Assessing the Impact of Weather on Traffic Intensity

in Weather, Climate and Society (2010), 2(1), 6068

This paper focuses on the effect of weather conditions on daily traffic intensities (the number of cars passing a specific segment of a road). The main objective is to examination whether or not weather ... [more ▼]

This paper focuses on the effect of weather conditions on daily traffic intensities (the number of cars passing a specific segment of a road). The main objective is to examination whether or not weather conditions uniformly alter daily traffic intensities in Belgium, or in other words whether or not road usage on a particular location determines the size of the impacts of various weather conditions. This general examination is a contribution that allows policymakers to assess the appropriateness of countrywide versus local traffic management strategies. In addition, a secondary goal of this paper is to validate findings in international literature within a Belgian context. To achieve these goals, the paper analyzes the effects of weather conditions on both upstream (toward a specific location) and downstream (away from a specific location) traffic intensities at three traffic count locations typified by a different road usage. Perhaps the most interesting results of this study for policymakers are the heterogeneity of the weather effects between different traffic count locations, and the homogeneity of the weather effects on upstream and downstream traffic at specific locations. The results also indicate that snowfall, rainfall, and wind speed diminish traffic intensity, and high temperatures increase traffic intensity. Further generalizations of the findings might be possible by studying weather impacts on local roads and by shifting the focus of research toward travel behavior. [less ▲]

The use of time use surveys to study activity participation: emerging issues

Conference (2009)

Time use surveys often are carried out to identify, classify and quantify social behaviour of people by focusing on the activities that people perform. Time use data, in the transportation field often ... [more ▼]

Time use surveys often are carried out to identify, classify and quantify social behaviour of people by focusing on the activities that people perform. Time use data, in the transportation field often referred to as activity-based data, can be used to study a variety of sociological, economic, and technological phenomena. Studying behaviour, social networks and transport patterns are a few of the topics that can be analysed based on these time use data. This first introductory paper discusses some emerging issues in the collection of travel-related data such as automatic spatial information recording using cell phones and GPS, and survey design experiences. On the one hand new technology offers the opportunity to record at a relative low cost a wide variety of the data, while on the other hand new problems occur. One of such problems for instance is the problems of ‘cold starts’ faced with GPS devices, clouding the first minutes of recording after each restart of the device after it was turned off completely. Notwithstanding, applications of new technologies offer the opportunity for performing detailed space-time analyses in different fields ranging from epidemiology to transportation science. Some of these applications are highlighted in this session. Next to the advantages and potential risks of new technologies, this introductory paper also discusses the combination of different modes to analyze space-time behaviour. In particular, this study investigates potential mixed mode design effects, observed in a large activity-based travel survey, using a PDA application on the one hand, and traditional paper and pencil diaries on the other hand. The mixed-mode effects are analysed using heteroscedastic linear regression models, taking into account not only mode-effects, but also potential fatigue-effects. The results show that in this mixed-mode survey no attrition effects are present, and that the survey mode (PDA versus paper and pencil) has no direct impact on the quantities investigated (number of out-of-home activities reported and number of trips). [less ▲]

Shifting Towards Environment-Friendly Modes: Profiling Travelers using Q-Methodology

in Proceedings of the 88th Annual Meeting of the Transportation Research Board (DVD-ROM) (2009)

Due to a variety of reasons, the previous century is characterized by an extraordinary growth in car use that has continued into the current century. This has resulted in serious environmental ... [more ▼]

Due to a variety of reasons, the previous century is characterized by an extraordinary growth in car use that has continued into the current century. This has resulted in serious environmental repercussions. Despite technological advancements, the externalities remain an ecological threat that can not be discarded by policy makers. Therefore, it is essential that policy makers focus on reducing car use and on stimulating the shift towards more environment-friendly transport modes. In this study, Q-methodology is adopted as the technique to segment people, and to ascertain which approaches and determinants matter to medium distance travel. Segmentation is important, as policy measures will be more efficient and effective if they are fine-tuned on specific target groups. The analysis revealed that four discourses preponderate the paradigm of environmentally sustainable transport: travelers who use public transport as a dominant alternative, car-dependent travelers, travelers with a positive perception of using public transport, and travelers with a preference for car use. Concerning rational, economic motives, individuals evaluate travel time reliability as most important. To increase the reliability policy makers should consider the use of separate bus lanes and traffic light manipulation. In addition, public transport can be made even more attractive, when costs of cars are made more variable by road or congestion charging. When the subjective motives are discussed, the differences between the different groups of travelers were more pronounced. Next to increasing the benefits of using public transport, policy makers should also pay attention to removing psycho-social barriers. [less ▲]

Investigating the Variability in Daily Traffic Counts Trough the Use of ARIMAX and SARIMAX Models: Assessing the Effect of Holidays on two diverse site locations

in Proceedings of the 88th Annual Meeting of the Transportation Research Board (DVD-ROM) (2009)

In this paper, daily traffic counts are explained and forecasted by different modeling philosophies, namely the ARIMAX and SARIMA(X) modeling approaches. Special emphasis is put on the investigation of ... [more ▼]

In this paper, daily traffic counts are explained and forecasted by different modeling philosophies, namely the ARIMAX and SARIMA(X) modeling approaches. Special emphasis is put on the investigation of the seasonality in the daily traffic data and on the identification and comparison of holiday effects at different site locations. To get prior insight in the cyclic patterns present in the daily traffic counts, spectral analysis provides the required framework to highlight periodicities in the data. Data originating from single inductive loop detectors, collected in 2003, 2004 and 2005, are used for the analyses. Four traffic count locations are investigated in this study, an upstream and downstream traffic count location on a highway that is excessively used by commuters and an upstream and downstream traffic count location on a highway that is typified by leisure traffic. The different modeling techniques pointed out that weekly cycles appear to determine the variation in daily traffic counts. The comparison between seasonal effects and holiday effects at different site locations revealed that both the ARIMAX and SARIMAX modeling approach are valid frameworks for the identification and quantification of possible influencing effects. The technique yielded the insight that holiday effects play a noticeable role on highways that are excessively used by commuters, while holiday effects have a more ambiguous effect on highways typified for their leisure traffic. Modeling of daily traffic counts on secondary roads, and simultaneous modeling of both the underlying reasons of travel and revealed traffic patterns, certainly are challenges for further research. [less ▲]

Surveying activity-travel behavior in Flanders: Assessing the impact of the survey design

in Macharis, C.; Turcksin, L. (Eds.) Proceedings of the BIVEC-GIBET Transport Research Day 2009, Part II (2009)

Ever since car ownership and car use started to increase in Western Europe and the USA, transportation planners attempted to model people’s travel behavior. In the context of the Feathers project a ... [more ▼]

Ever since car ownership and car use started to increase in Western Europe and the USA, transportation planners attempted to model people’s travel behavior. In the context of the Feathers project a dynamic activity-based travel demand framework is developed for Flanders. In this paper, the complete survey design of the data collection effort required for such dynamic activity-based model is discussed. A mixed survey design of using a PDA application on the one hand, and using traditional paper and pencil diaries on the other hand, turns out to be a very suitable way of collecting detailed information about planned and executed activity-travel behavior of households. The results show that no attrition effects are present, not on the number of out-of-home activities reported, nor on the number of trips reported. Moreover the survey mode (PDA versus paper and pencil) has no direct impact on the quantities investigated. Notwithstanding, it is essential for further analysis on the Feathers data to explicitly take into account mode effects because of two reasons. First, the effect of explanatory variables can be influenced by the survey mode. Second, the variance in the estimation of the quantity investigated can differ significantly. Heteroscedatisc linear regression models provide the required framework to explicitly take into account these mode effects. [less ▲]

Shifting Towards Environment-Friendly Modes: Profiling Travelers using Q-Methodology

in Transportation (2009), 36(4), 437-453

Due to a variety of reasons, the previous century is characterized by an extraordinary growth in car use that has continued into the current century. This has resulted in serious environmental ... [more ▼]

Due to a variety of reasons, the previous century is characterized by an extraordinary growth in car use that has continued into the current century. This has resulted in serious environmental repercussions. Despite technological advancements, the externalities remain an ecological threat that can not be discarded by policy makers. Therefore, it is essential that policy makers focus on reducing car use and on stimulating the shift towards more environment-friendly transport modes. In this study, Q-methodology is adopted as the technique to segment people, and to ascertain which approaches and determinants matter to medium distance travel. Segmentation is important, as policy measures will be more efficient and effective if they are fine-tuned on specific target groups. The analysis revealed that four discourses preponderate the paradigm of environmentally sustainable transport: travelers who use public transport as a dominant alternative, car-dependent travelers, travelers with a positive perception of using public transport, and travelers with a preference for car use. Concerning rational, economic motives, individuals evaluate travel time reliability as most important. To increase the reliability policy makers should consider the use of separate bus lanes and traffic light manipulation. In addition, public transport can be made even more attractive, when costs of cars are made more variable by road or congestion charging. When the s motives are discussed, the differences between the different groups of travelers were more pronounced. Next to increasing the benefits of using public transport, policy makers should also pay attention to removing psycho-social barriers. [less ▲]

Assessing the Impact of Weather on Traffic Intensity

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 ▲]

An activity-based approach for surveying and modelling travel behaviour: analysis of the mixed-mode design effects

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 ▲]

Travel time expenditure in Flanders: Towards a better understanding of travel behavior

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 ▲]

Social, economic and policy analysis of recreational fisheries in Flanders

Master's dissertation (2005)