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Intelligent Transport Systems, IET

Issue 2 • Date June 2008

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Displaying Results 1 - 11 of 11
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  • Advanced positioning technologies for co-operative systems

    Page(s): 81 - 91
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (418 KB)  

    The authors describe a systems approach for a future positioning system to be developed for the European co-operative vehicle infrastructure systems (CVIS) project that deals with increased transport safety and efficiency using advanced positioning, mapping and communication technologies. Positioning and mapping functions will be provided by the sub-project for positioning, mapping and location referencing (POMA), in which new methods for the combination of several positioning components will be developed. The whole positioning system setup of CVIS will then be deployed at DLR in Berlin. This setup will not only cover onboard components but also infrastructure-based sensors and sensor networks together with enhanced positioning algorithms. Furthermore, new functionalities for mapping and map matching as well as the consideration of integrity conditions and confidence circles are a major topic of the work. This new approach will ensure high accuracy and reliability of field trials spread over Europe. View full abstract»

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  • Multi-feature walking pedestrians detection for driving assistance systems

    Page(s): 92 - 104
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (856 KB)  

    Pedestrians are the most vulnerable urban traffic participants. In order to better protect them in pre-crash scenarios, it is necessary to detect them. Unfortunately, pedestrian detection is very difficult in highly cluttered urban scenarios, using cameras mounted on moving vehicle. A novel approach to walking pedestrian detection, using dense stereo vision systems, is presented. Multiple features combined into a Bayesian framework are used to yield a high rate of pedestrian detection. The feature set includes simple features such as width, height, lateral and longitudinal speed. It also includes complex motion features, such as the variance of the motion field caused by the pedestrians' legs and arms moving during walking and the periodicity of the pedestrians' walking pattern. View full abstract»

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  • 3D vehicle detection using a laser scanner and a video camera

    Page(s): 105 - 112
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (530 KB)  

    A new approach for vehicle detection performs sensor fusion of a laser scanner and a video sensor. This combination provides enough information to handle the problem of multiple views of a car. The laser scanner estimates the distance as well as the contour information of observed objects. The contour information can be used to identify the discrete sides of rectangular objects in the laser scanner coordinate system. The transformation of the three-dimensional coordinates of the most visible side to the image coordinate system allows for a reconstruction of its original view. This transformation also compensates size differences in the video image, which are caused by different distances to the video sensor. Afterwards, a pattern recognition algorithm can classify the object's sides based on contour and shape information. Since the number of available object hypotheses is enormously reduced by the laser scanner, the system is applicable in real time. In addition, video-based vehicle detection and additional laser scanner features are fused in order to create a consistent vehicle environment description. View full abstract»

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  • Event detection based on loop and journey time data

    Page(s): 113 - 119
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (367 KB)  

    An algorithm that examines the travel time (TT) and the corresponding loop-based information at the same time is proposed. It monitors TT and the traffic speeds on all the loops within the TT section continuously. Event alerts are activated when there is a significant reduction of speeds on at least one loop detector in addition to a significant increase in the TT. An event may be detected by TT at some stage, by loop data at another stage, or by a logical combination of two. The algorithm using fixed thresholds has been tested based on operational data collected in the National Traffic Control Centre. The thresholds are determined based on tradeoffs between detection and false alarm rates (FAR). Test results based on a full day of data indicate that the integrated algorithm has achieved an impressive detection rate and a FAR which should be easily manageable by operators. Further work would be needed to confirm operations and facilitate a practical implementation. View full abstract»

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  • Estimation of speed-flow and flow-density relations on the motorway network in the greater Copenhagen region

    Page(s): 120 - 131
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1043 KB)  

    The speed-flow and flow-density relations at the motorway network of the greater Copenhagen region are explored based on a large data sample consisting of a total of 5.3 million observations at 398 locations. It is concluded that the US Bureau of Public Road (BPR) speed-flow formula from 1964 is an adequate average description of the non-queuing conditions in static assignment models, while the variation of travel speed should be taken into account in meso- and micro-simulation models. The variance of the variation of the non-queuing conditions appears to be fairly independent of the flow. The flow-density curve for the non-queuing conditions should according to theory have a convex shape to be consistent with the speed-flow curve. This was confirmed by the data. It was also shown that the variance hereby is linearly increasing with density. A linearly decreasing relationship between density and flow may be assumed for the queuing situation. Data confirmed this, although less clearly than for the non-queuing situation. This equals a derived curved formulation of the speed-flow relationship. Data for the queuing situation revealed more variance in driving speed. The variance of the variation may be assumed constant in the flow-density curves, meaning an increasing variance of speed. Finally, it was concluded, that the speeds at the capacity limit is highly unstable, within a range from 30 to 90 km/h. The transition point between the non-queuing and queuing conditions was more clearly defined in the flow-density curves than in the speed- flow curves. View full abstract»

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  • Evaluation of in-vehicle dynamic speed assistance in Spain: algorithm and driver behaviour

    Page(s): 132 - 142
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (398 KB)  

    A method is presented to determine variable speed limits, taking account of road geometry and vehicle characteristics. This method is based on a mathematical vehicle model and a detailed digital map that contains every piece of data that may be relevant from a safety point of view. Objective safety criteria such as tyre-road friction and sight distance are used. The main purpose of calculating new limits is to improve safety and to increase the acceptance of these limits by drivers. These safe speed limits have been integrated into the Spanish intelligent speed adaptation system and a new interface has been developed in order to alert the driver before they reach dangerous stretches of road. Furthermore, this system has been tested under real driving conditions. Test results show that speeding on sharp bends is reduced and traffic is more homogeneous. Both effects lead to greater traffic safety. View full abstract»

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  • Preliminary results from the Danish Intelligent Speed Adaptation Project Pay As You Speed

    Page(s): 143 - 153
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (255 KB)  

    The driving behaviour of participants in the Danish intelligent speed adaptation (ISA) project 'Pay as You Speed' (PAYS) is described. The project is the first ISA project based on Pay as You Drive principles. Thus, the ISA equipment both notifies the driver that he/she is speeding ('information') and applies penalty points which decrease the driver's chance of a potential 30% discount on the cost of his/her automobile insurance ('incentive'). The results presented are based on the first 38 of 180 participants. The key result is that the combination of 'information' and 'incentive' almost eliminated speeding on rural roads while significant reductions in speeding were found also for urban roads and to some extent motorways. On roads with speed limits of 50, 80 and 110 km/h the proportion of distance travelled when speeding was reduced significantly. No significant results were found for motorways with speed limits of 130 km/h. In a future paper the final results from 'PAYS' will be presented. View full abstract»

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  • Controlled study of ISA effects: comparing speed attitudes between young volunteers and external controls, and the effect of different ISA treatments on the speeding of volunteers

    Page(s): 154 - 160
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (258 KB)  

    This study is a part of an ongoing ISA project in Denmark. Its aim was to clarify two human factors issues, (1) the difference in attitude between ISA-volunteers and non-volunteers, and (2) the relative impact on speeding of two factors, ISA-information and driver motivation. The first part of the study compared survey data from ISA-volunteers with those of non-volunteers. The two groups differed in their judgement of ISA features and anticipated effects of driving with ISA, whereas no differences were found in judgement of speed limits, attitude to speeding or reported driving style. The second part of the study was a driving experiment in which two factors, informative ISA and an economic incentive for not speeding, were manipulated between groups of volunteers. A control group had ISA switched off and received insurance discount independent of their speeding. This group did not reduce their speeding in the experiment period, whereas another group, also with ISA switched off but with insurance discount dependent on their speeding reduced their speeding by a small amount. Two groups, both driving with ISA switched on showed a substantial reduction in their speeding. The effect of informative ISA alone was substantial, which presumably prevented a further gain from combining ISA information with the incentive. View full abstract»

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  • Continuous subjective strain measurement

    Page(s): 161 - 169
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (162 KB)  

    Driver assistance and information systems are gaining more and more importance in modern vehicles. In addition to their specific functionalities, these systems also aim to optimise drivers' current strain, because overload as well as underload can increase errors, lead to critical situations and can create furthermore unpleasant experiences for the driver. As workload changes in a highly dynamic way, these systems have to react in a similarly dynamic manner. This requires a fast and dynamically changing estimation of the driver's strain. In recent studies, the author described the relationship among strain changes, driving manoeuvres and environmental factors. In order to further examine this dependency, a simulator study was conducted where traffic densities were varied and strain was measured continuously with the aim to analyse the level and time course of drivers' current strain. Implications for workload adaptive advanced driver assistance systems are discussed. View full abstract»

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  • Assessing the visual demand from in-vehicle information systems by means of the occlusion technique: the effects of participant age

    Page(s): 170 - 177
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    Occlusion is a measurement technique for assessing the visual demand and interruptability of in-vehicle information system (IVIS) tasks using a means for intermittent viewing of the IVIS displays/ controls. Testing the visual demand of IVIS tasks using occlusion is gaining international support, largely due to it being a relatively simple method to use. Although an ISO occlusion standard has been published, some important issues remain; these include developing a robust and fully detailed measurement protocol. The age of participants is an important individual difference potentially affecting the validity and reliability of results from occlusion. To develop an effective protocol, the age ranges of participants need to be specified; otherwise experimenters undertaking measurements with varying age samples for the same systems/tasks may come to different conclusions. To assess the impact of age on occlusion task performance, 60 participants in various age ranges were tested on four different IVIS tasks. The results showed age-related differences; in particular, the older participants showed a greater spread of measurements. Excluding the issues of representative samples, the results imply that purely to obtain minimal inter-subject variability an occlusion measurement should use younger/middle-aged participants only. View full abstract»

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Aims & Scope

IET Intelligent Transport Systems is an interdisciplinary journal devoted to research into the practical applications of intelligent transport systems and infrastructures.

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