Local failure mechanism of sand-blocking fence in latticed dune along desert roads

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.

The Value of Rural Access Roads: The Case Study of Chepyuk and Mitira Wards in Bungoma and Kirinyaga Counties

In this paper we assess the impact of road network on rural regions development using a case study of Chepyuk and Mitira wards. The two case study areas were selected owing to their comparable agro ecological conditions but different political orientation. The wards have identical agro economic activities due to their similarity in climatic and ecological conditions. Household incomes earned from agricultural enterprises and bid rent per unit area of land are used as indicators of development. The condition of road network is used as an indicator of accessing the rural regions in various seasons of the year. The study provides evidence of the economic advantages associated with better market access, primarily due to the good road infrastructure in Mitira compared to Chepyuk. The good road condition is advantageous to Mitira ward residents allowing them to access other markets hence improving the farm gate value of their products. On the other hand, the prices for Chepyuk products are cheap due to constrained market access necessitated by the poor road condition. For instance, the average price of a liter of milk in Chepyuk ward is Kshs.36.65 compared to Mitira where it goes at Kh.55.08. It therefore implies in Chepyuk milk has to be sold at lower price since access to alternative markets is constrained by poor road condition. The disparity in the road network quality has been occasioned by investment policy by both colonial and consecutive post-independence governments which have given preference to the region where Mitira region is located. This is against the constitutional requirement which proposes an equalization fund for infrastructure development to regions lagging behind in terms of development.

Structural Design of Roadbed and Pavement in Transition Section of Roads and Bridges

As the lifeline of social development,road and bridge projects are the main channel to realize resource transportation and economic circulation.Ensuring the quality of road and bridge project construction is crucial for the development of society,the economy,and people’s livelihoods.This paper studies the design of roadbed pavement structures in road and bridge transition sections.It aims to provide technical references and significance for China’s road and bridge engineering design and construction units,promoting scientific and standardized design in these actions.This will contribute to the safety and stable operation of road and bridge projects,offering effective technical support.Furthermore,it seeks to foster the sustainable and healthy development of China’s road and bridge engineering on a macro level.

Landslide susceptibility mapping of mountain roads based on machine learning combined model

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.

A Novel Network Screening Methodology for Rural Low-Volume Roads

Low-volume roads (LVRs) are an integral part of the rural transportation network providing access to remote rural areas and facilitating the movement of goods from farms to markets. These roads pose unique challenges for highway agencies including those related to safety management on the highway network. Specifically, traditional network screening methods using crash history can be effective in screening rural highways with higher traffic volumes and more frequent crashes. However, these traditional methods are often ineffective in screening LVR networks due to low traffic volumes and the sporadic nature of crash occurrence. Further, many of the LVRs are owned and operated by local agencies that may lack access to detailed crash, traffic and roadway data and the technical expertise within their staff. Therefore, there is a need for more efficient and practical network screening approaches to facilitate safety management programs on these roads. This study proposes one such approach which utilizes a heuristic scoring scheme in assessing the level of risk/safety for the purpose of network screening. The proposed scheme is developed based on the principles of US Highway Safety Manual (HSM) analysis procedures for rural highways and the fundamentals in safety science. The primary application of the proposed scheme is for ranking sites in network screening applications or for comparing multiple improvement alternatives at a specific site. The proposed approach does not require access to detailed databases, technical expertise, or exact information, making it an invaluable tool for small agencies and local governments (e.g. counties, townships, tribal governments, etc.).

基于ROADS的面向场景业务架构建模方法

ROAD元架构通过业务架构指导整个企业架构体系开发过程,是一组简单明确且高效的模型表达。针对已有的元架构体系中业务活动模型所采用的IDEF0图存在对多组件系统之间丰富的活动触发序列和信息交互场景描述能力不足的问题,提出在ROAD元架构基础上引入场景模型,与原来基于IDEF0的活动模型融合成为面向场景的活动模型,同时具备层次化描述能力和场景化时序表达能力。扩展后的ROADS元架构保留原架构的整体性和灵活性,且补充面向场景的系统建模能力,实现业务架构设计中的场景管理。最后以一个情景化外语教学系统为例,使用ROADS元架构方法建立场景化业务架构模型组,并对其进行讨论,为现有架构体系提供一种面向场景的扩展思路。

Modeling continuous traffic flow with the average velocity effect of multiple vehicles ahead on gyroidal roads

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.

Regeneration Potential of Woody Species at the Side of Secondary Roads Post-Logging of Loundoungou-Toukoulaka Forest Management Unit, Republic of the Congo

Natural regeneration is the basis of a dynamic and demographic balance of plant populations. The objective of this study was to assess the natural regeneration potential of woody species along secondary roads post-logging abandoned since 2008 and 2018. In the two Annual Allowable Cuts (AAC 2008 and AAC 2018), 24 regenerating sub-plots (i.e. 12 sub-plots for AAC 2008 and 12 sub-plots for AAC 2018) with a unit area of 5 m × 5 m were delimited with a total area of 0.06 ha (i.e. 0.03 ha for each AAC). The abundance and diversity of woody species were respectively inventoried and estimated. Two estimators of the specific richness were used to estimate the floristic diversity of each Annual Allowable Cuts (AAC). The results reveal globally 88 woody species in the AAC 2008 and 241 woody species in the AAC 2018, with respective average densities of 2933 stem/ha and 8033 stem/ha. There was a very highly significant difference between the mean densities of the two AAC (Kruskal-Wallis test;H = 2.36, p-value < 0.000). The results also highlight a great diversity and a relatively high abundance of woody species in the 2018 AAC compared to the 2008 AAC. Also, the spatial structuring of the sub-plots on the basis of Principal Component Analysis (PCA) demonstrates that the floristic composition of the two AAC is globally different. The study suggests silvicultural interventions and the long-term assessment of regenerating woody species along abandoned secondary roads in order to guarantee the sustainable management of their population.

Research Progress of Epoxy Asphalt Material for Roads

Asphalt is a semi-solid or solid mixture formed by hydrocarbons and non-metallic elements.It is widely applied in the fields of building waterproofing and road paving.Asphalt is a low noise,durable,and renewable pavement material.However,asphalt materials have some shortcomings such as liquefying at high temperatures and brittleness at low temperatures,which are less adaptable to different environments.Therefore,people have gradually shifted their focus to asphalt modification.This paper presents an in-depth analysis and research on the composition,structure,and performance of epoxy asphalt materials for roads,so that this material can be widely used.

Application of Modified Asphalt in Municipal Roads

The article expounds modified asphalt technology by introducing commonly used modifiers and fillers and analyzing the construction technology of modified asphalt.The use of modified asphalt in municipal roads provides new alternatives for asphalt pavement materials,but also solves the existing construction problems and reduces project costs.Therefore,the research and application of modified asphalt using new materials and new processes is a crucial aspect in road construction.

Design Strategy of Municipal Roads and Bridges Using BIM Technology

Under the rapid development of socio-economy and urbanization,the state’s attention toward urban infrastructure continues to increase.The construction of municipal road and bridge projects is related to people’s daily travel and transport safety,and it also plays an important role in promoting urban economic development.Therefore,modern technology should be fully utilized in the design of municipal roads and bridges to strengthen construction cost control and increase their social and economic benefits.In this paper,the characteristics and application status of BIM technology in municipal road and bridge design are analyzed,and corresponding road and bridge design strategies are explored to promote the healthy development of municipal road and bridge projects.

Analysis of the Application of Windbreak and Sand Fixation Technology in Desert Roads

In order to solve the problems in the construction of desert roads and improve the quality of desert roads in China,this paper discusses the current windbreak and sand fixation technologies in desert areas in China,and puts forward relevant suggestions and corresponding solutions for each problem.This paper is written with hopes of contributing to the development of windbreak and sand fixation technologies in China as well as the development of the economy,society and environment in China's deserts.

Identifying Achilles-heel roads in real-sized networks

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.

Processes and mechanisms of multi-collapse of loess roads in seasonally frozen ground regions: A review

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.

A Review of the DCP-DN Pavement Design Method for Low Volume Sealed Roads: Development and Applications

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.

Landscape Improvement Design of Mountainous Scenic Roads Under the Background of“All-for-one tourism”:A Case Study of Scenic Roads of Nanshan in Chongqing

"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.

Problems in Ecological Landscape and Traffic Safety of Urban Roads

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.

Mechanisms for Cross-Scaling, Flexibility and Social Learning in Building Resilience to Sea Level Rise: Case Study of Hampton Roads, Virginia

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.

The Landscape Design of Roads Afforestation of Jiangnan New District in Mudanjiang Municipality

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.

“One Belt,One Road”:China and the “Oil Roads”

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