Tapio Luttinen

Collective dynamics of pedestrians interacting with attractions.

In order to investigate collective effects of interactions between pedestrians and attractions, this study extends the social force model. Such interactions lead pedestrians to form stable clusters around attractions, or even to rush into attractions if the interaction becomes stronger. It is also found that for high pedestrian density and intermediate interaction strength, some pedestrians rush into attractions while others move to neighboring attractions. These collective patterns of pedestrian movements or phases and transitions between them are systematically presented in a phase diagram. The results suggest that safe and efficient use of pedestrian areas can be achieved by moderating the pedestrian density and the strength of attractive interaction, for example, in order to avoid situations involving extreme desire for limited resources.

Effects of switching behavior for the attraction on pedestrian dynamics

Walking is a fundamental activity of our daily life not only for moving to other places but also for interacting with surrounding environment. While walking on the streets, pedestrians can be aware of attractions like shopping windows. They can be influenced by the attractions and some of them might shift their attention towards the attractions, namely switching behavior. As a first step to incorporate the switching behavior, this study investigates collective effects of switching behavior for an attraction by developing a behavioral model. Numerical simulations exhibit different patterns of pedestrian behavior depending on the strength of the social influence and the average length of stay. When the social influence is strong along with a long length of stay, a saturated phase can be defined at which all the pedestrians have visited the attraction. If the social influence is not strong enough, an unsaturated phase appears where one can observe that some pedestrians head for the attraction while others walk in their desired direction. These collective patterns of pedestrian behavior are summarized in a phase diagram by comparing the number of pedestrians who visited the attraction to the number of passersby near the attraction. Measuring the marginal benefits with respect to the strength of the social influence and the average length of stay enables us to identify under what conditions enhancing these variables would be more effective. The findings from this study can be understood in the context of the pedestrian facility management, for instance, for retail stores.

Energy efficient traffic-based street lighting automation

The emerging LED technology enables intelligent street lighting that is based on sensing individual vehicles and dimming street lights accordingly. The potential energy savings are considerable, exceeding 50% on roads with low traffic. A possible reason why such applications are not yet emerging are financial uncertainties about the size of the savings, which are needed to motivate the investment. Another barrier to adoption are uncertainties about whether proposed approaches meet standards and regulations for traffic safety. In this paper, an energy efficient street lighting design that meets regulations for rural roads is implemented with the IEC 61499 distributed function block architecture. The intelligent lighting is co-simulated against a traffic simulation using cellular automata. Virtual metering in the IEC 61499 application is used to quantify energy savings in simulation scenarios with different traffic volumes. Across a range of traffic volumes representative of rural roads, our simulations indicate that smart dimming can deliver energy savings of 14% to 70%, with savings increasing as traffic density decreases.

Integration of Geographic Information System for Transportation with Real-Time Traffic Simulation System: Application Framework

Real-time traffic information applications (RTIA) collect real-time traffic data from a wide variety of detectors. The problem with these applications is that they are complex and hard to maintain because of the large number of distributed detectors involved. However, it is well recognized that traffic simulation systems have the ability to improve the efficiency of traffic analysis, prediction, and control. This paper presents an application framework that integrates a real-time traffic simulation system with RTIA. Within this framework, a geographic information system for transportation (GIS-T) architecture, combined with a temporal-spatial database, provides a flexible way to present the real-time traffic information for road users. Several critical system components are introduced as well, including a real-time dynamic traffic data exchange model. The real-time simulation system, a static traffic model in GIS-T, and a Java-based application architecture are also briefly discussed.

Trade-off between jerk and time headway as an indicator of driving style

Variation in longitudinal control in driving has been discussed in both traffic psychology and transportation engineering. Traffic psychologists have concerned themselves with “driving style”, a habitual form of behavior marked by it’s stability, and its basis in psychological traits. Those working in traffic microsimulation have searched for quantitative ways to represent different driver-car systems in car following models. There has been unfortunately little overlap or theoretical consistency between these literatures. Here, we investigated relationships between directly observable measures (time headway, acceleration and jerk) in a simulated driving task where the driving context, vehicle and environment were controlled. We found individual differences in the way a trade-off was made between close but jerky vs. far and smooth following behavior. We call these “intensive” and “calm” driving, and suggest this trade-off can serve as an indicator of a possible latent factor underlying driving style. We posit that pursuing such latent factors for driving style may have implications for modelling driver heterogeneity across various domains in traffic simulation.

The effect of dimmed road lighting and car headlights on visibility in varying road surface conditions

ABSTRACT  This article evaluates the potential of dimming road lighting in order to save energy and lower costs while avoiding any adverse effects on the visibility of drivers. An experimental study under varying road surface conditions was conducted to examine the combined effect of car headlights and different road lighting intensities on the visibility level. The luminance levels of the road surface, contrast and visibility level of the objects were measured from a stationary car under three road surface conditions: (a) dry, (b) wet, and (c) snowy conditions. The results support the feasibility of reducing road lighting intensity when car headlights are available. When within the range of car headlights, road lighting did not improve the visibility level. In the presence of car headlights, the average luminance providing a sufficient visibility level was found to be 0.19, 0.63, and 0.75 cd/m2 under dry, wet, and snowy conditions, respectively. This would allow an energy savings of 317 kWh/year/luminaire, representing savings of 80% luminaire/year for light emitting diode (LED) luminaires.

Classification Criteria and Application of Level of Service for Bicycle Lanes in China

The bicycle is an important part of the urban transportation system in China. Traditional research on bicycle levels of service concentrated on the cyclists’ perspective and neglected bicyclists’ particularity and diversity. The objectives of this research were to propose bicycle level-of-service (BLOS) models from the users’ perspective and to develop a new BLOS criterion on the basis of a new classification of persons. The key influential factors of BLOS were classified into three categories: safety, comfort, and air quality. The stepwise regression analysis was employed to develop the BLOS models on the basis of influential factors and volunteers’ ratings. To isolate the significant difference of the BLOS requirements, cyclists were divided into four groups: users with special requirements, attempters, frequent users, and enthusiasts. New BLOS criteria corresponding to the classification of cyclists and BLOS models were developed. Results showed that the nonmotorized vehicle lane width, the form of separation between motorized and nonmotorized vehicle lanes, moped speed, and proportion of roadside planting were the significant influential factors of the corresponding models. The fact that the developed BLOS models and classification criteria could improve cycling facilities proved to be quite applicable and reasonable. Results can be used to draw two classification maps of BLOS on the bike lanes of main roads in China as an example of an application. The results described in this paper can help decision makers find significant factors affecting cyclists’ satisfaction at road segments and determine the order of the improvements to be made in the nonmotorized vehicle lane.

Jamming transitions induced by an attraction in pedestrian flow

We numerically study jamming transitions in pedestrian flow interacting with an attraction, mostly based on the social force model for pedestrians who can join the attraction. We formulate the joining probability as a function of social influence from others, reflecting that individual choice behavior is likely influenced by others. By controlling pedestrian influx and the social influence parameter, we identify various pedestrian flow patterns. For the bidirectional flow scenario, we observe a transition from the free flow phase to the freezing phase, in which oppositely walking pedestrians reach a complete stop and block each other. On the other hand, a different transition behavior appears in the unidirectional flow scenario, i.e., from the free flow phase to the localized jam phase and then to the extended jam phase. It is also observed that the extended jam phase can end up in freezing phenomena with a certain probability when pedestrian flux is high with strong social influence. This study highlights that attractive interactions between pedestrians and an attraction can trigger jamming transitions by increasing the number of conflicts among pedestrians near the attraction. In order to avoid excessive pedestrian jams, we suggest suppressing the number of conflicts under a certain level by moderating pedestrian influx especially when the social influence is strong.

Impact of Impulse Stops on Pedestrian Flow

We numerically study the impact of impulse stops on pedestrian flow for a straight corridor with multiple attractions. The impulse stop is simulated by the switching behaviour model, a function of the social influence strength and the number of attendees near the attraction. When the pedestrian influx is low, one can observe a stable flow where attendees make a complete stop at an attraction and then leave the attraction after a certain amount of time. When the pedestrian influx is high, an unstable flow is observed due to strong social influence. In the unstable flow, attendees near the attraction are crowded out from the clusters by others due to the interpersonal repulsion. The expelled pedestrians impede the pedestrian traffic between the left and right boundaries of the corridor. These collective patterns of pedestrian flow are summarised in a schematic phase diagram.