Simulating pavement structural condition using artificial neural networks

This article aims to investigate the feasibility of incorporating of an artificial neural network (ANN) as an innovative technique for modelling the pavement structural condition, into pavement management systems. For the development of the ANN, strain assessment criteria are set in order to characterise the structural condition of flexible asphalt pavements with regards to fatigue failure. This initial task is directly followed with the development of an ANN model for the prediction of strains primarily based on in situ field gathered data and not through the usage of synthetic databases. For this purpose, falling weight deflectometer (FWD) measurements were systematically conducted on a highway network, with ground-penetrating radar providing the required pavement thickness data. The FWD data (i.e. deflections) were back-analysed in order to assess strains that would be utilised as output data in the process of developing the ANN model. A paper exercise demonstrates how the developed ANN model combined with the suggested conceptual approach for characterising pavement structural condition with regard to strain assessment could make provisions for pavement management activities, categorising network pavement sections according to the need for maintenance or rehabilitation. Preliminary results indicate that the ANN technique could help assist policy decision makers in deriving optimum strategies for the planning of pavement infrastructure maintenance.     

A multi-objective optimisation approach for sustainable pavement management

Addressing the multidimensional challenges involved in advancing the sustainability of pavement systems requires the development of optimisation-based decision support system (DSS) for pavement management with the capability to identify optimally sustainable pavement maintenance and rehabilitations (M&R) strategies. The main objective of this research work is to develop a multi-objective optimisation framework that hosts a comprehensive and integrated pavement life cycle costs–life cycle assessment model that covers the pavement’s whole life cycle, from the extraction and production of materials to construction and maintenance, transportation of materials, work-zone traffic management, usage and end-of-life. The capability of the proposed DSS is analysed in a case study aiming at investigating, from a full life cycle perspective, the extent to which a number of pavement engineering solutions are efficient in improving the environmental and economic aspects of pavement sustainability, when applied in the management of a road pavement section. Multiple bi-objective optimisation analyses considering accordingly agency costs, user costs and greenhouse gas emissions were conducted based on a multi-objective genetic algorithm. Pareto fronts were obtained for each analysis, originating a set of non-dominated maintenance and rehabilitation solutions. Posteriorly, a multi-criteria decision analysis method was used to find the best compromise solution for pavement management.     

Concrete bridge inspection with a mobile GPR system

A detailed knowledge of the present condition of bridges is essential for the planning of maintenance and rehabilitation. Mobile ground penetrating radar (GPR) systems are efficient tools for obtaining information such as depth of rebar, asphalt pavement thickness and concrete damage beneath the pavement. Non-destructive testing, quasi-continuous results and efficient data acquisition are the main advantages of mobile GPR systems. In this paper, benefits and limitations of mobile GPR systems are discussed using examples from EMPA's recent work. The emphasis is on the investigation of pavement thicknesses and depths of rebar on concrete bridges.     

Estimation of pavement rehabilitation cost using pavement management data

Estimation and scheduling of future pavement maintenance and rehabilitation (M&R) works are one of the primary concerns of highway agencies due to the limited allocations in budget and resources. Two approximate methods for estimation of pavement rehabilitation cost are presented and compared in this study based on highway present condition index (HPCI) and rehabilitation history. The former is based on pavement condition, while the latter is based on historical and statistical trends. Database from a pavement management system (PMS) of various highway sections surveyed in Korea were used in this study to establish a relationship between HPCI and pavement service life and to analyse the trends of rehabilitation periods. The two simple methods presented provide useful information and probable range for the various highway agencies to guide them in the preliminary planning, budgeting, estimating and scheduling of their future pavement M&R works.     

谈路面维护和修复管理系统的离散优化模型

随着公路建设和高速公路网在的迅速发展,路面维护和修复活动的管理已变得尤为重要。论文提出了涉及管理体制4个不同群体的离散优化模型,不同群体分别为:政府、高速公路代理人、承包商和普通用户。这4个最优决策模型的制定及二元决策变量的线性整数规划问题。目标函数和约束条件都是基于路面状况指数。数值实验对四川省的公路系统的数据进行分析,其表明了该模型的可行性和有效性。     

User costs in pavement construction and rehabilitation alternative evaluation

The decision-making processes used by many state transportation agencies in US and Canada for selecting a strategy for pavement rehabilitation primarily depend on initial construction and maintenance costs for identifying the most economically efficient pavement rehabilitation alternative. While this approach is appropriate for optimally allocating increasingly limited funds in the face of increasing investment backlog, it is not economically efficient because it does not account for user costs. Despite a significant body of research, the state transportation agencies are hesitant to include user costs in their pavement life-cycle cost analysis processes because of a lack of availability of standard method of calculating user costs. This article presents the results of a study conducted to review the pavement alternative selection processes used by the Ohio Department of Transportation and recommend ways to include user costs in the decision-making process. Incorporating user costs in the decision-making processes right from project-development phase will help transportation agencies stay focused on the customer and minimise overall impact of rehabilitation of the highway system.     

A Spatial‐Bayesian Technique for Imputing Pavement Network Repair Data

Abstract: Pavement construction and repair history is necessary for several pavement management functions such as developing pavement condition prediction models and developing maintenance and rehabilitation (M&R) trigger values based on past repair frequencies. It is often difficult to integrate M&R data with condition data since these data are often stored in disparate heterogeneous databases. This article provides a computational technique for estimating construction and M&R history of a pavement network from the spatiotemporal patterns of its condition data. The technique is founded on Bayesian and spatial statistics and searches pavement condition data in groups of adjacent pavement sections for evidence of repair. The developed technique was applied to a pavement network in Texas and has been found to have a 74% precision and a 95% accuracy in estimating repair history data.     

Empirical Markovian-based models for rehabilitated pavement performance used in a life cycle analysis approach

Two empirical Markovian-based models are presented in this paper to predict the transition probabilities associated with rehabilitated pavement. The first model predicts the staged-homogenous transition probabilities as required by the staged-homogenous Markov model. The second model predicts the non-homogenous transition probabilities as applicable to the non-homogenous Markov model. In both the models, the deterioration transition probabilities are predicted as a function of the corresponding values associated with original pavement and two adjustment factors reflecting the impacts of increased traffic load applications and decreased pavement strength. The predicted transition probabilities are used to estimate the future distress ratings required for developing the corresponding life cycle performance curve. The life cycle performance/cost ratio is used to evaluate the cost-effectiveness of potential long-term M&R plans. The life cycle performance is defined as the area falling under the life cycle curve. The life cycle cost is estimated to include initial construction cost, routine maintenance cost, major rehabilitation cost, and added user cost due to work zone. Two proposed cost models are used in the case study for estimating routine maintenance and added user costs. The case study indicates that the proposed empirical Markovian-based models have provided reasonable estimates of the transition probabilities as reflected by the corresponding life cycle performance curves.     

The effect of waste tire thread mesh on the dynamic behaviour of asphalt mixtures

The crack potential of the pavement under various loading conditions and temperature variations has been a problem for the application of asphalt pavements. Crack generation in asphalt pavement increases the maintenance and rehabilitation costs. Two principal solutions for the problem of asphalt pavement cracking have been introduced: first, applying a thicker asphalt pavement and, second, making an asphalt mixture with modified characteristics. The effects of different types of reinforcement on the cracking potential of asphalt pavement as a substantial characteristic of asphalt mixture has been questioned, and a variety of different experiments have been developed to determine these effects. The use of tire cord mesh in reinforcing asphalt pavement has been introduced and accurately observed in this research. In this paper, the crack potential of asphalt pavement reinforced with tire cord mesh is evaluated with emphasis on introducing experimental methods and analysing their results. The results show that the tire cord mesh reinforcement significantly increases the asphalt pavement resistance against cracking and increases its service life while decreasing maintenance and rehabilitation costs.     

路面管理理论与方法的研究进展及趋势

路面是交通基础设施的主要组成部分,路面管理是公路资产管理的重要内容。论文全面回顾了国际国内近年来路面管理领域的最新研究进展,主要包括路面管理过程中路面状况评价、路面性能预测,以及管理策略优化的常用方法、指标及模型,对比分析了人工神经网络、模糊逻辑和遗传算法等人工智能技术在路面管理中的应用;并对路面管理的发展趋势——公路资产管理这一热点问题进行了探讨。     

高速公路沥青路面早期破坏现象分析及防治

通过分析指出我国高速公路沥青路面在常规设计标准下出现的早期破坏现象，从管理工作、材料、施工、设计、养护等各个角度分析了早期损坏产生的原因，提出了各种切实有效的防治措施，建议根据不同的交通和气候条件选择采用不同的路面结构，在设计和施工阶段确保高速公路的路基、路面完好，从而达到预期的设计年限。     

Grouping Pavement Condition Variables for Performance Modeling Using Self-Organizing Maps

Different modeling techniques have been employed for the evaluation of pavement performance, determination of structural capacity, and performance predictions. The evaluation of performance involves the functional analysis of pavements based on the history of the riding quality. The riding comfort and pavement performance can be conveniently defined in terms of roughness and pavement distresses. Thus different models have been developed relating roughness with distresses to predict pavement performance. These models are too complex and require parsimonious equations involving fewer variables. Artificial neural networks have been used successfully in the development of performance-prediction models. This article demonstrates the use of an artificial intelligence neural networks self-organizing maps for the grouping of pavement condition variables in developing pavement performance models to evaluate pavement conditions on the basis of pavement distresses.     

路面管理系统养护需求分析模型应用分析

研究以公路路面管理系统为工具,依托庐—铜高速公路路面养护需求分析,从养护质量标准、养护费用模型、养护决策模型等方面详细论述了路面管理系统中路面养护需求分析模型的构建思路与方法,为实际管理工作中路面养护计划的编制提供参考。     

Artificial intelligence and networking in integrated building management systems

In recent years the emphasis has moved towards integrating all a building's systems via centralised building management systems (BMS). To provide a more intelligent approach to the facility management, safety and energy control in building management systems (IBMS), this paper proposes a methodology for integrating the data within a BMS via a single multi-media networking technology and providing the BMS with artificial intelligence (AI) through the use of knowledge-based systems (KBS) technology. By means of artificial intelligence, the system is capable of assessing, diagnosing and suggesting the best solution. This paper outlines how AI techniques can enhance the control of HVAC systems for occupant comfort and efficient running costs based on occupancy prediction. Also load control and load balancing are investigated. Instead of just using pre-programmed load priorities, this work has investigated the use of a dynamic system of priorities which are based on many factors such as area usage, occupancy, time of day and real time environmental conditions. This control strategy which is based on a set of rules running on the central control system, makes use of information gathered from outstations throughout the building and communicated via the building's data-bus.     

风景园林研究中的人工智能方法综述

人工智能的出现为风景园林研究智能化、数字化提供了机遇与挑战。首先介绍了人工智能的相关概念、发展,以及在风景园林研究中的作用,并在前人分类的基础上,根据人工智能的属性和应用,将风景园林研究中常用的人工智能方法分为人工生命类、智能随机优化类和机器学习类;然后针对每类中的典型算法系统论述了其原理、发展、特征,以及在风景园林分析、设计和评估等领域的具体应用与存在的问题;进而指出建立混合智能系统的必要性与未来发展前景;最后探讨了风景园林研究中人工智能方法的局限性,指出风景园林智能化的发展趋势。     

Fuzzy Representation of Pavement Condition for Efficient Pavement Management

Abstract: Many government agencies and private consulting companies manage large pavement networks in terms of infrastructure condition assessment and maintenance planning. Efficient pavement management is supported by pavement management systems (PMSs), which includes models for pavement condition assessments considered “valuable” by agency's engineers. The objective of this article is to define a pavement condition model able to overcome surveyors’ subjectivity in rating distresses and thus provide meaningful pavement conditions for the agencies to employ in project planning. The article proposes a fuzzy inference model for calculating pavement condition ratio (PCR) specifically tailored on the Alabama Department of Transportation Pavement (ALDOT) guidelines and policies. Applied to several surveyors’ ratings, the proposed model has the ability to smooth distress extent differences among surveyors producing PCR values within acceptable range of variability. The proposed approach has the intention of not only enhancing pavement condition characterization but also to exploit the opportunity made available by automation in the collection and interpretation of pavement data which are anyway characterized by an inherent subjectivity.     

A life cycle assessment of in-place recycling and conventional pavement construction and maintenance practices

The application of in-place recycling techniques has emerged as a practical and effective way to enhance the sustainability of agency pavement management decisions for asphalt-surfaced pavements. However, the potential environmental benefits resulting from applying in-place recycling techniques have not been fully documented in the literature. This paper presents a comprehensive pavement life cycle assessment (LCA) model that extends the typical pavement LCA's system boundaries to include the environmental impacts resulting from the usage phase and the production of the energy sources. The results of the application of the pavement LCA model to a specific highway rehabilitation project in the state of Virginia showed that in-place recycling practices and an effective control of the pavement roughness can improve significantly the life cycle environmental performance of a pavement system.     

Network‐Level Road Pavement Maintenance and Rehabilitation Scheduling for Optimal Performance Improvement and Budget Utilization

Abstract: This article discusses how to efficiently and completely solve a bi‐objective pavement maintenance and rehabilitation‐scheduling problem, which aims at optimizing two objectives of pavement condition improvement and budget utilization in a simultaneous manner. This problem may be addressed by the weighting method, constraint method, ranking method, and various metaheuristic methods. However, none of these methods can guarantee the complete Pareto‐optimal solution set, which would potentially lead to suboptimal decisions. In this article, a parametric method is suggested to solve the bi‐objective pavement maintenance and rehabilitation‐scheduling problem. The effectiveness and efficiency of the parametric method is investigated and demonstrated through a case study using the real‐world data set from the Dallas District's Pavement Management Information System. A performance comparison between the widely used weighting method and the parametric method clearly justifies the computational advantages of the parametric method.     

提高混凝土路面裂缝修补成功率的探讨

通过QC课题活动采取改进工艺及改善管理等办法 ,解决了北方地区大荷载混凝土路面裂缝的修补问题 ,为提高高速公路混凝土路面管养水平提供参考