Search Results (63)

When urban underground interchange tunnels pass beneath a water-rich spoil-disposal landfill, water–mud inrush risk is jointly controlled by artificial fill, geological conditions, tunnel-group construction disturbance, and environmental constraints. This study investigates the section beneath the Bujiuwo spoil-disposal landfill in the North Extension Project of Qiaocheng East Road, Shenzhen, and aims to identify key risk factors and reveal their hierarchical transmission mechanism. Based on engineering investigation data, design documents, construction risk sources, and expert questionnaires, an indicator system containing 18 risk factors was established. The decision-making trial and evaluation laboratory method was used to calculate the influence degree, affected degree, centrality, causality, and centrality-derived weight of each factor. Adversarial interpretive structural modeling was then introduced to extract the topological hierarchy and identify key coupling loops. The results show that structural fissure water pressure, vertical clearance, landfill water level, emergency pumping and drainage capacity, and spoil-fill thickness act as key nodes in the DEMATEL risk-relation network. Two key loops were identified: the landfill water level–structural fissure water pressure loop and the vertical clearance–additional stress of tunnel group–damage rate of anti-seepage membrane loop. A hierarchical control strategy is proposed, including source control, channel blockage, construction disturbance control, monitoring, early warning, and emergency management. From a sustainability perspective, the proposed framework supports groundwater protection, pollution prevention, maintenance of landfill containment integrity, and reduction in construction-induced environmental risks. Full article

Repeated non-equidistant unmanned aerial vehicle (UAV) inspections of slope-road cracks require measurements from different distances, poses, and image scales to remain comparable and sufficiently precise for engineering-state decisions. Existing studies rarely integrate cross-view physical conversion, measurement uncertainty, and a project-defined minimum detectable change. We develop an engineering-detectability framework that defines cross-period criteria for crack width and displacement and derives equivalent widths for ideal, representative non-standard, and arbitrary viewpoints. First-order error propagation and reliability allocation convert the minimum detectable change into accuracy requirements for range, field of view, and normalized image coordinates. Crack-boundary coordinates and localization uncertainties provide a common interface for interchangeable detection and photogrammetric modules. Validation combines a controlled fixed-camera sequence with a close-range field-camera multiview test of seven physical openings under local coplanarity. All six determinate stages in the controlled sequence agreed with the digital image correlation (DIC) comparison, while one borderline stage required review. Across the seven openings, the four-view means gave a mean absolute error (MAE) of 0.196 mm and a root mean square error (RMSE) of 0.270 mm, with cross-view coefficients of variation (CVs) of 0.33–4.93%. An illustrative error budget demonstrates reverse screening of system configurations from project thresholds. The framework therefore connects viewpoint-equivalent measurements, uncertainty constraints, and engineering-state decisions in an auditable chain. Full article

In the construction process of a super-long-span short-distance continuous variable cross-section tunnel, multiple geometric mutations along the alignment induce significant discontinuity and asymmetry in the mechanical response of the surrounding rock-support system, which differs significantly from that of conventional single-variable-section tunnels. This aggravates local asymmetric stress concentration and sudden deformation surges, posing severe construction risks. To reveal the influence of different excavation methods on the mechanical response of the surrounding rock-support system during the construction of this type of tunnel, the Tangshan Road Interchange and Connection Line Project was added based on the Qingdao Qingyin Expressway. The large-span continuous variable cross-section sections of A, B, and C in the north line of the Tangshan Road Tunnel were selected as the research objects, and a three-dimensional finite element numerical model was established and rigorously validated against field monitoring data from three representative cross-sections. Three typical construction methods—the Distributed Bench Excavation Method (DBM), Double Sidewall Drift Method (DSM), and Distributed Double Sidewall Drift Method (DDSM)—were systematically compared and studied. The results indicate that the section transition zones (A → B and B → C) are the most sensitive key control areas. Compared with DBM, DDSM significantly reduced the vault initial support stress in Section A by 38.1% (from 6.51 to 4.03 MPa), the left and right spandrel stresses by 17.9% and 26.9%, respectively, and peak bolt axial forces by over 20%. Although DSM achieves maximum lateral convergence reduction (reducing haunch convergence by 32.8% in Section C), DDSM delivers the optimal comprehensive control by effectively restricting vault settlement and balancing support stress distribution. The field monitoring trend was highly consistent with the numerical simulation results, which confirms the accuracy of the established model. The research results can provide a reference for the selection of construction methods and deformation control of large-span continuous variable cross-section tunnels. Full article

Expressway interchange guide signs must support rapid route decisions under limited viewing time, high information load, and potential vehicle occlusion. This study developed a human-centered framework for optimizing guide-sign information and presentation in complex expressway networks by integrating an on-road field experiment, driving simulation, eye-movement measures, physiological responses, and driving behavior. The field experiment involved ten drivers unfamiliar with the Fuzhou expressway network and yielded 119 valid sign-reading episodes. A separate simulation experiment with 60 licensed drivers examined character heights of 55, 65, and 75 cm and roadside, median-side, and dual-side installation under three ordinal traffic background conditions. Drivers generally initiated visual search in the upper-left region of sign panels and focused on route-relevant place names and directional arrows. Descriptive observations suggested that usable control-point information could support route inference when the destination was absent, whereas the absence of both destination and usable control-point information was accompanied by more sustained deceleration and more dispersed visual search. Effective viewing distance increased across the tested character-height conditions. At a design speed of 120 km/h and an assumed recognition time of 2.6 s, the required viewing distance was approximately 86.7 m. The mean viewing distance for the 55 cm condition was below this requirement, whereas the 65 and 75 cm conditions exceeded it. The findings were applied to Xiuzhai Interchange. In a dynamic screen-based route-choice test, 24 of 25 participants made acceptable choices. Overall, guide signs in complex networks should be designed as coordinated information systems integrating control-point hierarchy, information continuity, character height, and installation position. Full article

Noise in long highway tunnels and underground interchanges poses a significant environmental concern, affecting both drivers and nearby residents. This research develops an acoustic finite element model of a long tunnel in Leuven Measurement Systems (LMS) Virtual Lab to characterize the tunnel noise field, and the effectiveness of different noise mitigation measures was also evaluated and optimized accordingly. The model is validated against in situ monitoring data, with deviations controlled within 3 dB(A) and strong agreement confirmed by the Kappa consistency test. Both simulations and measurements show that sound pressure levels (SPLs) are generally highest near the tunnel center and lower toward the portal, exhibiting periodic fluctuations rather than a monotonic decrease. The dominant noise energy is concentrated between 125 Hz and 500 Hz. SPLs at 1.8 m above the road surface are noticeably higher than at 1.2 m and 1.5 m, indicating greater noise exposure for drivers of large vehicles compared with smaller vehicles. Noise reduction performance is further assessed for different lining materials and pavement types. Installing sound-absorbing panels in the tunnel midsection provides effective attenuation, with expanded perlite panels, single-layer metal micro-perforated panels, and FC quiet perforated panels (FC-PP) performing best, while porous asphalt shows superior noise reduction compared with conventional dense-graded asphalt pavements. Full article

Demand-responsive transport (DRT) services are increasingly recognised as an effective solution for enhancing accessibility, particularly in low-demand and peripheral areas. Existing scientific research has investigated DRT as a feeder service to modal interchange nodes, with a specific focus on railway hubs. In this study, an accessibility indicator is developed to compare direct road-based access to regional hubs with multimodal access combining road and rail, enabled by DRT services. The indicator is derived from a detailed analysis of road travel times and scheduled rail services and is applied within a regional-scale framework. Under the hypothesis that travel originates in the centre of each municipality in the area under consideration, two travel times are calculated: the time for the road alternative, based on the characteristics of the road network, and the time for the combined alternative, based on the attributes of the rail network. The resulting indicator allows for identification of the alternative that is more time-competitive for medium-distance travel on a regional scale and for mapping accessibility to attraction centres on a municipal basis. The methodology is applied to a case study in Sicily, Southern Italy. The analysis considers trips from all Sicilian municipalities to the metropolitan areas of Palermo, Catania, and Messina, assessing both the current situation and future scenarios based on planned railway infrastructure upgrades. The results indicate that, while direct road access remains the most efficient option for a large share of municipalities, the multimodal DRT–rail alternative becomes competitive in areas located near railway stations, particularly under scenarios that include major rail interventions, such as the upgrading and speed enhancement of the Palermo–Catania railway corridor. Full article

Lane departure can cause lateral vehicle collisions and, in severe cases, lead to vehicles running off the road. Such incidents often occur on curved sections and ramps. This study focuses on loop ramps. To quantify the impact of geometric alignment characteristics of loop ramps on lane departure behaviors, unmanned aerial vehicle (UAVs) aerial photography was used to collect operation videos of 10 loop ramps at 6 interchanges, and 762 pieces of vehicle trajectory data under free-flow conditions were extracted based on DataFromSky. Combined with the indicators of equivalent radius and trajectory design curvature difference, vehicle trajectories were systematically classified into three patterns via k-means clustering: in the direction of centrifugal force (IDCF), against the direction of centrifugal force (ADCF), and no-offset normal driving (NOND). A multinomial logistic regression model was constructed to analyze the influence of loop ramp geometric alignment characteristics on departure behaviors. The results show that for the horizontal alignment elements of loop ramps, an increase in circular curve radius, a decrease in circular curve length, and a decrease in the length of the transition curve entering the circular curve all increase the risk of IDCF; conversely, the increase in these geometric parameters tend to increase the risk of ADCF. For the vertical alignment elements, there is a significant nonlinear negative correlation between the adjacent maximum gradient difference and lane departure behaviors. For the cross-section of loop ramps, widening can significantly suppress the risk of IDCF but slightly increase the risk of ADCF. This study reveals the synergistic influence mechanism of the three-dimensional (horizontal, vertical, and cross-sectional) geometric characteristics of combined alignments on lane departure behaviors at interchange loop ramps. Full article

The objective of this research is to determine whether levels of road accessibility in urban, peri-urban, and sub-urban localities within the municipalities of Mexicali and San Felipe, in Baja California, Mexico, can be associated with processes of territorial expansion, population growth, and changes in urban marginalization levels. This is assessed through a methodology that combines ex-ante and ex-post analysis, the use of the Urban Marginalization Index (UMI) at the AGEB scale, and a hierarchical accessibility classification (Levels A, B, and C), thereby contributing a replicable tool for analyzing socio-spatial impacts derived from road infrastructure. To this end, modernization, maintenance, and reconstruction works, as well as the construction of an interchange carried out between 2006 and 2017 along Federal Highway No. 5—specifically the Mexicali–San Felipe section—were examined in relation to the accessibility they provide to ten nearby localities. UMI values were estimated for 134 AGEB using data from 2000, 2010, and 2020, which enabled the assessment of changes in quality of life before, during, and after the execution of these works. The results show significant population growth in six localities, accompanied by territorial expansion processes. Localities with direct connection to the study corridor tended to exhibit middle to low marginalization levels, while those with indirect accessibility or direct access through another federal highway section tended toward middle to high levels, with some shifting to middle to low. It is concluded that road accessibility constitutes a relevant factor in the progressive improvement in socioeconomic conditions and quality of life in urban, peri-urban, and sub-urban areas. Full article

Interchange merging areas are critical safety hotspots in urban road networks, where complex vehicle interactions challenge traffic safety and efficiency. Improving safety performance at these locations is essential for developing sustainable, resilient, and intelligent urban transportation systems. To overcome the limitations of single-driver simulators, this study developed a multi-driver simulation platform based on Unity3D (Version 2022.3.1f1c1), enabling real-time interaction among multiple human drivers. High-resolution trajectory data were collected from 231 valid interaction events. An eight-direction relative position model was employed to classify behaviors into four patterns: longitudinal, lateral, front cut-in, and rear cut-in. Risk was quantified using time-exposed and time-integrated Anticipated Collision Time metrics, with events subsequently clustered into low (n = 138), medium (n = 67), and high-risk (n = 26) categories. An ordered logit regression model identified key risk factors. The results quantitatively demonstrate that interaction risk escalates significantly with abrupt speed changes (OR = 16.22) and late-stage occurrence of speed extremes (OR = 6.76) in the interacting vehicle, as well as large initial speed differences (OR = 2.45). Conversely, stable speed regulation and adaptive acceleration by the subject vehicle proved to be potent mitigating factors. These findings provide actionable insights for the development of intelligent collision warning systems and the sustainable design of interchange infrastructure. Full article

To investigate the impact of “bright to dark” uneven lighting conditions on driver recognition of retroreflective guide signs in the diverging zones of underwater ramp interchanges, this study adjusts the luminance contrast between adjacent lighting segments in a tunnel to explore its effect on the recognition distance of retroreflective guide signs, thereby providing a basis for the rational design of lighting conditions in this area. Based on the driver’s safe recognition process, the minimum sight distance requirements for retroreflective guide signs were first determined under three representative operating speeds. Following the tunnel lighting design principles specified in Chinese standards, eight dark-environment luminance levels and nineteen bright-environment luminance levels were established. A total of 124 non-uniform “bright–dark” lighting combinations were then generated by varying the luminance difference in 1 cd/m² increments. Subsequently, 24 passenger car drivers were selected to conduct dynamic recognition experiments of guide signs under the “bright–dark” lighting transition conditions in the tunnel ramp diverging zone. Recognition distances were measured using a non-contact speedometer to capture the driver’s distance to the sign. A regression model was developed to quantify the relationship between sign recognition distance, luminance difference, and dark-environment luminance. The model’s accuracy is reflected in the fact that 92.7% of the predicted values had an absolute error of less than 10 m compared to the observed values. The results show that luminance difference has a significant impact on recognition distance, which increases initially and then stabilizes as luminance difference grows. When the dark-environment luminance is below 3.5 cd/m², the effect of luminance difference on recognition distance is more pronounced than when it exceeds 3.5 cd/m². Based on these findings, threshold values of bright-environment luminance ensuring safe recognition distances under varying dark-environment luminance conditions are proposed. It is further recommended that, for design speeds of 100 km/h or higher, the dark-environment luminance should not be lower than 2.5 cd/m² to maintain safe visibility of retroreflective guide signs. Full article

In response to the growing safety challenges posed by large-scale and specialized freight transportation on China’s rapidly expanding highway network, this study investigates the operational characteristics of trucks in interchange diverging areas—a critical segment with elevated accident risks. Leveraging high-frequency trajectory data collected from 16 interchanges, we analyze speed profiles and acceleration behavior of heavy trucks across key sections: the diversion influence zone, preparation zone, transition segment, and deceleration lane. A key contribution of this work is the development of a continuous speed prediction model based on Partial Least Squares Regression, which integrates road geometric parameters and driving behavior features to estimate speeds at four critical cross-sections of the diverging process. Furthermore, we propose a comprehensive safety evaluation framework incorporating three novel indicators: longitudinal speed consistency, lateral stability, and deceleration comfort. The model demonstrates strong performance, with all mean absolute percentage errors below 10% during validation using data from four independent interchanges. Comparative analysis with existing safety standards confirms the practical applicability and accuracy of the proposed methodology. This research offers three major contributions: (1) a systematic approach for processing large-scale trajectory data and predicting truck speeds in diverging areas; (2) a safety assessment framework tailored for geometric design consistency evaluation; and (3) empirical support for optimizing traffic safety facilities in interchange design and operation. The findings address a significant gap in current highway design guidelines and provide actionable insights for enhancing safety in truck-dominated transportation environments. Full article

When driving at highway speeds, the airtightness and ventilation mode of the cabin can significantly affect the in-cabin air quality. Accordingly, this study conducted on-road driving experiments along four highways in Tainan City, Taiwan, to examine the effects of different ventilation strategies and driving speeds on the concentrations of three pollutants (carbon dioxide (CO₂), PM_2.5, and PM₁₀) in the cabin of a mid-size sedan. During the test, the vehicle will travel at a constant speed of 60, 70, 80, 90, 100, 110 and 120 km/h depending on the traffic conditions. When driving on the system interchanges, the vehicle speed was maintained at 40 and 50 km/h. Ventilation strategies are divided into fresh air mode and recirculation air mode. The results revealed that leakage ventilation at high speeds allowed more outdoor air to infiltrate the cabin. This reduced the CO₂ concentration but slightly increased the particulate matter (PM) when the ventilation system was operated in the recirculation mode. The continuous use of the recirculation air mode for extended periods resulted in a potentially hazardous increase in the CO₂ concentration. Thus, periodic switching to the fresh air mode is recommended to ensure that the in-cabin CO₂ concentration remains below the ASHRAE threshold of 1000 ppm. In the fresh air mode, the PM_2.5 and PM₁₀ concentrations decreased as the vehicle speed increased. In the recirculation mode, the cabin filters maintained lower in-cabin PM levels than in the fresh-air mode. The experimental data were fitted using a curve-fitting technique to quantify the relationships between the vehicle speed and the in-cabin CO₂, PM_2.5, and PM₁₀ concentrations under the two ventilation strategies. The findings of this study provide useful practical guidelines for optimizing the vehicle ventilation strategy to improve the in-cabin air quality and enhance occupant health and safety during highway driving. Full article

Accurate cost estimation during the conceptual and feasibility phase of highway projects is essential for informed decision making by public contracting authorities. Existing approaches often rely on pavement cross-section descriptors, general project classifications, or quantity estimates of major work categories that are not reliably available at the early planning stage, while focusing on one or more key asset categories such as roadworks, bridges or tunnels. This study makes a novel contribution to both scientific literature and practice by proposing the first early-stage highway construction cost estimation model that explicitly incorporates roadworks, interchanges, tunnels and bridges, using only readily available or easily derived geometric characteristics. A comprehensive and practical approach was adopted by developing and comparing models across multiple machine learning (ML) methods, including Multilayer Perceptron-Artificial Neural Network (MLP-ANN), Radial Basis Function-Artificial Neural Network (RBF-ANN), Multiple Linear Regression (MLR), Random Forests (RF), Support Vector Regression (SVR), XGBoost Technique, and K-Nearest Neighbors (KNN). Results demonstrate that the MLR model based on six independent variables—mainline length, service road length, number of interchanges, total area of structures, tunnel length, and number of culverts—consistently outperformed more complex alternatives. The full MLR model, including its coefficients and standardized parameters, is provided, enabling direct replication and immediate use by contracting authorities, hence supporting more informed decisions on project funding and procurement. Full article

Increasing the lighting luminance in the diverging zone of interchange in highway tunnels can generally enhance driving safety. However, it creates a bright–dark luminance contrast with the adjacent road. A pronounced contrast can induce new driving risks. This underlying mechanism remains unclear. Three key factors, i.e., the luminance of the dark environment, the bright–dark luminance ratio, and the position of the small target, are identified in this paper, which affect drivers’ visual recognition abilities. Based on fundamental tunnel lighting design rules, a series of naturalistic driving tests on the visual recognition distance for small targets with 132 conditions were designed. It combined three dark environment luminance levels (1.5~3.5 cd/m²), four bright–dark luminance ratios (2~5), and eleven small target positions (−50~+50 m). Twenty-four drivers were randomly selected and drove vehicles under the different scenarios. Their visual recognition distances for small targets were recorded and analyzed. The results show that visual recognition distances for small target visuals under different bright–dark lighting environments vary significantly, and the shortest distances occur exactly at the luminance boundary. Both decreasing the bright–dark luminance ratio and proportionally increasing the luminance levels of the bright and dark environments can markedly improve the visual recognition distance. A multi-parameter regression model was developed to correlate the visual recognition distance at the bright–dark luminance boundary with the luminance of the dark environment and the bright–dark luminance ratio. Based on drivers’ required safe sight distance, a method for setting lighting luminance in the diverging zone of interchange was proposed. The methodology and findings offer technical support for lighting design and safety management in the diverging zone of interchange in highway tunnels. Full article

Low-cost sensors have demonstrated their advances in acquiring hyper-localized data compared to traditional, high-maintenance air quality monitoring stations. The study aims to leverage the mobility of participants equipped with low-cost wearable monitors (LWMs) by comparing their exposure to particulate matter (PM) across indoor-home, outdoor-walking, and hybrid-commuting micro-environments. The LWMs would be calibrated first through field co-location and the multiple linear regression models. The coefficient of determination (R²) of PM_1.0 and PM_2.5 increased to over 0.85 after calibration, along with the reduced root mean square error of 2.25 and 3.46 μg/m³, respectively. The 26-day PM data collection with geographic locations could identify individual exposure patterns, local source contributions, and hotspot maps. Commuting constituted a small fraction of daily time (4–8%) but contributed a disproportionate impact, accounting for 11% of individual PM exposure. Indoor-home PM_2.5 exposure varied significantly among the urban districts. Based on the PM_2.5 hotspot map, the elevated concentration was mainly concentrated in dense residential areas and historical industrial areas, as well as interchanges of major roads and the highway system. LWMs acting as non-regulatory instruments can complement monitoring stations to provide missing short-term and hyper-localized air pollution data. Future studies should integrate long-term monitoring and citizen science across seasons and geographical regions to address pollutant spatiotemporal variability for building and city sustainability. Full article