexity of transfer mechanisms and the diversity of shear failure modes of reinforced concrete (RC) beams, the accuracy of current shear capacity equations fluctuates obviously with variations in shear parameters, and the scope of these equations is limited. Based on the distinct failure mechanism in concrete compression zone (CCZ), a modified formula for the height of CCZ was proposed in this study from the perspective of preventing early yielding of longitudinal reinforcement, and the concrete shear expression compatible with both low- and high-strength RC beams is obtained. Second, through the rotation law of diagonal crack angle, different stages of the cooperative working mechanism between concrete and stirrups were analyzed, and the calculation principle of the shear contribution of stirrups was proposed. Furthermore, the shear capacity formula of RC beams with web reinforcement based on rezoned compression zone was established. The sub-items of the formula directly reflect the shear contribution of three parts, namely, the shear compression zone, diagonal tension zone, and stirrups. In addition, the formula reflects the influences of the main shear parameters such as concrete strength, longitudinal reinforcement ratio, stirrup ratio, shear span to depth ratio, and size effect. Finally, based on a shear database, the proposed and current commonly used formulas were verified, and the prediction accuracy and parameter sensitivity of each formula were compared and evaluated. The results show that the adopted distinct failure mechanism in CCZ can reflect the evolution of shear failure modes with shear span ratio. The proposed shear capacity formula has higher accuracy and stability, is less sensitive to a wide range of changes in shear parameters, and has better applicability to high-strength and large-size specimens.

In order to promote the development of China's bridge engineering subject, the academic research status, hot issues, existing problems, correspondent countermeasures and development prospects about bridge engineering at home and abroad (including high performance materials, function of bridge and its analysis, bridge design theories, steel and composite structure bridges, bridge disaster prevention and mitigation, bridge foundation, and bridge monitoring, evaluation and reinforcement) were studied systematically. Firstly, China's bridge engineering construction achievements were summarized and the development trend of bridge engineering in the future was introduced. Secondly, all aspects of the field in bridge engineering were analyzed in detail: ultra high performance concrete (UHPC) and CFRP materials in high performance materials; vehicle load and temperature in bridge function; anti-fatigue design of steel bridge, its maintenance technology and steel-concrete composite bridges in steel and composite bridges; and seismic performance, wind resistance, fire resistance, anti-explosion, collision and more than one disasters, multi-disaster coupling in bridge disaster prevention and mitigation. Finally, the mechanical characteristics and construction control in the jointless bridges, bridge decks, cable-stayed bridges during construction and the impact of computer technology on bridge engineering were analyzed. This paper is supposed to provide new perspectives and basic data for academic researches on bridge engineering subject.

To provide references to construction of a long sea-crossing steel bridge, the construction project of Hong Kong-Zhuhai-Macao Bridge (HZMB) were summarized. The project construction constraints, project goal & concept, and bridge landscape design were introduced, which showed the main consideration factors for long steel bridge type selection including seismic performance, durability, constructability, structure operation & maintenance and environment protection. For the design issues, emphasis has given to key points of fatigue design, optimized parameters results, fatigue structure detail and the full-size fatigue model test of the orthotropic steel panel of single-cell cantilevered box girder, and the respond condition of tuned mass damper to vortex shedding was introduced. For the construction quality control, the technical management for specialized bridge engineering products was introduced based on technical requirement of quality control/quality assurance QA/QC, quality control and acceptance standard. Several firstly used standards including new technologies (stainless steel bars, girder maintenance vehicle etc.) can provide a reference for the establishment and improvement of standard in Chinese industry. New technology and skills of processing, fabrication, welding and testing in the production of steel structure were introduced, the requirement for which can increase production efficiency, improve working environment for workers, eliminate man-made error, improve production precisions and maintain the quality stability of steel structure. Then the erection methods for the three cable-stayed bridges were introduced for offshore lifting. For the coating protection and maintenance, environment protection indicators such as content limitation of volatile organic compounds (VOC) and characteristics of maintenance vehicle system inside and outside the girder box were introduced. The results show that the requirements of Four Standardizations has promoted the technical innovations of all construction process for steel structure and application in mechanized, automated manufacture, and application of information technology, and has enhanced overall production capacity and management level of Chinese steel manufacture enterprises. Offshore prefabricated construction has promoted the development and applications of equipment with large structure and the innovation of lifting method. The successful experience has opened up a new path to design and construction of offshore bridge engineering; however, the effects of the paving scheme of steel deck remain to be verified in reality.

The research progress of active deicing and pavement snow melting technologies at home and abroad was summarized to understand the scope of improvement. First, the deicing and snow melting mechanisms of pavement were reviewed, and based on the mechanism, the pavements were categorized as self-stress flexible pavement, low freezing point pavement, and energy conversion pavement. Second, the pavement performance and snow melting characteristics of different pavements were analyzed. The pavement performance depends on the properties of both the asphalt and cement concrete pavements. Important aspects of the asphalt pavement include high-and low-temperature properties, water stability, adhesion properties, and durability. The tensile and compressive properties of cement concrete pavement are important as well. The snow melting characteristics include anti-friction performance of the pavement, bonding between snow layer and pavement surface, deicing performance, snow melting rate, applicable temperature, and long-term stability. The effects of material, structure, environment, and heating parameters on the working performance of active deicing and pavement snow melting were also analyzed in detail. For pavement selection, the advantages of different active deicing technologies were compared based on the snow melting effects, economic cost, energy saving, and environmental protection. Finally, it was proposed that the active deicing and snow melting systems be combined with the snow disaster-assessment system and early snow warning system.

In order to improve the technology of highway bridge inspection and evaluation in China, the current situations and trends of structure inspection and condition assessment of bridges were summarized. Damage of the appearance of the bridge, internal defects, principles of inspection of geometry and mechanical characteristics, content and methods of inspection were analyzed in detail. Meanwhile, current situations of the comprehensive inspection technology of prestressed force for PC bridges were commented. Meanwhile, the methods for safety evaluation of in-service RC bridges and PC bridges were summarized, with a summary of the latest research results of the evaluation of fatigue life capability for steel bridge. The comprehensive analyses show that, the intelligent nondestructive testing is the development trend of bridge inspection technology. The intelligent inspection technologies, such as image recognition and sonic CT technology, are widely applied to the inspection of damage of the bridge appearance and internal defects. Comprehensive prestressed inspection technology characterized by prestressed positioning, corrosion, grouting compactness and the tension of prestressed tendon provides a significant method to evaluate the bearing capacity of in-service prestressed concrete. As for the evaluation technology of concrete bridge, the concrete bridge damage evaluation method featured by crack properties, and prestressed condition extends the possibility of quantitative evaluations for the safety of in-service damaged concrete bridge. Finally, in the evaluation of the fatigue life capability of the steel bridge, the nominal stress method based on S-N curve of structural fatigue detail is the major method for evaluation. Whereas, the fracture mechanics method featured on the modern crack detection technology is promising in the evaluation of the fatigue life capability of the steel bridge.

To promote the development of intelligent pavement, the development status of intelligent pavement technologies and future development trends are reviewed. The paper firstly addresses the definition of intelligent pavement. Accordingly, the architecture of intelligent pavement is explicitly specified, which is divided into the following layers:information perception and acquisition, information integration and processing, integrated service, and energy supply. Then, the major technologies of intelligent pavement are highlighted, including information acquisition technology, information management and analysis technology, energy collection and utilization technology, self-adaptive technology, and cooperative vehicle and infrastructure technology based on intelligent pavement. Moreover, the design and construction methods of intelligent pavement are discussed. Finally, the problems and shortcomings of the status of current research are specified, as well as prospects for the future development of intelligent pavement. Results show that intelligent pavement is composed of specific structural materials, perceptive networks, information centers, communication networks, and energy systems that possesses various intelligent capabilities to provide services for humans, vehicles, and the environment. The development of intelligent pavement will help develop the road network potential and help it to adapt to future vehicles. In terms of the process of pavement information acquisition, the technical difficulties involved with the durability and practicability of sensors still need to be solved. Various energy collection and self-adaptive technologies of intelligent pavement should focus on low cost and high performance issues. The Internet of Things, big data, cloud computing, and various artificial intelligence methods have broad application prospects in the monitoring and management of intelligent pavement. As a new type of pavement, the design and construction of intelligent pavement can be combined with building information modeling, modular road construction, 3D printing technology, and intelligent compaction technology to integrate a new set of construction technologies.

To promote the development of China's new energy automobile industry and technology, the current status of several key links in China's new energy automobile industrial chain, including the integrated industry of new energy vehicles, key components, and infrastructures were systematically reviewed in this article, starting from the development status of domestic new energy vehicles. In addition to the progress made in domestic new energy vehicle technology, progress in power battery technology, driving motor technology, and fuel cell technology were summarized. Next, the gaps and deficiencies in the development of new energy vehicles in China were analyzed and summarized by benchmarking the technological frontiers of international pure electric vehicles, plug-in hybrid electric vehicles, fuel cell vehicles, power battery, and driving system. Based on the analysis of the current status, the existing problems in the development of new energy vehicles in China were extensively analyzed from six different aspects, namely strategic policy, core technology, research and development production, industrial system, demonstration and promotion, and product sales. Furthermore, the countermeasures and suggestions for the future industrial development of China's new energy vehicles and directions for technological breakthroughs were provided from six different aspects, namely top layer design, independent innovation, basic support, industrial ecology, support system, and business model. Finally, the development paths of domestic new energy automobile industry and technology for the future were discussed. In terms of industrial layout, enterprises dealing with vehicles and their related parts should be rationally arranged to promote enterprise clustering and industrial agglomeration. For pure electric vehicles, the development of an integrated electric chassis and the new power battery system should be prioritized. For plug-in hybrid electric vehicles, attention should be focused on high-performance hybrid powertrains and the dedicated engines and dynamic coordinated control technologies. For fuel cell vehicles, the development of fuel cell stacks and key materials should be the focus while considering the development of fuel cell systems and core components.

Authors reviewed the development of car following theory from a system point of view. Based on the modeling ideas, car following models were divided into point of view of traffic engineering and statistical physics. In the point of view of traffic engineering, car following models were classified into stimulus-response models, safety distance models, psycho-physical models and artificial intelligence models. In the point of view of statistical physics, car following models were classified into optimal velocity models, intelligent driver models, and cellular automata models. Then, various types of modeling ideas, model structure, parameter calibration, and related research were elaborated. Finally, development trends and research directions of car following models were proposed. It can provide reference for car following modeling of considering traffic flow characteristics in China.

In order to raise the quality of small and medium span bridge and explore the adaptation of steel-concrete composite girders in China, indexes was analyzed including the material utilization amount per square meter of concrete and steel, prefabricated weight of units, construction convenience, replacement of components and quality controllability of 5 bridge girders with close spans by comparison method, based on the standard drawing of U-shaped steel plate composite girders, I-shaped steel plate composite girder in America, and standard drawing of prefabricated pre-stressed concrete slabs, T-shaped girder and box girder assembled by Ministry of Transport of China. Based on it, a connotation of steel-composite girder bridges with small and medium span was put forward based on material, type of cross section, structure and bridge system. The results of economic comparison show that, in the bridge span of 5-20 m, the concrete amount of U-shaped composite girders is just 1/5 of the prefabricated pre-stressed concrete slabs, and the steel amount is almost the same. In the span of 20-40 m, the concrete amount of I shaped steel plate composite girder is about 1/3-1/2 of the prefabricated pre-stressed concrete T shaped girder and box girder, while the steel amount is about 3/2. The results of technical comparison show that, composite girder is with high industrialization degree and quality controllability, light unit weight, simple splicing and connection structure, as well as the fast construction speed. The redundancy of multi-girder is high and it is convenient to replace members. Adopting integration and information technology of the design, construction and maintenance, integration technology of structural and attaching facilities, the high performance composite girder with high bearing capacity, disaster bearing and construction efficiency can be built.

To clarify the progress in research on eco-driving in China and abroad, advances in eco-driving were reviewed including its impact factors, control strategies, effects, and implications. The following impact factors on eco-driving were introduced: driver personality, external stimulus information, road and traffic conditions, vehicle characteristics, and driving parameters. Further, an optimized control strategy for eco-driving was introduced, and its effects were analyzed. Finally, the implications of eco-driving were summarized, including static and dynamic eco-driving training methods, eco-driving assistance systems, and ecological intelligent transportation. The analysis of the research indicated that eco-driving can reduce fuel consumption by approximately 30% and reduce pollutant emissions by 20%-30%, without changing the structure of the vehicle. In addition, further research is required to establish the theoretical foundations of eco-driving strategies, and to develop an ecological driving assistance system that is suitable for China both quantitatively and visually. Finally, it will be necessary to strengthen the promotion of eco-driving and incorporate it into the driving test training system, so as to comprehensively save energy and reduce emissions in China.

In order to promote the development of China's road engineering subject, the academic research status, hot issues, existing problems, correspondent countermeasures and development prospects about road engineering at home and abroad (including subgrade engineering, pavement engineering, highway retaining structures, road geometric designs) were studied systematically. Firstly, subgrade settlement and deformation characteristics, settlement controls in subgrade widening, subgrade stability analysis methods, and special subgrade treatment techniques, etc. were reviewed. Secondly, asphalt and its mixtures, cement concrete pavements and pavements in permafrost regions were analyzed respectively. Then based on the characteristics of retaining structures, the application conditions of highway retaining walls, their strengthening principles, the calculations in their designs and so on were summarized. Finally, new ideas and techniques in the intelligent alignment selection, 3D road design technology, designs of road intersections, vehicle driving characteristics prediction technology for route designs, alignment design quality evaluation technology, etc. were dissected. Hopefully, the research can provide new perspectives and basic data for the academic researches on road engineering subject.

Vehicles will be the principal form of road traffic load in the future, and their operational stability is directly related to the skid resistance performance of asphalt pavements. The anti-sliding performance of asphalt pavements is affected by various uncertain factors. To understand the current status of research on skid resistance performance in asphalt pavement fields at home and abroad, current research advances on several topics were overviewed and summarized. These topics included contact mechanical models for tire-pavements, road adhesion properties, calculation method for kinetic friction coefficients, uncertainty factors, evaluation indices, and attenuation models of anti-sliding performance. The research also focused on the applications of anti-skid performance in the safety of autonomous vehicles. The existing contact mechanical methods of tire-pavement were comparatively analyzed, the uncertain factors in the design, construction and operation stage were discussed, and the existing evaluation indices and attenuation models of skid resistance performance were summarized. Finally, prospective developments in the skid resistance performance of asphalt pavements were discussed. Analysis results show that Persson's theory of hysteresis friction, which is based on fractal theory, is applicable to the calculation of the dynamic friction coefficient of asphalt pavements. The dimensional deformation of rubber as a response to surface roughness and the temperature dependence of sliding friction were also considered. The adhesion coefficient estimation method based on the μ-s curve could estimate the actual adhesion characteristics of asphalt pavement more accurately by considering the variability of the peak adhesion coefficient of the road surface. There are several limitations in the current research associated with skid resistance of asphalt pavements, including the tire-pavement interaction mechanism, evaluation indices, and attenuation models. Further research should be focused on time-varying characteristics, uniformity, and perception parameters for the skid resistance requirements of autonomous vehicles. To summarize, the implementation of the anti-sliding evaluation index based on time effects is invaluable in the development of pavement anti-sliding layer designs and evaluation of asphalt pavement skid resistance. It is also an important way to improve the service performance throughout the lifetime of asphalt pavements in China.

In order to further improve the precision and efficiency of pavement disasters using two-dimensional images, convolutional neural network (CNN) was introduced to recognize and measure pavement disasters. First, pavement images were divided into equal-sized maps, which were used as training samples of disaster recognition CNN. Then disaster recognition CNN1 was established by the structural design, before-feedback algorithm and sample tests. Subsequently, all equal-sized maps were input into well-trained disaster recognition CNN1, and the results were used as training samples of crack feature extraction model CNN2 and pit slot feature extraction model CNN3. Meanwhile, the crack feature extraction model CNN2 and the pit slot feature extraction model CNN3 were established with the same procedures. Afterwards, the pavement crack and images of pit slot were extracted by well-trained CNN2 and CNN3. Last but not least, the influences of image resolution ratio on the CNN recognition, precision of feature extraction, and efficiency were analyzed. The results show that various pavement disasters can be accurately recognized by CNN1, and the average errors of crack length and crack width of CNN2 are 4.27% and 9.37% respectively. The accuracy rate of crack disease severity level is 98.99%. There is no error of the number of pit slot CNN3, and the average error of each pit slot area is 13.43%. The accuracy rate of pit slot disease severity level is 95.32%. Thus CNN systems show high accuracy. The disaster recognition CNN1 and feature extraction CNN2 for testing original images in CPU conditions take up to 704 ms·sheet^-1 and 5 376 ms·sheet^-1 on average, whilst the disaster recognition CNN1 and feature extraction CNN2 for testing images after the acceleration by graphics processor in GPU conditions take up to 192 ms·sheet^-1 and 1 024 ms·sheet^-1 on average. Thus CNN systems present high efficiency in GPU condition. Compared with other methods, CNN presents high accuracy and efficiency in recognition and measurement of cracks and pit slot when image solutions are higher than 70 dpi.

In the process of driving a vehicle, drivers always face high or low risks caused either by their own or due to the external conditions, i.e. the driving risks. Identification, analysis, and evaluation of driving risks hence serve as an effective countermeasure for risk management. The key problems in gaining a complete understanding of dangerous driving behaviors and the research progress of driving risks observed in numerous types of drivers are summarized. From the perspective of individual characteristics and driving behaviors of the drivers, this paper explores the status of current research in this field using the mapping knowledge domain (MKD) to explain the development process and structural relationship of different driving risks studies. Through the Web of Science Core Collection database, this paper obtained 3 406 articles in English literature that were related to driving risks, which were published between 1986 and 2020 (up to 29th February, 2020). It was observed that this collection covered the studies from a total of 8 684 authors and obtained 6 018 related key words, and were systematically analyzed based on the method of MKD. The analysis shows that the international research in the field of driving risk mainly focuses on young drivers, old drivers, novice drivers and professional drivers; moreover, it was centered on the topics of alcohol driving, drug driving, distracted driving, and fatigue driving. When compared with the international research, several studies in the field of distracted driving and fatigue driving are available in China. However, the research and experimental methods for drunk driving and drug driving are relatively scant. Furthermore, for the selection of research objects, it is necessary to increase the in-depth research on the elderly drivers and novice drivers, including the evaluation of fitness-to-drive along with the education training of the elderly drivers, as well as the exploration of feasibility among novice drivers' graduated driver license system.Concerning research methods, the common international methods include questionnaire surveys, driving simulator experiments, real vehicle experiments, and naturalistic driving studies. In comparison, the field of naturalistic driving studies has not been fully developed and utilized in China. In summary, a combination of various methods needs to be considered to promote a comprehensive understanding of driving behaviors and driving risks from different perspectives.

In order to deepen the understanding of the fatigue problem of orthotropic steel bridge deck (OSD), the fatigue performance and its evaluation methods of OSDs, new-type OSD structure and fatigue reinforcement of OSDs were analyzed and summarized. The main problems restricting fatigue research of OSDs were discussed. The current state and development tendency of the fatigue problem of OSDs were explored as well. The results show that compared with the fatigue problem of skeletal structures such as main girder and main truss, the fatigue problem of OSDs is a spatial structure fatigue problem codetermined by fatigue performance of multiple complex structural details, whose fatigue failure mode, fatigue performance, anti-fatigue optimization design and fatigue cracking reinforcement are more complex than skeletal structures. The fatigue damage mechanism, evaluation method of fatigue performance for building and existing OSDs as well as feasible method for fatigue reinforcement are important foundation for whole life-cycle design theory of steel bridge and research topic to be solved urgently in the sustainable development of bridge engineering. Relying on innovative design concept and high performance materials, the progresses of new structural system and details are the significant development orientations of OSDs. The advanced fabrication technology represented by intelligent manufacturing and detection technology of fatigue crack represented by infrared thermography (IRT) and ultrasonic phased array provide an important support for the further improvement of fatigue performance of OSDs and development of fatigue crack detection technology.

In order to promote the development of bridge incremental launching construction technology, the technology widely used in current bridge construction was reviewed. The method for determining key parameters of the launching nose, influence of beam construction accuracy on incremental launching process, force analysis of incremental launching process, force analysis of local stress and improvement measures and incremental launching construction control were introduced and summarized. The results show that the influences of local stress status in the process of multipoint incremental launching and construction error on bearing beam, and the optimization problem of cable tension when cable reinforcement method is used in substructure are still prominent. Finally, some existing problems on walking type incremental launching construction at present in China are mentioned and the further development trend of incremental launching construction is investigated.

To advance the development of bridge health monitoring (BHM) technology and ensure the safety of bridge operations, the current academic research status was investigated. The latest progress made by BHM in terms of systems and applicability, damage monitoring algorithms, data preprocessing, safety warning, and digital twin technology was reviewed. Then, current areas of active research and future development directions of BHM technology were identified. Comprehensive analysis shows that, in terms of the BHM system and its applicability, the correlation mechanism between structural response parameters and health indicators must be studied, and smart sensor devices with long-life noncontact automatic collection should be developed. Establishing an automated, networked, and intelligent integrated system for multisource data collection, transmission, storage, analysis, evaluation, and early warning is a key research direction. In terms of structural damage monitoring algorithms, methods of selecting different artificial neural networks and correction methods based on heterogeneous scenes are needed. Meanwhile, the construction of multilevel coupled intelligent algorithms based on data-driven and model correction real-time interaction for multisource information flow is a main focus of research. In terms of monitoring data preprocessing, further research on and development of multi-source heterogeneous data fusion methods based on deep learning are required. Dynamic signal extraction algorithms for damaged structures under the influence of complex environments must be established, and the precise separation of structure monitoring data must be realized. In terms of safety and early warning of damaged structures, early warning indicators and systems should be established to supplement conventional damage safety assessment based on reliability theory and monitoring data. The use of structural monitoring data to reflect overall mechanical behavior, combined with intelligent detection information of local damage for service performance evaluation, is an important development direction. Digital twin technology is still in its infancy in BHM. Integrating digital twin technology into multilevel composite algorithms, establishing a structured multisource heterogeneous big-data intelligent fusion mechanism, developing a digital interconnection, real-time interactive intelligent bridge operation, and maintenance monitoring system, are other important development directions.

In order to summarize the status and further research concerns of the theory and technology in seismic design for bridges, a brief review on state of the art of bridge seismic design was conducted. The design process based on component strength of a ductile system was introduced, and the framework and progress of the performance-based seismic design theory for bridges were expressed and discussed. Specifically, the displacement-based seismic design process and the full probability seismic design and evaluation method were introduced. The isolation and energy dissipation devices that were frequently used in practical bridges were briefly reviewed, including the configuration, the isolation mechanism, the analysis model, and the applications. The recent progress in seismic isolation for bridges and energy dissipation technique was introduced and discussed. The design objective of bridge seismic isolation was changing from seismic responses alleviation to structural performance control, including the performance control of the isolation system under the non-seismic loading and the post-earthquake structural performance and rehabilitation requirements during the life cycle. The recent research focus, for example, the new type of post-earthquake structural systems of resilience was discussed. The detailed configuration and mechanism of rocking foundation and prestressed segmental bridge columns were introduced, and advantages of resilient systems in post-earthquake performance were analyzed. Furthermore, the major concerns in bridge seismic design in the near future were discussed. Meanwhile, new design methods and new structural systems of bridges with recentering capacity and low damage features will be primarily concerned.

To promote the development of road construction machinery discipline in China, the research progress, hot topics, existing problems, specific countermeasures and development prospects of academic research in road construction engineering at home and abroad were systematically summarized from six aspects, including earthmoving machinery, compact machinery, pavement construction machinery, bridge machinery, tunnel machinery and maintenance machinery. In the aspect of the earthmoving machinery, the bulldozer, the excavator, the loader, the grader and so on were reviewed. Reviews of the compact technology and equipment included the static roller, the tire roller, the circular vibrating roller, the vertical vibrating roller, the impact roller, the intelligent compaction technology and equipment and so forth. Reviews of the road construction machinery included the asphalt mixing plant, the asphalt paver, the concrete batch plant, the concrete paving equipment, the stabilized soil mixing plant, etc. Reviews of the bridge machinery included the bridge girder erection machine, the moving form work bridge machine, etc. Reviews of the tunnel machinery included the ejector anchor machine, the shield tunneling machine, etc. As for the maintenance machinery, the sweeping machine, the deicing equipment, the inspection equipment, the asphalt miller, the recycler, the sealer, the cement road repair equipment and so on were reviewed. It is supposed to provide new perspectives and basic data for academic researches on road construction machinery engineering discipline.

Based on the technical framework of automated highway systems (AHSs), the influence of different driving factors such as primary application, communications technology, green energy technology, and automated driving technology, the evolution of concepts, development of technology, and future changes in intelligent roads (IRs) were reviewed in this paper. According to the current development trend in information technology, the concept and technical framework of IRs have been extended and expanded on the basis of studies on AHSs. The direction of evolution of the IR system in the future, and its system architecture, which consists of a management layer, network layer, and application layer, were presented. Meanwhile, focusing on the current popular technologies and the development direction of science and technology in the future, the status of research on emerging technologies driving the rapid development of IRs were summarized, such as ubiquitous wireless communication, high-precision positioning and navigation, vehicle platoon control, wireless charging, road intelligent materials, road active safety control technology, vehicle-to-road information interaction for Mobility-as-a-Service, intelligent decision planning technology combined with infrastructure, etc. Based on the development characteristics of these eight key technologies, some recommendations on the application and promotion of IR technology in the future are presented. Meanwhile, the influence and impact of emerging technologies such as vehicle-integrated integration, intelligence parallel systems, artificial intelligence, and traffic information security on the future development of IR were analyzed. Finally, this paper systematically predicted the commercialization promotion route of IR technologies, and that the application of IR will further reduce the cost of technologies and equipment in autonomous driving, providing a safer, more stable and efficient traffic environment for autonomous driving in the future. The research results of this paper have significance as reference for current and future technology research and development of IR and engineering applications of IR.

The vehicle-in-the-loop simulation test method can validate the performance of autonomous vehicles safely and efficiently in complex environments and extreme conditions. This paper develops an indoor rapid-testing platform for autonomous vehicles based on vehicle-in-the-loop. This platform is comprised of seven subsystems:front-axle rotatable drum bench, automobile test bench detection system, virtual scenario automatic generation subsystem, virtual sensor simulation subsystem, driving simulators, autonomous vehicle, and result analyzing and evaluating automatically subsystem. The driving resistance was simulated by independently loading torque on the rollers supporting the four wheels of the automobile, so that different road adhesion coefficients were simulated. Slope, roll, and yaw follower mechanisms were used to simulate three degrees-of-freedom such as the pitch angle, roll angle, and course angle. Virtual reality technology was adopted to simulate various road traffic scenarios to verify performance indicators, such as intelligent perception and decision-making behavior of the autonomous vehicle, by means of flexible integration of the vehicle dynamics model, sensor simulators, simulations of complex traffic environments, and test cases. A closed loop system was modeled by coupling the automobile, the virtual simulation scenarios and the test bench in order to research and develop a number of key technologies, including the structural design of multi degrees-of-freedom and high-dynamic detection bench, automatic reconstruction method of virtual test scenes, and methods of simulation and injection for sensor data, which can meet the need to test the performance of autonomous vehicles in various scenarios. Further, to verify the effectiveness of the test platform, U-turn trajectory tracking control was taken as a research example. Based on a simplified vehicle kinematics model and the Model Predictive Control algorithm, a large amount of experiments was performed in virtual scenarios of U-turns to test the efficiency of the trajectory tracking control algorithm on the autonomous vehicle. The results showed that the platform could simulate automobile driving conditions on the road realistically, and the trajectory tracking effect of the autonomous vehicle in the virtual scenario is satisfactory. The deviation from the predicted trajectory is less than 8%, which demonstrates the effectiveness of the test platform.

In order to lessen drawbacks of traditional bridge construction methods, accelerate the speed of bridge construction, reduce maintenance costs of bridges, and enhance the quality and the durability of bridges, the study analyzed the necessity and the development potentials of the accelerated bridge construction(ABC). It also described the basic systems and component divisions of the accelerated bridge construction, the types and developing trend of prefabricated bridge decks, the connections between concrete decks and steel girders. Three major types of the prefabricated bridge girders and material combinations, prestress systems and their major construction technologies of prestressed segmental concrete box girder bridges, and the main cross-sectional types and joint configurations of concrete or composite bridges for medium or short spans were presented. This article also discussed the applicability and the superiority of the precast high-performance concrete decks and the multi-beam composite bridges connected with group studs in the ABC for medium or short spans. The characteristics of integral precast piers recently used in bridges for crossing bays and long rivers in China were also discussed. This study focused on the current theoretical research methods and developments for ABC system, especially for the steel-concrete composite bridges, precast segmental concrete box girder bridges or the steel-concrete box girder bridge, and the precast segmental bridge pier and other bridge types. The problems that include the shear capacity of group studs, the mechanisms of joint connections between concrete decks and group studs, complex behavior analysis of composite beams, lateral load distributions of multi-girder bridges, dynamic influence analysis of the externally prestressed composite bridges, durability and fatigue of composite beams and others were investigated. Some deficiencies in the rapid construction of bridges in China, such as the study and development of ABC design, innovation of construction-bridge system mechanism, and similar issues. were pointed out. The key factors that restrict the development of this field were analyzed. Meanwhile, the development of bridge industrialization, information and ABC technology in China were outlooked. It was proposed that the ABC was a good alternative with great market potentials for many municipal or highway bridges that span from 25 m to 50 m span with limited girder heights or wide widths, including the bridges that are seasonally affected in northern of China. Important issues worthy of further research were put forward to promote advancement in the bridge infrastructure construction technology, innovation and development.

To evaluate the performance of existing car-following models when applied to Chinese drivers, five representative car-following models were calibrated and validated. Based on 60 Chinese drivers' driving data with a total mileage of 16×10⁴ km collected in the Shanghai Naturalistic Driving Study, 2 100 stable urban-expressway car-following periods were automatically extracted using radar and vehicle controller area network (CAN) data. A 5-fold cross validation technique was used to generate calibration and validation datasets. Specifically, the 50 car-following periods for each driver were randomly divided into five equal subsets; therefore, the model calibration and validation processes were repeated five times. In each iteration, four subsets were used to calibrate the car-following model and the remaining subset was used to conduct intra-driver validation. Based on the calibration dataset, values of parameters were calibrated using genetic algorithms for the Gazis-Herman-Rothery, Gipps, intelligent driver, full velocity difference, and Wiedemann models. The performance of these models on predicting inter-vehicle spacing were then validated with validation datasets. The results showed that the full velocity difference (FVD) model had the lowest error term on the validation dataset (21%), and the smallest standard deviation of errors. Compared to the Wiedemann model used by VISSIM, the FVD model is more easily calibrated and demonstrates a higher and more robust performance, justifying its suitability to be applied for microscopic traffic simulations in China. These results would be valuable for developing intelligent vehicles and microscopic traffic simulation tools tailored to the characteristics of Chinese drivers as well as road and traffic environments in China.

Weathering steel (WS) with superior durability has already attracted the extensive attention of bridge designers, and it has become an inevitable trend to expand the application of WS bridges in China. In view of the present lack of design theory and methodology of WS bridges in the country, the application and research status of WS, and the design methodology of WS bridges were reviewed in this study. This was done by reviewing the domestic and overseas literature on WS and WS bridges, and by referring to the construction experience of WS bridges in America, Japan, and Europe. The achievements and relevant issues of the existing studies were summarized and analyzed, including the corrosion mechanism of WS under the coupling effect of environment and load, degradation in mechanical properties of WS after corrosion, design theory and detail design method of WS bridges, and so on. Analysis results show that when the Cl^- and SO₂ concentrations are below 3 mg·(m²·d)^-1 and 20 mg·(m²·d)^-1 in the atmosphere, respectively, or the ISO corrosivity category is C2, C3 in the non-marine atmospheres, the application of unpainted WS is feasible. The cracking and spalling of protective rust layers is observed when the WS specimen is subjected to load. It provides a channel for oxygen diffusion, which weakens the protection of rust layers to the substrate and causes further corrosion of steel. In this case, localized corrosion is more likely to occur. The inappropriate use of unpainted WS can cause severe corrosion, which results in the degradation of mechanical properties of WS, especially in the states of stress corrosion and corrosion fatigue. A detailed design method of the steel bridges is essential to ensure the corrosion resistance of WS. Regular maintenance can prolong the service life of the structure. Life-cycle cost of steel bridges is significantly reduced with the application of WS. The analysis results can provide an effective reference for further studies on the corrosion mechanism and mechanical properties of WS in the future and are useful for the design and construction of WS bridges.

The Lighthill, Whitham, and Richards (LWR) model can be used to describe the macroscopic state of traffic flow. In addition, the study of the LWR model for a mixed traffic flow containing cooperative adaptive cruise control (CACC) vehicles and manual vehicles in connected and autonomous vehicular environments can provide theoretical tools for the analysis of the macroscopic dynamic characteristics of mixed traffic flow. The CACC model, validated by the partners for advanced transit and highways (PATH) of California, Berkeley using test data, was employed as the car-following model of CACC vehicles. Moreover, the intelligent driver model (IDM) was used as the manual driven model in the connected and autonomous vehicular environment. The fundamental diagram under different CACC penetrations was derived, and the tangent slope of the mixed fundamental diagram was then theoretically proved to be the wave speed propagating through the mixed platoon. Based on this, the framework for the LWR model of mixed traffic flow was built, and then, the LWR model for such a traffic flow mixed with CACC vehicles was obtained. Finally, numerical simulations were performed to study the characteristics of shockwaves, under six different equilibrium conditions. The results indicate that the LWR model obtained is capable of adequately describing the shockwave speeds in the mixed traffic flow, under different CACC penetrations. The relative errors of theoretical shockwave speeds and simulation values are controlled to be below 10%, under different CACC penetrations. It is noted that the relative errors are relatively large, approximately 19% to 26% when the shockwave is transforming from a forward wave to a backward wave; however, the absolute errors are still small. The research results can provide a reference for describing the macroscopic state of traffic flow mixed with CACC vehicles, and benefit the research progress of other macroscopic models for such a mixed traffic flow. Further, the proposed framework for the LWR model of mixed traffic flow can be applied to various CACC and manual-connected car-following models. In addition, the framework can provide theoretical support for other types of mixed traffic flow when an LWR model is required.

In the process of road traffic infrastructure construction and maintenance, we are facing significant issues such as the traffic safety and efficiency, and the harmony between human and nature. In view of the above problems, the incompatibilities between urban compact pavement and social development needs were analyzed, and a concept of using porous materials as an eco-friendly pavement material was proposed. The appliance of porous materials on pavement makes it possible to add environmental protection functions such as water permeation, noise reduction, heat dissipation and tail gas decomposition to the traffic function. Furthermore, the design concepts, research progress and key issues of the design framework of eco-friendly porous pavement materials were further discussed. It is of great significance to further study the function and performance of porous pavement materials, the mechanical model of the porous structure, and behavior theory. Because it can not only expand the function of the pavement, but also enrich and develop the knowledge system of modern road engineering and related subject, and promote the development of modern road engineering technology and the development of related social industries.

In order to promote the theoretical development of vehicle-bridge interaction (VBI) and application of VBI simulation techniques, this review systematically summarizes the state of the art, remaining gaps, and predicted trends in the research field of VBI in terms of both theory and application. From a theoretical perspective, numerical models for vehicles, bridges, and road surface roughness, as well as numerical methods for solving the time-variant dynamical system of VBI, were thoroughly examined. Following a comprehensive review, it was found that these numerical models are able to achieve increasingly realistic simulations of VBI. For future theoretical research, it is advised that finite element modeling techniques and optimized numerical methods should be improved upon to further increase the accuracy and efficiency of VBI simulation. From an application perspective, six applications of VBI (dynamic impact factor, fatigue of highway bridges, damage detection, vibration control, ease of driving on bridges, and vehicle weight identification) are discussed to highlight the uses of VBI in research fields relating to bridge safety and serviceability. The remaining gaps in these research areas are also identified and corresponding future research is proposed. The current research demonstrates that VBI simulation has become an important tool in many relevant research fields, while its applications also show promising prospects in other related fields. For future research, the suitability and accuracy of VBI models need to be adjusted for the specific issues targeted, relevant theories need to be further developed for targeted research, and existing technologies need to be improved from the perspective of engineering practice.