1,720,972 research outputs found
The use of simulation in the design of a road transport incident detection algorithm
Full text linkAutomatic incident detection is becoming one of the core tools of urban traffic management, enabling more rapid identification and response to traffic incidents and congestion. Existing traffic detection infrastructure within urban areas (often installed for traffic signal optimization) provides urban traffic control systems with a near continuous stream of data on the state of traffic within the network. The creation of a simulation to replicate such a data stream therefore provides a facility for the development of accurate congestion detection and warning algorithms. This paper describes firstly the augmentation of a commercial traffic model to provide an urban traffic control simulation platform and secondly the development of a new incident detection system (RAID-Remote Automatic Incident Detection), with the facility to use the simulation platform as an integral part of the design and calibration process. A brief description of a practical implementation of RAID is included along with summary evaluation results
Simulating the impacts of strong bus priority measures
No full textPolicies to reduce levels of traffic congestion and pollution in major urban areas often focus strongly on the concept of a sustainable transport system, but to achieve this vision a significant modal shift from private car to public transport will be required. This paper reports on a recent research study which provides a framework within which to model the behavioral responses of travelers following the implementation of strong bus priority measures (where road capacity is deliberately removed from general traffic and given to buses). A summary of the different behavioral responses which can be expected is given and results from a practical implementation of the framework which has been based on two commercial transport modeling packages (CONTRAM and TRIPS) are discussed. These results suggest firstly that the effect of implementing such strong bus priority measures is as dependent on the characteristics of the local travelers as on the scheme itself and secondly that implementing too strong a scheme may not benefit public transport overall
A data fusion framework for travel time estimation in urban traffic networks
No full textUnderlying all attempts to manage urban traffic congestion is the need for a comprehensive knowledge and understanding of the state of all parts of the network at all times. This need has given rise to a diverse range of real time traffic detection methodologies and while much research on network state estimation has been carried out based on these data sources, the different characteristics of the detection datasets often potentially produce differing (if not conflicting) estimates of either the absolute value or the short term trend in urban travel times. This paper presents a theoretical data fusion framework which enables two of the commonest forms of real time traffic data to be combined to create a single best estimate of travel time along an urban road segment. It is proposed that rather than the unidirectional evolutionary approach of many existing travel time estimation systems, improvements in the absolute accuracy of the travel time estimates and reductions in time lag effects can be achieved by combining the currency (but limited spatial relevance) of inductive loop data with the accuracy (but post-event nature) of number plate recognition and matching data. This is achieved by applying a principle of memory to the estimated travel time series where, rather than being discarded as the estimated series evolves, previous estimates are reassessed when their accuracy is revealed at a future moment in time, with the revealed error being translated back to the current time point to improve the accuracy of future estimates. This paper proposes a generic data fusion framework based on this principle, building on both existing and emerging real time traffic detection systems and existing research into urban travel time estimation
Comparison of signalized junction control strategies using individual vehicle position data
No full textThis paper is concerned with the development of control strategies for urban signalized junction that can make use of individual vehicle position data from localization probes on board the vehicles. Strategy development involves simulating the behaviour of vehicles as they negotiate junctions controlled by prototype strategies and evaluating performance. Two strategies are discussed in this paper, a simple auctioning agent strategy and an extended auctioning agent strategy where a machine learning approach is used to enable agents to be trained by a human expert to improve performance. The performance of these two strategies are compared with each other and with the MOVA algorithm in simulated tests. The results show that auctioning agents using individual vehicle position data can out perform MOVA, but that this performance can be improved further still by using learning auctioning agents trained by a human expert
Determining rail network accessibility
No full textThe usual representation of optimal path finding problems within transport networks is focused on well established algorithms for identifying the optimal path (or set of paths) between two specific network nodes. When the required solution is the identification of the optimal route between every possible pair of nodes in the network however, these algorithms are inefficient.The Floyd-Warshall algorithm provides an efficient way to compare all possible paths through each pair of nodes more efficiently, requiring only N3 comparisons for a network of N nodes. To illustrate the potential of this approach to network analysis within transport research, this paper considers the issue of determining accessibility between railway stations (on the route between Weymouth and London Waterloo) served by a mixture of high-speed and stopping services.A rail network is physically defined by the locations of tracks, but travel times are also dependent on whether stations are visited by high-speed services as well as stopping services. A single rail route therefore has to be represented not as a (topologically) straight line, but as a more traditional graph with high connectivity between nodes. Reformulating this into a matrix-based definition allows the Floyd-Warshall algorithm to efficiently determine the optimal routing (and hence travel times) between<br/
The use of simulation modelling in the design of a road transport incident detection algorithm
No full textAutomatic incident detection is becoming one of the core tools of urban traffic management, enabling rapid responses to developing congestion. Existing incident detection systems however can be hard to calibrate and require the system to be operational before the process can begin. This paper reports on the development of a new incident detection system ('RAID'), with the facility to use simulation modelling as an integral part of the calibration process. A commercial traffic simulation model was augmented with additional code developed to mimic the data and messages produced by a real urban traffic control system. These messages could then be fed directly into an offline version of the developed detection algorithms. This approach allows the network managers to both visualise the system in operation and assess the impact of changing rule settings or traffic detector placements without the need for any on-street infrastructure to be installed
Are we looking where we are going? An exploratory examination of eye movement in high speed driving
No full textThis paper reports on results of an exploratory study aimed at examining driver glance behaviour, near the onset of and during congestion on motorways and how it is affected by factors external to the vehicle. Data has been collected on eye movements from six test subjects, each undertaking three test drives. Analysis has examined average glance times and fraction of time spent looking into a number of broadly defined areas. The study has revealed that on the whole drivers spend 80% of their time looking into a ‘forward’ area and, on average, look away from the forward scene for around 0.65 sec. at a time. In addition to variations between subjects, factors such as road section were found to contribute to variation, however no firm dependence on the level of traffic flow was found. It is hoped that this exploratory study has helped to reveal a number of ‘baseline’ dependencies regarding glance behaviour, and further, that this information will be of use to a range of fields, from the design of invehicle telematics systems, though to simulation science
Signal control using vehicle localization probe data
No full textThis paper presents a simulation test bed and methodology for evaluating urban signalized junction control algorithms that use localization probe data from all vehicles in the local area. The simulator is based on SIAS Paramics micro-simulation software with bespoke software modules built on top for automatic network generation, localization data processing and signal control. Localization algorithms tested use a hierarchical structure of auctioning agents. Early tests of control algorithms on an isolated signalized junction indicate performance that compares favourably with the MOVA algorithm using inductive loop data.<br/
Running a Satellite MSc programme in China: experiences of teaching from the first year joint MSc Transportation Planning and Engineering programme between the University of Southampton and the Beijing Jiaotong University
No full textIn September 2005 the School of Civil Engineering and the Environment at the University of Southampton launched its joint MSc programme in Transportation Planning and Engineering (TPE) with the Beijing Jiaotong University (BJTU), China. Through a collaborative agreement, the existing TPE MSc Programme taught in Southampton was offered to students at BJTU as a mirror of the UK programme in terms of module content, material delivery and methods of assessment. Students taking the course at BJTU enrolled as University of Southampton students and had the same rights as their UK counterparts.This paper will highlight some personal reflections of the authors on the educational, managerial and quality assurance lessons learned from the first 12-months of the programme
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