Traffic congestion detection in large-scale scenarios using vehicle-to-vehicle communications

Cooperative vehicular systems are currently being investigated to design innovative ITS (Intelligent Transportation Systems) solutions for road traffic management and safety. Through the wireless exchange of information between vehicles, and between vehicles and infrastructure nodes, cooperative systems can support novel decentralized strategies for ubiquitous and more cost-attractive traffic monitoring. In this context, this paper presents and evaluates CoTEC (COperative Traffic congestion detECtion), a novel cooperative technique based on Vehicle-to-Vehicle (V2V) communications designed to detect road traffic congestion. CoTEC is evaluated under large-scale highway scenarios using iTETRIS, a unique open source simulation platform created to investigate the impact of cooperative vehicular systems. The obtained results demonstrate CoTEC's capability to accurately detect and characterize road traffic congestion conditions under different traffic scenarios and V2V penetration rates. In particular, CoTEC results in congestion detection probabilities higher than 90%. These results are obtained without overloading the cooperative communications channel. In fact, CoTEC reduces the communications overhead needed to detect road traffic congestions compared to related techniques by 88%.     

OSM/高德路网匹配融合技术在道路空间化中的应用

“六合一”道路编码是交管业务中用来定位事故和违法的基础文本数据,缺乏空间位置信息,而已有的常用路网数据如高德路网,都是基于多车道路段表达的路网且现势性相对于OSM（OpenStreetMap）路网较低,难以满足交管业务的需求。针对上述问题,以高德路网作为基础、高现势性的OSM路网作补充,将轨迹聚类分析中的LCSS（longest common subsequence）算法应用在路网匹配过程中,并对匹配后的路网使用Stroke方法进行路网融合。实验结果表明,使用LCSS算法可以达到良好的路网匹配效果。最后基于此开发了一套路网匹配融合程序,并在武汉市交通管理局投入使用。     

Understanding information proactiveness and the content management system adoption in pre-implementation stage

The overall technology acceptance literature does not pay sufficient attention to the issue of the mandated use of systems as the traditional acceptance models (e.g. TAM) were originally built, tested, and validated by being applied to technologies that were mainly voluntary in nature, that is, the users had the choice of whether to use or not use the technology. Few have studied end users' proactive motivation to use information and attitude toward newly implemented technologies within organizational contexts, before end-users start using the technology or pre-implementation stage. This research proposes that information proactiveness has influences on the content management systems adoption beliefs such as perceived ease of use and perceived usefulness. The proposed model was empirically tested using the data collected from content management systems end-users. As theorized, information proactiveness was found to be a significant determinant of system users' perceived ease of use but not perceived usefulness in pre-implementation stage. Furthermore, perceived behavioral control was found to be a strong determinant of systems users' attitude. The study findings provide important insights on enhancing system users' adoption behavior in pre-implementation stage.     

Confidentiality Protection in Cloud Computing Systems

Current cloud computing systems pose serious limitation to protecting users'' data confidentiality. Since users'' sensitive data is presented in unencrypted forms to remote machines owned and operated by third party service providers, the risks of unauthorized disclosure of the users'' sensitive data by service providers may be high. Many techniques for protecting users'' data from outside attackers are available, but currently there exists no effective way for protecting users'' sensitive data from service providers in cloud computing. In this paper, an approach is presented to protecting the confidentiality of users'' data from service providers, and ensures that service providers cannot access or disclose users'' confidential data being processed and stored in cloud computing systems. Our approach has three major aspects: 1) separating software service providers and infrastructure service providers in cloud computing, 2) hiding information of the owners of data, and 3) data obfuscation. An example to show how our approach can protect the confidentiality of users'' data from service providers in cloud computing is given. Experimental results are presented to show that our approach has reasonable performance.     

Exploring schema-driven differences in situation awareness between road users: an on-road study of driver,cyclist and motorcyclist situation awareness

Collisions between different road users make a substantial contribution to road trauma. Although evidence suggests that different road users interpret the same road situations differently, it is not clear how road users' situation awareness differs, nor is it clear which differences might lead to conflicts. This article presents the findings from an on-road study conducted to examine driver, motorcyclist and cyclist situation awareness in different road environments. The findings suggest that, in addition to minor differences in the structure of different road users' situation awareness (i.e. amount of information and how it is integrated), the actual content of situation awareness in terms of road user schemata, the resulting interaction with the world and the information underpinning situation awareness is markedly different. Further examination indicates that the differences are likely to be compatible along arterial roads, shopping strips and at roundabouts, but that they may create conflicts between different road users at intersections. Interventions designed to support compatible situation awareness and behaviour between different road users are discussed.     

Modelling domestic water demand: An agent based approach

The urban water system is a complex adaptive system consisting of technical, environmental and social components which interact with each other through time. As such, its investigation requires tools able to model the complete socio-technical system, complementing “infrastructure-centred” approaches. This paper presents a methodology for integrating two modelling tools, a social simulation model and an urban water management tool. An agent based model, the Urban Water Agents' Behaviour, is developed to simulate the domestic water users’ behaviour in response to water demand management measures and is then coupled to the Urban Water Optioneering Tool to calculate the evolution of domestic water demand by simulating the use of water appliances. The proposed methodology is tested using, as a case study, a major period of drought in Athens, Greece. Results suggest that the coupling of the two models provides new functionality for water demand management scenarios assessment by water regulators and companies.     

A general framework for trajectory data warehousing and visual OLAP

In this paper we present a formal framework for modelling a trajectory data warehouse (TDW), namely a data warehouse aimed at storing aggregate information on trajectories of moving objects, which also offers visual OLAP operations for data analysis. The data warehouse model includes both temporal and spatial dimensions, and it is flexible and general enough to deal with objects that are either completely free or constrained in their movements (e.g., they move along a road network). In particular, the spatial dimension and the associated concept hierarchy reflect the structure of the environment in which the objects travel. Moreover, we cope with some issues related to the efficient computation of aggregate measures, as needed for implementing roll-up operations. The TDW and its visual interface allow one to investigate the behaviour of objects inside a given area as well as the movements of objects between areas in the same neighbourhood. A user can easily navigate the aggregate measures obtained from OLAP queries at different granularities, and get overall views in time and in space of the measures, as well as a focused view on specific measures, spatial areas, or temporal intervals. We discuss two application scenarios of our TDW, namely road traffic and vessel movement analysis, for which we built prototype systems. They mainly differ in the kind of information available for the moving objects under observation and their movement constraints.     

基于两级筛选机制及深度学习组合模型实现短时交通流预测

准确实时的短时交通流预测对现代交通管理服务体系的构建至关重要.为了充分挖掘并利用不同路段短时交通流交互作用而表现出的时空特性,构建由自相关函数、互相关函数和KNN算法组成的两级筛选机制评估与目标路段的相关性优化路段组合,实现空间信息深度挖掘;提出一种GCN-GRU组合预测模型,利用图卷积网络(GCN)全局处理路段拓扑信息的优势进一步捕捉短时交通流的空间特性,并借助门控循环单元(GRU)对时间信息的长时记忆能力提取其时间特性.利用实测高速公路短时交通流数据进行验证,仿真结果表明,采用两级筛选机制对路段进行有效筛选并引入深度学习组合模型,预测性能明显改善,优于堆栈式自编码网络(SAEs)和GRU等经典模型.     

A Dynamic Transportation Model for the Stockholm Area: Implementation Issues Regarding Departure Time Choice and OD-pair Reduction

Road traffic congestion is an increasing problem in urban areas. Building new roads often attracts latent demand and turns parts of the city into building sites for several years. Policy measures that stimulate more effective use of the existing network, such as variable road pricing, are therefore becoming increasingly popular among policy makers and citizens. These measures are often aimed at changing the temporal distribution of traffic. Yet transportation models taking departure time choice into account are rare. This paper describes the implementation of an urban transportation application for Stockholm, which includes departure time choice, mode choice and time dependent network assignment. Through iterations between demand and supply the objective of the transportation model is to forecast effects of congestion charges, intelligent transport systems and infrastructure investments on departure time choice. The complexity of large-scale departure time choice modelling and dynamic traffic assignment is high, which results in very long run times. Therefore, research on how to increase model efficiency is needed. This paper describes choices made in the implementation for a more efficient model.     

The social and political construction of technological frames

It is widely accepted that the successful adoption of an information system depends to a great extent on users' perceptions of the information system. It follows then that an understanding of users' cognitive frames should be a key factor in managing the adoption of information systems. To reach such an understanding is not an easy task as cognitive frames are dynamic phenomena. For example, what an individual perceives as ‘ease of use’ and ‘usefulness’ may depend not only on intrinsic qualities of the information system but also on the changing contexts in which the information system is evaluated. This work argues that the management of information systems' adoption is a social and political process in which stakeholders frame and reframe their perceptions of an information system. A case study carried out in a European bank illustrates how the Bank's technical team influenced users' technological frames, including those of senior management in order to ensure a smooth implementation process. In conclusion, the paper introduces a set of theoretical propositions relating to the social and political processes that occur during information systems adoption.     

Heuristics for Scheduling Data Requests Using Collective Communications in a Distributed Communication Network

The collective communication process studied here involves the ability of users to request information from diverse sources (both in terms of locality and data type) and receive this information before the users' deadlines expire. A model has been developed and examined for the case when the network is oversubscribed and not all requests in the system can be satisfied. This model is based upon systems that are in use or are planned for development. The heuristics presented for scheduling data traffic do not have explicit control of the network; the heuristics work with a network manager to configure and set up single-source, multiple-destination information channels that allow users to receive information. The goal is to create a near-optimal set of collective communication information channels that will satisfy the users' requests. Four components are employed to create value functions that are used to order the importance of the information channels for presentation to the network manager. In addition, two different weightings for the relative importance of different priority levels are considered. Simulation studies have been performed that evaluate the performance of the heuristics developed. It is shown that the heuristics perform well compared to the upper and lower bounds developed. These results can be used to develop techniques that can be deployed in actual military systems. Furthermore, the model and heuristics studied here can be applied to other domains, such as business applications that utilize the internet to obtain critical information.     

Objective Workload and Behavioural Response in Airport Radar Control Rooms

Previous research indicated that peak traffic and the duration of radio-communications were good predictors of behavioural response of air traffic controllers working in air route traffic control centres. In this study we investigated if these two measures of workload were generalisable to controllers (ATCs) working in radar facilities serving major airports. 3,110 observations were made on radar sectors at the 13 major radar control rooms in the U.S.A. A large number of air traffic variables and communication tasks were measured. Behavioural ratings were made by expert-observer ATC's. The results replicated previous findings that peak traffic and the duration of radio-communications functioned as behavioural stressors. Time monitoring and stand-by time also were found to predict behavioural responses. Careful consideration of these and other results led to the conclusion that peak traffic is the most generalisable environmental stressor for ATC's behaviour whereas the other workload measures are more correctly viewed as concomitants of the demand characteristics of ATC work.     

A model to estimate and interpret the energy-efficiency of movement patterns in urban road traffic

Urban road traffic is highly dynamic. Traffic conditions vary in time and with location and so do the movement patterns of individual road users. In this article, a movement pattern is the behaviour of a car when traversing a road link in an urban road network. A movement pattern can be recorded with a global navigation satellite system (GNSS), such as the Global Positioning System (GPS). A movement pattern has a specific energy-efficiency, which is a measure of how fuel-intensively the car is moving. For example, a car driving uniformly at medium speed consumes little fuel and, therefore, is energy-efficient, whereas stop-and-go driving consumes much fuel and is energy-inefficient. In this article we introduce a model to estimate the energy-efficiency of movement patterns in urban road traffic from GNSS data. First, we derived statistical features about the car's movement along the road. Then, we compared these to fuel consumption data from the car's controller area network (CAN) bus, normalized to the car's overall range of fuel consumption. We identified the optimal feature set for prediction. With the optimal feature set we trained, tested and verified a model to estimate energy-efficiency, with the fuel consumption serving as ground truth. Existing fuel consumption models usually view movement as a snapshot. Thus, the behaviour of the car remains unknown that causes a movement pattern to be energy-efficient or energy-inefficient. Our model views movement as a process and allows to interpret this process. A movement pattern can, for example, be energy-inefficient because the car is driving in stop-and-go traffic, because it is travelling at high speed, or because it is accelerating. Our model allows to distinguish between these different types of behaviours. Thus, it can provide new insights into the dynamics of urban road traffic and its energy-efficiency.     

高速公路智能管控系统外部数据接入设计与实现

目前高速公路运营管理中,传统机电系统中的视频监控、收费系统等已经稳定运行多年,但功能相对单一,信息孤岛现象比较严重。为解决这一问题,重点探讨了高速公路智能管控系统如何与系统外部的专用短程通信(DSRC)道路交通流、全程断面的交通流监测数据、气象状态的监测数据、交通事件的视频检测数据进行无缝接入进行设计。同时,兼顾路网层面的信息服务,实现与交通运输部、省交通运输厅路网中心、周边高速路网、地方道路管理部门、气象部门等之间的数据共享与交换。为高速公路运行状态监测、预警、辅助决策、应急管理、信息发布等功能提供数据支撑。     

基于车路云一体化的混合交通系统优化控制综述

汽车行业正在进行智能化与网联化的发展变革,智能网联汽车的出现使交通管理者找到缓解交通拥堵、提高道路安全以及减少能源消耗的一种解决方案.对此,调研混合交通流模型、智能网联汽车协同控制、交通管理等领域的最新成果,系统地论述基于车路云一体化的智慧交通系统优化控制的研究现状与进展.首先,分析基于车路云一体化的混合交通系统的框架,梳理各部分的组成与作用;其次,总结混合交通流的建模方法,探究交通现象本质,归纳各类方法的特点、优势以及局限性;再次,探讨混合交通系统优化控制问题,围绕交通流稳定性、交通安全、交通效率和绿色交通4个方面分析智能化与网联化在交通方面的潜能,并梳理在不同交通场景下的控制对象与控制目标,总结具有借鉴意义的控制方法;最后,对车路云一体化发展进程中存在的问题与挑战进行总结,并对未来发展指明方向.     

A V2I communication-based pipeline model for adaptive urban traffic light scheduling

Adaptive traffic light scheduling based on realtime traffic information processing has proven effective for urban traffic congestion management. However, fine-grained information regarding individual vehicles is difficult to acquire through traditional data collection techniques and its accuracy cannot be guaranteed because of congestion and harsh environments. In this study, we first build a pipeline model based on vehicle-to-infrastructure communication, which is a salient technique in vehicular adhoc networks. This model enables the acquisition of fine-grained and accurate traffic information in real time via message exchange between vehicles and roadside units. We then propose an intelligent traffic light scheduling method (ITLM) based on a “demand assignment” principle by considering the types and turning intentions of vehicles. In the context of this principle, a signal phase with more vehicles will be assigned a longer green time. Furthermore, a green-way traffic light scheduling method (GTLM) is investigated for special vehicles (e.g., ambulances and fire engines) in emergency scenarios. Signal states will be adjusted or maintained by the traffic light control system to keep special vehicles moving along smoothly. Comparative experiments demonstrate that the ITLM reduces average wait time by 34%–78% and average stop frequency by 12%–34% in the context of traffic management. The GTLM reduces travel time by 22%–44% and 30%–55% under two types of traffic conditions and achieves optimal performance in congested scenarios.     

A GIS-based environmental modelling system for transportation planners

This paper describes a GIS-based environmental modelling system, termed TRAEMS, for use by transport planners in assessing the environmental effects of road traffic plans. The system utilises capabilities of GIS to integrate the output from a transport planning activity with land use information to model the environmental impacts of different road traffic scenarios. TRAEMS enables planners to test transport related environmental impacts at the same time as they are testing the traffic carrying efficiencies of network plans. The suitability of this type of environmental modelling for planning purposes is illustrated using a case study.     

考虑多源不确定信息的路网交通拥堵状态辨识方法

拥堵状态辨识是道路运行状态评估的重要内容,是交通系统流量调控和管理的重要参考指标.在智能交通系统（Intelligent transport system,ITS）普及化程度越来越高的后交通时代,如何实现海量数据下对多源不确定交通拥堵状态的辨识是非常重要的内容.首先,基于多元集对分析建立一种新的路网交通拥堵状态刻画模型;然后,通过改进证据理论中Dempster组合规则实现交通信息融合,并推导出当前交通拥堵状态的准确表达值;最后,在数值模拟的基础上,使用重庆市南岸区的交通检测数据进行仿真分析,结果表明本方法能准确直观地反映出实时交通拥堵状态,具有潜在的实际应用价值.     

Effect of button location on driver's visual behaviour and safety perception

Although buttons are a frequently used type of control in car interiors, little research has been undertaken on how the usage of buttons affects the visual behaviour of the driver. In this study, the aim was to analyse the effect of push button location and auditory feedback on drivers' visual time off road and safety perception when driving in a real traffic situation. The effect of six button locations (five on the centre stack, one near the gear stick) was tested. Drivers' visual behaviour was studied in real traffic on a motorway. An eye tracking system recorded the visual behaviour of eight drivers who, in 96 repeated trials each, were instructed to press a specific button. Data analysis focused on the drivers' visual time off road and safety perception in relation to the location of the button to be pressed. Auditory feedback did not show a significant effect on visual time off road. The time off road increased significantly as the angle increased between the normal line of sight and button location for the five buttons placed on the centre stack. Results for the button located close to the gear stick, with the highest eccentricity, produced a short time off road. This unexpected finding is discussed in terms of three potential explanations: 1) the role of perceptual discrimination; 2) risk perception; and 3) motor control.