Showing papers by "Haibo Chen published in 2002"

Cleaning of Matched License Plate Data

Abstract: Three methods for identifying outlying journey time observations collected as part of a motorway license plate matching exercise are presented. Each method is examined to ensure that it is comprehensible to transport practitioners, is able to correctly classify outliers, and is efficient in its application. The first method is a crude method based on percentiles. The second uses a mean absolute deviation test. The third method is a modification of a traditional z- or t-statistical test. Results from each method and combinations of methods are compared. The preferred method is judged to be the third method alone, which uses the median rather than the mean as its measure of location and the inter-quartile range rather than the standard deviation as its measure of variability. This method is seen to be robust to both the outliers themselves and the presence of incident conditions. The effectiveness of the method is demonstrated under a number of typical and atypical road traffic conditions. In particular, th...

Instrumented city database analysts using multi-agents

Abstract: The Instrumented City (iC) database is a multi-purpose, transport-related database facility for use by the entire academic transport research community. Data from the UK Leicester City Council and Nottinghamshire County Council Traffic Management Computers is logged and archived on a continuous basis, by the Leeds University’s Institute for Transport Studies. Since its inception in 1992, the iC database has been used for various real-time applications such as air quality and noise monitoring, modelling and forecasting. This paper describes the framework that demonstrates the feasibility of using multi-agents as information analysts to process and manage the iC database. The agents are adaptive, interactive and personal. They can be trained via the interactions with the users to be personalised for individual preferences. These agents are designed to be responsible for (1) data clean-up to remove outliers; (2) missing data substitutions; (3) statistical data analysis; (4) data mining to enhance the understanding of the relationships between traffic and air quality, noise and health; and (5) knowledge discovery by identifying unknown but potentially important patterns.

A study of the characteristics of traffic incident duration on motorways

Abstract: In this paper, two types of incidents, vehicle breakdown and traffic crash, are studied. First, the characteristics of the incidents are analysed. Secondly, the potential factors that may affect incident duration such as vehicle type, incident time, incident location, number of vehicles involved, and incident severity, are discussed. Based on the analysis of the characteristics of the incidents, an incident duration model is developed. This model is based on fuzzy logic theory, which is a promising mathematical approach to model the process characterised by subjectivity, ambiguity, uncertainty, and imprecision, which can be seen in the incident duration. Analysis shows that the incident duration has a Weibull distribution. Although, there is no significant difference in duration between the vehicle breakdown and traffic crash, the factors that affect duration are different. The result shows that fuzzy logic models have good performance to predict the incident duration. It provides a different approachs to analyse the incident duration other than the statistical methods.

Using Non-Parametric Tests to Evaluate Traffic Forecasting Performance.

Abstract: This paper proposes the use of a number of nonparametric comparison methods for evaluating traffic flow forecasting techniques. The advantage to these methods is that they are free of any distributional assumptions and can be legitimately used on small datasets. To demonstrate the applicability of these tests, a number of models for the forecasting of traffic flows are developed. The one-step-ahead forecasts produced are then assessed using nonparametric methods. Consideration is given as to whether a method is universally good or good at reproducing a particular aspect of the original series. That choice will be dictated, to a degree, by the user’s purpose for assessing traffic flow.