Highway Alignment Research Articles

Development of lateral acceleration prediction models and consistency evaluation criteria for horizontal curves with gradient on two lane rural highways

Objectives The challenge of combined horizontal and vertical highway alignments continues to be a concern in transportation design, particularly regarding truck stability. This study analyses the stability of trucks on horizontal curves combined with ascending or descending gradients using center of gravity (CoG) height and curve geometry as parameters. It also develops models that predict lateral stability of trucks and criteria for evaluating geometric design consistency based on vehicle stability. Method A smartphone application was used to collect real-time data on lateral acceleration experienced by two-axle trucks on curves with gradient. Results Findings show a lower safety margin against rollover on curves with descending gradient compared to ascending ones. Key factors affecting stability are identified as radius and length of horizontal curve, suggesting improvements in rollover stability by increasing these parameters. Geometric design consistency evaluation criteria were developed based on lateral acceleration, categorizing curves with gradient as good, fair, or poor. Predictive models were developed to quantify the impact of CoG height of truck and curve geometry on lateral acceleration, aiding in consistency assessment. Conclusion Outcomes of research will be useful for the design of safer horizontal curves with gradient by prioritizing vehicle stability

Development of Motorway Horizontal Alignment Databases for Accurate Accident Prediction Models

The safe and efficient operation of highways minimizes the environmental impact, reduces accidents, and promotes the reliability of the transportation infrastructure, all in support of sustainable transportation. The horizontal alignment of highways holds particular importance as it directly impacts driver behavior, vehicle stability, and overall road safety. In many cases, highway inventory data held by infrastructure operators may contain inaccurate or outdated information. The accuracy of the variables used in crash prediction models eliminates possible bias in the variable estimators. This research proposes a methodology to obtain accurate horizontal geometric features from digital imagery based on the analysis of the planimetry, feature geolocation and centerline azimuth sequence. The reliability of the method is verified by means of numerical and statistical procedures. This methodology is applied to 150 km of motorway segments in Portugal. Although it is found that the geometric characteristics of most of the inventory segments closely matched the extracted alignments, very significant differences are found in some sections. The results of the proposed procedure are illustrated with several examples. Finally, the propagation of error in the determination of the geometric design independent variables in the fitting of the statistical models is discussed based on the results.

Measurement of the on-road wind environment in channelled roadways

A road test was undertaken to characterize the complex wind environment experienced by vehicles in channelled roadways. Channelled roadways consist of highways that are bordered by forests, hills, or other terrain features. A test vehicle was outfitted with three fast-response pressure probes in front of the vehicle located at 1 m, 2 m, and 3 m above the ground. Measurements were acquired on three highway routes in Canada with varying degrees of surrounding terrain, roadside forest cover, and in different wind conditions. Reference wind conditions were established using a network of federally-managed weather stations. The study identified that the effects of terrain and roadside forests can cause changes in wind direction of more than 50∘ to 90∘ relative to nearby reference weather stations. Directional channelling of winds was observed in forested and complex terrain, where changes in the wind direction mimicked the changes in highway alignment. The on-road video files were analysed using a machine-learning algorithm to quantitatively assess road-side forests and terrain and to identify fully-channelled sections of highway. Generalized channelled-flow trends were identified by considering the wind conditions in the channelled sections of all three routes. A linear relationship between the flow direction in the channel to that of the reference conditions was observed when the reference wind direction and the highway was within ±50∘. As the reference wind direction approached perpendicularity to the channelled segments, greater variations in the on-road wind direction were observed due to the unsteady flow within the channel. On-road wind speeds on each route were a maximum when the reference wind direction was approximately aligned with the highway and decreased to approximately 20% of the reference wind speed when the reference wind was perpendicular to the channel.

Landslide-Hazard-Avoiding Highway Alignment Selection in Mountainous Regions Based on SAR Images and High-Spatial-Resolution Precipitation Datasets: A Case Study in Southwestern China

Landslides recurrently cause severe damage and, in some cases, the full disruption of many highways in mountainous areas, which can last from a few days to even months. Thus, there is a high demand for monitoring tools and precipitation data to support highway alignment selections before construction. In this study, we proposed a new system highway alignment selection method based on coherent scatter InSAR (CSI) and ~1 km high-spatial-resolution precipitation (HSRP) analysis. Prior to the CSI, we calculated and analyzed the feasibility of Sentinel-1A ascending and descending data. To illustrate the performance of the CSI, CSI and SBAS–InSAR were both utilized to monitor 80 slow-moving landslides, which were identified by optical remote-sensing interpretation and field investigation, along the Barkam–Kangting Highway Corridor (BKHC) in southwestern China, relying on 56 Sentinel-1A descending images from September 2019 to September 2021. The results reveal that CSI has clearer deformation signals and more measurement points (MPs) than SBAS-InSAR. And the maximum cumulative displacements and rates of the landslides reach −75 mm and −64 mm/year within the monitoring period (CSI results), respectively. Furthermore, the rates of the landslides near the Jinchuan River are higher than those of the landslides far from the river. Subsequently, to optimize the highway alignment selection, we analyzed the spatiotemporal evolution characteristics of feature points on a typical landslide by combining the −1 km HSRP, which was calculated from the 30′ Climatic Research Unit (CRU) time-series datasets, with the climatology datasets of WorldClim using delta spatial downscaling. The analysis shows that the sliding rates of landslides augment from the back edge to the tongue because of fluvial erosion and that accelerated sliding is highly related to the intense precipitation between April and September each year (ASP). Consequently, three solution types were established in our method by setting thresholds for the deformation rates and ASPs of every landslide. Afterward, the risk-optimal alignment selection of the BKHC was finalized according to the solution types and consideration of the construction’s possible impacts. Ultimately, the major problems and challenges for our method were discussed, and conclusions were given.

Highway Alignment Optimization Design Method Based on Multi-Objective Particle Swarm Optimization

Highway alignment design is a nonlinear multi-objective optimization problem. Due to the uncertainty and complexity of the constraints, it is challenging to develop a suitable model for 3D road alignment design. To comprehensively consider the constraints and realize the intelligent design, this study puts forward a novel highway alignment model to optimize the horizontal and vertical alignment design, in which the length utility cost and structure construction cost are projected into the optimization space. Finally, the numerical solution is carried out by MOPSO on MATLAB platform. The results show that this method can effectively solve the problem of highway alignment design under the condition of realizing the highway design specifications, shortening the design cycle, and improving the design quality, which verifies the feasibility of the optimization algorithm for the horizontal and vertical alignment optimization design of highway.

Research on Evaluation Index System of Urban Landscape Design Driven by Information Integration Technology

Abstract This study focuses on the urban landscape design of city A, and uses information fusion technology to evaluate. Through the analysis of the measured data by the entropy weighting method and the ensemble optimal weighting method, and compared with the established index system, the results reveal the weights of different landscape elements. Regarding ecological landscape, the CR value was 0.003, in which landscape diversity and green space rate were the leading indicators, and the weights were 0.2976. The weights of landscape dominance and uniformity were relatively medium, both of which were 0.1579. In the evaluation of aesthetic landscape, the CR value was 0.0309, and the highway alignment and urban landscape indicators in the urban landscape were the most important, with a weight of 0.2044, while the weight of the indication information was the lowest, only 0.0266. The CR value of the cultural landscape was 0.0518, of which the weight of scenic connectivity was the highest (0.5559), followed by the number and scale of scenic spots (0.3537), and the weight of historical and cultural elements was the lowest (0.0904). In the past few years, landscape design has accounted for the most significant proportion of landscape construction investment, especially reaching a peak of about 57,000 yuan in 2022. From 2018 to 2022, the cumulative investment in urban landscape design is about 246664 yuan.

Research on optimization design of highway route alignment based on vehicle operating speeds

Research on optimization design of highway route alignment based on vehicle operating speeds

Establishing the necessary measures for carrying out the activity in security conditions during the execution of work on the Iernut - Chetani highway alignment, Mures county

The purpose of this work is to establish the regime of methane releases (explosive gas) following the execution of the underpass works of the Sibiu-Pitesti highway in the Curtea de Argeș-Pitesti sector. INSEMEX Petroșani executed during the period 01-04.11.2022 on-site measurements at four highway underpasses with a total length of 843m as well as in the areas adjacent to these underpasses, noting that these underpasses are from wells in operation and are connected to the SRM Merișani Station. Based on the measurements and observations made, the analysis of the elements taken into study, as well as the existing records and documentation, INSEMEX Petroșani made the present work.

Modeling car and heavy commercial vehicle crashes on two-lane rural highways using the Poisson-Tweedie regression approach

This article develops vehicle type–based crash-prediction models for cars and heavy commercial vehicles (HCVs) as a function of the curve geometry and vehicle-based design consistency criteria under heterogeneous traffic conditions on two-lane, two-way rural highways, specifically in hilly terrains. A National Highway (NH-953) connecting Netrang and Rajpipla in India was selected. There are 38 curves in the study section, each having a different curve geometry. Speed data were collected using the radar gun for cars and HCVs. The geometric design consistency was evaluated using Criterion I (the difference between operating and design speeds). The results show that 53% of the curves for cars have good consistency, compared to 32% and 29% of the curves for HCVs, which have fair and poor consistency, respectively. The Poisson-Tweedie regression technique, which provides a unified framework to model over-dispersed, under-dispersed, zero-inflated, count-data, and multiple-response variables, was used to develop the crash prediction models. The results revealed that crashes (cars and HCVs) decrease as the curve radius, deflection angle, and length increase. Similarly, as the tangent length increases, the difference between operating and design speeds increases, making inconsistent highway alignment, resulting in increased chances of crashes. The results of the present study can help highway authorities to evaluate highway alignment consistency and develop corresponding proactive strategies to improve highway safety.

Safety Evaluation for Highway Geometric Design Based on Spatial Path Properties

Safety is an important aspect of road design. In highway geometric design, road engineers use a two-stage design method due to its convenience, but the available two-dimensional design tools on the market are believed to impose limitations. Horizontal and vertical alignment parameters are considered and determined at the designer’s discretion, potentially downplaying the three-dimensional characters of spatial curves. This study focuses on the three-dimensional characteristics of highway alignments and investigates a safety evaluation method to establish the relationship between crash rate and spatial curve properties. This will necessitate an analytical investigation into the effects of higher-order properties, such as curvature and torsion, on the geometry of spatial Cartesian curves. First, these combinations of horizontal and vertical alignments were categorized into six classifications, each with its own spatial expression in mathematical form. After manipulating the curvature and torsion of the spatial curve algebraically, the correlation between geometric design variables and crash rate was ultimately established. A few cases involving geometric design data and crash facts were utilized for verification. The results revealed a considerable positive correlation between curvature or torsion variance and crashes per million vehicles kilometers, as a slight difference between curvature and torsion could also be spotted. And curvature distribution is correlated with collision frequency more closely than torsion spatial variation.

Parameters Modeling and Probing of Highway Structural Deterioration: Case study of F-209 Segment of Ondo - Ore Pavement, Southwestern Nigeria

The construction of highway route is influenced by geology, geotechnical, topography, and geomorphology of the terrain. However, for pavement that failed structurally, a critical investigation is required to ascertain the cause(s) of its failure, so that such study can assist during the rehabilitation/re-construction phase. Based on this, the incessant failed Ondo – Ore was studied using integrated methods. Electrical resistivity involving four vertical electrical sounding, ten dynamic cone penetration test, three coring by trial pits at 1.0 to 3.0 m offset from the edge of the highway at different chain-age, and laboratory geotechnical-geochemical analysis adopting standard procedures. The VES characterized the geological sequence within the highway alignment to be topsoil, subsoil, weathered layer, and basement rock. The topsoil/subsoil and the weathered layer on which the highway is founded is sandy clay and clay with resistivity less than 200 ohm-m. The depths to basement ranged from 33.5 to 45.1 m. The trial pits recordings are consistent with the results of the VES, geotechnical, and geochemical analysis, distinctly distinguishing the upper 1 m into clayey soil (sandy clay, clayey hardpan) laterite, and silt-clay-sand mixture. The engineering competence of the topsoil/subsoil on which the road is founded is poor, although is inactive SC-SM, A-7-5/A-7-6 lateritic soil type (silica-sesquioxide ratio of 1.67). The clay mineralogy is within the illite – montmorillonite group. The SNG, SN, and SNP contributions of the soil as subgrade, subbase, and base material are very low (<1.0). The regression models of all parameters correlated positively, although weak for RD and DCPI, in-situ CBR and MR, RD and in-situ CBR; while strong for soaked CBR and in-situ CBR, ER and MR. Consequently, based on the GI and CBR values, the expected average thickness of the highway should range between 191 mm (good segment) to 445 mm (for weak segment) (avg. 312 mm) which is far thicker than 274 mm measured along the highway alignment during reconnaissance survey. Therefore, it can be concluded that the failure of the highway is as a result of low soaked CBR/in-situ CBR values with low strength coefficient; and low design thickness across the highway. In addition, lack of drainage at the shoulders of the highway is also causative factor. Hence, the need for effective design of roads (to specification) and maintenance strategy was therefore advocated.

Electrical Resistivity Imaging for Identifying Critical Sulfate Concentration Zones Along Highways

Assessing sulfate concentration levels and their distributions within road alignments is crucial for the design of highway projects. Sulfate minerals in soils react with calcium-based additives, leading to sulfate-induced heaving and pavement failures. However, a reasonable assessment of the extent and levels of sulfate concentration using current practices, such as conventional laboratory-based methods, is still challenging because of the spatial heterogeneity of sulfate minerals and their seasonal fluctuations. This study aims to assess the application of electrical resistivity imaging (ERI) to determine levels and distributions of sulfate concentration. Finite element and least-squares optimization were used to process the data and generate subsurface inverted resistivity profiles. Fourteen ERI surveys were carried out for two sites with a potentially high risk of sulfate-induced heaving to help determine the extent of critical sulfate concentration zones. Laboratory tests (sulfate and moisture content tests) were conducted on ten samples collected from the field sites to validate ERI findings. The results showed that electrical resistivities of critical sulfate concentration zones are significantly lower than typical ranges of electrical resistivity of earth materials because of the abundance of salt ions in pore water, which facilitates the flow of electric current. The findings of this study were consistent with laboratory test results in determining the sulfate concentration levels. This study showed that ERI successfully provides a rapid and continuous assessment of critical sulfate concentration zones within highway alignments. The findings of this study will help materials and pavement engineers determine where alternative materials and pavement designs are needed.

Design Issues in Widening of Unspiraled Horizontal Curves

In highway alignment, when the traveled way is widened for unspiraled horizontal curves, a linear increase, widening from zero to its maximum value along the application length, leads to an undesired straight edge or an apparent kink, since there is no transition curve between the tangent section of the road and the main circular curve (unlike spiraled horizontal alignment where gradual and proportional offsets of widening can easily be accomplished with respect to the transition curve). Although compound curves or modified spirals can be employed to solve this problem, using complex curves for simple (unspiraled) alignment has not been a favored approach. This paper addresses this issue and proposes using a single circular arc on the inside edge of widening where possible. On trying many circular arcs iteratively until certain conditions are met, within a given range of superelevation runoff length, several arcs have been produced for each cell of the widening table provided by AASHTO. All the arcs satisfied the all-governing condition of sharing the same tangent with the main circular curve at the end of the application distance. Provided that the superelevation runoff length falls within the limits determined in the paper, the work presents a simple and time saving approach for designers to adapt. Although the computations are based on 7.2 m traveled way width, similar arcs can easily be produced by others for various widths. The paper, therefore, shows how to map the application domain of such arcs for given curve parameters.

Sustainable Cost Optimisation Measures for The Lifecycle of Tolled Highway Projects in Malaysia

The implementation and maintenance of highway infrastructure often requires significant capital throughout its life cycle which affects stakeholders including the government, developers, operators, users, etc. Furthermore, the sustainability aspect and existing toll systems in Malaysia are currently in the midst of being re-evaluated in order to attain a long-term gain that benefits both road users and relevant stakeholders. The objective of this study is to propose a Life Cycle Cost Analysis (LCCA) model for sustainable highway projects in Malaysia which considers certain cost optimisation measures throughout the stages of concept, design, construction, and operation & maintenance. The proposed LCCA model intends to act as a cost optimisation tool that provides sustainability recommendations for toll systems, highway alignments, pavement maintenance and rehabilitation, existing policies, contract and project type, material, equipment, time-cost factor, etc. Additionally, a relationship between the financial efficiency of toll systems and the affect it has on the overall cost of highway projects was established. The significance of cost pertaining to highway infrastructure components and the perception of toll systems was evaluated via a survey questionnaire; distributed to a select group of senior and principal engineers. The survey utilised a 5-point Likert scale which assisted in forming a regression analysis along with determining a correlation between toll systems and the overall cost of highway projects. Secondary data obtained from a reputable consultancy aided in understanding highway components that could potentially undergo further cost optimisation. Lastly, the sustainable and cost optimised LCCA model consists of recommendations and measures intended for a new age of sustainable highway projects in Malaysia.

Quantitative evaluation of attraction intensity of highway landscape visual elements based on dynamic perception

In order to quantify the aesthetic attraction of visual elements of highway landscape space, the concept of visual attraction intensity of highway landscape space is proposed, and the factors and indicators of visual attraction elements are clarified. Based on the perspective of human factors, taking passengers as the main attraction, taking 30 landscape elements from three typical highway landscape scenes, namely mountain highway landscape, plain highway landscape and elevated highway landscape, as the research object. The real-time evaluation and data processing system of subjective landscape preference has been independently developed, and combined with the processing and analysis of human-machine-environment synchronous quantitative analysis technology and in-depth learning, a “subjective+objective” quantitative evaluation model of highway landscape visual element attraction intensity based on dynamic perception has been constructed, revealing the quantitative relationship between highway landscape visual attraction elements and attraction intensity, The quantitative method and action law of the attraction intensity of highway landscape and the dynamic aesthetic perception of the attraction subject is clarified. It is found that the change of highway planning alignment, high green view rate and low enclosure have positive effects on the subjective preference score of the landscape (0.690), and there is a significant positive correlation between green view rate and enclosure; the richer the landscape elements such as mountains, trees and water bodies, the stronger the visual attraction, but the complexity of the landscape elements increases the cognitive load of the area of interest. Among the physiological indicators, there are significant correlations between EEG and ECG (0.790), EDA and ECG (0.632), and subjective preference and passengers' eye-movement behavior and EDA; as well as the change pattern of attraction intensity based on the dynamic perception of tunnel area. The results show that the attraction intensity of visual elements of highway landscape space based on dynamic perception is consistent with human aesthetic preference, visual perception and physiological response, which verifies the scientificity, appropriateness and accuracy of eye-movement analysis method and physiological analysis method for quantitative evaluation of aesthetic preference of highway landscape.

Relationship between Highway Geometric Characteristics and Accident Risk: A Multilayer Perceptron Model (MLP) Approach

The traffic safety of mountain highway has always been one of the taking point. This study aims to collect road design data in large-scale research and analyzes the accident risk of highway geometric alignment. Accordingly, a method based on satellite maps and clustering algorithms is proposed to calculate the geometric alignment of the highway plane and its longitudinal section. The reliability of the method was verified on Nanfu highway in Chongqing, China. The planar and longitudinal sectional geometries of the four highways in Chongqing were obtained by the above method, and the corresponding 36,439 traffic accidents which occurred from 2010 to 2016 were used as the research objects. The accident risk of the highway geometry was analyzed based on the SHAP and MLP theories. The results show that the fitting and prediction abilities of the MLP model are better than those of the negative binomial model, and its correlation coefficient is improved by 33.2%. In addition, compared with the negative binomial model, the MLP model can estimate more accurately and flexibly the complex nonlinear relationship between the independent and the dependent variables.

Research on Safe Following Distance on an Expressway Based on Braking Process Analysis

As an important part of the vehicle active collision avoidance system, improvement of the minimum safe following distance model has aroused the interest of researchers at home and abroad. According to the characteristics of the safe driving of vehicles on expressways, the braking process of vehicles is analyzed using the principle of kinematics. According to the requirements of the safe following distance between vehicles, the safe following distance of different braking system structures, different following states, different speeds and different slope sections on expressways is quantitatively analyzed. Three different safe following distance calculation methods based on braking deceleration under different slope conditions are established. Matlab software was used for simulation analysis. The simulation results show that the calculation method of the safe following distance meets the requirements of keeping safe distance in the Implementation Regulations of Road Traffic Safety Law of the People’s Republic of China and provides a more specific reference basis for speed limit used on expressways. This study provides a theoretical basis for the application and interpretation of the parking sight distance value stipulated in the Design Specification for Highway Alignment, and has certain practical guiding significance for improving the density and transportation efficiency of expressway vehicles and reducing the incidence of rear-end traffic accidents.

Effect of Motion Cues on Highway Driving Performance in Simulated Driving

The motion system is a major component of a driving simulator. It provides motion cues in various directions with different degrees of freedom (DOF). Different DOF could influence response variables widely used in highway design safety evaluation conducted in simulators. Few studies, though, have comprehensively explored the effect of driving simulator motion cues on driving performance. The high-fidelity Tongji University Driving Simulator (TUDS) was used to separately compare five dependent variables: speed, speed change, lane deviation, longitudinal acceleration, and lateral acceleration. The Wilcoxon signed-rank test was used to examine the difference for each variable using 8-DOF and fixed-base motion system configurations for nine types of combined highway alignments. A subjective assessment of participants’ driving experience was conducted, and the chi-square test for each term was used to compare the difference in motion system fidelity and adverse reactions between the two configurations. Results show that: (1) speed and lateral acceleration are more likely to be significantly affected by motion cues than speed change, lane deviation, and longitudinal acceleration; (2) the horizontal curve with up-grade is the type of combined alignment where speed and lateral acceleration are mostly affected; (3) characteristics of the five variables in different combined alignments vary between the two simulators; (4) the 8-DOF motion system provides better perceived motion fidelity than the fixed-base system does, and the 8-DOF simulator causes less discomfort and tiredness in simulator sickness; and (5) the presence of motion cues is suggested for highways with complex combined curves when focusing on speed and lateral acceleration.

Influence of highway space alignment continuous degradation in 3-dimensional space on autonomous vehicle trajectory deviation based on PreScan simulation

Influence of highway space alignment continuous degradation in 3-dimensional space on autonomous vehicle trajectory deviation based on PreScan simulation

Study on Highway Alignment Optimization Considering Rollover Stability Based on Two-Dimensional Point Collision Dynamics

In order to reduce the influence of unreasonable road alignment design on vehicle driving safety, a study on road alignment optimization and vehicle driving safety based on two-dimensional point collision dynamics was carried out. First, through the two-dimensional point collision dynamics model, the relationship of the kinematic parameters before and after vehicle collision was deduced. Second, according to the vehicle–road coupling dynamic model analysis after collision, the safety threshold between the radius of the circular curve and the road superelevation was derived by taking vehicle rollover as the critical condition. Next, the road alignment optimization scheme based on vehicle rollover stability after collision was proposed. Finally, the rationality of the optimization scheme was verified by PC-Crash simulation. The simulation results showed that the proposed optimization scheme of the minimum radius and superelevation of the circular curve meets the safety requirements of vehicle rollover. This study optimized the relevant indicators of the road alignment under the premise of ensuring vehicle rollover stability and provides a reference for the improvement and optimization of road alignment design. It also has important guiding significance for the formulation of vehicle driving safety management measures.