scispace - formally typeset
Search or ask a question

Showing papers in "Journal of transportation and statistics in 2004"


Journal Article
TL;DR: An advantage of the Bayesian network method presented here is its complex approach where system variables are interdependent and where no dependent and independent variables are needed.
Abstract: This paper describes the Bayesian network method for modeling traffic accident data and illustrates its use. Bayesian networks employ techniques from probability and graph theory to model complex systems with interrelated components. The model is built using two car accident data for 1998 from Slovenia, and inferences are made from the model about how knowledge of the values of certain variables influences the probabilities for values of other variables or outcomes. An advantage of the Bayesian network method presented here is its complex approach where system variables are interdependent and where no dependent and independent variables are needed.

58 citations


Journal Article
TL;DR: A Bayesian based methodology is developed for estimating the posterior distribution of the correlation of travel times between links along a corridor.
Abstract: The estimation and forecasting of travel times has become an increasingly important topic as Advanced Traveler Information Systems (ATIS) have moved from conceptualization to deployment. This paper focuses on an important, but often neglected, component of ATIS - the estimation of link travel time correlation. Natural cubic splines are used to model the mean link travel time. Subsequently, a Bayesian based methodology is developed for estimating the posterior distribution of the correlation of travel times between links along a corridor. The approach is illustrated on a corridor in Houston, Texas, that is instrumented with an Automatic Vehicle Identification system.

28 citations


Journal Article
TL;DR: In this article, the authors examined the U.S. domestic airline network and found that the effects of 9/11 have affected all network classes, with the largest impact on the point-to-point variants.
Abstract: This paper examines the U.S. domestic airline network. Using an exhaustive definition of the airline network and a cross-section pooled time series dataset for 35 consecutive quarters covering 1995:Q1 to 2003:Q3, domestic scheduled air transportation was analyzed. Results suggest the existence of increased vertical disintegration of market segments following the events of September 11, 2001 (9/11). The effects of 9/11 have affected all network classes, with the largest impact on the point-to-point variants. The expansion of Southwest Airlines affected all variants of the networks positively, with a proportionately larger impact on the point-to-point over the hub and spoke variants. The results of this study are expected to help inform both operational and decisionmaking and policymaking. Results may also be useful to manufacturers in projecting the size and mix of of the aircraft fleet that are expected to be compatible with the evolving network.

26 citations


Journal Article
TL;DR: In this article, a methodology to estimate current U.S. commodity inflows to a substate region using a supply-side, commodity-by-industry, input-output model and commodity flow data for states is described.
Abstract: This paper describes a methodology to estimate current U.S. commodity inflows to a substate region using a supply-side, commodity-by-industry, input-output model and commodity flow data for U.S. states. Because the 1993 Commodity Flow Survey does not capture data below the state level, the estimation of commodity flows to a particular substate region of the United States has always proven difficult. By combining state level commodity flow data with the supply side, commodity-by-industry, input-output model, an estimate of commodity flows to smaller regions can be carried out entirely based on the regional industrial structure. Since the actual substate flows are typically unobserved, the accuracy of the methodology is unknown. However, by applying the same methodology to larger regions, with actual states used as the forecast region, the estimates can be compared with actual flows while maintaining an acceptable level of accuracy.

26 citations


Journal Article
TL;DR: In this paper, a generalized linear modeling technique with quasilikelihood approach was adopted to develop the models for predicting motorcycle crashes at signalized intersections on urban roads in Malaysia, and traffic entering the intersection, approach speed, lane width, number of lanes, shoulder width, and land use at the approach of the intersections were found to be significant in describing motorcycle crashes.
Abstract: Because more than half the motor vehicles in Malaysia are motorcycles, safety of this from of transportation is an important issue. As part of a motorcycle safety program, Malaysia became the first country to provide exclusive motorcycle lanes in the hopes of reducing motorcycle crashes along trunk roads. However, little work has been done to address intersection crashed involving motorcycles. This paper provides models for predicting motorcycle crashes at signalized intersections on urban roads in Malaysia. A generalized linear modeling technique with quasilikelihood approach was adopted to develop the models. Traffic entering the intersection, approach speed, lane width, number of lanes, shoulder width, and land use at the approach of the intersections were found to be significant in describing motorcycle crashes. These findings should enable engineers to draw up appropriate intersection treatment criteria specifically designed for motorcycle lane facilities in Malaysia and elsewhere.

16 citations


Journal Article
TL;DR: The relevance of posting the 40 mph minimum speed limit on the Interstate Highway System has been increasingly called into question since the National Highway System Designation Act of 1995 repealed the federally sanctioned maximum speed limit.
Abstract: The relevance of posting the 40 mile per hour (mph) minimum speed limit on the Interstate Highway System has been increasingly called into question since the National Highway System Designation Act of 1995 repealed the federally sanctioned maximum speed limit. In this study, data were collected on major interstate highways in Florida to evaluates speed distribution relative to the 40 mph posted minimum speed limit. The data revealed that the 15th percentile speed at all sites was 60 mph or above on both four-lane and six-lane highway sections. The analysis showed that the average speed at all sites was approximately 5 standard deviations above the 40 mph minimum. The coefficient of variation ranged from 7% to 11%, while the trimmed variance analysis showed that vehicles traveling below 55 mph contributed insignificantly to the variation in Traffic speeds. A comparison of data collected before the speed limit rose from 65 mph to 70 mph showed that the average speed increased by 5 mph, while the variance did not change significantly. The coefficient of variation, however, increased significantly. The results reported here suggest that speed variability at the lower end of the distribution is not a significant factor in traffic operating characteristics on Florida rural interstate highways.

14 citations


Journal Article
TL;DR: Analysis and forcasts of trends related to road traffic and pedestrian casualties and fatalities in Great Britain are presented and it is shown that at the aggregate level it is unlikely that, for the numbers that are killed or seriously injured, these targets will be achieved.
Abstract: This paper presents analyses and forcasts of trends related to road traffic and pedestrian casualties and fatalities in Great Britain. For people killed and seriously injured, these forecasts are based on extrapolation of the absolute of the absolute number of casualties. For casualties classified as slight, forecasts are made of the rate of casualties per 100 million vehicle-kilometers. Forecasts, using autoregressive models, are then compared with government targets and show that at the aggregate level it is unlikely that, for the numbers that are killed or seriously injured, these targets will be achieved.

13 citations


Posted Content
TL;DR: The borderplex econometric forecasting system includes two blocks of transportation equations as discussed by the authors, one for northbound surface traffic across the international bridges from Ciudad Juarez, Mexico and the other dealing with passenger, cargo, and mail flows at El Paso International Airport.
Abstract: El Paso, Texas and Ciudad Juarez, Mexico jointly comprise a large cross- border metropolitan economy. El Paso is an important port-of-entry for international cargo, as well as a key transit point for regional trade flows in the southwestern United States. Reflective of those traits, the borderplex econometric forecasting system includes two blocks of transportation equations. One sub-system models northbound surface traffic across the international bridges from Ciudad Juarez. The other deals with passenger, cargo, and mail flows at El Paso International Airport. To gauge model reliability, an analysis of borderplex transportation variable forecast accuracy relative to a random walk benchmark is completed. Empirical evidence is mixed with respect to model precision for the 1998-2003 sample period for which data are currently available.

13 citations


Journal Article
TL;DR: In this article, the authors developed a method, termed the three-intervention approach, to provide a flexible solution to the problem of dealing with events in the middle of the time series rather than for the most recent observations.
Abstract: Whenever an unusual event disrupts the structural patterns of a time series, one of the aims of a forecaster is to model the effects of that event, with a view to establishing a new basis for forecasting. Intervention analysis has long been the method of choice for such adjustments, but it is often represented as a procedure for dealing with events in the middle of the time series rather than for the most recent observations. This paper develops a method, termed the three-intervention approach, to provide a flexible solution to this problem.

7 citations


Journal Article
TL;DR: In this article, the authors examined the effect of extreme price values on the Fisher and Toernqvist index formulas and concluded that the relative robustness of the two indexes is improved by using Taylor series approximations.
Abstract: This paper examines the effects of extreme price values on the Fisher and Toernqvist index formulas. Using a simple model, the paper first considers the impact of outliers on the unweighted arithmetic, harmonic, and geometric means of a collection of values. Then, under the same model, the effect of a single extremely high or low price on the price index formulas (weighted means) is investigated. Further investigation using Taylor series approximations leads to some general conclusions regarding the relative robustness of the Fisher and Toernqvist indexes. These are illustrated with empirical results based on airfare data from the U.S. Department of Transportation's Origin and Destination Survey.

6 citations


Journal Article
TL;DR: This paper addresses the problem of forecasting the demand for a large number of bus and Metro tickets in the Madrid metropolitan area using monthly data from 1987 to 2002 using both traditional dynamic transfer function causal models as well as new variants of unobserved component models estimated by least squares using automatic identification and linear techniques in the optimization on the frequency domain.
Abstract: This paper addresses the problem of forecasting the demand for a large number of bus and Metro tickets in the Madrid metropolitan area using monthly data from 1987 to 2002. The database is subject to several calendar events, outliers, changing levels of service, and changing seasonality effects that further complicate the analysis and the models' forecasts. The transport agency needs estimates of all effects, as well as a forecast, of the pattern of monthly revenues and use of the transport network. The paper uses both traditional dynamic transfer function causal models as well as new variants of unobserved component models estimated by least squares using automatic identification and linear techniques in the optimization on the frequency domain.

Journal Article
TL;DR: In this article, a comprehensive field study was conducted throughout California to characterize the unregistration rate of light duty vehicles in the state, based on an analysis of more than 98,000 vehicle records.
Abstract: Motivated by the need to develop regional air pollution control strategies, a comprehensive field study was conducted throughout California to characterize the unregistration rate of light duty vehicles in the state. Based on an analysis of more than 98,000 vehicle records, the average unregistered rate was found to be 3.38+/-0.13%. This included vehicles unregistered for a period of less than 3 months (2.4% of the total), vehicles unregistered between 3 months and 2 years (0.95% of the total), and vehicles unregistered for more than 2 years (0.03% of the total). About half of the counties had unregistration rates between 2% and 4%, with most counties' rates below 5%. The unregistered fleet was more heavily weighted toward older vehicles than the registered fleet. Department of Motor Vehicles (DMV) unregistration rates were compared with the field study rates. DMV estimates ranged from 6.2% to 7.5%, which were higher than those obtained in the field study. It was also found that 1.7% of the vehicles identified in the survey were registered outside the state or the country.