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See detailAssessing the Impact of Weather on Traffic Intensity
Cools, Mario ULg; Moons, Elke; Wets, Geert

in Proceedings of the 87th Annual Meeting of the Transportation Research Board (DVD-ROM) (2008)

The investigation of weather effects on traffic intensity is important from a road safety point of view, because traffic intensity is noted as the first and primary determinant of traffic safety. Next to ... [more ▼]

The investigation of weather effects on traffic intensity is important from a road safety point of view, because traffic intensity is noted as the first and primary determinant of traffic safety. Next to traffic safety, weather conditions affect other predominant traffic variables, namely traffic demand and traffic flow. Therefore the main objective of this study is the identification and comparison of weather effects on traffic intensity at different site locations. To assess the impact of weather conditions on traffic intensity, the upstream and downstream traffic of four traffic count locations are considered. The traffic intensity data originate from minute data coming from single inductive loop detectors, collected by the Flemish Traffic Control Center. Data concerning weather events were recorded by the Royal Meteorological Institute of Belgium. The main modeling philosophy envisaged in this study to identify and quantify weather effects is the linear regression approach. Most appealing result of this study for policy makers, is the heterogeneity of the weather effects between different traffic count locations, and the homogeneity of the weather effects on upstream and downstream traffic at a certain location. The results also indicated that snowfall, rainfall and wind speed have a clear diminishing effect on traffic intensity, while maximum temperature significantly increases traffic intensity. Further generalizations of the findings are possible by studying weather effects on local roads and by shifting the scope towards travel behavior. Simultaneously modeling of weather conditions, traffic intensity rates, collision risk and activity travel behavior is certainly a key challenge for further research. [less ▲]

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See detailInvestigating Effect of Holidays on Daily Traffic Counts: Time Series Approach
Cools, Mario ULg; Moons, Elke; Wets, Geert

in Transportation Research Record: Journal of the Transportation Research Board (2007), 2019

In this paper, different modeling philosophies are explored in order to explain and forecast daily traffic counts. The main objectives of this study are the analysis of the impact of holidays on daily ... [more ▼]

In this paper, different modeling philosophies are explored in order to explain and forecast daily traffic counts. The main objectives of this study are the analysis of the impact of holidays on daily traffic, and the forecasting of future traffic counts. Data coming from single inductive loop detectors, collected in 2003, 2004 and 2005, were used for the analysis. The different models that were investigated showed that the variation in daily traffic counts could be explained by weekly cycles. The Box-Tiao modeling approach was applied to quantify the effect of holidays on daily traffic. The results showed that traffic counts were significantly lower for holiday periods. When the different modeling techniques were compared with respect to forecasting with a large forecast horizon, Box-Tiao modeling clearly outperformed the other modeling strategies. Simultaneous modeling of both the underlying reasons of travel, and revealed traffic patterns, certainly is a challenge for further research. [less ▲]

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See detailAn activity-based approach for surveying and modelling travel behaviour: analysis of the mixed-mode design effects
Cools, Mario ULg; Moons, Elke; Wets, Geert

Conference (2007)

Reports from various international organisations, like for instance the European Commission’s White paper “European transport policy for 2010: time to decide” show that policy makers acknowledge the ... [more ▼]

Reports from various international organisations, like for instance the European Commission’s White paper “European transport policy for 2010: time to decide” show that policy makers acknowledge the increasing importance of mobility. Mobility is not just considered to be a cornerstone for economic growth, but also seen as a social need that offers people the opportunity for self-fulfilment and relaxation. In order to lead an efficient policy, governments require reliable predictions of travel behaviour, traffic performance, and traffic safety. Thus, traffic and transportation models can provide the right framework to support long-term decisions. On an international level, activity-based models have become one of the leading paradigms to model travel behaviour. The most important characteristic of these models is that travel is considered as a derivative from the activities that individuals and households need or wish to perform. This means that travel is no longer seen as an isolated fact in these models, which is a great advantage in comparison to the classic models. The development of activity-based models requires very specific data. Since a special emphasis was laid on the dynamic character of the model, both the planned and executed activities were surveyed. 2500 households were selected using a stratified cluster technique. The selected household were asked to fill out an activity-diary and to report rescheduling decisions during a one-week period. Approximately one half of the households received a PDA-module; the other half was surveyed by means of a traditional paper-and-pencil diary. Although both data collection modes were designed in such way that the correspondence of the questions was optimised, it remains essential to identify differences in the data that are introduced by using multiple modes. This paper starts with describing the differences that existed in the questionnaire design of the two modes, and then further explores the statistical differences in terms of some key observations, such as average number of trips reported, and average travel time. [less ▲]

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See detailInvestigating Effect of Holidays on Daily Traffic Counts: Time Series Approach
Cools, Mario ULg; Moons, Elke; Wets, Geert

in Proceedings of the 86th Annual Meeting of the Transportation Research Board (CD-ROM) (2007)

In this paper, different modeling philosophies are explored in order to explain and forecast daily traffic counts. The main objectives of this study are the analysis of the impact of holidays on daily ... [more ▼]

In this paper, different modeling philosophies are explored in order to explain and forecast daily traffic counts. The main objectives of this study are the analysis of the impact of holidays on daily traffic, and the forecasting of future traffic counts. Data coming from single inductive loop detectors, collected in 2003, 2004 and 2005, were used for the analysis. The different models that were investigated showed that the variation in daily traffic counts could be explained by weekly cycles. The Box-Tiao modeling approach was applied to quantify the effect of holidays on daily traffic. The results showed that traffic counts were significantly lower for holiday periods. When the different modeling techniques were compared with respect to forecasting with a large forecast horizon, Box-Tiao modeling clearly outperformed the other modeling strategies. Simultaneous modeling of both the underlying reasons of travel, and revealed traffic patterns, certainly is a challenge for further research. [less ▲]

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See detailTravel time expenditure in Flanders: Towards a better understanding of travel behavior
Cools, Mario ULg; Moons, Elke; Wets, Geert

in Proceedings of the 10th International Conference on Computers in Urban Planning and Urban Management (CUPUM) (CD-ROM) (2007)

In modern societies, mobility is considered to be vital for human development. In order to lead an efficient policy and achieve environmental goals, governments require reliable predictions of travel ... [more ▼]

In modern societies, mobility is considered to be vital for human development. In order to lead an efficient policy and achieve environmental goals, governments require reliable predictions of travel behavior. In this paper, the travel time expenditure in Flanders is investigated. The focus is put on the time spent on commuting. Two modeling approaches are used for the analysis of daily travel time expenditure, namely the Poisson regression approach and the classical linear regression approach. In this paper it is shown that socio-demographics, day-effects and transportation preferences are contributing significantly in the explanation of variability in daily commuting time and that multiplicative effects of the transportation preferences form good approximations of the travel time ratios. [less ▲]

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See detailRegular events in travel behaviour research: setup of a longitudinal websurvey
Cools, Mario ULg; Moons, Elke; Wets, Geert

Conference (2006)

One of the leading paradigms in modern travel behaviour research is the activity based approach, which considers travel as a derivative from the activities that individuals and households need or wish to ... [more ▼]

One of the leading paradigms in modern travel behaviour research is the activity based approach, which considers travel as a derivative from the activities that individuals and households need or wish to perform. Longitudinal designs provide the required framework for a better understanding of the dynamics of travel behaviour. Longitudinal data can be used to analyze behavioural adjustments some time before (response leads) or after (response lags) the occurrence of an event, or for instance to analyze routine behaviour. The questionnaire used to collect the data will be an activity diary. The respondents are asked to fill in all their activities performed that day. The diaries have to be filled in at least twice a week. These moments are randomly selected, but in weeks when a special event occurs, the days around this special event are questioned as well. Performing a longitudinal study has certain drawbacks however. The respondent burden can cause different side-effects, such as panel attrition, decreasing representativeness and, reporting errors. Thus, next to refreshing the sample regularly, trying to keep the respondents motivated is essential. A first step in lowering the respondent burden is to make the activity diaries user-friendly. An internetbased questionnaire makes interaction with respondents possible. The respondent’s current results can be graphically displayed (e.g. geographical map of activity-pattern), potentially awakening or strengthening the interest in the study. Logical rules (e.g. two activities on two different locations require a trip in between) can be formulated, and the interaction with the respondents allows the researcher to get feedback on “strange” answers, or on missing values, thus improving the data quality. This paper describes some potential paths to minimise sample attrition (e.g. internet-based interaction with respondents) and ways to refresh the sample. These findings are applied to the study of travel behaviour of Flemish households around school holidays. [less ▲]

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