A parking model hierarchy

The last decade has seen considerable developments in computer assisted design procedures which enable planners to investigate the impacts of changes in the transport system. These developments have become more available to analysts through the introduction of microcomputers and computer graphics. Unfortunately, the impacts of parking on the transport have not been incorporated explicitly in many of these models since their prime concern is the movement of traffic. Parking system design and policy analysis can, however, benefit greatly from these developments in computer technology and availability. The design of parking systems can be improved and the investigation of policy impacts can be trialed or refined prior to their introduction using microcomputer packages. This paper outlines some developments in these areas. More specifically, it outlines a hierarchy or microcomputer models and information systems that can investigate parking policy and study the level of service provided by parking systems.     

Distributions of travel time variability on urban roads

Reliability is an important factor in route, mode and also departure time choice analysis and is a key performance indicator for transport systems. However, the current metrics used to measure travel time variability may be not sufficient to fully represent reliability. Better understanding of the distributions of travel times is needed for the development of improved metrics for reliability. A comprehensive data analysis involving the assessment of longitudinal travel time data for two urban arterial road corridors in Adelaide, Australia, demonstrates that the observed distributions are more complex than previously assumed. The data sets demonstrate strong positive skew, very long upper tails, and sometimes bimodality. This paper proposes the use of alternative statistical distributions for travel time variability, with the Burr Type XII distribution emerging as an appropriate model for both links and routes. This statistical distribution has some attractive properties that make it suitable for explicit definition of many travel time reliability metrics. Copyright © 2011 John Wiley & Sons, Ltd.     

Effective arterial road incident detection: A Bayesian network based algorithm

Timely and accurate incident detection is an essential part of any successful advanced traffic management system. The complex nature of arterial road traffic makes automated incident detection a real challenge. Stable performance and strong transferability remain major issues concerning the existing incident detection algorithms. A new arterial road incident detection algorithm TSC_ar is presented in this paper. In this algorithm, Bayesian networks are used to quantitatively model the causal dependencies between traffic events (e.g. incident) and traffic parameters. Using real time traffic data as evidence, the Bayesian networks update the incident probability at each detection interval through two-way inference. An incident alarm is issued when the estimated incident probability exceeds the predefined decision threshold. The Bayesian networks allow us to subjectively build existing traffic knowledge into their conditional probability tables, which makes the knowledge base for incident detection robust and dynamic. Meanwhile, we incorporate intersection traffic signals into traffic data processing. A total of 40 different types of arterial road incidents are simulated to test the performance of the algorithm. The high detection rate of 88% is obtained while the false alarm rate of the algorithm is maintained as low as 0.62%. Most importantly, it is found that both the detection rate and false alarm rate are not sensitive to the incident decision thresholds. This is the unique feature of the TSC_ar algorithm, which suggests that the Bayesian network approach is advanced in enabling effective arterial road incident detection.     

Dense network traffic models,travel time reliability and traffic management. Ii: Application to network reliability

This paper is the second of a pair of papers discussing two main themes concerning dense network modelling. These themes are: (1) the changing nature of traffic management technology and the underlying objectives behind traffic management practice, and (2) the use of measures of network reliability in models, especially as an element of the evaluation of alternative network configurations. This paper develops and applies the second theme, the use of network reliability concepts in the evaluation of traffic networks, through consideration of variations in travel times, distinction between local street and arterial road networks, and the definition and application of a set of reliability indices that may be used to study different trip movements in a network. It indicates how these indices may be used in appraising different traffic management plans for a dense network of local streets and arterial roads, using a case study application.     

Book Review

This paper examines the relationship between investment in transportation infrastructure capital and the debt-to-gross domestic product (GDP) ratio. We analyse the effect of bringing forward investment originally planned for future years to be executed during times of economic crisis and also consider the possible advantages of carrying out such investments with private sector financing. This paper presents a model which shows how policy aimed to encourage investment in transportation infrastructure projects through private sector participation may help raise long-term GDP and thus lead to a lower debt-to-GDP ratio. The theoretical model is then applied to current empirical data from Israel.     

Profile of the accident prone older driver

Accident histories and other related records of elderly drivers were used to develop a profile of the accident prone older driver in Michigan. Elderly drivers were defined as drivers with age greater than or equal to 65 years. The variables used in the study were developed by stratifying drivers age, sex, and residency; type of accident and violation; and number of traffic infraction points received. Comparisons were made between these strata, and the statistical significance of observed patterns in cross tabulated data was tested by performing the chi-square test. The results of the study indicate that, by and large, the elderly drivers from urban areas as compared to those from rural areas, and male drivers as compared to females are more likely to be cited for traffic violations. The statistical analysis showed some recognizable traits of the “young” elderly drivers that suggest prioritized safety countermeasures oriented toward them.     

如何分析一场比赛

停维修站时间的选择有什么重要性？一个“燃油校正”的单圈是什么？在下文中,您将了解如何从F1比赛画面里获得更多信息     

Estimating probability distributions of dynamic queues

Queues are often associated with uncertainty or unreliability, which can arise from chance or climatic events, phase changes in system behaviour, or inherent randomness. Knowing the probability distribution of the number of customers in a queue is important for estimating the risk of stress or disruption to routine services and upstream blocking, potentially leading to exceeding critical limits, gridlock or incidents. The present paper focuses on time-varying queues produced by transient oversaturation during demand peaks where there is randomness in arrivals and service. The objective is to present practical methods for estimating a probability distribution from knowledge of the mean, variance and utilisation (degree of saturation) of a queue available from computationally efficient, if approximate, time-dependent calculation. This is made possible by a novel expression for time-dependent queue variance. The queue processes considered are those commonly used to represent isolated priority (M/M/1) and signal-like (M/D/1) systems, plus some statistical variations within the common Pollaczek-Khinchin framework. Results are verified by comparison with Markov simulation based on recurrence relations.     

Selatm — a GIS based program for evaluating the safety benefits of local area traffic management schemes

Particular safety problems relate to traffic on local streets. Local Area Traffic Management (LATM) schemes are often implemented with the objective of counteracting these safety problems. One analytical difficulty in appraising the effectiveness of LATM in dealing with safety problems has been the ‘footloose’ nature of accident locations in a local street network. Seldom are there distinct ‘blackspot’ locations. An area‐wide approach is needed and the interaction between the system and arterial road network must be considered. The paper describes the development of a Safety Evaluation Method for Local Area Traffic Management (termed SELATM). It is a GIS‐based program for analysing accident patterns over time and the evaluation of the safety benefits of LATM schemes. The evaluation is perform at different network levels for various accident variables. The thrust of the program involved the integration of network data with data on accidents and the installed devices to generate summary accident statistics for the various network levels allowing for before and after comparison with a control area. This program as developed is applied to a LATM scheme at Enfield, a suburb in metropolitan Adelaide.