Four-Wheel Independent Steering(4WIS)Vehicles can independently control the angle of each wheel,demonstrating superior trajectory tracking performance under normal conditions.However,on intermittent icy and snowy road...Four-Wheel Independent Steering(4WIS)Vehicles can independently control the angle of each wheel,demonstrating superior trajectory tracking performance under normal conditions.However,on intermittent icy and snowy roads,the presence of time-varying adhesion coefficients,time-varying cornering stiffness,and the irregularities due to ice and snow accumulation introduce multiple uncertainties into the steering system,significantly degrading the trajectory tracking performance of 4WIS vehicles.In response,this paper proposes a robust Tube Model Predictive Control(Tube-MPC)trajectory tracking control method for 4WIS.In this method,a Bi-directional Long Short-Term Memory neural network is established for online estimation of tire cornering stiffness under different road adhesion coefficients,providing accurate estimation of time-varying cornering stiffness for each wheel to mitigate the uncertainties of time-varying adhesion coefficients and cornering stiffness.Additionally,considering the road irregularities caused by snow accumulation on intermittent icy and snowy roads,a trajectory tracking controller that integrates Tube-MPC and robust Sliding Mode Control is proposed.The nominal MPC model,developed from the estimated tire cornering stiffness,utilizes the sliding surface and the optimal auxiliary control unit law for the tube is derived from the reaching law in Tube-MPC,aiming to minimize the trajectory tracking error while enhancing the controller’s robustness against road uncertainties.The experiments show that the proposed method outperforms the Tube-MPC algorithm in terms of trajectory accuracy and robustness.This method demonstrates excellent trajectory tracking accuracy under intermittent icy and snowy road conditions,and it lays a theoretical foundation for future studies on vehicle stability and trajectory tracking under such road conditions.展开更多
On-site inspection of municipal road subgrade and pavement is of great significance for ensuring the quality,safety,and durability of urban road infrastructure.This paper analyzes its key technologies,introduces non-d...On-site inspection of municipal road subgrade and pavement is of great significance for ensuring the quality,safety,and durability of urban road infrastructure.This paper analyzes its key technologies,introduces non-destructive testing methods such as ground-penetrating radar and ultrasonic testing,elaborates on the multifaceted roles of inspection in engineering construction as well as relevant standards,explores site challenges,key technologies,and corresponding measures,and points out future research directions in intelligent sensing and predictive maintenance.展开更多
Vegetation plays a major role in soil protection against erosion effects,and studies have also highlighted its importance in retaining sediments from roadside slopes.Yet,hydro-sedimentological studies under natural pr...Vegetation plays a major role in soil protection against erosion effects,and studies have also highlighted its importance in retaining sediments from roadside slopes.Yet,hydro-sedimentological studies under natural precipitation conditions are still scarce in semi-arid areas due to difficulties in monitoring the few and very concentrated precipitation events.Quantifying sediment connectivity and yield at watershed scale,often highly impacted by the erosion of unpaved roads,is necessary for management plans.This study aims to evaluate the efficiency of native vegetation on roadside slope segments in Caatinga biome in retaining sediments and conserving the soil in a semi-arid area of Brazil.Surface runoff,sediment concentration,and yield measurements were measured from 34 natural precipitation events in four years on two slopes with and without vegetation.The runoff coefficients of the plot with no vegetation varied from 3.0%to 58.0%,while in the vegetated plot,they showed variation from 1.0%to 21.0%.The annual specific sediment yield ranged from 4.6 to 138.7 kg/(hm^(2)•a)for the vegetated plot and from 34.9 to 608.5 kg/(hm^(2)•a)for the unvegetated one.These results indicate a 4 to 12 times higher soil loss on the unvegetated slope in relation to the vegetated one and demonstrate that natural Caatinga vegetation acts as an effective barrier against surface-transported sediments.Moreover,natural Caatinga vegetation present on the slope plays an important role in breaking connectivity between sediment flows from unpaved roads and the watershed drainage system.These findings indicate that investments in unpaved road and roadside slope restoration,not only enhance road infrastructure but also promote environmental gains by reducing the impact of erosion.展开更多
Fly ash(FA),a major solid waste from coal-fired industries,represents a critical pathway for the green disposal of bulk solid waste and the low-carbon construction of transportation infrastructure,holding significant ...Fly ash(FA),a major solid waste from coal-fired industries,represents a critical pathway for the green disposal of bulk solid waste and the low-carbon construction of transportation infrastructure,holding significant strategic importance.In recent years,extensive research has been conducted on the mechanisms,optimization,and applications of FA-based road engineering materials.This review focuses on FA-based road engineering material systems,synthesizing previous studies from three perspectives:cement concrete pavement materials,asphalt mixture pavement materials,and stabilized soil road materials.The findings reveal that FA significantly enhances road material performance through its pozzolanic activity,micro-nano filling effects,and interfacial strengthening.In cement concrete systems,the synergistic interaction of pozzolanic reactions and microsphere filling achieves microstructural densification.Integrating particle size optimization,nano-modification,and alkali activation techniques can overcome the mechanical strength and durability limitations of traditional FA systems.For asphalt mixtures,leveraging FA’s porous adsorption characteristics and chemical bonding effects optimizes the asphalt-aggregate interface adhesion,while alkali activation further extends its application scope.In stabilized soil systems,FA enhances soil integrity by forming cementitious networks,with structural reinforcement achievable through alkali activation and composite stabilization.However,current research still faces unresolved challenges.These include elemental imbalances and performance limitations in single-FA-based road engineering materials,insufficient high-value applications of FA carbon sequestration technology in road materials,lack of systematic frameworks for environmental risk assessments of FA-based road systems,and constrained application scenarios for FA in road engineering.Future research should focus on innovating activation technologies to enhance the reactivity of FA,co-utilizing multi-source solid wastes,researching carbon sequestration technologies for FA-based road engineering materials,establishing environmental monitoring and evaluation systems,and promoting the application of FA in subgrade filling.The conclusions provide comprehensive insights for industrial solid waste recycling and low-carbon road construction,supporting sustainable,lowcarbon,and high-quality development in road engineering.展开更多
Ensuring a minimum operational level of road networks in the presence of unexpected incidents is becoming a hot subject in academic circles as well as industry. To this end, it is important to understand the degree to...Ensuring a minimum operational level of road networks in the presence of unexpected incidents is becoming a hot subject in academic circles as well as industry. To this end, it is important to understand the degree to which each single element of the network contributes to the operation and performance of a network. In other words, a road can become an ＂Achilles-heel＂ for the entire network if it is closed due to a simple incident. Such insight of the detrimental loss of the closure of the roads would help us to be more vigilant and prepared. In this study, we develop an index dubbed as Achilles-heel index to quantify detrimental loss of the closure of the respective roads. More precisely, the Achilles-heel index indicates how many drivers are affected by the closure of the respective roads （the number of affected drivers is also called travel demand coverage）. To this end,roads with maximum travel demand coverage are sorted as the most critical ones, for which a method known as ＂link analysis＂--is adopted. In an iterative process, first, a road with highest traffic volume is first labeled as ＂target link,＂ and second, a portion of travel demand which is captured by the target link is excluded from travel demand. For the next iteration, the trimmed travel demand is then assigned to the network where all links including the target links run on the initial travel times. The process carries on until all links are labeled. The proposed methodology is applied to a large- sized network of Winnipeg, Canada. The results shed light on also bottleneck points of the network which may warrant provision of additional capacity or parallel roads.展开更多
The current limitation in maintenance budget and resources necessitates developing new cost-effective techniques for gravel roads management systems (GRMS). Thus, the Wyoming Technology Transfer Center (WYT2) has star...The current limitation in maintenance budget and resources necessitates developing new cost-effective techniques for gravel roads management systems (GRMS). Thus, the Wyoming Technology Transfer Center (WYT2) has started developing a holistic automated GRMS. Utilizing smartphones in gravel roads data collection is one of the main features in the proposed system. In this study, smartphones were used to collect gravel roads condition data in terms of International Roughness Index (IRI) and corrugation to develop an objective computational method to estimate the riding quality on gravel roads. The developed method will help local agencies to reduce subjectivity in their data collection process and support them with a solid computational justification for their evaluation data and decisions. Two analyses have been carried out to achieve the purpose of this study. Artificial Neural Network ANN method and linear regression were used to develop the riding quality model. The linear regression resulted in a model that has a 0.8242 coefficient of determination (R2) value which means that the developed riding quality model can represent 82.42% of the collected data. The achieved R2 value is considered sufficient for GRMS purposes. In addition, the developed ANN model has a prediction accuracy of 92.5%. The achieved prediction accuracy shows that the ANN model can predict the riding quality significantly better than the linear regression, with 12.5% higher accuracy. Furthermore, thresholds for the gravel roads IRI were suggested and introduced in this study to be the first IRI thresholds for gravel roads in the literature. Based on the suggested threshold, the gravel roads IRI has three classes: smooth, acceptable and rough. The gravel road segment can be classified in terms of IRI to be smooth, acceptable, or rough if its IRI value is less than 284, between 284 and 496, or more than 496 inch/mile, respectively.展开更多
Usually, the collapsible loess widely distributed across the world can serve as a type of foundation soil that meets its strength requirement after dense compaction and elimination of collapsibility. However, many pro...Usually, the collapsible loess widely distributed across the world can serve as a type of foundation soil that meets its strength requirement after dense compaction and elimination of collapsibility. However, many problems such as cracks and differential settlement still occur in loess roads in the seasonally frozen ground regions after several years of op- eration. Many studies have demonstrated that these secondary or multiple collapses primarily result from the repeated freezing-thawing, wetting-drying, and salinization-desalinization cycles. Therefore, we conducted a research program to （1） monitor the in-situ ground temperatures and water content in certain loess roads to understand their changes, （2） study the effects of freezing-thawing, wetting-drying, and salinization-desalinization cycles on geotechnical properties and micro-fabrics of compacted loess in the laboratory, and （3） develop mitigative measures and examine their engineered effectiveness, i.e., their thermal insulating and water-proofing effects in field and laboratory tests. Our results and advances are reviewed and some further research needs are proposed. These findings more clearly explain the processes and mechanisms of secondary and multiple collapse of loess roads. We also offer references for further study of the weakening mechanisms of similar structural soils.展开更多
Widespread implementation of the DCP-DN design method for low volume roads has been promoted internationally over the past decade or so. The method has progressed from a simple determination of the in situ CBR investi...Widespread implementation of the DCP-DN design method for low volume roads has been promoted internationally over the past decade or so. The method has progressed from a simple determination of the in situ CBR investigation based on DCP-CBR correlations with respective cover requirements to a more sophisticated method using the DCP penetration data directly and omitting any need to use correlations with the CBR. This paper summarises the development of the method, and some of its advantages and compares the design structures with other recognised and widely implemented designs.展开更多
"All-for-one tourism" emphasizes the transformation of tourism from the original single scenic spot service to "traveling on the road",and advocates the guiding destination service of integrating t..."All-for-one tourism" emphasizes the transformation of tourism from the original single scenic spot service to "traveling on the road",and advocates the guiding destination service of integrating transportation and surrounding scenery sources.As the most abundant carrier of tourism environment,mountainous scenic spots are valued more by the development of natural tourism resources.In addition to the characteristics of scenic spots,how to use scenic roads to create a regional atmosphere has become a focus of tourism construction.Taking scenic roads of Nanshan in Chongqing as an example,this study analyzed the key points of road landscape upgrading under different construction levels,and put forward design strategies from the perspective of regional characteristics and regional cultural elements,so as to effectively enhance the regional landscape characteristics of the roads,with a view to providing reference for relevant planning and design.展开更多
This study mainly analyzed problems in ecological landscape and traffic safety of urban roads, and in view of these problems, proposed the design concepts, principles and focuses of urban road eco-landscape ensuring t...This study mainly analyzed problems in ecological landscape and traffic safety of urban roads, and in view of these problems, proposed the design concepts, principles and focuses of urban road eco-landscape ensuring traffic safety.展开更多
This case study examines how the Hampton Roads Sea Level Rise Preparedness and Resilience Intergovernmental Planning Pilot Project, a whole-of-government and whole-of-community approach to planning for and adapting to...This case study examines how the Hampton Roads Sea Level Rise Preparedness and Resilience Intergovernmental Planning Pilot Project, a whole-of-government and whole-of-community approach to planning for and adapting to sea level rise, addressed coastal resilience in a southeastern Virginia watershed that spans multiple jurisdictions. Meeting the challenge of sea level rise requires that actors across multiple sectors—citizens, community organizations, industry and government—understand the risks and work together to make critical decisions regarding adaptation strategies and actions. The case study area includes Little Creek Amphibious Base, which is bordered by the cities of Norfolk and Virginia Beach. Adaptation responses to sea level rise by the military base and the local governments will impact each other and the residents of the area, but no cooperative agreements are in place for a joint or collaborative response. This case study examines public and private infrastructure at risk, the infrastructure interdependencies, and mechanisms for providing collaborative solutions. Engagement of area residents and other stakeholders is also integral to the process of adaptation, which includes educating about sea level rise risk and provides a mechanism for social learning that enables stakeholders to participate in critical adaptation decisions. The case study demonstrates a method to improve resiliency in the case study area and inform a regional, multi-sectoral response to sea level rise adaptation strategies.展开更多
Based on road characters in Jiangnan New District in Mudanjiang Municipality,four typical roads were selected to carry out road afforestation design with consideration of local building features and local vegetations,...Based on road characters in Jiangnan New District in Mudanjiang Municipality,four typical roads were selected to carry out road afforestation design with consideration of local building features and local vegetations,in order to integrate both of landscape effects,in terms of improving and beautifying city environment,and of ecological effects,such as filtering air,reducing temperature,increasing humidity,and reducing noise.展开更多
In the past one and a half years,if one were to have sifted through the keywords of reports,comments,and studies on China’s economy and politics,the'One Belt,One Road'initiative(abbrev.as'OBOR'hereaft...In the past one and a half years,if one were to have sifted through the keywords of reports,comments,and studies on China’s economy and politics,the'One Belt,One Road'initiative(abbrev.as'OBOR'hereafter)must have been one of the most popular words.When展开更多
According to the primary study on green plant species and arrangement of Xi'an urban road,the major problems about plant construction in Xi'an urban roads were analyzed in this study,and the greening plant arr...According to the primary study on green plant species and arrangement of Xi'an urban road,the major problems about plant construction in Xi'an urban roads were analyzed in this study,and the greening plant arrangement in Xi'an urban road was discussed to provide references for Xi'an urban road greening.An analysis of the road in Xi'an plant problems and plant configuration for the road less than the existence of specific proposals for Xi'an Green has been building the road from.展开更多
In the future connected vehicle environment,the information of multiple vehicles ahead can be readily collected in real-time,such as the velocity or headway,which provides more opportunities for information exchange a...In the future connected vehicle environment,the information of multiple vehicles ahead can be readily collected in real-time,such as the velocity or headway,which provides more opportunities for information exchange and cooperative control.Meanwhile,gyroidal roads are one of the fundamental road patterns prevalent in mountainous areas.To effectively control the system,it is therefore significant to explore the evolution mechanism of traffic flow on gyroidal roads under a connected vehicle environment.In this paper,we present a new continuum model with the average velocity of multiple vehicles ahead on gyroidal roads.The stability criterion and KdV-Burger equation are deduced via linear and nonlinear stability analysis,respectively.Solving the above KdV-Burger equation yields the density wave solution,which explores the formation and propagation property of traffic jams near the neutral stability curve.Simulation examples verify that the model can reproduce complex phenomena,such as shock waves and rarefaction waves.The analysis of the local cluster effect shows that the number of vehicles ahead and the radius information,and the slope information of gyroidal roads can exert a great influence on traffic jams.The effect of the first and second terms are positive,while the last term is negative.展开更多
Roads affect wildlife significantly through direct mortality but also through behavioral change. We explored the ef- fects of unsurfaced sand roads with a low traffic volume on the travelling behavior of gopher tortoi...Roads affect wildlife significantly through direct mortality but also through behavioral change. We explored the ef- fects of unsurfaced sand roads with a low traffic volume on the travelling behavior of gopher tortoises Gopherus polyphemus in scrub habitat in central Florida, as evidenced by the tracks left by tortoises on sand roads. Tortoises （and most other taxa leaving tracks on the roads） did not appear to make use of roads for travel but attempted to cross them, the success of which was influ- enced by the size of the individual. Smaller animals （presumably younger tortoises） were more challenged than larger animals by both sand road widths and depths of vehicle ruts in sand roads. Sand roads may present both physical and physiological challenges to gopher tortoises, particularly to small ones. This research provides further evidence that the negative influence of roads in fragmenting the environment is not limited to vehicle mortality [Current Zoology 61 （4）： 578-585, 2015].展开更多
Landslide susceptibility mapping of mountain roads is frequently confronted by insufficient historical landslide sample data,multicollinearity of existing evaluation index factors,and inconsistency of evaluation facto...Landslide susceptibility mapping of mountain roads is frequently confronted by insufficient historical landslide sample data,multicollinearity of existing evaluation index factors,and inconsistency of evaluation factors due to regional environmental variations.Then,a single machine learning model can easily become overfitting,thus reducing the accuracy and robustness of the evaluation model.This paper proposes a combined machine-learning model to address the issues.The landslide susceptibility in mountain roads were mapped by using factor analysis to normalize and reduce the dimensionality of the initial condition factor and generating six new combination factors as evaluation indexes.The mountain roads in the Youxi County,Fujian Province,China were used for the landslide susceptibility mapping.Three most frequently used machine learning techniques,support vector machine(SVM),random forest(RF),and artificial neural network(ANN)models,were used to model the landslide susceptibility of the study area and validate the accuracy of this evaluation index system.The global minimum variance portfolio was utilized to construct a machine learning combined model.5-fold cross-validation,statistical indexes,and AUC(Area Under Curve)values were implemented to evaluate the predictive accuracy of the landslide susceptibility model.The mean AUC values for the SVM,RF,and ANN models in the training stage were 89.2%,88.5%,and 87.9%,respectively,and 78.0%,73.7%,and 76.7%,respectively,in the validating stage.In the training and validation stages,the mean AUC values of the combined model were 92.4% and 87.1%,respectively.The combined model provides greater prediction accuracy and model robustness than one single model.展开更多
The latticed dunes in the Tengger Desert are widely distributed,and the sand-blocking fence placed here are highly susceptible to local failure due to complex wind-sand activities,posing a serious threat to the safe o...The latticed dunes in the Tengger Desert are widely distributed,and the sand-blocking fence placed here are highly susceptible to local failure due to complex wind-sand activities,posing a serious threat to the safe operation of the highway.To explore the local failure mechanism of sand-blocking fence in the latticed dune area,the local failure of sand-blocking fence in the latticed dune areas along the Wuhai-Maqin Highway in China was observed.Taking the first main ridge of the latticed dune as the placement location,the structure of the wind-sand flow field of sand-blocking fence placed at top,the bottom and the middle of windward slope was analyzed by Computational Fluid Dynamics(CFD).The results show that when placed at top of the first main ridge,the wind speed near the sand-blocking fence is the highest,up to 15.23 m/s.Therefore,the wind load strength on the sand barrier is correspondingly larger,up to 232.61 N∙m-2.As the strength of material continues to decrease,the nylon net is prone to breakage.The roots of the angle steel posts are susceptible to hollowing by vortex action,which can cause sand-blocking fence to fall over in strong wind conditions.When placed at the bottom of windward slope,wind speed drop near sand-blocking fence is greatest,with the decrease of 12.48-14.32 m/s compared to the original wind speed.This is highly likely to lead to large-scale deposition of sand particles and burial of the sand-blocking fence.When placed in the middle of windward slope,sand-blocking fence is subjected to less wind load strength(168.61N∙m-2)and sand particles are mostly deposited at the bottom of windward slope,with only a small amount of sand accumulating at the root of sand-blocking fence.Based on field observations and numerical modelling results,when the sand-blocking fence is placed in latticed dune area,it should be placed in the middle of the windward slope of the first main ridge as a matter of priority.Besides the sand-blocking fence should be placed at the top of the first main ridge,and sand fixing measures should be added.展开更多
Estimating intercity vehicle emissions precisely would benefit collaborative control in multiple cities.Considering the variability of emissions caused by vehicles,roads,and traffic,the 24-hour change characteristics ...Estimating intercity vehicle emissions precisely would benefit collaborative control in multiple cities.Considering the variability of emissions caused by vehicles,roads,and traffic,the 24-hour change characteristics of air pollutants(CO,HC,NO_(X),PM_(2.5))on the intercity road network of Guangdong Province by vehicle categories and road links were revealed based on vehicle identity detection data in real-life traffic for each hour in July 2018.The results showed that the spatial diversity of emissions caused by the unbalanced economywas obvious.The vehicle emissions in the Pearl River Delta region(PRD)with a higher economic level were approximately 1–2 times those in the non-Pearl RiverDelta region(non-PRD).Provincial roads with high loads became potential sources of high emissions.Therefore,emission control policies must emphasize the PRD and key roads by travel guidance to achieve greater reduction.Gasoline passenger cars with a large proportion of traffic dominated morning and evening peaks in the 24-hour period and were the dominant contributors to CO and HC emissions,contributing more than 50%in the daytime(7:00–23:00)and higher than 26%at night(0:00–6:00).Diesel trucks made up 10%of traffic,but were the dominant player at night,contributed 50%–90%to NO_(X) and PM_(2.5) emissions,with amarked 24-hour change rule of more than 80%at night(23:00–5:00)and less than 60%during daytime.Therefore,targeted control measures by time-section should be set up on collaborative control.These findings provide time-varying decision support for variable vehicle emission control on a large scale.展开更多
[Objective] The aim was to study on resource utilization of indigenous plants in roads in order to solve resource shortage of indigenous plant in bioengi- neering. [Method] Based on northwestern loess plateau area, we...[Objective] The aim was to study on resource utilization of indigenous plants in roads in order to solve resource shortage of indigenous plant in bioengi- neering. [Method] Based on northwestern loess plateau area, we conducted research on selection of indigenous plants and survey on the species which could live in adverse condition, mainly by surveying, with frequent tests as a supplement, to make a comprehensive observation and evaluation on plant combinations which are to be extensively applied. [Result] The research indicated that in central dividing strips, four arbors, including Platycladus orientalis （Linn.）Franco, Sabina chinensis, Sabinachinen- sis（Linn.）Ant., and Ulmus purnila L., and nine frutices, including Lycium chinense, Tamarix austromongolica, Rosa xanthina Lindl., Forsythia suspense, Atriplex canescens, Amygdalus triloba, Hippophae rharnnoides Linn., Arnorpha fruticosa L., and Syzygium aromaticum could be planted. In addition, Gleditsia sinensis Lain, Robinia pseudoacacia L, Elaeagnus angustifolia L., Rhus typhina, Salix babylonica, Salixmatsudana and Fraxinus chinensis, tall and strong, are suitable to be planted as border trees, presenting a good vision. Frutices, limited by height, are usually with more branches, which will provide a good landscape if grown with tall plants. Prunus dacidiana and Ulmus pumila L., prone to be damaged by insects, should be planted with other species to stop the infestation in space. [Conclusion] The research laid foundation for selection of indigenous plants in roads, providing references for resource shortage of indigenous plant for bioengineedng.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.52405112,U24A20199)the Postdoctoral Fellowship Program of CPSF(Grant No.GZB20240973).
文摘Four-Wheel Independent Steering(4WIS)Vehicles can independently control the angle of each wheel,demonstrating superior trajectory tracking performance under normal conditions.However,on intermittent icy and snowy roads,the presence of time-varying adhesion coefficients,time-varying cornering stiffness,and the irregularities due to ice and snow accumulation introduce multiple uncertainties into the steering system,significantly degrading the trajectory tracking performance of 4WIS vehicles.In response,this paper proposes a robust Tube Model Predictive Control(Tube-MPC)trajectory tracking control method for 4WIS.In this method,a Bi-directional Long Short-Term Memory neural network is established for online estimation of tire cornering stiffness under different road adhesion coefficients,providing accurate estimation of time-varying cornering stiffness for each wheel to mitigate the uncertainties of time-varying adhesion coefficients and cornering stiffness.Additionally,considering the road irregularities caused by snow accumulation on intermittent icy and snowy roads,a trajectory tracking controller that integrates Tube-MPC and robust Sliding Mode Control is proposed.The nominal MPC model,developed from the estimated tire cornering stiffness,utilizes the sliding surface and the optimal auxiliary control unit law for the tube is derived from the reaching law in Tube-MPC,aiming to minimize the trajectory tracking error while enhancing the controller’s robustness against road uncertainties.The experiments show that the proposed method outperforms the Tube-MPC algorithm in terms of trajectory accuracy and robustness.This method demonstrates excellent trajectory tracking accuracy under intermittent icy and snowy road conditions,and it lays a theoretical foundation for future studies on vehicle stability and trajectory tracking under such road conditions.
文摘On-site inspection of municipal road subgrade and pavement is of great significance for ensuring the quality,safety,and durability of urban road infrastructure.This paper analyzes its key technologies,introduces non-destructive testing methods such as ground-penetrating radar and ultrasonic testing,elaborates on the multifaceted roles of inspection in engineering construction as well as relevant standards,explores site challenges,key technologies,and corresponding measures,and points out future research directions in intelligent sensing and predictive maintenance.
基金the National Council for Scientific and Technological Development (CNPq) for funding the field studies and for the research productivity fellowship (CNPq/PQ) awarded to Pedro Henrique Augusto MEDEIROS and José Carlos de ARAúJOthe Coordination for the Improvement of Higher Education Personnel (CAPES) for the doctoral scholarship awarded to Teresa Raquel Lima FARIAS (2117/13-4)the Foundation for the Support of Scientific and Technological Development in the State of Ceará (FUNCAP) for the master scholarship awarded to Maria Thereza Rocha CHAVES。
文摘Vegetation plays a major role in soil protection against erosion effects,and studies have also highlighted its importance in retaining sediments from roadside slopes.Yet,hydro-sedimentological studies under natural precipitation conditions are still scarce in semi-arid areas due to difficulties in monitoring the few and very concentrated precipitation events.Quantifying sediment connectivity and yield at watershed scale,often highly impacted by the erosion of unpaved roads,is necessary for management plans.This study aims to evaluate the efficiency of native vegetation on roadside slope segments in Caatinga biome in retaining sediments and conserving the soil in a semi-arid area of Brazil.Surface runoff,sediment concentration,and yield measurements were measured from 34 natural precipitation events in four years on two slopes with and without vegetation.The runoff coefficients of the plot with no vegetation varied from 3.0%to 58.0%,while in the vegetated plot,they showed variation from 1.0%to 21.0%.The annual specific sediment yield ranged from 4.6 to 138.7 kg/(hm^(2)•a)for the vegetated plot and from 34.9 to 608.5 kg/(hm^(2)•a)for the unvegetated one.These results indicate a 4 to 12 times higher soil loss on the unvegetated slope in relation to the vegetated one and demonstrate that natural Caatinga vegetation acts as an effective barrier against surface-transported sediments.Moreover,natural Caatinga vegetation present on the slope plays an important role in breaking connectivity between sediment flows from unpaved roads and the watershed drainage system.These findings indicate that investments in unpaved road and roadside slope restoration,not only enhance road infrastructure but also promote environmental gains by reducing the impact of erosion.
基金supported by the following grants:Research on Key Technologies and Large-Scale Application of Resource Utilization of Industrial Solid Waste in Expressways(No.202300196)Science and Technology Development Plan Project of the Silk Road Economic Belt Innovation-Driven Development Pilot Zone and Wuchangshi National Independent Innovation Demonstration Zone(No.2023LQ03002)Research Initiation Program for High-Level Talents Introduced on a FullTime Basis in Ningxia,China(No.2024BEH04052).
文摘Fly ash(FA),a major solid waste from coal-fired industries,represents a critical pathway for the green disposal of bulk solid waste and the low-carbon construction of transportation infrastructure,holding significant strategic importance.In recent years,extensive research has been conducted on the mechanisms,optimization,and applications of FA-based road engineering materials.This review focuses on FA-based road engineering material systems,synthesizing previous studies from three perspectives:cement concrete pavement materials,asphalt mixture pavement materials,and stabilized soil road materials.The findings reveal that FA significantly enhances road material performance through its pozzolanic activity,micro-nano filling effects,and interfacial strengthening.In cement concrete systems,the synergistic interaction of pozzolanic reactions and microsphere filling achieves microstructural densification.Integrating particle size optimization,nano-modification,and alkali activation techniques can overcome the mechanical strength and durability limitations of traditional FA systems.For asphalt mixtures,leveraging FA’s porous adsorption characteristics and chemical bonding effects optimizes the asphalt-aggregate interface adhesion,while alkali activation further extends its application scope.In stabilized soil systems,FA enhances soil integrity by forming cementitious networks,with structural reinforcement achievable through alkali activation and composite stabilization.However,current research still faces unresolved challenges.These include elemental imbalances and performance limitations in single-FA-based road engineering materials,insufficient high-value applications of FA carbon sequestration technology in road materials,lack of systematic frameworks for environmental risk assessments of FA-based road systems,and constrained application scenarios for FA in road engineering.Future research should focus on innovating activation technologies to enhance the reactivity of FA,co-utilizing multi-source solid wastes,researching carbon sequestration technologies for FA-based road engineering materials,establishing environmental monitoring and evaluation systems,and promoting the application of FA in subgrade filling.The conclusions provide comprehensive insights for industrial solid waste recycling and low-carbon road construction,supporting sustainable,lowcarbon,and high-quality development in road engineering.
文摘Ensuring a minimum operational level of road networks in the presence of unexpected incidents is becoming a hot subject in academic circles as well as industry. To this end, it is important to understand the degree to which each single element of the network contributes to the operation and performance of a network. In other words, a road can become an ＂Achilles-heel＂ for the entire network if it is closed due to a simple incident. Such insight of the detrimental loss of the closure of the roads would help us to be more vigilant and prepared. In this study, we develop an index dubbed as Achilles-heel index to quantify detrimental loss of the closure of the respective roads. More precisely, the Achilles-heel index indicates how many drivers are affected by the closure of the respective roads （the number of affected drivers is also called travel demand coverage）. To this end,roads with maximum travel demand coverage are sorted as the most critical ones, for which a method known as ＂link analysis＂--is adopted. In an iterative process, first, a road with highest traffic volume is first labeled as ＂target link,＂ and second, a portion of travel demand which is captured by the target link is excluded from travel demand. For the next iteration, the trimmed travel demand is then assigned to the network where all links including the target links run on the initial travel times. The process carries on until all links are labeled. The proposed methodology is applied to a large- sized network of Winnipeg, Canada. The results shed light on also bottleneck points of the network which may warrant provision of additional capacity or parallel roads.
文摘The current limitation in maintenance budget and resources necessitates developing new cost-effective techniques for gravel roads management systems (GRMS). Thus, the Wyoming Technology Transfer Center (WYT2) has started developing a holistic automated GRMS. Utilizing smartphones in gravel roads data collection is one of the main features in the proposed system. In this study, smartphones were used to collect gravel roads condition data in terms of International Roughness Index (IRI) and corrugation to develop an objective computational method to estimate the riding quality on gravel roads. The developed method will help local agencies to reduce subjectivity in their data collection process and support them with a solid computational justification for their evaluation data and decisions. Two analyses have been carried out to achieve the purpose of this study. Artificial Neural Network ANN method and linear regression were used to develop the riding quality model. The linear regression resulted in a model that has a 0.8242 coefficient of determination (R2) value which means that the developed riding quality model can represent 82.42% of the collected data. The achieved R2 value is considered sufficient for GRMS purposes. In addition, the developed ANN model has a prediction accuracy of 92.5%. The achieved prediction accuracy shows that the ANN model can predict the riding quality significantly better than the linear regression, with 12.5% higher accuracy. Furthermore, thresholds for the gravel roads IRI were suggested and introduced in this study to be the first IRI thresholds for gravel roads in the literature. Based on the suggested threshold, the gravel roads IRI has three classes: smooth, acceptable and rough. The gravel road segment can be classified in terms of IRI to be smooth, acceptable, or rough if its IRI value is less than 284, between 284 and 496, or more than 496 inch/mile, respectively.
基金supported by the National Key Basic Research Program of China (973 Program) (No. 2012CB026106)the Science and Technology Major Project of Gansu Province (No. 143GKDA007)+2 种基金the West Light Foundation of CAS for Dr. G. Y. Lithe Program for Innovative Research Group of the Natural Science Foundation of China (No. 41121061)the Foundation of the State Key Laboratory of Frozen Soils Engineering of CAS (No. SKLFSE-ZT-11)
文摘Usually, the collapsible loess widely distributed across the world can serve as a type of foundation soil that meets its strength requirement after dense compaction and elimination of collapsibility. However, many problems such as cracks and differential settlement still occur in loess roads in the seasonally frozen ground regions after several years of op- eration. Many studies have demonstrated that these secondary or multiple collapses primarily result from the repeated freezing-thawing, wetting-drying, and salinization-desalinization cycles. Therefore, we conducted a research program to （1） monitor the in-situ ground temperatures and water content in certain loess roads to understand their changes, （2） study the effects of freezing-thawing, wetting-drying, and salinization-desalinization cycles on geotechnical properties and micro-fabrics of compacted loess in the laboratory, and （3） develop mitigative measures and examine their engineered effectiveness, i.e., their thermal insulating and water-proofing effects in field and laboratory tests. Our results and advances are reviewed and some further research needs are proposed. These findings more clearly explain the processes and mechanisms of secondary and multiple collapse of loess roads. We also offer references for further study of the weakening mechanisms of similar structural soils.
文摘Widespread implementation of the DCP-DN design method for low volume roads has been promoted internationally over the past decade or so. The method has progressed from a simple determination of the in situ CBR investigation based on DCP-CBR correlations with respective cover requirements to a more sophisticated method using the DCP penetration data directly and omitting any need to use correlations with the CBR. This paper summarises the development of the method, and some of its advantages and compares the design structures with other recognised and widely implemented designs.
基金Sponsored by Social Science Planning Project of Chongqing(2019YBSH085)Graduate Education Innovation Fund Project of Chongqing Jiaotong University(2018S0143)Graduate Education Innovation Fund Project of Chongqing Jiaotong University(2019S0101).
文摘"All-for-one tourism" emphasizes the transformation of tourism from the original single scenic spot service to "traveling on the road",and advocates the guiding destination service of integrating transportation and surrounding scenery sources.As the most abundant carrier of tourism environment,mountainous scenic spots are valued more by the development of natural tourism resources.In addition to the characteristics of scenic spots,how to use scenic roads to create a regional atmosphere has become a focus of tourism construction.Taking scenic roads of Nanshan in Chongqing as an example,this study analyzed the key points of road landscape upgrading under different construction levels,and put forward design strategies from the perspective of regional characteristics and regional cultural elements,so as to effectively enhance the regional landscape characteristics of the roads,with a view to providing reference for relevant planning and design.
文摘This study mainly analyzed problems in ecological landscape and traffic safety of urban roads, and in view of these problems, proposed the design concepts, principles and focuses of urban road eco-landscape ensuring traffic safety.
文摘This case study examines how the Hampton Roads Sea Level Rise Preparedness and Resilience Intergovernmental Planning Pilot Project, a whole-of-government and whole-of-community approach to planning for and adapting to sea level rise, addressed coastal resilience in a southeastern Virginia watershed that spans multiple jurisdictions. Meeting the challenge of sea level rise requires that actors across multiple sectors—citizens, community organizations, industry and government—understand the risks and work together to make critical decisions regarding adaptation strategies and actions. The case study area includes Little Creek Amphibious Base, which is bordered by the cities of Norfolk and Virginia Beach. Adaptation responses to sea level rise by the military base and the local governments will impact each other and the residents of the area, but no cooperative agreements are in place for a joint or collaborative response. This case study examines public and private infrastructure at risk, the infrastructure interdependencies, and mechanisms for providing collaborative solutions. Engagement of area residents and other stakeholders is also integral to the process of adaptation, which includes educating about sea level rise risk and provides a mechanism for social learning that enables stakeholders to participate in critical adaptation decisions. The case study demonstrates a method to improve resiliency in the case study area and inform a regional, multi-sectoral response to sea level rise adaptation strategies.
基金Supported by Special Project for Teaching Reform of Mudanjiang Normal University(2013JGZX0072)Project for Teaching Reform of Mudanjiang Normal University(2013ALZX019)+1 种基金Training Program of Mudanjiang Normal UniversityHorizontal Topic of Mudanjiang Normal University(KH0472)~~
文摘Based on road characters in Jiangnan New District in Mudanjiang Municipality,four typical roads were selected to carry out road afforestation design with consideration of local building features and local vegetations,in order to integrate both of landscape effects,in terms of improving and beautifying city environment,and of ecological effects,such as filtering air,reducing temperature,increasing humidity,and reducing noise.
文摘In the past one and a half years,if one were to have sifted through the keywords of reports,comments,and studies on China’s economy and politics,the'One Belt,One Road'initiative(abbrev.as'OBOR'hereafter)must have been one of the most popular words.When
文摘According to the primary study on green plant species and arrangement of Xi'an urban road,the major problems about plant construction in Xi'an urban roads were analyzed in this study,and the greening plant arrangement in Xi'an urban road was discussed to provide references for Xi'an urban road greening.An analysis of the road in Xi'an plant problems and plant configuration for the road less than the existence of specific proposals for Xi'an Green has been building the road from.
基金supported by Guangdong Basic and Applied Research Foundation(Project No.2022A1515010948,2019A1515111200,2019A1515110837,2023A1515011696)the National Science Foundation of China(Project No.72071079,52272310).
文摘In the future connected vehicle environment,the information of multiple vehicles ahead can be readily collected in real-time,such as the velocity or headway,which provides more opportunities for information exchange and cooperative control.Meanwhile,gyroidal roads are one of the fundamental road patterns prevalent in mountainous areas.To effectively control the system,it is therefore significant to explore the evolution mechanism of traffic flow on gyroidal roads under a connected vehicle environment.In this paper,we present a new continuum model with the average velocity of multiple vehicles ahead on gyroidal roads.The stability criterion and KdV-Burger equation are deduced via linear and nonlinear stability analysis,respectively.Solving the above KdV-Burger equation yields the density wave solution,which explores the formation and propagation property of traffic jams near the neutral stability curve.Simulation examples verify that the model can reproduce complex phenomena,such as shock waves and rarefaction waves.The analysis of the local cluster effect shows that the number of vehicles ahead and the radius information,and the slope information of gyroidal roads can exert a great influence on traffic jams.The effect of the first and second terms are positive,while the last term is negative.
文摘Roads affect wildlife significantly through direct mortality but also through behavioral change. We explored the ef- fects of unsurfaced sand roads with a low traffic volume on the travelling behavior of gopher tortoises Gopherus polyphemus in scrub habitat in central Florida, as evidenced by the tracks left by tortoises on sand roads. Tortoises （and most other taxa leaving tracks on the roads） did not appear to make use of roads for travel but attempted to cross them, the success of which was influ- enced by the size of the individual. Smaller animals （presumably younger tortoises） were more challenged than larger animals by both sand road widths and depths of vehicle ruts in sand roads. Sand roads may present both physical and physiological challenges to gopher tortoises, particularly to small ones. This research provides further evidence that the negative influence of roads in fragmenting the environment is not limited to vehicle mortality [Current Zoology 61 （4）： 578-585, 2015].
基金the financial support from the National Natural Science Foundation of China(No.U2005205,No.42007235,No.41972268)the Science and Technology Innovation Platform Project of Fuzhou Science and Technology Bureau(No.2021-P-032)。
文摘Landslide susceptibility mapping of mountain roads is frequently confronted by insufficient historical landslide sample data,multicollinearity of existing evaluation index factors,and inconsistency of evaluation factors due to regional environmental variations.Then,a single machine learning model can easily become overfitting,thus reducing the accuracy and robustness of the evaluation model.This paper proposes a combined machine-learning model to address the issues.The landslide susceptibility in mountain roads were mapped by using factor analysis to normalize and reduce the dimensionality of the initial condition factor and generating six new combination factors as evaluation indexes.The mountain roads in the Youxi County,Fujian Province,China were used for the landslide susceptibility mapping.Three most frequently used machine learning techniques,support vector machine(SVM),random forest(RF),and artificial neural network(ANN)models,were used to model the landslide susceptibility of the study area and validate the accuracy of this evaluation index system.The global minimum variance portfolio was utilized to construct a machine learning combined model.5-fold cross-validation,statistical indexes,and AUC(Area Under Curve)values were implemented to evaluate the predictive accuracy of the landslide susceptibility model.The mean AUC values for the SVM,RF,and ANN models in the training stage were 89.2%,88.5%,and 87.9%,respectively,and 78.0%,73.7%,and 76.7%,respectively,in the validating stage.In the training and validation stages,the mean AUC values of the combined model were 92.4% and 87.1%,respectively.The combined model provides greater prediction accuracy and model robustness than one single model.
文摘The latticed dunes in the Tengger Desert are widely distributed,and the sand-blocking fence placed here are highly susceptible to local failure due to complex wind-sand activities,posing a serious threat to the safe operation of the highway.To explore the local failure mechanism of sand-blocking fence in the latticed dune area,the local failure of sand-blocking fence in the latticed dune areas along the Wuhai-Maqin Highway in China was observed.Taking the first main ridge of the latticed dune as the placement location,the structure of the wind-sand flow field of sand-blocking fence placed at top,the bottom and the middle of windward slope was analyzed by Computational Fluid Dynamics(CFD).The results show that when placed at top of the first main ridge,the wind speed near the sand-blocking fence is the highest,up to 15.23 m/s.Therefore,the wind load strength on the sand barrier is correspondingly larger,up to 232.61 N∙m-2.As the strength of material continues to decrease,the nylon net is prone to breakage.The roots of the angle steel posts are susceptible to hollowing by vortex action,which can cause sand-blocking fence to fall over in strong wind conditions.When placed at the bottom of windward slope,wind speed drop near sand-blocking fence is greatest,with the decrease of 12.48-14.32 m/s compared to the original wind speed.This is highly likely to lead to large-scale deposition of sand particles and burial of the sand-blocking fence.When placed in the middle of windward slope,sand-blocking fence is subjected to less wind load strength(168.61N∙m-2)and sand particles are mostly deposited at the bottom of windward slope,with only a small amount of sand accumulating at the root of sand-blocking fence.Based on field observations and numerical modelling results,when the sand-blocking fence is placed in latticed dune area,it should be placed in the middle of the windward slope of the first main ridge as a matter of priority.Besides the sand-blocking fence should be placed at the top of the first main ridge,and sand fixing measures should be added.
基金supported by the Natural Science Foundation of China(No.U1811463,41975165)the National Key Research Program of China(No.2018YFB1601100)+1 种基金the Science Foundation Project of Guangdong(No.2019A1515010812)the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(No.NY221125).
文摘Estimating intercity vehicle emissions precisely would benefit collaborative control in multiple cities.Considering the variability of emissions caused by vehicles,roads,and traffic,the 24-hour change characteristics of air pollutants(CO,HC,NO_(X),PM_(2.5))on the intercity road network of Guangdong Province by vehicle categories and road links were revealed based on vehicle identity detection data in real-life traffic for each hour in July 2018.The results showed that the spatial diversity of emissions caused by the unbalanced economywas obvious.The vehicle emissions in the Pearl River Delta region(PRD)with a higher economic level were approximately 1–2 times those in the non-Pearl RiverDelta region(non-PRD).Provincial roads with high loads became potential sources of high emissions.Therefore,emission control policies must emphasize the PRD and key roads by travel guidance to achieve greater reduction.Gasoline passenger cars with a large proportion of traffic dominated morning and evening peaks in the 24-hour period and were the dominant contributors to CO and HC emissions,contributing more than 50%in the daytime(7:00–23:00)and higher than 26%at night(0:00–6:00).Diesel trucks made up 10%of traffic,but were the dominant player at night,contributed 50%–90%to NO_(X) and PM_(2.5) emissions,with amarked 24-hour change rule of more than 80%at night(23:00–5:00)and less than 60%during daytime.Therefore,targeted control measures by time-section should be set up on collaborative control.These findings provide time-varying decision support for variable vehicle emission control on a large scale.
文摘[Objective] The aim was to study on resource utilization of indigenous plants in roads in order to solve resource shortage of indigenous plant in bioengi- neering. [Method] Based on northwestern loess plateau area, we conducted research on selection of indigenous plants and survey on the species which could live in adverse condition, mainly by surveying, with frequent tests as a supplement, to make a comprehensive observation and evaluation on plant combinations which are to be extensively applied. [Result] The research indicated that in central dividing strips, four arbors, including Platycladus orientalis （Linn.）Franco, Sabina chinensis, Sabinachinen- sis（Linn.）Ant., and Ulmus purnila L., and nine frutices, including Lycium chinense, Tamarix austromongolica, Rosa xanthina Lindl., Forsythia suspense, Atriplex canescens, Amygdalus triloba, Hippophae rharnnoides Linn., Arnorpha fruticosa L., and Syzygium aromaticum could be planted. In addition, Gleditsia sinensis Lain, Robinia pseudoacacia L, Elaeagnus angustifolia L., Rhus typhina, Salix babylonica, Salixmatsudana and Fraxinus chinensis, tall and strong, are suitable to be planted as border trees, presenting a good vision. Frutices, limited by height, are usually with more branches, which will provide a good landscape if grown with tall plants. Prunus dacidiana and Ulmus pumila L., prone to be damaged by insects, should be planted with other species to stop the infestation in space. [Conclusion] The research laid foundation for selection of indigenous plants in roads, providing references for resource shortage of indigenous plant for bioengineedng.
