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.     

Intersection Modeling for Highway Alignment Optimization

Abstract:   When optimizing a highway alignment, it is desirable to consider new and modified intersections along it. This article develops methods for locally optimizing intersections within highway alignment optimization processes. Design and operational characteristics for intersections are reviewed from the literature. The formulation considers the major costs that are sensitive to intersection characteristics. Genetic algorithms are used for optimal search. The proposed methods are implemented on an artificial study area and on a real one through the use of geographic information systems. The results show how the methods work for local optimization of intersections as well as for optimizing entire alignments. These methods can be used for improving search flexibility, thus allowing more effective intersections. They also provide a basis for extending the alignment optimization from single highways to networks .     

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 to Identify and Classify the Vertical Alignment of Existing Roads

A detailed knowledge of the geometric characteristics of already built roads is necessary for various tasks related to their exploitation. However, sufficiently accurate or updated information about their geometric characteristics is frequently not available. Therefore, it is common to collect data of road geometry normally by means of a vehicle equipped with various sensors and, from the data obtained, generate analytically a geometric design that fits reality as closely as possible. There are several procedures to recreate the horizontal alignment of existing roads. However, no such effort has been made for vertical alignment. Knowledge of vertical profile's geometry is important for safety traffic studies as sight distance. This article presents a method of obtaining the geometrical elements of the vertical profile of highways through the longitudinal slope of their centerline points. The procedure has been successfully validated by its application on five rural highways in Spain.     

道路线形对双车道公路通行能力的影响研究

双车道公路在选线时,由于平、纵线形指标选取的范围较大,它们之间的组合导致了双车道公路线形差异较大,通行能力也不尽相同。因此,平纵线形是影响双车道公路通行能力的主要因素。根据实测数据和已有研究,认为半径大于400m的平曲线和坡度小于3%的纵坡不影响道路的通行能力。定义有效曲度和有效梯度2个概念来分别表示平曲线的弯曲程度和竖曲线的陡峭程度,给出计算方法,并探讨其有关性质。根据仿真结果和速度差原则分别将有效曲度和有效梯度分为了7级和6级,将有效曲度和有效梯度进行组合,构造出42组不同道路线形下的双车道公路,在进行的仿真实验中,得到了相应的小客车速度-流量、流量-跟车率关系,最终得出不同道路线形条件下的双车道公路通行能力值。     

GPS–GIS-Based Procedure for Tracking Vehicle Path on Horizontal Alignments

Abstract:   This article presents a global positioning system–geographic information system (GPS–GIS)-based procedure for the deduction of the horizontal alignment of a road based on the path of a control vehicle. Using differential GPS surveying, field data were collected at a 0.1-second interval, under different speed conditions on a 25-km section of a two-lane rural highway in eastern Ontario. The raw GPS data were post-processed to filter out the possible errors and then imported into a GIS environment for analysis and interpretation of the results. An extension for ArcView was written to determine the geometric features of the highway horizontal alignment, including the tangents, spirals, and circular curves. Values were obtained for the radius and length of nine circular curves, length of spirals, and the lateral position of the vehicle path along the straight and curved segments. These values were compared with the same features of the actual highway alignment. The results showed that the developed procedure and ArcView extension could produce the horizontal alignment of a road quickly, accurately, and for a relatively low cost. In addition to the extraction of the horizontal alignment of a road, the procedure can be used to track the actual vehicle path under normal driving conditions and compare it with the horizontal alignment of a road in an investigation concerning driver behavior.     

公路隧道设计中相关问题的讨论

分析了公路隧道线形设计与平面线形设计的要点,探讨了公路隧道结构形式的选择策略及常用的结构形式在工程中出现的问题,并对公路的防排水设计方法进行了论述,为公路隧道设计积累了经验。     

A deep reinforcement learning approach to mountain railway alignment optimization

The design and planning of railway alignments is the dominant task in railway construction. However, it is difficult to achieve self-learning and learning from human experience with manual as well as automated design methods. Also, many existing approaches require predefined numbers of horizontal points of intersection or vertical points of intersection as input. To address these issues, this study employs deep reinforcement learning (DRL) to optimize mountainous railway alignments with the goal of minimizing construction costs. First, in the DRL model, the state of the railway alignment optimization environment is determined, and the action and reward function of the optimization agent are defined along with the corresponding alignment constraints. Second, we integrate a recent DRL algorithm called the deep deterministic policy gradient with optional human experience to obtain the final optimized railway alignment, and the influence of human experience is demonstrated through a sensitivity analysis. Finally, this methodology is applied to a real-world case study in a mountainous region, and the results verify that the DRL approach used here can automatically explore and optimize the railway alignment, decreasing the construction cost by 17.65% and 7.98%, compared with the manual alignment and with the results of a method based on the distance transform, respectively, while satisfying various alignment constraints.     

Prescreening and Repairing in a Genetic Algorithm for Highway Alignment Optimization

Abstract:   The method of handling infeasible solutions in an evolutionary search algorithm [e.g., genetic algorithms (GAs)] is crucial to the effectiveness of the solution search process. This problem arises because solution search steps, techniques, and operators used in GAs (such as reproduction, mutation, and recombination) are normally  " blind " to the constraints, and thus GAs can generate solutions that do not satisfy the requirements of the problems. In GA-based highway alignment optimization (HAO), many infeasible solutions, which violate model constraints, are also possibly generated, and evaluation of such solutions is wasteful. This study focuses on ways to avoid wasting computation time on evaluating infeasible solutions generated from the GA-based HAO, and develops a prescreening and repairing (P&R) method for an efficient search of highway alignments. The key idea of the P&R method is to repair (before the very detailed alignment evaluation) any candidate alignments whose violations of design constraints can be fixed with reasonable modifications. However, infeasible alignments whose violations of constraints are too severe to repair are discarded (prescreened) before any detailed evaluation procedure is applied. The proposed P&R method is simple, but significantly improves computation time and solution quality in the GA-based HAO process. Such improvements are demonstrated with a test example for a real road project. Through the example study, it is shown that the model incorporating the P&R method can find a good solution much faster (by approximately 23%) than the model with the conventional penalty method. In addition, the P&R method allows the model to evaluate about 70% more solutions than that it can evaluate with the penalty method for the same number of generations.     

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.     

公路设计中需要考虑的交通安全因素分析

本文从行车视距、平面线形、纵断面线形、平面交叉和平纵组合等五个方面,对公路设计中需要考虑的主要交通安全因素进行了分析研究,以期为提高公路设计质量、保障行车安全提供参考。     

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.     

新时期农村公路排水问题的解决对策

随着公路网的进一步完善,农村公路建设得到了长足发展,但是我国在农村公路排水设施工程方面还存在较多问题.结合农村公路的实际情况,以排水设施的设计规范为依据,将农村公路排水类型分为路界地表和地下排水、路线横向排水、穿越集镇路段排水等形式,针对不同类型的排水提出了农村公路排水解决方法.此外还介绍了江苏省和山西省结合地方实际情况出台的相关文件,以期为农村公路建设起到积极推动作用.     

Two algorithms for reconstructing vertical alignments exploring the neural dynamics model of Adeli and Park

Vertical alignment reconstruction obtains alignment parameters by fitting geometric components to a set of measured points representing the profile of an existing road or railroad, which is essential in alignment consistency analysis and maintenance to ensure safety and comfort. The neural dynamics model of Adeli and Park is explored and improved for reconstructing vertical alignments with constraints. The structure of the dynamics model is modified to include three layers: parameter layer, intermediate layer, and energy layer. The number of nodes in the parameter or intermediate layers corresponds to the number of independent parameters defining a vertical alignment. The number of nodes in the energy layer is the sum of the number of deviations and the number of constraints in the alignment reconstruction problem. The coefficients connecting nodes between the parameter layer and the intermediate layer determine the integral operations, which define the Levenberg–Marquardt algorithm of the dynamics model (LMADM) and the steepest descent algorithm of the dynamics model (SDADM). Both the LMADM and SDADM methods satisfy the Lyapunov stability theorem, but the LMADM method outperforms the SDADM method in its objective function value and computation time. Experiment results demonstrate that there are multiple local optima for a vertical alignment reconstruction, and the solutions obtained by the LMADM method are the best obtained so far, compared with those reported in the literature, with 57.1% and 23.4% decreases of the mean squared error for the highway and the railroad examples, respectively.     

浅谈山丘地区公路边坡绿化设计--从潭邵高速公路上边坡绿化设计谈起

山丘地区特殊的地域，使得开挖行为在公路修筑过程中极为普遍，造成的裸露边坡若不及时加以覆盖，则会造成水土流失。做好山丘地区公路边坡绿化设计，能更有效地实现其可持续发展。通过对潭邵高速公路上边坡绿化设计的概述，探讨了山丘地区公路边坡绿化设计中需注意的几点问题。     

Instance–Based Learning for Highway Accident Frequency Prediction

Accurate predictions of highway accident frequency may help traffic engineers design and test solutions for the improvement of highway safety. However, accident frequency prediction is by no means an easy task due to the large number of factors affecting accident occurrence and the complicated interactions among them. Many studies have been conducted to uncover the relationship between the roadway environment and corresponding accident frequencies. These studies used statistical approaches such as linear regression analysis. The actual relationship between the roadway environment and corresponding accident frequencies has not been approximated with an acceptable certainty because it usually coincided with the mathematical models assumed by the researchers. This paper describes an application of a machine learning method, instance–based learning (IBL), to highway accident frequency predictions. We developed an IBL system and applied this system to highway accident frequency predictions. The data set used contains accident data from the main Utah highways for a 5–year period (1988–1992). Experimental results show that the IBL method is applicable to highway accident predictions and compared favorably with linear regression analysis and neural networks.     

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.     

高速公路路基加宽土工格栅加筋优化技术研究

基于分析高速公路改扩建工程新老路基间不协调变形的原因、控制技术方法及控制标准,对高速公路改扩建路基加宽土工格栅加筋优化技术进行了研究。以京港澳高速公路石家庄至磁县（冀豫界）段改扩建工程典型试验段为研究对象,建立了高速公路路基加宽有限元计算模型,分析了施工期路基填筑高度和竣工后15 a的地表附加沉降、附加水平位移和路面横坡比变化规律。采用土工格栅加筋新路基技术,通过改变土工格栅的弹性模量、加筋层数和加筋长度等技术参数,研究分析了土工格栅参数变化对路基表面沉降量及路面横坡比的影响。根据计算结果提出了高速公路路基加宽土工格栅加筋优化设计技术方案,该研究结果为高速公路改扩建土工格栅加筋路基设计提供了技术参考。     

Spiral Spline Curves for Highway Design

Techniques for automating the design of highways are examined. It is accepted design practice to reduce the straight-line parts of the horizontal alignment of a designed center line as much as possible. This can be accomplished manually by using clothoid templates. This article describes the use of spiral splines that behave in a manner such that the horizontal alignment may be automatically designed as a composition of clothoid segments. The resulting methods are suitable for microcomputer implementation.     

山区危险路段公路线形设计安全性分析

山区公路工程设计过程中,必须更加重视安全分项设计,尤其是在危险路段,应妥善调查各种潜在的交通安全风险源,并根据具体的风险源类型制定针对性的安全设计方案。本文以山区危险路段的线形特点为研究背景,选取平曲线半径和横坡率两个指标作为研究对象,定量分析了两种指标对线形安全的影响,并从曲率变化协调性和行车视距合理性角度对山区危险路段安全性进行分析,提出了相应的设计参考及控制措施。