Road Design Research Articles

Gender-based risk analysis of vehicle control loss due to localized water puddles: an analytical approach

Adverse weather conditions significantly increase the risk of traffic accidents, yet most studies focus on uniform conditions across all tires. This study investigates the impact of asymmetric drag forces when only one tire encounters a local water puddle, causing potential vehicle control loss. Using analytical methods, we calculate drag forces and their transmission to the steering wheel, accounting for variations in water film thickness, vehicle speed, and driver gender. The results indicate that female drivers face higher risks of control loss, with critical speeds decreasing as water film thickness increases. The study highlights that localized water puddles, especially at low speeds and water depths exceeding 3 cm, pose significant risks. These findings can inform road safety guidelines and vehicle design standards to mitigate accident risks in adverse weather conditions.

A Rapid Evaluation Method of Permafrost Bearing Capacity in the Tibetan Plateau Region Based on the Correlation Between CPT-CBR

Permafrost, as a soil type under unique environmental conditions, has bearing characteristics that are highly susceptible to thermo-hydraulic environments. Rapid evaluation of the bearing characteristics of in situ permafrost at various depths in perennially frozen regions is a critical scientific issue urgently needing resolution in the road design and construction sectors in China. To address this, this study investigates the correlation between CPT parameters and laboratory mechanical indices under the combined effects of multiple factors in frozen sandy soils. By conducting both CPT and CBR tests on frozen sandy soils, the study analyzes the trends in changes in cone tip resistance (qc) and CBR values under the influence of temperature (T), moisture content (ω), and compaction degree (K) and establishes a functional relationship between them. Based on the standard requirements for indoor CBR, an evaluation criterion using qc for assessing the bearing capacity of frozen sandy soil is proposed. The results indicate that both CBR values and qc increase initially and then stabilize as K increases. With decreasing temperature, both indices stabilize after an initial increase, with turning points at −3.1 °C for CBR values and −2.5 °C for qc. As ω increases, both indices first increase and then stabilize, with a turning point at 40%ω. There is a robust linear relationship between the CBR values and qc, with the ratio of predicted CBR values to actual values showing a histogram and log-normal distribution accounting for 81% and 51.3%, respectively, within a 20% accuracy level, indicating good predictive performance. Referring to the highway subgrade specifications for indoor CBR, a standard for evaluating the bearing capacity of frozen sandy soils using CPT technology is proposed. This study provides new insights for geological surveys in perennially frozen regions and a theoretical basis for the application of CPT technology in evaluating the bearing capacity of permafrost.

Identifying vehicle types from trajectory data based on spatial-semantic information

ABSTRACT Obtaining information about various vehicle types traveling on road networks is crucial for estimating traffic loads on roads, evaluating the adequacy of road design standards, and providing personalized navigation guidance. Traditional intrusive and non-intrusive methods for vehicle-type identification often encounter challenges such as high maintenance costs, incomplete coverage of all roads, and technical limitations in adverse weather conditions. In recent years, vehicle GNSS trajectory data accumulation has provided a continuous, dynamic, wide-coverage, and cost-effective data resource for identifying vehicle types. However, existing trajectory-based methods still have some drawbacks in micro-trip segmentation and limitation of movement features. Hence, this paper proposes a novel approach for identifying vehicle types by leveraging spatial-semantic information from trajectory data. This proposed method initially detects staying points from trajectory data, then utilizes DBSCAN clustering on these detected staying points to adaptively segment original vehicle trajectories into various micro-trips in a steady-moving pattern. Subsequently, several statistical indicators related to velocity and acceleration are calculated as movement features for each micro-trip. Additionally, each vehicle trajectory’s driving-road hierarchy and staying-place information are quantified as the geo-semantic features. Finally, the calculated movement and geo-semantic features are utilized for two classification tasks using three typical classification models. Experimental results demonstrate that the proposed method achieves reliable performance in identifying various vehicle types by incorporating adaptive micro-trip segmentation and multiple spatial-semantic features, particularly outperforming fixed-size trip segmentation and using only movement features. Furthermore, it is observed that the classification accuracy of coaches, trucks, and semis is consistently higher than that for large, medium, and small passenger cars, indicating that the vehicle purposes may be more distinguishable than vehicle loads.

Differential influences of road physical design attributes on pedestrian versus driver traffic accident frequencies

Differential influences of road physical design attributes on pedestrian versus driver traffic accident frequencies

Life-cycle assessment tools for road design: analysing linearity assumptions

Road infrastructure significantly impacts how people move, live, and the emissions associated with travel behaviour. The design of roads is crucial in mitigating emissions. This paper reviews existing transport Life-Cycle Assessment tools that have been developed by various entities and can be used for roads. The review focuses on several aspects in terms of data sources used in the analysis, the methods of estimating carbon emissions, the underlying software that is used to make the estimates and any limitations of the tools. A critical issue identified in Life-Cycle Assessment analysis is the erroneous assumption that relationships within the assessed systems are linear. The current tools focusing on transport infrastructure assessment were developed based on the linear assumptions and limitations of the Life-Cycle Assessment analysis. A significant research gap identified is that existing Life-Cycle Assessment tools are not integrated with the design process. The analysis is an add-on process to design and the results of an assessment are not then used iteratively to enhance the design. A case study on aggregate road design found that road area significantly correlates with emissions, slope adjustments reduce emissions, and soil type impacts emissions, suggesting future research should explore nonlinear relationships for sustainable road design.

Study of Distribution of Free Flow Speeds on Urban Road Sections Depending on Their Functional Purpose and One-Way Traffic—Evidence from Kharkiv (Ukraine)

Data on the distribution of the free flow speed (FFS) of cars are used to solve a wide range of tasks in the field of road transport, starting from road design and ending with the development of traffic modeling and simulation programs. The purpose of this study was to obtain the distribution of vehicle speeds on typical sections of the city road network, characterized by the presence of one-way traffic. The data were obtained by field observations using a portable radar. As a result, statistical characteristics and speed distribution laws for four sections of streets in the city of Kharkiv were analyzed. It was shown that the characteristics of FFS distributions differ depending on the functional class of the streets. Average FFS values on main street segments were on average 19 km/h higher. The one-way traffic has less impact on the FFS distribution, especially for arterial streets. The characteristics of FFS distributions differ depending on the type and functional class of streets; they can be described with sufficient accuracy by typical distribution laws, such as Normal, Log-normal, Gamma, and Chi-square. The results of this study can be useful for traffic modeling problems.

Spatial heterogeneity analysis between street network configurations and various service activities: evidence from the Wuhan metropolitan area

China’s economic growth is increasingly being driven by the contemporary service industry in the context of a new economy. This study aims to examine the spatial heterogeneous relationship between various service industry activities and street network design configurations by integrating multisource big data and geospatial analysis to provide insightful implications for human-centered design for compact cities by taking the case study of an inland megacity in central China, Wuhan. Street configurations under the walking/driving modes including closeness, betweenness, severance and efficiency, are characterized from the perspective of spatial design network analysis and angular distance to effectively reflect network shapes and subjective perceptions when navigating through the streets. The point-like, point-axis and ring patterns of various service activities are identified using the kernel density estimation (KDE). Then two sets of densities are analyzed to investigate whether various service activities are spatially associated with specific street metrics and whether spatial stratified heterogeneity exists. The results show that severance and efficiency are two promising indicators to represent the human-scale street design besides the conventional street centrality indices. The spatial mismatch is mainly observed between street metrics and the tourism sector whereas spatial clusters are detected in other types of service activities. Diverse service activities have distinct location preferences for street designs under different transport modes. The walking mode values global closeness and betweenness, while the driving mode values severance and efficiency.

Deprioritising cars beyond rerouting: Future research directions of the Barcelona Superblock

The Barcelona Superblock is an urban transformation strategy that has gained considerable momentum in the last few years and holds the promise to transform neighbourhoods and cities to be more liveable and sustainable by deprioritising cars. The implementation of Superblocks in different geographies reveals a flexible conceptual interpretation and adaptation. Here, a combination of mobility, street transformation, and ancillary measures is proposed to form the core of successful Superblock implementation. A critical perspective reveals challenges and research needs for a future research agenda along five domains: to quantify sustainability impacts, to perform integrated analysis, to determine optimal locations for implementation, to explore costs and to establish ways for their rapid realisation. Research along these domains is put forward to inform and guide the transformation of public street space to tackle liveability, urbanisation, climate adaptation and climate mitigation. The Superblock is an urban design concept that seeks to bring about a sustainability transition not only in re-arranging routes for cars but also in assigning space to alternative uses. For successful transfer policy transfer, increased evidence-based quantification of positive sustainability impacts and pursuing an integrative agenda that justifies Superblock location choices are argued for, including establishing specific street designs to achieve multiple sustainability impacts.

PROPERTIES OF BITUMEN MODIFIED WITH ADHESIVE ADDITIVES BASED ON RENEWABLE RAW MATERIALS

The main quality characteristics of road petroleum bitumen are: adhesive properties that determine the adhesion of binders to mineral materials; rheological properties that determine technological and operational parameters; physical and chemical properties that determine resistance to weather, climate and operational factors during the service life (aging resistance). Bitumen is the main binder of asphalt pavements, so it is the properties of bitumen that determine the performance of asphalt concrete. The adhesion of bitumen to mineral material, such as crushed stone or glass, is one of the main indicators in the design and construction of roads. This indicator determines the strength and service life of the road surface. Whereas a lack of cohesion can lead to significant damage to asphalt concrete. Since most distillation and oxidised bitumen have low adhesive properties, it is necessary to introduce adhesive additives to them. The most common method of improving the adhesion of bitumen binders to stone materials contained in asphalt mixtures is the use of adhesive additives (surfactants): cationic, anionic and non-ionic. The problem of producing high-quality road bitumen is quite acute. There is an increasing number of studies aimed at the production of asphalt pavements from alternative renewable bioresources. That is why, in this paper, it is proposed to modify binding surfactants of plant origin. These surfactants are obtained by amidation of rapeseed oil. Such additives are profitable in terms of production, affordable, environmentally friendly and made from renewable raw materials, which are grown in sufficient quantities in Ukraine. The resulting additives were used to modify the bitumen and determine its adhesion to the surfaces of crushed stone and glass.

Experimental Study Unraveling Flow Allocation Patterns at Crossroad Intersections During Urban Flooding

Urban roads can effectively handle peak flows during extreme storms by serving as surface flood passages, provided the flow remains within safety thresholds for vehicles and pedestrians. However, studies on flow allocation at crossroad intersections are limited. Previous research has overlooked important factors: road transverse slope and turning radius. This study built a “two in, two out” laboratory crossroad intersection to examine flow allocation patterns. Experiments explored the effects of road longitudinal slope, boundary conditions, and the combined influence of turning radius and side slope. The results indicated that at flatter slopes, flow allocation is more influenced by road slope, while at steeper slopes, the inflow Froude number ratio becomes more significant. The combined effect of the turning radius and side slope results in a flow allocation that differs by 44.3% compared to rectangular orthogonal channel intersections. A straightforward formula is proposed to calculate the flow allocation ratio based on experimental results and inflow power ratio. These findings could improve road intersection designs for better flood mitigation, offering a practical tool for planning flood-resilient road networks.

The Longitudinal Push-Out Effect and Differential Settlement Control Measures of the Transition Section of Road and Bridge Induced by Freeze–Thaw Inducing

The environmental influence of seasonal freezing and thawing forces the longitudinal shear effect of the bridge abutment, and the differential settlement between the subgrade and the bridge abutment will significantly affect traffic safety. In this work, based on the finite element simulation analysis method, the longitudinal push-out effect and differential settlement of the transition section caused by cycles are systematically investigated, and the treatment results under different control measures (buffer layer thickness) are compared and analyzed. The results show that changing the thickness of the buffer material in the transition section has no significant influence on the overall temperature field of the subsurface. The longitudinal displacement of the transition region will be obvious under the condition of seasonal cycle, and its longitudinal thrust effect on the abutment shows a typical periodic law with the seasonal change. As the depth of the lower soil layer from the surface increases, the pushing effect becomes weaker and weaker. The development of the different subsoil settlements in the transition section also showed periodic changes with the passage of seasons. The differential settlement of the transition section after the buffer layer treatment can be effectively controlled, and the maximum value of the surface settlement of the roadbed after the 5 cm thick buffer material is reduced by 35%, compared with the two deformations of frostshocked bridges, where differential settlement after the buffer material treatment creates only tip deformation. After using a 15 cm thick buffer layer material treatment, the maximum settlement value of the surface settlement of the road base is reduced from 0.2 m to 0.01 m, which will not affect safety and driving comfort. The research conclusions can provide a reference for the design of road and bridge transition sections in frozen areas.

Toward Climate Resilient Asphalt Binder Selection in Canada

Climate change and extreme weather events present a fundamental challenge to pavement engineering and planning practice, given that transportation infrastructure has traditionally been planned and designed using historical climate data under the implicit assumption that climate is stationary and future conditions will resemble past ones. Transportation professionals should consider future risks scenarios in road design, material selection and system operations. This will be challenging given the inherent uncertainties in any climate projections. However, changes might be needed since transportation professionals are expected to deliver cost-effective and climate-resilient transportation infrastructure. The material selection plays an important role in the durability of flexible roads; therefore, it is important to consider the whole road design life cycle in terms of climate change and extreme weather events impact on asphalt selection as well as to consider different traffic speeds. This led to the development of the NRC Climate Adaptation and Asphalt Selection Tool (CAAST).

Urban form and seasonal PM2.5 dynamics: Enhancing air quality prediction using interpretable machine learning and IoT sensor data

This study investigates the critical issue of how urban form characteristics influence PM2.5 concentrations, a key concern for public health in densely populated cities. Traditional monitoring methods have faced data gaps and methodological limitations. To address this, we employed interpretable machine learning (ML) models with data from 1,069 Internet-of-Things (IoT) sensors across Seoul, South Korea (September 2020–August 2023). Over 80 urban form variables—including density, transportation, road design, building morphology, and land use—were analyzed using Recursive Feature Elimination to identify key factors affecting PM2.5 concentrations within three buffer zones (300-m, 500-m, 1-km). The random forest model demonstrated the highest accuracy, with an R² of 95 % for autumn and 96 % for spring. Our findings show higher PM2.5 levels in colder months, driven by road width and building density in autumn and traffic and industrial activity in winter. In summer, green spaces and meteorological conditions were primary factors, while spring air quality was notably impacted by localized traffic emissions around highways and bus stops. This study offers robust predictions and actionable insights for urban planning and air quality management. Future research could integrate additional environmental variables and expand sensor coverage to further refine predictive models.

Exploration of Integrating Ideological and Political Education into the Curriculum of “Road Survey and Design” from the Perspective of Moral and Intellectual Education in the New Era

In the context of the new era and the goal of moral and intellectual education, the design of ideological and political education in curriculum holds significant importance for civil engineering majors. By incorporating ideological and political education into the curriculum, students’ political awareness, comprehensive qualities, innovative spirit, social responsibility, environmental consciousness, attention to social development, and technological innovation can be cultivated. After integrating ideological and political content into the “Road Survey and Design” course, there have been significant improvements in students’ political awareness, comprehensive qualities, innovative spirit, social responsibility, environmental consciousness, career development awareness, and teachers’ instructional capabilities.

Stiffness evaluation of coarse unbound granular materials using large-scale repeated load triaxial test

This research investigates the effect of downscaling coarse unbound granular material (UGM) for characterization of the resilient modulus with large-scale repeated load triaxial testing. Four open-graded and two dense-graded materials are downscaled based on the particle size distribution curve and upper sieve size for subbase materials of crushed rock (CR) 22/125 mm and CR 0/125 mm as defined by the Norwegian road design regulation.The results were evaluated using the K-θ model and Uzan’s model. The findings for CR 4/22 mm, CR 6/32 mm, CR 8/45 mm, and CR 11/63 mm indicate that downscaling of coarse open-graded UGMs could be applicable for characterization of the resilient modulus. The results for dense-graded UGMs CR 0/22 mm and CR 0/63 mm indicate that downscaling reduces the resilient modulus. Further research should include complementary gradings and rock types.

Understanding the Factors Affecting Traffic Danger for Children: Insights From Focus Group Discussions

Children’s safety on urban roads is a critical concern with young pedestrians and cyclists being among the most vulnerable groups to traffic-related dangers. The prioritization of motor vehicle traffic in road infrastructure poses significant risks to child pedestrians and cyclists navigating city streets. Furthermore, children’s independent mobility has been restricted due to traffic danger and their parents’ concerns about it. Given the important implications of this issue, a serious gap was identified in that no measure of traffic danger exists, with outcomes (e.g., collisions) being used as a proxy. Identifying factors contributing to traffic danger, how they interact, and how they impact traffic are imperative to identify where mitigation is needed to address these problems. This article delves into the complexities of traffic risks for children, focusing on intersections and streets. Six focus groups, including experts (<em>n</em> = 3), parents (<em>n</em> = 2), and children aged 8 to 12 (<em>n</em> = 1), were conducted to gather insights on factors impacting traffic danger. Thematic analysis revealed eight key themes, highlighting the importance of addressing traffic volume, speed, vehicle size, road design, driver behavior, visibility, and land use. These findings contribute to a comprehensive framework for understanding traffic danger for children. Additionally, the article examines how stakeholders’ perspectives align with standard measures of traffic danger in the literature.

Recognition of Street Landscape Patterns in Kunming City Based on Intelligent Decision Algorithm and Regional Cultural Expression

The integration of intelligent decision-making algorithms with urban cultural expression is becoming a hot topic in both academic and practical fields for exploring urban street landscapes. Exploring the application strategies of intelligent decision-making algorithms and regional cultural expression in street landscape pattern recognition and innovative design is a key step. The single layout of urban street construction, cultural deficiency, ecological imbalance, and low resident participation seriously constrain the overall quality improvement of the city. To address this dilemma, this study delved into Kunming City and selected the ten “most beautiful streets”, such as Dianchi Road, for research. By using the Analytic Hierarchy Process, a comprehensive evaluation system covering multiple dimensions, such as the street layout, plant landscape, and historical culture, was constructed to analyze the street landscape of Kunming. The research results indicate that the top four roads in terms of weight evaluation scores are Cuihu Ring Road, Jiaochang Middle Road, Qingnian Road, and Beijing Road, with values of 0.2076, 0.1531, 0.1274, and 0.1173. The weight reveals that each street has its unique landscape factors, such as the profound cultural heritage of Cuihu Ring Road and the beautiful plant landscape of Jiaochang Middle Road. Further analysis also reveals the close relationship between various factors in the evaluation model, emphasizing the importance of supplementing material and cultural elements in street landscape design. The significance of this study goes beyond a single analysis of the street landscape in Kunming City. Drawing a regional street landscape pattern map sets an example for other cities to build distinctive, eco-friendly, culturally rich, and highly humanized street spaces, providing reference and inspiration. More importantly, this study promotes the application and development of intelligent decision-making algorithms in the field of urban landscapes. Future research will further optimize algorithms to improve their adaptability and accuracy in complex environments.

Uncovering heterogeneous effects of link-level street environment on e-bike and e-scooter usage

This study investigates how the street environment influences e-bike and e-scooter flows at the link level, considering their distinct spatial travel patterns. An angle-based spatial autoregressive quantile regression (SAQR) model is developed to analyze fine-scale street environments in Washington, D.C. We observe distinct spatial travel patterns between e-bikes and e-scooters, and e-scooter usage is more concentrated in city centers. Link design and network design have stronger impacts on the usage of e-bike and e-scooter than land use features. However, land use features are more likely to affect the flow of these two modes differently. Specifically, streets with dedicated bike lanes, traffic signals, wider width, higher betweenness centrality, and a higher proportion of entertainment and office land tend to attract more e-bike and e-scooter trips. In addition, bike-friendly facilities, particularly buffered bike lanes, exhibit more pronounced impacts. The findings provide policy implications for nuanced street design guidelines to facilitate electric micromobility usage.

Case–control study of fatal bicycle crashes in peri-urban areas of Delhi

ObjectivesThere is a lack of evidence on interventions to improve the safety of cycling use in low- and middle-income countries. We investigated the impact of road design and traffic characteristics...

Proceedings of the 2024 Australasian Road Safety Conference - Hobart, Tasmania, Australia

Proceedings of the 2024 annual Australasian Road Safety Conference held in Hobart, Tasmania, Australia. The proceedings provide the Extended Abstracts and Posters describing research, educational and policing program implementation and policy and management strategies related to all aspects of road safety and especially related to the conference theme of Target 2030: What's the pathway forward? Almost 600 delegates from 20 countries attended the face-to-face conference. Authors of accepted Extended Abstracts represented international and local institutions from all aspects of their respective communities including research centres, private companies, government agencies and community groups. These Extended Abstracts provide an indication of the important work being done in Australia, New Zealand and internationally as part of the United Nations, One UN Vision for Road Safety to reduce the number of crashes on the road by 50 percent by 2030. Almost 200 Extended Abstract manuscripts were accepted for long, short and poster sessions. Each Extended Abstract was peer-reviewed by two experts with relevant expertise. Authors were also provided the option of submitting a Full Paper. Those authors who chose to submit a Full Paper for consideration in the Journal of Road Safety (JRS) could do so based on the outcome of the peer review of their Extended Abstract. Submitted Full Papers undergo peer-review by three independent experts matched by their sector. The matching pairs academic authors iwth academic reviewers and practitioner authors with practitioner reivewers. Inclusion in the JRS follows acceptance by the peer-reviewers.The conference covered a comprehensive range of topics including speed, infrastructure and road design, cyclist safety, motorcyclist safety, pedestrian safety, road safety education, licensing, vehicle design, impairment due to distraction from mobile phones, alcohol, drugs as well as the impacts of climate change on future transport systems road safety, road safety issues for Indigenous people groups across New Zealand and Australia, integrating road safety into local Government, automated enforcement, gig economy road safety, older drivers, etc.