The local spatial autocorrelation and the kernel method for identifying black zones. A comparative approach

This article aims to determine the location and the length of road sections characterized by a concentration of accidents (black zones). Two methods are compared: one based on a local decomposition of a global autocorrelation index, the other on kernel estimation. After explanation, both methods are applied and compared in terms of operational results, respective advantages and shortcomings, as well as underlying conceptual elements. The operationality of both methods is illustrated by an application to one Belgian road.     

Estimating the traffic safety effect of studded tires.

Swedish accident and exposure data from December 1989 to February 1990 are used to estimate the risk of involvement in an accident on a slippery road when using studded tires compared with the risk when driving with summer tires. Two methods have been used, one involving both accident and exposure data, the other using only accident data. Both methods give similar estimates, indicating that studded tires reduce the risk of involvement in slippery road accidents by 20%-50%.     

基于TWW函数的道路交通安全灰色评价方法研究

在研究国内外道路交通安全评价方法的基础上,根据我国道路交通安全现状及道路交通安全监督管理的要求,将灰色系统理论应用于道路交通安全评价,建立了一套基于TWW函数的道路交通安全灰色评价指标体系,并对6省市的交通安全水平进行了比较研究.     

轮胎/路面噪声及其测量

轮胎 /路面噪声是道路交通噪声的重要噪声源 ,其产生的机理相当复杂 ,影响的因素也很多。本文介绍了产生轮胎 /路面噪声的主要机理及影响因素 ,同时介绍了目前轮胎 /路面噪声几种主要的测量方法 ,及各自的特点     

Assessing the ‘system’ in safe systems-based road designs: Using cognitive work analysis to evaluate intersection designs

While a safe systems approach has long been acknowledged as the underlying philosophy of contemporary road safety strategies, systemic applications are sparse. This article argues that systems-based methods from the discipline of Ergonomics have a key role to play in road transport design and evaluation. To demonstrate, the Cognitive Work Analysis framework was used to evaluate two road designs – a traditional Melbourne intersection and a cut-through design for future intersections based on road safety safe systems principles. The results demonstrate that, although the cut-through intersection appears different in layout from the traditional intersection, system constraints are not markedly different. Furthermore, the analyses demonstrated that redistribution of constraints in the cut-through intersection resulted in emergent behaviour, which was not anticipated and could prove problematic. Further, based on the lack of understanding of emergent behaviour, similar design induced problems are apparent across both intersections. Specifically, incompatibilities between infrastructure, vehicles and different road users were not dealt with by the proposed design changes. The importance of applying systems methods in the design and evaluation of road transport systems is discussed.     

Impact of infrastructure and local environment on road unsafety. Logistic modeling with spatial autocorrelation

This article aims at modeling the impact of road characteristics and local spatial environment on road (un)safety. The study applies to Belgium where some 1500 people are killed annually on the roads. This statistic corresponds to one of the highest risks in Europe. Road unsafety is expressed here as whether an hectometer of road belongs to a black zone; a black zone is defined as a segment of road where roads accidents are concentrated. Logistic modeling including spatial autocorrelation is used and compared to non-spatial regression. It is shown that a spatial model is needed to avoid biased estimated parameters. Results show that local environment and road infrastructure play a substantial role in the co-occurrence of road accidents. Hence, education and enforcement cannot be the only measures taken to reach a sustainable road safety. To attain their objectives of accident reduction, public authorities should also take their responsibilities in the matter of securing road infrastructure.     

基于功率谱密度的路面评价与特征参数提取

介绍了道路路面数据测量系统的构成和数据预处理方法。针对测量的海量道路路面数据,阐述了路面数据的功率谱密度分析与传统的功率谱分析的差异,解读了GB/T7031-2005中的倍频程滤波和路面分级方法,提出了基于拟合直线的斜率截距路面特征参数提取方法和基于功率谱密度曲线的路面分级百分比例特征参数提取方法。在介绍路面评价和特征参数提取方法的基础上,使用真实的路面测量数据作为例子,充分显示了这两种路面特征参数提取方法的效果。实例分析结果表明,使用这两种路面特征参数提取方法来评价和分析道路路面数据,计算过程快捷方便,处理效果简单明显,可在道路路面数据的特征参数提取及其它工程振动信号的统计分析中推广应用。     

Modeling of dynamic vehicle–road interactions for safety-related road evaluation

Usually, road safety is assessed by following adequate highway geometric design standards and can be controlled later by measurement and expertise. Nevertheless, interactions between vehicle dynamics and road characteristics cannot be simultaneously analyzed for these two means of safety evaluation. In this study, an analytical method based on road/vehicle physical interactions applied to road diagnosis is proposed. Vehicle “point” and “bicycle” models are used in this first approach. French highway geometric design standards and a statistical method are presented and evaluated on a real curve case. The proposed numerical criterion, for the “bicycle” model, is then compared to these two classical methods for the considered road section. Its advantages are that it takes into account several combined parameters, that road defects are precisely localized and that it provides hierarchically classified solutions to the road managers. After this comparison step, further improvements should be focused on the modeling of successive curves and on the improvement of the informations given to the road manager.     

Speed cameras in Sweden and Victoria, Australia—A case study

In this article, the ideas behind two different speed camera systems in Australia, Victoria, and Sweden are explored and compared. The study shows that even if the both systems technically have the same aim – to reduce speeding – the ideas of how that should be achieved differ substantially. The approach adopted in Victoria is based on the concept that speeding is a deliberate offence in which a rational individual wants to drive as fast as possible and is prepared to calculate the costs and benefits of his behaviour. Therefore, the underlying aim of the intervention is to increase the perceived cost of committing an offence whilst at the same time decrease the perceived benefits, so that the former outweigh the latter. The Swedish approach, on the other hand, appears to be based on a belief that road safety is an important priority for the road users and one of the reasons to why road users drive too fast is lack of information and social support.In order to evaluate road safety interventions and how their effects are created together with the ambition to transfer technology, there is a need for a comprehensive understanding of the systems and their modi operandi in their specific contexts. This study has shown that there are major differences between the ideas behind the two speed camera programs in Victoria, Australia and Sweden and that these ideas have an impact on the actual design of the different systems and how these are intended to create road safety effects.     

Estimating the human recovery costs of seriously injured road crash casualties

Road crashes result in substantial trauma and costs to societies around the world. Robust costing methods are an important tool to estimate costs associated with road trauma, and are key inputs into policy development and cost–benefit analysis for road safety programmes and infrastructure projects. With an expanding focus on seriously injured road crash casualties, in addition to the long standing focus on fatalities, methods for costing seriously injured casualties are becoming increasingly important. Some road safety agencies are defining a seriously injured casualty as an individual that was admitted to hospital following a road crash, and as a result, hospital separation data provide substantial potential for estimating the costs associated with seriously injured road crash casualties. The aim of this study is to establish techniques for estimating the human recovery costs of (non-fatal) seriously injured road crash casualties directly from hospital separation data. An individuals’ road crash-related hospitalisation record and their personal injury insurance claim were linked for road crashes that occurred in New South Wales, Australia. These records provided the means for estimating all of the costs to the casualty directly related to their recovery from their injuries. A total of 10,897 seriously injured road crash casualties were identified and four methods for estimating their recovery costs were examined, using either unit record or aggregated hospital separation data. The methods are shown to provide robust techniques for estimating the human recovery costs of seriously injured road crash casualties, that may prove useful for identifying, implementing and evaluating safety programmes intended to reduce the incidence of road crash-related serious injuries.     

Attacker-defender models and road network vulnerability

The reliability of road networks depends directly on their vulnerability to disruptive incidents, ranging in severity from minor disruptions to terrorist attacks. This paper presents a game theoretic approach to the analysis of road network vulnerability. The approach posits predefined disruption, attack or failure scenarios and then considers how to use the road network so as to minimize the maximum expected loss in the event of one of these scenarios coming to fruition. A mixed route strategy is adopted, meaning that the use of the road network is determined by the worst scenario probabilities. This is equivalent to risk-averse route choice. A solution algorithm suitable for use with standard traffic assignment software is presented, thereby enabling the use of electronic road navigation networks. A variant of this algorithm suitable for risk-averse assignment is developed. A numerical example relating to the central London road network is presented. The results highlight points of vulnerability in the road network. Applications of this form of network vulnerability analysis together with improved solution methods are discussed.     

道路路面测量数据的特征参数提取与统计分析

介绍道路路面数据测量系统的构成和数据预处理方法。针对测量的道路路面数据,阐述由路面数据提取可表征其特性的特征参数,包括基本统计量、国际平整度指数和功率谱密度参数等。在路面特征参数提取基础上,以北京地区真实海量路面测量数据为例,进行道路路面特征参数的统计分析,得到可反映、表征该地区路面特点的统计分析结果。总结道路路面特征参数提取与统计分析方法,展望其应用前景。     

Road Damage Detection and Classification Using Mask R-CNN with DenseNet Backbone

Automatic road damage detection using image processing is an important aspect of road maintenance. It is also a challenging problem due to the inhomogeneity of road damage and complicated background in the road images. In recent years, deep convolutional neural network based methods have been used to address the challenges of road damage detection and classification. In this paper, we propose a new approach to address those challenges. This approach uses densely connected convolution networks as the backbone of the Mask R-CNN to effectively extract image feature, a feature pyramid network for combining multiple scales features, a region proposal network to generate the road damage region, and a fully convolutional neural network to classify the road damage region and refine the region bounding box. This method can not only detect and classify the road damage, but also create a mask of the road damage. Experimental results show that the proposed approach can achieve better results compared with other existing methods.     

Hotspots identification and ranking for road safety improvement: An alternative approach

During the last decade, the concept of composite performance index, brought from economic and business statistics, has become a popular practice in the field of road safety, namely for the identification and classification of worst performing areas or time slots also known as hotspots. The overall quality of a composite index depends upon the complexity of phenomena of interest as well as the relevance of the methodological approach used to aggregate the various indicators into a single composite index. However, current aggregation methods used to estimate the composite road safety performance index suffer from various deficiencies at both the theoretical and operational level; these include the correlation and compensability between indicators, the weighting of the indicators as well as their high “degree of freedom” which enables one to readily manipulate them to produce desired outcomes (0060, 0065 and 0070). The objective of this study is to contribute to the ongoing research effort on the estimation of road safety composite index for hotspots’ identification and ranking. The aggregation method for constructing the composite road safety performance index introduced in this paper, strives to minimize the aforementioned deficiencies of the current approaches. Furthermore, this new method can be viewed as an intelligent decision support system for road safety performance evaluation, in order to prioritize interventions for road safety improvement.     

Overdispersion in modelling accidents on road sections and in empirical bayes estimation

In multivariate statistical models of road safety one usually finds that the accident counts are ‘overdispersed’. The extent of the overdispersion is itself subject to estimation. It is shown that the assumption one makes about the nature of overdispersion will affect the maximum likelihood estimates of model parameters. If one assumes that the same overdispersion parameter applies to all road sections in the data base, then, the maximum likelihood estimate of parameters will be unduly influenced by very short road sections and insufficiently influenced by long road sections. The same assumption about the overdispersion parameter also leads to an inconsistency when one estimates the safety of a road section by the Empirical Bayes method. A way to avoid both problems is to estimate an overdispersion parameter (φ) that applies to a unit length of road, and to set the overdispersion parameter for a road section of length L to φL. How this would change the estimates of regression parameters for road section models now in use requires examination. Safety estimation by the Empirical Bayes method is altered substantially.     

Under-reporting of road crash casualties in France

INTRODUCTION: Police crash data, which are the basis for safety research in most countries, are incomplete and biased. We focus here on the extent of under-reporting in France, and how it is related to casualty and crash characteristics. METHODS: Police data are compared with a road trauma registry, on the Rh?ne county, after record-linkage. The study covers the 1997-2001 period, totalling 59,714 casualties. A multivariate analysis is conducted, modelling the probability of being police-reported among casualties in the registry, as a function of crash and casualty characteristics. Results are expressed as relative risks (RR) and adjusted probabilities. RESULTS: Police reporting rate is 37.7%. Under-reporting varies mainly according to injury severity (RR=0.35 for slightly injured versus severely injured), to road user type and third party involvement (yes/no): comparing casualties with no third party versus those with one, RR=0.32 among motorcyclists whereas RR=0.78 among car occupants. Under-reporting also varies with road type, road environment (metropole/rural) and type of police force, all of which are structurally dependent. CONCLUSION: Any study based on police crash data may be quite misleading. We are therefore working on obtaining unbiased estimates of road casualties figures, by extrapolating the Rh?ne road trauma registry to the nation-wide level.     

Suggestions for an improved system for statistical data about road accidents and road traffic

Data information systems for road accidents and road traffic must satisfy high standards of relevance and quality. The general outline of an improved system for collecting road accident data is given. The system is characterized by the use of statistical sampling methods. The police, the insurance companies and the hospitals are recommended as sources of information about the total accident population. A statistical sample of all identified accidents is then investigated in more detail by special local investigation groups. A hypothetical numerical example is given to show how the suggested system would work in practise. Road accident data should not be isolated from road traffic data. An improved system for collecting information on road traffic is also discussed. This consists of a basic system (founded on statistical sampling methods) for estimation of the total volume of traffic and a few other essential variables such as the volume divided into speed and vehicle types.     

Additional road markings as an indication of speed limits: Results of a field experiment and a driving simulator study

Although speed limits are indicated by road signs, road users are not always aware, while driving, of the actual speed limit on a given road segment. The Roads and Traffic Agency developed additional road markings in order to support driver decisions on speed on 70 km/h roads in Flanders-Belgium. In this paper the results are presented of two evaluation studies, both a field study and a simulator study, on the effects of the additional road markings on speed behaviour. The results of the field study showed no substantial effect of the markings on speed behaviour. Neither did the simulator study, with slightly different stimuli. Nevertheless an effect on lateral position was noticed in the simulator study, showing at least some effect of the markings. The role of conspicuity of design elements and expectations towards traffic environments is discussed. Both studies illustrate well some strengths and weaknesses of observational field studies compared to experimental simulator studies.     

Dynamic Stiffness Assessment of Construction Materials by the Resonant and Non-resonant Methods

Dynamic stiffness of pavement surfaces is a structural property related to surface vibration and traffic noise. It is one of the mechanisms involved in tire/road noise generation. An equipment for measuring dynamic stiffness was designed and built to perform in-situ nondestructive testing on road surfaces. Laboratory studies on samples are presented to compare different measurement procedures. Measurements of the dynamic stiffness were carried out by the Resonant and Non-resonant Method. Moreover, a Dynamic Stiffness Index is proposed in order to compare the stiffness of the studied samples. Construction materials with different characteristics were studied, from resilient materials for acoustic insulation to rigid materials for pavement construction. Results show that the Non-resonant Method is more suitable for dynamic stiffness measurements, since this method could be carried out on real pavements, and both, driving point and transfer functions could be measured simultaneously. Little dynamic stiffness differences were found among road construction materials, compared to those of the resilient materials. However, the presented testing procedures are able to establish differences among these materials.     

Review Paper on Road Vehicle Vibration Simulation for Packaging Testing Purposes

Inefficient packaging constitutes a global problem that costs hundreds of billions of dollars, not to mention the additional environmental impacts. An insufficient level of packaging increases the occurrence of product damage, while an excessive level increases the packages' weight and volume, thereby increasing distribution cost. This problem is well known, and for many years, engineers have tried to optimize packaging to protect products from transport hazards for minimum cost. Road vehicle shocks and vibrations, which is one of the primary causes of damage, need to be accurately simulated to achieve optimized product protection. Over the past 50 years, road vehicle vibration physical simulation has progressed significantly from simple mechanical machines to sophisticated computer‐driven shaking tables. There now exists a broad variety of different methods used for transport simulation. Each of them addresses different particularities of the road vehicle vibration. Because of the nature of the road and vehicles, different sources and processes are present in the vibration affecting freight. Those processes can be simplified as the vibration generated by the general road surface unevenness, road surface aberrations (cracks, bumps, potholes, etc.) and the vehicle drivetrain system (wheels, drivetrain, engine, etc.). A review of the transport vibration simulation methods is required to identify and critically evaluate the recent developments. This review begins with an overview of the standardized methods followed by the more advanced developments that focus on the different random processes of vehicle vibration by simulating non‐Gaussian, non‐stationary, transient and harmonic signals. As no ideal method exists yet, the review presented in this paper is a guide for further research and development on the topic. Copyright © 2015 John Wiley & Sons, Ltd.