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    25 February 2025, Volume 53 Issue 2
    Traffic Safety
    NIU Shifeng, TAI Yinghao, CHANG Dongfeng, YU Pengcheng
    2025, 53(2):  1-11.  doi:10.12141/j.issn.1000-565X.240189
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    Single-vehicle accidents often occur in time periods with low traffic volume and poor road conditions, and their fatality rate is significantly higher than the average mortality rate of traffic accidents. To explore the key factors affecting the accident severity degree of single-vehicle accidents, based on the single-vehicle traffic accident data from 2015 to 2019 in some regions of China, this paper selected 24 accident-influencing factors from aspects such as people, vehicles, roads, and the environment. The temporal stability of the accident data was tested by the log-likelihood ratio test which found that there was temporal instability in the accident data, so it should be divided into five years for separate modeling. Then, a random parameter Logit model considering the mean-variance heterogeneity was constructed. The marginal effects of accident factor variables were compared. The results show that the temporal stability models of the five different years all have good fitting effects. The model can effectively capture the unobserved heterogeneity, and the captured parameters under different time models also exhibit randomness. The results of model parameter estimation indicate that four accident factors, namely the type of intersection and road section, passenger cars, motorcycles, and accident liability, have temporal stability, while other accident-influencing factors only have significant effects in individual years. The accident factor of protective facilities also have temporal stability. Accident factor variables such as passenger cars, motorcycles, the state of vehicle headlights, vehicle safety conditions, hitting fixed objects, and accident liability will significantly increase the possibility of casualties in single-vehicle accidents. Variables such as the type of protective facilities and visibility greater than 100 meters will significantly reduce the severity of injuries.

    ZHANG Chi, GUO Tingyu, HU Ruilai, GAO Yanyang, ZHOU Yuming
    2025, 53(2):  12-26.  doi:10.12141/j.issn.1000-565X.230674
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    Excessive temperature of the truck brake hub is a primary factor leading to brake failure. To enhance the safety of trucks traveling on continuous downhill sections, this study refined the average longitudinal slope design parameters and investigated the correlation between driver braking behavior and the temperature rise characte-ristics of truck brake hubs. Based on driver braking behavior, it proposed a reliability design method for longitudinal slope length. Firstly, a continuous downhill section of an expressway in the western mountainous area was selected for real vehicle test, and the road longitudinal slope parameters and driver braking behavior data were collected. Secondly, according to the measured data, the evaluation indexes were proposed: displacement intensity coefficient and brake hub temperature gradient. This study investigated the relationship between displacement intensity coefficient and road profile, both longitudinal and transverse, as well as the relationship between displacement intensity coefficient and brake hub temperature gradient through regression analysis. Finally, a reliability model was constructed based on the driver’s braking behavior and critical temperature. Using the Monte Carlo simulation, critical slope lengths corresponding to different average longitudinal slopes on continuous downhill sections were determined and compared with the specification. The results indicated that there is a weak correlation between the radius of the circular curve and the displacement intensity coefficient, while there is a significant positively correlation between the longitudinal slope gradient and the displacement intensity coefficient, and the goodness of fit r2 is 0.95. When the longitudinal slope gradient is greater than 2%, the braking measures taken by drivers are mostly sustained braking, which is more different from the braking behavior of drivers mostly taking point braking when the longitudinal slope gradient is less than 2%. The displacement intensity coefficient and the temperature gradient of the braking hub are significantly positively correlated with the goodness-of-fit r2 is 0.845. When the proportion of the driver braking for 85%, the braking behavior of the driver at this time with the specification of defining the conditions of the slope length is basically the same. When the reliability is 0.95, the average longitudinal slope is 2.1%~3.0%, and the critical value of the continuous slope length is 14.95~30.12 km. The given reference values take into account the randomness in the real driving environment, and provide a basis for the design of the slope length with an average slope of less than 2.5%.

    REN Wenhao, ZHAO Xiaohua, CHEN Chen, FU Qiang
    2025, 53(2):  27-37.  doi:10.12141/j.issn.1000-565X.240122
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    Freeway driving in foggy conditions poses significant safety risks and accident hazards. The connected collision warning information system (CCWIS) offers a novel approach to addressing this challenge, and its impact on driving behavior is fundamental to demonstrating its effectiveness. This study employed driving simulation technology to create a CCWIS testing platform. Considering dense fog weather conditions, it designs two driving environments: a baseline traditional and a comparative connected. And a typical collision risk scenario involving a sudden braking maneuver by a slow-moving vehicle ahead was constructed. A total of 27 participants were recruited to conduct driving simulation experiments to yield fine-grained microscopic data on driving behavior. An evaluation indicator system was developed from multiple dimensions, including stability, safety, and compliance, to quantitatively describe and statistically analyze the effectiveness of CCWIS during different interaction stages with the lead vehicle (slow-speed car-following and the frout vehicle emergency braking stage). The results indicate that, regarding stability, collision warning information may lead to a decrease in driving stability for a period during the slow-speed car-following stage. After the vehicle in the slow-speed car-following stage has decelerated to a stable state and during the front vehicle emergency braking stage, it exhibits better stability compared to scenarios without collision warning information. In terms of safety, collision warning information significantly reduces risks in terms of time, acceleration, and distance across multiple dimensions during the driving process. Regarding compliance, collision warning information can improve the level of driver compliance with preceding vehicle information, reducing the differences in driver compliance with preceding vehicle information between the slow-speed car-following and the front vehicle emergency braking stages. The results of this study can provide platform and theoretical support for the test and application of connected collision warning information systems in foggy environments of freeways.

    WU Biao, REN Hongze, ZHENG Lianqing, ZHU Xichan, MA Zhixiong
    2025, 53(2):  38-47.  doi:10.12141/j.issn.1000-565X.240346
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    As the focus of research and development of intelligent connected vehicles, the test and evaluation of autonomous driving systems must focus on the real performance of vehicles in complex weather and complex traffic flow scenarios. This research proposed a method for constructing complex scenarios based on weather complexity and traffic complexity to meet the testing requirements of intelligent driving systems in challenging traffic environments. Using natural driving data from China’s large-scale field operational test project (China-FOT), the study analyzed vehicle dynamics parameters such as speed, longitudinal acceleration, lateral acceleration, and yaw rate. By fitting safety boundary envelopes, driving behavior risk levels were defined, and hazardous scenarios in natural driving were identified. These scenarios help clarify the fundamental scene types related to the functional safety of navigation-based intelligent driving. A traffic interaction coupling method, incorporating multiple dynamic target features, was applied to construct complex scenario types. The quantified natural weather factors were used to construct influence indicators, such as light factor, rainfall factor, fog factor, which are employed to characterize the weather complexity through the distribution of natural driving behavior characteristics. The complexity parameters, including encounter angle, relative distance, relative speed, were constructed using the Support Vector Machines and K-fold cross validation methods to characterize the traffic state of the complex scenarios. In order to ascertain the complexity of the test scenario, a closed field vehicle test was conducted, during which the real test performance evaluation parameters were employed to verify the rationality of the complex scenario construction. This research indicates the necessity to construct a test scenario that can accurately portray the real-world complex traffic environment for the navigation pilot driving functions. This will facilitate the optimization and iteration of the autonomous driving system of intelligent connected vehicles.

    YUE Yongheng, LEI Wenpeng
    2025, 53(2):  48-57.  doi:10.12141/j.issn.1000-565X.240225
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    In response to the issue of reduced road environment perception accuracy for intelligent vehicles under extreme haze conditions, this paper proposed a joint haze environment perception algorithm based on an improved CycleGAN and YOLOv8. Firstly, the CycleGAN algorithm was used as the framework for image defogging preprocessing. A self-attention mechanism was incorporated into the generator network to enhance the network’s feature extraction capability. Additionally, to minimize color discrepancies with real images, a self-regularized color loss function was introduced. Secondly, in the object detection phase, the lightweight GhostConv network was first used to replace the original backbone network, reducing computational complexity. Furthermore, the GAM attention mechanism was added to the neck network to effectively improve the network’s ability to interact with global information. Finally, the WIoU loss function was used to mitigate harmful gradients caused by low-quality samples, improving the model’s convergence speed. Experiments conducted on the RESIDE and BDD100k datasets validate the proposed algorithm. Results show that the structural similarity between dehazed and original images is 85%. Compared to the original CycleGAN algorithm and the AODNet algorithm, the proposed approach improves the peak signal-to-noise ratio (PSNR) by 2.24 dB and 2.5 dB, respectively, and the structural similarity index (SSIM) by 15.4% and 36.3%, respectively. Additionally, the improved YOLOv8 algorithm demonstrates enhancements over the original algorithm, with precision, recall, and mean average precision (mAP) increasing by 2.5%, 1.8%, and 1.1%, respectively. The experimental results confirm that the proposed algorithm outperforms traditional algorithms in terms of recall and detection accuracy, demonstrating its practical value

    Traffic & Transportation Engineering
    BI Jun, WANG Jianing, WANG Yongxing
    2025, 53(2):  58-67.  doi:10.12141/j.issn.1000-565X.240219
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    The prediction of the number of available charging piles in public charging stations is of great significance for the formulation of intelligent charging recommendation strategy and the reduction of users’ charging queue time. At present, the research on the operating state of charging stations typically focuses on charging load forecasting, with relatively little attention given to the utilization of charging piles within the stations. Additionally, there is a lack of support from real-world data. Therefore, based on the actual operation data of charging stations, this paper proposed a prediction model of available charging piles in charging stations based on the combination of long short-term memory network (LSTM) and fully connected network (FC), which effectively combines the historical charging state sequence and related features. Firstly, the order data from a specific charging station in Lanzhou was transformed into the number of available charging piles, followed by data preprocessing. Secondly, an LSTM-FC-based predictive model for the operational status of the charging station was proposed. Finally, three parameters—input step size, number of hidden layer neurons, and output step size—were individually tested. To validate the predictive performance of the LSTM-FC model, it was compared with the original LSTM network, BP neural network model, and support vector regression (SVR) model. The results show that the mean absolute percentage error of LSTM-FC model is reduced by 0.247%, 1.161% and 2.204% respectively, which shows high prediction accuracy.

    WANG Xiaofei, LUO Zhen, WANG Shaohua, PAN Ling, ZENG Qiang
    2025, 53(2):  68-79.  doi:10.12141/j.issn.1000-565X.240047
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    China’s “14th Five-Year Plan” places higher demands on green transportation development, with emissions from traffic operations being the primary source of carbon emissions in the transportation sector. To investigate the factors influencing carbon emissions of passenger cars on highway curved segments, this study conducted on-site driving tests using OBD-equipped vehicles to collect driving data from typical curved road segments in Guangdong Province, and obtains carbon emission data through the IPCC carbon emission accounting method. Re-levant evaluation indicators influencing passenger car emissions were selected based on road alignment, and gray relational analysis was used to calculate the correlations between these indicators. The results indicate that among the geometric alignment elements of horizontal curve sections, indicators such as the proportion of transition curve length and transition curve parameters are significantly correlated with the segmental carbon emission rate. The radius of the circular curve is also significantly correlated within a specific range. For non-geometric factors, indicators such as the standard deviation and mean of acceleration show significant correlations with carbon emissions, and these two indicators are further associated with geometric factors like transition curve parameters and the proportion of transition curve length. Based on the results of the grey relational analysis, eight correlated indicators were selected, and a grey GM(1, N) model was developed to predict the total carbon emissions of passenger cars on horizontal curve sections. The prediction results show an average relative error of 5.10% compared to the actual values. The predictive performance of the model surpasses that of traditional multiple regression models, demonstrating outstanding performance and reliability in scenarios with limited data.The findings of this study can identify key design and operational parameters significantly influencing carbon emissions, providing a theoretical basis for the low-carbon optimization and management of highway horizontal curve sections.

    ZHANG Yandi, HUI Bing, MA Ziye, LI Yuanle, WANG Hainian
    2025, 53(2):  80-91.  doi:10.12141/j.issn.1000-565X.240152
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    In order to accurately quantify aggregate loss in chip seals and address the limitations of traditional methods that overlook the shape and orientation of chip seals, this study utilized indoor 3D laser scanning equipment to capture point cloud data of chip seals before and after stripping. By introducing the minimum intra-class variance, the elevation segmentation threshold was determined, allowing for the spatial stripping contours. This enables the calculation of stripping area indicators and provides the error distribution of the laser method for measu-ring stripping areas. Individual stripped aggregates were reassembled, and the stripping mass and stripping area indicators for each stripped region were compared. Additionally, the AIMS-Ⅱ system was employed to examine the shape characteristics of the spalling aggregates. The results demonstrated the mean relative error for 75 stripping area samples was 4.07%, indicating high detection accuracy. The standard deviation of the spalling area calculation ranged from 1.73 to 3.89, confirming the good detection stability. A comparison of the mass loss and spalling area of each spalling region revealed a general trend of increasing mass loss with increasing spalling area; however, discrepancies were observed where increased spalling area corresponded to decreased mass loss. Shape analysis using AIMS-II indicated that flaky aggregates tend to have large spalling areas but small masses, whereas needle-like aggregates typically have large mass loss but small spalling areas.

    LI Ping, WANG Hongbo, CHEN Chaohe
    2025, 53(2):  92-106.  doi:10.12141/j.issn.1000-565X.240165
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    Stability and safety of floating wind turbine platforms in deep and distant sea environments are the core issues of floating offshore wind turbine systems. This paper analyzed the effects of multiple load control parameters on the design wave parameters under extreme wave loads by numerical simulation based on two design wave methods of long and short-term, and evaluated the structural strength of the floating offshore wind turbine platform using different design wave methods. The results show that: the traditional load control parameters of mid-longitudinal profile, mid-transverse profile and waterline plane cannot accurately capture the most dangerous loading conditions suffered by the floating offshore wind turbine platform, and the structural strength analysis of the floating offshore wind turbine platform also needs to take into account the stress concentration phenomenon at different structural connection locations, and thus needs to consider the influence of more load control parameters on the structural strength; the long term statistical design wave method can reflect the complexity of the marine environment more comprehensively, and can obtain the structural strength of the floating offshore wind turbine platform using different design wave methods. The long-term statistical design wave method can more comprehensively reflect the complexity of the marine environment and obtain the design wave parameters of the floating offshore wind turbine platform in the most dangerous state, while the short-term design wave method has the advantage of quickly assessing the structural strength of extreme wave conditions. The two can be used in conjunction with each other in accordance with the different design stages of the floating offshore wind turbine platform. The search for the most dangerous working conditions through the design wave method can not be compared with only the height of the wave parameters in the design.Calculation results show that the maximum stress obtained from two different design wave methods does not necessarily correspond to the highest wave height. This indicates that the wave height alone cannot determine the most critical condition. A comprehensive analysis of factors such as wave height, wave period, wave direction, and phase is required to assess their impact on structural strength. These findings are of significant importance for the structural design and safety evaluation of floating wind turbine platforms.

    Architecture & Civil Engineering
    CAO Jixing, HAN Mengfan, BAO Chao, HE Haijie, LIU Yingyang
    2025, 53(2):  107-114.  doi:10.12141/j.issn.1000-565X.240124
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    Fiber-reinforced polymer (FRP) reinforcement and self-tapping screw reinforcement are two commonly used methods for strengthening timber structures. Currently, research on reinforced glued laminated timber (glulam) structures primarily focuses on changes in strength after reinforcement, with relatively limited data on lateral resistance performance. Moreover, studies on reinforcing earthquake-damaged glulam frames are scarce. To investigate the lateral resistance performance of earthquake-damaged glued laminated timber (glulam) frames reinforced using different methods, two earthquake-damaged glulam frames were strengthened separately with carbon fiber-reinforced polymer (CFRP) and self-tapping screws, along with the addition of diagonal braces. The specimens were subjected to horizontal cyclic loading, and the experimental results were compared and analyzed. The test results indicate that both reinforcement methods effectively prevented the longitudinal splitting of the timber. However, compared to the specimen reinforced by self-tapping screw, the specimen reinforced by fiber-reinforced polymer shows significantly higher initial stiffness and peak load-carrying capacity, which can better suppress the development of cracks. The hysteretic curves of both frames exhibit a relatively anti “S” shape, with an obvious pinching effects. On the basis of the tests, simplified models of two frames were established using Open Sees. The models were calibrated based on experimental data. The hysteretic curves obtained from the calibrated models were in good agreement with the experimental results, verifying the accuracy and rationality of the model and laying the foundation for further parameter analysis. Furthermore, the influence of gravity loading for the specimens on the elastic stiffness and the maximum loading capacity was also investigated. It indicates that gravity load has an undeniable impact on the lateral resistance performance of timber frames, providing a scientific parameterized analysis for the seismic damage of reinforced timber frames.

    ZHANG Haiyan, CHEN Haibiao, WU Bo, LI Mengyuan
    2025, 53(2):  115-123.  doi:10.12141/j.issn.1000-565X.240043
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    Textile reinforced mortar (TRM) strengthening is a method of using mortar as an inorganic adhesive to stick textile onto the surface of components to form a strengthening layer. It has advantages such as light weight, high strength, minimal change in cross-sectional dimensions, good high-temperature resistance, and excellent durability, and thus has gained widespread attention in recent years. TRM typically uses polymer-modified cement mortar as the adhesive, but the production of cement has high energy consumption and carbon emissions. To achieve the “dual carbon” goals, this paper proposed to replace cement with geopolymer, which has much lower production energy consumption and carbon emissions while offering mechanical properties similar to cement, thus forming a textile reinforced mesh-enhanced geopolymer mortar (TRGM) strengthening method.This paper employed carbon textile reinforced geopolymer mortar to strengthen two-way reinforced concrete slabs. The flexural performance tests and finite element analysis were conducted on the unstrengthened and strengthened slabs with different aspect ratios and different numbers of TRGM layers. The strengthening effect of TRGM, the contribution of bidirectional fibers to bearing capacity, and the force transmission mechanism of the strengthened slabs were investigated. The results show that TRGM strengthening can effectively improve the post-cracking stiffness and flexural carrying capacity of two-way slabs and inhibit crack propagation, especially the widthwise cracks. The strengthening effect of TRGM increases with the increase in the aspect ratio of the two-way slabs. The bearing capacity of the strengthened slab with one layer of TRGM was greatly influenced by the overlap of the textile and strengthening construction quality, which made the strengthening efficiency of one layer of TRGM lower than that of two layers. The overlap of the fiber mesh may affect the strength of the fibers, and the design should ensure that the fibers have sufficient overlap length. After the widthwise reinforcement yielding, the ratio of bending moment borne in the widthwise direction to the lengthwise direction gradually decreased, since the contribution of the longitudinal reinforcement and fibers to the bearing capacity gradually increased. As the mid-span deflection increases, the proportion of tensile force borne by the fibers shows a wave-like trend, first decreasing, then increasing, and subsequently decreasing again.

    LI Tao, LI Yue, SHU Jiajun, ZHANG Ruihai, LIU Bo
    2025, 53(2):  124-135.  doi:10.12141/j.issn.1000-565X.240291
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    To reduce the environmental pollution caused by waste rubber tires, it is an effective solution to process them into derived aggregates and apply them in engineering reinforcement. Currently, geogrid reinforcement technology is widely used in embankment and slope projects. However, due to the limitation of soil resources, most of the local fine aggregates are used for backfill and compaction, which leads to the geogrid not being able to give full play to the reinforcing effect. Therefore, this paper proposed the method of composite reinforced embankment of waste tire rubber particles and geogrid to solve the above problems. The influence of rubber particle content (0%, 5%, 10%, 15%, and 20%) on the shear characteristics of the mixed soil was examined using a triaxial shear testing system. Additionally, pullout tests on geogrids were conducted to investigate the effects and mechanisms of rubber particle content on the pullout characteristics of uniaxial, biaxial, and triaxial geogrids. Finally, the deformation characteristics and stability of reinforced soil embankment with rubber granular soil mixture were analyzed by indoor tests and numerical simulation methods. The results indicate that the elastic modulus of the mixed soil gradually decreases as the rubber particle content increases. At the same time, the shear strength index shows an initial increase followed by a decrease, reaching its maximum value at a content of 15%. The peak tensile force of the three types of geogrids in the mixed soil follows the same trend with its maximum value at a content of 15%. The addition of 15% rubber particles in bi-axial and tri-axial geogrid-reinforced embankments reduces the settlement of the embankment by approximately 19% and 23%, respectively, as well as the lateral earth pressure by approximately 18% and 23%. The presence of the composite reinforcement layer significantly limits the development depth of the slope failure slip surface, thus enhances the embankment’s resistance to deformation.

    YANG Yi, WANG Zhe, ZHANG Zhiyuan
    2025, 53(2):  136-148.  doi:10.12141/j.issn.1000-565X.240266
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    The high extreme negative pressure that occurs in the corner area of the roof of a low-rise building is the focus of the wind-resistant design of its envelope. Based on the aerodynamic principle and the standard building model of TTU (Texas Tech University), this paper designed a new streamlined add-on accessories in the corner area of roof according to the wind flow patterns in the roof corner. By altering parameters such as the height and length of additional components, it conducted a comparative study involving rigid model pressure measurements in wind tunnel tests under 10 working conditions and Large Eddy Simulation (LES). The study aimed to explore the impact of these new types of additional components on wind loads in roof corner zones, aerodynamic optimization for wind resistance of roofs, and the accuracy of LES simulations.The study shows that: 1) the wind tunnel test results show that the installation of add-on accessories in the roof corner area can effectively reduce the extreme negative pressure in the corner area, and the most unfavorable mean negative pressure in the roof corner area can be reduced by 10%, and the most unfavorable extreme negative pressure can be reduced by 25% under the 10 working conditions studied; 2) the NSRFG(Narrowband Synthesis Random Flow Generation)method is used to generate the inlet turbulence, and the wind load distribution pattern in the TTU model under various conditions is obtained by the LES simulation. Although the absolute value of the mean wind pressure coefficient of the roof under some working conditions simulation results are larger (the mean error is 13.88%), and the extreme wind pressure coefficient is smaller (the mean error is 9.72%), it is overall consistent with the wind tunnel test, indicating that the NSRFG method has good accuracy; 3) LES numerical simulation parameter study shows that the influence of the length of the add-on accessories on the wind load in the roof corner area is greater than that of the height, the extreme wind pressure coefficient in the roof corner area decreases by 6.15% after the height of the equal length add-on accessories increase by 1 times; the extreme wind pressure coefficient in the roof corner area decreases by 10.77% after the length of the equal height add-on accessories increase by 0.8 times.

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