Panichpapiboon, Sooksan
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Panichpapiboon, Sooksan
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sooksan.pa@kmitl.ac.th
17 results
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Item type:Publication, Characterization of Passenger Search Time Under Varying Supply-Demand Imbalance(2026-08-01)Passenger search time is an essential variable in a street-hail taxi operation. Fundamentally, the statistical distributions of passenger search time form the basis of analytical and simulation models for describing the taxi system’s dynamics. To create accurate analytical and simulation models that realistically represent the dynamics of the actual taxi system, it is inevitable to characterize the type of statistical distributions that can effectively model the empirical distributions. While the probability distribution functions of passenger search time are critical elements of analytical and simulation models, their empirical distributions under different levels of supply-demand imbalance have not been characterized in any existing studies. In this paper, based on more than eight million real taxi trips in Bangkok, Thailand, and formal statistical analysis, we identify the probability distributions that can effectively model the empirical distributions of passenger search time under different levels of taxi supply-demand imbalance. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A review of information dissemination protocols for vehicular ad hoc networks(2012-01-01); Pattara-Atikom, WasanWith the fast development in ad hoc wireless communications and vehicular technology, it is foreseeable that, in the near future, traffic information will be collected and disseminated in real-time by mobile sensors instead of fixed sensors used in the current infrastructure-based traffic information systems. A distributed network of vehicles such as a vehicular ad hoc network (VANET) can easily turn into an infrastructure-less self-organizing traffic information system, where any vehicle can participate in collecting and reporting useful traffic information such as section travel time, flow rate, and density. Disseminating traffic information relies on broadcasting protocols. Recently, there have been a significant number of broadcasting protocols for VANETs reported in the literature. In this paper, we classify and provide an in-depth review of these protocols. © 2012 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Time-headway distributions on an expressway: Case of bangkok(2015-01-01)Traffic flow modeling is one of the fundamental keys to solving a traffic engineering problem. Among many parameters, time headway is frequently used to model traffic flow characteristics. A statistical analysis of time headways is immensely important to both theoretical traffic modeling and simulation-based traffic modeling. Basically, it allows researchers to describe an inherently random pattern of traffic flows. Past studies have mainly focused on the time headways of vehicles on highways, freeways, and arterials. However, studies of time headways on urban expressways are rather limited and still need further investigation. In this paper, the author investigates and characterizes the time-headway distributions of vehicles traveling on an urban expressway in Bangkok, Thailand. Particularly, the exponential distribution, the lognormal distribution, and the generalized extreme value (GEV) distribution are used to model the time headways. It is found that the GEV distribution is most effective in modeling time headways. In fact, the GEV distribution can describe more than 90% of the empirical distributions on most lanes and sections of the expressway. On the other hand, the exponential distribution is the least effective distribution. It can only describe the empirical distributions during the periods when the traffic is extremely light. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Real-Time Vehicle Maneuvering Detection with Digital Compass(2021-01-01) ;Leakkaw, PuttipongVehicle maneuverings are important pieces of information for many applications such as traffic incident detection and driving behavior recognition. On a macroscopic level, an unusually large number of some maneuvering events (e.g., lane changes) may suggest that a road incident occurs. On a microscopic level, vehicle maneuverings can tell how each individual person drives (e.g., safely or unsafely). A number of smartphone-based maneuvering detection methods have been proposed. However, most of them typically rely on accelerometer and gyroscope, and thus require the smartphone to be placed at a specific position on a vehicle and in a specific orientation. In this work, we take a rather different approach from most of the existing methods. Particularly, we investigate how effective it is to detect vehicle maneuverings by relying only on a signal from a digital compass on a smartphone. To this end, we introduce a simple rule-based maneuvering detection method which only takes the heading angles measured by the digital compass as inputs. This allows the smartphone to be placed freely at any position on the vehicle and in any orientation. Our results show that the digital compass can be used to detect turns and u-turns extremely well, and its accuracy on lane change detection is at an acceptable level. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Irresponsible forwarding under real intervehicle spacing distributions(2013-01-01); Cheng, LinOne approach to the distribution of traffic information in a self-organizing traffic information system is multihop broadcasting. In this approach, each vehicle may simply rebroadcast an information packet that it receives from the others. However, rebroadcasting results in redundant retransmissions of the same information, leading to a useless occupation of the radio channel. Minimizing redundancy, while still guaranteeing reachability in the network, is a challenging task in multihop broadcasting. In our previous work, we introduced a new probabilistic-based broadcasting scheme, i.e., Irresponsible Forwarding (IF) , which could effectively reduce the redundancy. However, in the previous work, we only considered the scenario where the intervehicle spacing was exponentially distributed. In this paper, we generalize the concept of IF such that it can be applied to any intervehicle spacing distribution. In addition, we evaluate the performance of the IF protocol when it is applied in a realistic scenario (i.e., using real traffic traces). This paper shows that the IF protocol is able to limit packet redundancy all hours of the day effectively. © 1967-2012 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Lane Change Detection with Smartphones: A Steering Wheel-Based Approach(2020-01-01); Leakkaw, PuttipongLane change is a valuable piece of traffic information. An abnormally high number of lane changes on a road section typically suggests that some lanes are blocked due to traffic incidents. Currently, the lane change information of vehicles on an urban road is typically obtained from over-roadway fixed sensors such as surveillance cameras. However, using fixed sensors has limitations in terms of cost and coverage. It is more effective to collect the lane change information directly from each individual vehicle. In addition, lane changing behavior of a driver can help assess his driving risk. One convenient way to detect a lane change directly from each vehicle is to take advantage of sensors on smart mobile devices such as smartphones. In this paper, we explore a new way to identify a lane change event based on a pattern of steering wheel angles detected by a smartphone. This is distinguishable from all of the existing steering wheel-based lane change detection methods, which need to retrieve the steering wheel angle signal from the On-board Diagnostic (OBD) port of the vehicle via the Controller Area Network-Bus (CAN-Bus). In addition, unlike others, our method does not require a lot of complex features to make an accurate detection. In fact, we demonstrate that a high level of accuracy can already be attained with a single simple feature called rotation span. Results show that the proposed detection method performs very well both in terms of precision and recall. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, What Separates High-Performing Taxis From the Rest? A Case Study in Bangkok(2024-01-01)Taxi is a public transportation system widely used in many cities, including Bangkok, Thailand. It provides a convenient way for people to move around the city. However, past studies have shown that the Bangkok taxi system is highly inefficient. In fact, most taxis are vacant most of the time. Despite this fact, there are highly efficient taxis that outperform the others in terms of gaining higher revenue. Learning what these high-performing taxis do differently is essential to improving the overall system's efficiency. In this paper, we investigate the key factors that differentiate high-performing taxis from low-performing ones. Identifying these factors allows us to draw significant insights into improving each taxi's performance. Based on an analysis of real taxi trajectory data, this study shows that the two crucial factors that separate high-performing taxis from low-performing taxis are the passenger searching time and the ability to select less congested search routes. Thus, an effective solution needs to concentrate on improving these two factors. Enhancing other elements, such as passenger delivery time and delivery route, is much less effective and will not have any critical impact. Lastly, this paper presents an effective regression model for predicting the efficiency of an individual taxi based on its average vacant time and the proportion of time spent in congestion during a passenger search. The model performs well, with only an 8.28% error rate. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Exploiting wireless communication in vehicle density estimation(2011-07-01); Pattara-Atikom, WasanVehicle density is one of the main metrics used for assessing road traffic condition. High vehicle density indicates that traffic is congested. Currently, most vehicle density estimation approaches are designed for infrastructure-based traffic information systems. These approaches require detection devices such as inductive loop detectors or traffic surveillance cameras to be installed at various locations. Consequently, they are not appropriate for an emerging self-organizing vehicular traffic information system, where vehicles have to collect and process traffic information without relying on any fixed infrastructure. In this paper, we consider a few methods for estimating vehicle density based on the number of vehicles in the vicinity of the probe vehicle and the number of vehicles in a communication cluster. © 2011 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Effects of intervehicle spacing distributions on connectivity of VANET: A case study from measured highway traffic(2012-10-11) ;Cheng, LinConnectivity is an important property for information dissemination in a vehicular ad hoc network. Basically, connectivity ensures that a message from a source can be spread to reach all the vehicles in the network. Over the past few years, there have been a significant number of studies on connectivity models for vehicular ad hoc networks. Most of them rely on the key assumption that the intervehicle spacing distribution is exponential. However, based on a new empirical analysis, it is shown that during most periods of the day the intervehicle spacing distribution can better be described by other statistical distributions. This certainly affects the connectivity analysis. In this article, we discuss how the connectivity of a vehicular ad hoc network in a highway traffic scenario will change when the intervehicle spacing distribution is not exponential. © 1979-2012 IEEE. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A Big Data Analysis on Urban Mobility: Case of Bangkok(2022-01-01); Khunsri, KavepolDesigning an efficient on-demand mobility service requires comprehensive knowledge of the statistical characteristics of trips. In other words, it is critical to know how long passengers typically spend on a trip and how far they usually travel. Likewise, it is important to learn how much time a driver spends searching for passengers. This study presents a statistical analysis of taxi trips in Bangkok based on real traces of 5,853 taxis over the period of three months. Significant insights on trip volume, trip time, trip distance, and origin-destination distance are derived. In addition, the probability distributions of trip time, trip distance, and origin-destination distance are also characterized based on two goodness-of-fit tests. To our knowledge, this characterization is done for the first time for Bangkok taxi trips. It is shown that a lognormal distribution can best describe the empirical trip time distribution. On the other hand, a Weibull distribution can best describe the empirical trip distance distribution and the empirical origin-destination distance distribution. These distributions are essential to traffic simulation. Finally, the efficiency of the Bangkok taxi system is also quantified both at the system level and at the agent level.
