Transportation Letters: The International Journal of Transportation Research, Mar 4, 2016
The present paper employs advanced statistical modeling in order to assess the spatial factors th... more The present paper employs advanced statistical modeling in order to assess the spatial factors that may influence the maneuverability of Powered Two-Wheelers (PTW) in urban corridors during overtaking. Using trajectory data from video recordings, two types of maneuvers are examined: those that occur with a lane change and those conducted without speed change and/or lane change (on the fly). The modeling approach has two parts: First, the probability to conduct an overtake is statistically modeled. Second, a Multiple Indicators-Multiple Causes (MIMIC) latent variable model is developed to assess the microscopic traffic characteristics and other critical factors that may affect the maneuverability of PTW. Results show that during overtaking, speed difference from the preceding vehicle is the most significant factor. Further results from the MIMIC model indicate that the PTW maneuverability is related to the type of overtake, the distance between the PTW and the vehicle being overtaken, as well as speeds.
Transportation Research Board 95th Annual MeetingTransportation Research Board, 2016
The study of maneuverability of vehicles in high demand urban road networks through vehicles’ tra... more The study of maneuverability of vehicles in high demand urban road networks through vehicles’ trajectories is a challenge for traffic engineers and researchers. The collection of such high resolution data has been exclusively supported by costly fixed location camera systems and computer vision algorithms in isolated or sequential sections. Recently, with the advances in computer vision, low cost cameras have been used with quite a success in extracting kinematic characteristics. In this paper, the authors discuss several limitations accompanying the use of camcorders and how they can be alleviated with the use of Unmanned Aerial Vehicles (UAVs). Following, a low-cost semi-automatic way of extracting detailed vehicle trajectory data through UAV video footage is presented. Steps to reduce errors due to camera instability and to achieve sufficient calibration are also described. Two experiments are presented; the first refers to vehicle tracking at a four legged intersection and the second to tracking pedestrian flow. Following, a discussion concerning the use of UAVs to replace or extend current systems’ capabilities is conducted.
ABSTRACT We discuss recent findings on the statistical properties of short-term traffic flow in u... more ABSTRACT We discuss recent findings on the statistical properties of short-term traffic flow in urban freeway systems. In, particular, the complexity, nonlinearity and nonstationarity of freeway travel speed patterns are studied using the recurrence plots and the recurrence quantification analysis. Results indicate a variable statistical behavior of the speed’s temporal evolution, especially during the morning and peak periods of both the weekdays and weekend. Moreover, a clear deterministic evolution of speed patterns with variable nonlinear and laminar characteristics is observed during congested conditions.
Short-term demand forecasting is essential for the public transit system, allowing for effective ... more Short-term demand forecasting is essential for the public transit system, allowing for effective operations planning. This is especially relevant in the highly uncertain environment created by the SARS‑CoV‑2 pandemic. In this paper, we attempt to develop accurate prediction models of transit ridership in Athens, Greece, using Autoregressive Fractional Integrated time series models enhanced with SARS‑CoV‑2-related exogenous variables. The selected exogenous variables are, from the one hand, the ratio of weekly SARS‑CoV‑2 infections over the infections 3 weeks before (capturing the dynamics of the pandemic, as a proxy for fear of transmitting the disease while commuting), and from the other hand, an index of the stringency of the government’s SARS‑CoV‑2-related measures and regulations. The developed ARFIMAX models have been fitted separately on bus and metro ridership data and wield comparable and statistically significant results. In both models, the exogenous variables prove to be statistically significant and their values are intuitive, suggesting a linear interrelation between them and transit ridership.
European Transport Conference, 2000, Cambridge, United Kingdom, 2000
To address the significant problem of traffic safety, the riskier of road user behaviours can be ... more To address the significant problem of traffic safety, the riskier of road user behaviours can be identified and then targeted by traffic safety campaigns, which have proven to be effective in a number of circumstances. Effective campaigns must target the right groups of drivers with the appropriate message. Using a large data base of 20,725 questionnaires from19 European countries, this paper uses a combination of factor analysis and tree based regression to determine relatively homogeneous driver groups which share attitudes toward safety, in an effort to design and implement more effective safety campaigns. To achieve this, the question of driver behaviour toward safety is addressed by examining habits such as attitudes toward speeding, reckless driving, seat belt use, and drinking and driving. The results suggest that speeding and general reckless (dangerous) behaviour are related, perhaps capturing driver's risk taking behaviour. Similarly, seat belt use and driving under the influence of alcohol are also related and may represent a driver's law abiding tendency. Further, young male drivers appear to be the demographic group which can benefit the most from systematic safety campaigns. (A) For the covering abstract see ITRD E107957.
Transportation Letters: The International Journal of Transportation Research, Mar 4, 2016
The present paper employs advanced statistical modeling in order to assess the spatial factors th... more The present paper employs advanced statistical modeling in order to assess the spatial factors that may influence the maneuverability of Powered Two-Wheelers (PTW) in urban corridors during overtaking. Using trajectory data from video recordings, two types of maneuvers are examined: those that occur with a lane change and those conducted without speed change and/or lane change (on the fly). The modeling approach has two parts: First, the probability to conduct an overtake is statistically modeled. Second, a Multiple Indicators-Multiple Causes (MIMIC) latent variable model is developed to assess the microscopic traffic characteristics and other critical factors that may affect the maneuverability of PTW. Results show that during overtaking, speed difference from the preceding vehicle is the most significant factor. Further results from the MIMIC model indicate that the PTW maneuverability is related to the type of overtake, the distance between the PTW and the vehicle being overtaken, as well as speeds.
Transportation Research Board 95th Annual MeetingTransportation Research Board, 2016
The study of maneuverability of vehicles in high demand urban road networks through vehicles’ tra... more The study of maneuverability of vehicles in high demand urban road networks through vehicles’ trajectories is a challenge for traffic engineers and researchers. The collection of such high resolution data has been exclusively supported by costly fixed location camera systems and computer vision algorithms in isolated or sequential sections. Recently, with the advances in computer vision, low cost cameras have been used with quite a success in extracting kinematic characteristics. In this paper, the authors discuss several limitations accompanying the use of camcorders and how they can be alleviated with the use of Unmanned Aerial Vehicles (UAVs). Following, a low-cost semi-automatic way of extracting detailed vehicle trajectory data through UAV video footage is presented. Steps to reduce errors due to camera instability and to achieve sufficient calibration are also described. Two experiments are presented; the first refers to vehicle tracking at a four legged intersection and the second to tracking pedestrian flow. Following, a discussion concerning the use of UAVs to replace or extend current systems’ capabilities is conducted.
ABSTRACT We discuss recent findings on the statistical properties of short-term traffic flow in u... more ABSTRACT We discuss recent findings on the statistical properties of short-term traffic flow in urban freeway systems. In, particular, the complexity, nonlinearity and nonstationarity of freeway travel speed patterns are studied using the recurrence plots and the recurrence quantification analysis. Results indicate a variable statistical behavior of the speed’s temporal evolution, especially during the morning and peak periods of both the weekdays and weekend. Moreover, a clear deterministic evolution of speed patterns with variable nonlinear and laminar characteristics is observed during congested conditions.
Short-term demand forecasting is essential for the public transit system, allowing for effective ... more Short-term demand forecasting is essential for the public transit system, allowing for effective operations planning. This is especially relevant in the highly uncertain environment created by the SARS‑CoV‑2 pandemic. In this paper, we attempt to develop accurate prediction models of transit ridership in Athens, Greece, using Autoregressive Fractional Integrated time series models enhanced with SARS‑CoV‑2-related exogenous variables. The selected exogenous variables are, from the one hand, the ratio of weekly SARS‑CoV‑2 infections over the infections 3 weeks before (capturing the dynamics of the pandemic, as a proxy for fear of transmitting the disease while commuting), and from the other hand, an index of the stringency of the government’s SARS‑CoV‑2-related measures and regulations. The developed ARFIMAX models have been fitted separately on bus and metro ridership data and wield comparable and statistically significant results. In both models, the exogenous variables prove to be statistically significant and their values are intuitive, suggesting a linear interrelation between them and transit ridership.
European Transport Conference, 2000, Cambridge, United Kingdom, 2000
To address the significant problem of traffic safety, the riskier of road user behaviours can be ... more To address the significant problem of traffic safety, the riskier of road user behaviours can be identified and then targeted by traffic safety campaigns, which have proven to be effective in a number of circumstances. Effective campaigns must target the right groups of drivers with the appropriate message. Using a large data base of 20,725 questionnaires from19 European countries, this paper uses a combination of factor analysis and tree based regression to determine relatively homogeneous driver groups which share attitudes toward safety, in an effort to design and implement more effective safety campaigns. To achieve this, the question of driver behaviour toward safety is addressed by examining habits such as attitudes toward speeding, reckless driving, seat belt use, and drinking and driving. The results suggest that speeding and general reckless (dangerous) behaviour are related, perhaps capturing driver's risk taking behaviour. Similarly, seat belt use and driving under the influence of alcohol are also related and may represent a driver's law abiding tendency. Further, young male drivers appear to be the demographic group which can benefit the most from systematic safety campaigns. (A) For the covering abstract see ITRD E107957.
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