A Polynomial Parametric Curve (PPC‐CURVE) for the Design of Horizontal Geometry of Highways

Abstract: The use of transition curves in the road design is a solution to make the gradual evolution of curvature and, at the same time, to improve the comfort level of drivers and provide a good visual perception of the curve. Clothoid is the most widely used transition curve in road design so far, because it ensures the continuity of the curvature with the other geometric elements of the alignment. However, several researches allow the use of polynomial functions as an alternative to the clothoid. Such use is permitted in accordance with the verification of allowable vehicle–road dynamics. Polynomial solutions of transition curves can be a valuable alternative for the traditional solutions (first transition curve, circular arc, second transition curve). A fifth‐degree polynomial parametric curve (PPC‐curve) for the design of highway alignment is proposed in this article. An analysis of the theoretical aspects to solve more complex geometrical problems recurring in practical highway geometric design is carried out. With regard to this problem, a shape parameter giving flexibility to the polynomial solution in relation to project needs has also been introduced. To implement the procedure, an original computer program has been developed. Numerical applications have been performed for comparison with the traditional solutions.     

A Customized Particle Swarm Method to Solve Highway Alignment Optimization Problem

Abstract: Optimizing highway alignment requires a versatile set of cost functions and an efficient search method to achieve the best design. Because of numerous highway design considerations, this issue is classified as a constrained problem. Moreover, because of the infinite number of possible solutions for the problem and the continuous search space, highway alignment optimization is a complex problem. In this study, a customized particle swarm optimization algorithm was used to search for a near‐optimal highway alignment, which is a compound of several tangents, consisting of circular (for horizontal design) and parabolic (for vertical alignment) curves. The selected highway alignment should meet the constraints of highway design while minimizing total cost as the objective function. The model uses geographical information system (GIS) maps as an efficient and fast way to calculate right‐of‐way costs, earthwork costs, and any other spatial information and constraints that should be implemented in the design process. The efficiency of the algorithm was verified through a case study using an artificial map as the study region. Finally, we applied the algorithm to a real‐world example and the results were compared with the alignment found by traditional methods.     

浅谈旧路改造工程线形设计

以广东省东莞市北王公路扩建工程的线形设计为例,对既满足汽车行驶各方面要求,又经济节省的线形设计进行了探讨,为旧路改造工程线形设计提供了参考依据。     

基于车载GNSS数据的公路测绘及事故多发路段分析

采用车载GPS系统对某公路路段的平面坐标数据进行测绘与数据采集,使用专家打分法对公路环境与事故进行关联性分析,并关联坐标方位角与事故发生之间的关系。结果表明,采用车载GPS系统可以对公路路段信息进行有效采集,包括平面坐标数据和计算坐标方位角;K65~K67公路直线段和曲线段事故次数平均值分别为11次和32次,曲线段事故平均次数约为直线段事故次数的3倍。专家评分结果与事故次数之间具有较高的关联性,即专家评分较高的路段,事故次数较少,而专家评分较低的路段,事故次数较多;公路线形对公路交通事故的影响与专家评分结果相吻合。     

Optimizing Design of Highway Horizontal Alignments: New Substantive Safety Approach

Abstract:   Highway agencies are continually facing safety problems on highways, especially on horizontal alignments. Traditionally, the geometric design implicitly considers safety through satisfying minimum design requirements for different geometric elements. This article presents a new substantive-safety approach for the design of horizontal alignments based not only on minimum design guidelines, but also on actual collision experience. The curve radii, spiral lengths, lane width, shoulder width, and tangent lengths are determined to optimize the mean collision frequency along the highway. The model allows the parameters of the horizontal alignment to vary within specified ranges. The model also considers any specified physical obstructions in selecting the optimal alignment. Collision experience is addressed using existing collision prediction models for horizontal alignments and cross sections. The model is applicable to two-lane rural highways for which collision prediction models exist. Application of the model is presented using numerical examples. The proposed substantive-safety approach takes horizontal alignment design one step further beyond the minimum-guideline concept, and therefore should be of interest to highway designers.     

Use of Heading Direction for Recreating the Horizontal Alignment of an Existing Road

This article proposes a new method for fitting the horizontal alignment of a road to a set of (x, y) points. Those points can be obtained from digital imagery or GPS‐data collection. Unlike current methods that represent road alignment through its curvature, the proposed method describes the horizontal alignment as a sequence of headings. An analytic–heuristic approach is introduced. The proposed method produces unique solutions even for complex horizontal alignments. Some examples and a case study are presented. This solution may not be accurate enough for road redesign, but it allows researchers and departments of transportation to obtain accurate geometric features.     

Preliminary Highway Design with Genetic Algorithms and Geographic Information Systems

A method that integrates geographic information systems (GIS) with genetic algorithms (GAs) for optimizing horizontal highway alignments between two given end points is presented in this article. The proposed approach can be used to optimize alignments in highly irregular geographic spaces. The resulting alignments are smooth and satisfy minimum-radius constraints, as required by highway design standards. The objective function in the proposed model considers land-acquisition cost, environmental impacts such as wetlands and flood plains, length-dependent costs (which are proportional to the alignment length), and user costs. A numerical example based on a real map is employed to demonstrate application of the proposed model to the preliminary design of horizontal alignments.     

基于GIS的公路安全信息管理系统研究及应用

利用GIS技术手段建立了唐山市道路信息电子数据库和道路网络,在Visual Stidio2008平台基础上,进行Web GIS唐山市公路安全信息管理系统的开发,实现了集城市公路安全评价决策分析、交通事故影响范围缓冲分析、交通事故紧急救援最佳路径分析等功能于一体的数字化公路安全信息管理系统。     

运行车速理论在现代高等公路路线设计中的应用

道路路线设计的最终目的是服务于运行车辆的行驶需求。其中,公路中运行车辆行驶速度是公路线路设计中一项重要指标参数。基于此,文章中主要以车辆行驶特性作为阐述视角,谈及了公路路线线形对运行车速的主要影响。     

基于数据库动态操作的路径搜寻算法设计与应用

根据基于GIS等数据库管理系统对道路交通数据管理和操作的方便性,采用了一种改进的路径搜寻算法,通过数据库的动态操作、调整搜寻范围,减少计算数据量,尤其是通过计算过程中数据的动态调整,实现了快速最短路径搜寻,并将该算法在城市车辆诱导系统中得到应用.     

基于GPS/GIS数据的路网层次划分研究--北京的实践

提出采用载有GPS设备的浮动车,结合路网GIS数据对路网层次进行分析的新方法。详细介绍了整个研究框架和数据处理的过程,以及整个研究体系在北京的实际应用情况。根据采集的数据,分析了北京市不同层次路网的土地利用情况、功能发挥情况、出行者对不同层次路网的选择行为特征以及不同层次路网的可达性,获取了很多有价值的结论和发现。     

A sequential exploration algorithm for the design optimization of horizontal road alignment

Most computer-aided optimization procedures for horizontal alignment optimization of roads require the use of information such as horizontal points of intersection (PIs) to determine an alignment. In these methods, to obtain parameters such as the radius of the curve corresponding to a specific PI, the previous and next PIs must be known. In this paper, a sequential exploration algorithm (SEA) is proposed, and the algorithm continuously explores the entire optimization space through certain steps. Only the parameters of the previous node are required to determine the current node's parameters during the exploration process, avoiding the tight coupling between PIs in traditional optimization algorithms. Furthermore, the proposed SEA does not require assumptions about the positions and numbers of the PIs, and it can design near-optimal road alignments that match geometric restrictions and automatically take transition curves into account. Another feature of the proposed algorithm is that it directly optimizes the geometric element parameters based on the actual milepost, and it is a fully collaborative optimization approach that does not require secondary optimization nesting during the optimization process. Analyses comparing the optimization effects of different algorithms are performed on a numerical case, that is, a problem of avoiding obstacles, and two actual cases from the literature, that is, a new road design problem and an existing road reconstruction problem. It is discovered that the proposed SEA results in an approximately 3% to 10% improvement in optimization effects when compared to two current cutting-edge optimization algorithms. This work offers a new perspective on road alignment optimization by merging discrete and continuous optimizations, with a discrete component handling optimization accuracy and a continuous component handling real optimization.     

Investigating the Use of 3D Graphics, Haptics (Touch), and Sound for Highway Location Planning

Abstract:  Planning of transportation infrastructure requires analyzing combinations of many different types of geospatial information (maps). Conventional Geographic Information Systems (GIS) or Computer Aided Design systems limit the planner's ability to perceive and effectively use multiple data layers together. To improve the planner's ability to interact with multiple layers of disparate spatial information, we present a novel computer system, which combines vision with haptics (touch) and sound. In this new form of Multi-Sensory Information System (MSIS), visual information is augmented by a three-dimensional haptic device (PHANToM) and by sound (sonification). In a recent study, we investigated how engineering students used this multi-sensory GIS for planning the location (the alignment) of a new road. The results indicate that certain forms of vision, haptics, and audio were used preferentially to represent certain types of spatial data. A generalization of such a multi-sensory approach could provide researchers with the basis for further development and, eventually, the augmentation of established procedures with the MSIS in highway location planning and related areas.     

Semiautomatic Extraction of Road Horizontal Alignment from a Mobile LiDAR System

This article proposes a method to semiautomatically extract the road axis through a mobile LiDAR system, a recent popular technology for transportation‐related applications, road estimation and even to enhance driver safety. In particular, the approach developed has two components: (1) the feature extraction from LiDAR data to model the road axis, and (2) the estimation of the horizontal alignment that meets the requirements and practice for a transportation authority. Given the massive and complex character of the data captured by the system, a hierarchical (coarse‐to‐fine) and robust strategy based on segmentation, parameterization and filtering, which determine the road centerline together with the geometric elements that compose its horizontal alignment, such as straight lines, circular arcs, and clothoids, has been developed and implemented. Test results using a simulated and a real data are discussed and validated. The experimental results obtained with real cases guarantying relative accuracies under 2%, being a useful approach to produce accurate estimations of the horizontal geometric features of the road alignment.     

基于熵权法的农村公路交通安全分析及改善对策

对农村公路交通安全现状进行了分析,建立了影响其交通安全的评价指标体系,利用熵权法对指标进行评价,找出了机动车驾驶员、道路线形、交通安全标识、路侧环境四个关键影响因素,提出了农村公路交通安全改善对策。     

山区公路路线方案曲线定线基本方法与探讨

针对山区地形复杂多变、日益提升的行车安全与整体舒适度要求,按照立体空间连续曲线阐释、曲线定线方法以及平纵设计时总体原则,通过初拟北京房山区石水路路线方案实例,对曲线定线予以探究。     

Modeling Road Centerlines and Predicting Lengths in 3-D Using LIDAR Point Cloud and Planimetric Road Centerline Data

Abstract:   Transportation is one of a few engineering domains that work with linear objects—roads. Accurate road length information is critical to numerous transportation applications. Road lengths can be obtained via technologies such as ground surveying, global positioning systems (GPS), and Distance Measurement Instruments (DMI). But using these methods for data collection and length determination is time-consuming, labor intensive, and costly. The purpose of this study was to assess the accuracy and feasibility of an alternative. This article reports on a study that provides an alternative to obtaining road centerline lengths by measurement; instead it proposes using geographic information systems (GIS) and light detection and ranging (LIDAR) point cloud data. In this study, a three-dimensional (3-D) vector model based on linear referencing systems (LRS) concepts was developed to represent road centerlines in a 3-D space and to predict their 3-D lengths. A snapping approach and an interpolation approach to obtain 3-D points along lines when working with LIDAR point clouds were proposed and discussed. Quality control measures were initiated to validate the approach. The accuracy of the predicted 3-D distances was evaluated via a case study by comparing them to distances measured by DMI. The results were also compared to road lengths obtained by draping planimetric road centerlines on digital elevations models (DEMs) constructed from LIDAR points. The effects of the average density of 3-D points on the accuracy of the predicted distances were evaluated. This study concluded that the proposed 3-D approach using LIDAR data was efficient in obtaining 3-D road lengths with an accuracy that was satisfactory for most transportation applications.     

A modified motion planning algorithm for horizontal highway alignment development

A horizontal alignment can be represented by three key factors: number of horizontal points of intersection (HPIs), their locations, and corresponding horizontal curve radii. Deciding all the three factors simultaneously requires extensive effort, which is not practically feasible in the manual alignment development process. Most available computer‐aided methods prioritize some or all the three factors in the automated alignment development processes. However, approximation in HPI location or pre‐selection of HPI number and curve radius are the few limitations of these methods. This study presents a modified motion‐planning based algorithm for developing new horizontal alignments with optimized costs and impacts. It simultaneously uses a low‐discrepancy sampling technique to develop increasingly dense potential HPIs, rapidly exploring random trees to find a suitable number of intermediate HPIs at appropriate locations and sequential quadratic algorithm to select optimally fitted curve radii. The proposed algorithm is integrated with the GIS database for realistic location‐dependent cost and environmental impact assessment. Two real‐world study areas were selected to compare the results with the one reported in the literature and to evaluate backtracking capability. Results indicated the proficiency of the proposed algorithm in developing new alignments. The sensitivity analyses revealed the effect of design speed and right‐of‐way width on the alignment generation. The proposed algorithm can automate the new horizontal highway alignment development process and support highway engineers in planning and development.     

A Method for Automatically Recreating the Horizontal Alignment Geometry of Existing Railways

Periodic recreation of existing railway horizontal alignment geometry is needed for smoothing the deviations arising from train operations. It is important for calibrating track and rebuilding existing railways to ensure safety and comfort. Track calibration repairs the existing distorted track centerline to match the smoothed recreated alignment, which may differ considerably from the originally designed track centerline. Identifying the boundaries of all the geometric elements including tangents, circular curves, and transition curves is the key problem. Existing methods recreate the horizontal alignment semi‐automatically and can only generate a locally optimized solution while considering a few constraints. Based on the principle that the attributions of all the measured points to geometric elements should be consistent with the ranges of recreated geometric elements (i.e., for points‐alignment consistency), a method called swing iterations is proposed to reclassify point placements and identify all the tangents, circular curves, and transition curves simultaneously. In a swing iteration, the boundary of a geometric element segment repeatedly changes from left to right, then from the right to left, and finally stabilizes. Before the swing iterations, preliminary tangents and curves are identified based on the heading gradient (i.e., the rate of change of heading), and are set as initial values for the swing iterations. A genetic algorithm is developed to further refine the entire recreated alignment after the swing iterations. In the above processes, multiple constraints are handled. Applications demonstrate that this method can identify all horizontal geometric elements automatically and generate an optimized recreated alignment geometry for an existing railway while satisfying all the applicable constraints.     

Automatic geometry measurement for curved ramps using inertial measurement unit and 3D LiDAR system

Although road geometry data can be automatically collected using instruments mounted on survey vehicle, measurement of curved ramp geometry is still of low effectiveness and accuracy due to manual or semi-automatic detection of PC (Point of Curvature)/PT (Point of Tangent) as well as influences of vehicle vibration and wandering. In this study a new method is presented for automatic measurement of ramp geometry in network level using IMU (Inertial Measurement Unit) and 3D LiDAR (Light Detection And Ranging) system. Firstly, horizontal alignment measurements are implemented: 1) an improved K-Mean clustering method and linear fitting method are integrated for automatic PC/PT station detection; 2) an algorithm is developed for automatic lane marking identification and localization for vehicle's trajectory calibration; 3) curve radius and length are measured based on roadway centerline. Subsequently, pavement slope is calibrated using IMU and transverse profiling data. Finally, nine segments are chosen from highway ramps as test bed, and validation tests are conducted using the field measurement. The test results show the average errors for curve detection and curve radius measurement are 5.89% and 1.99% respectively, and the P-value for longitudinal and cross slope measurement are 0.621 and 0.989 respectively, which indicate the proposed method is robust in ramp geometry measurement. The significant of the proposed method is three folds. First, it integrates and synchronizes the IMU and 3D LiDAR system in geometry measurement. Second, it solves the common problems of mobile survey on vehicle wandering and vibration. Third, it is of high accuracy and effectiveness, and can be used for roadway survey in network level.