bluuebunny/crossref_metadata_2025 huggingface dataset:
Virginia Department of Transportation's Dashboard Performance Measurement and Reporting System: Going the Full Monty
Authors: Gifford Jonathan L. , Carlisle W. Homer
Published: April 2007

State highway administrations (SHAs) often have difficulty completing highway construction projects on time and on budget. Obstacles to successful project completion arise in both planning and active construction. To tackle its costs and schedule problems, the Virginia Department of Transportation (VDOT) in 2002 launched a program called the Dashboard to support its goal of completing all highway construction projects on time and on budget. The agency used existing technology to develop a new web-based performance measurement tool that is designed to report the status of construction projects in all stages of development throughout the state in real time. The tool uses a simple stoplight format to display project status. This new tool is also available to the public through the Dashboard website, launched in March 2003. This study reviews the experience of one SHA in introducing web-based performance measures to its construction program. The study surveys the Dashboard's development, its performance assessment tools, the new forms of accountability it provides, and the experience of VDOT stakeholders in using the Dashboard to achieve the goals of overcoming delay and cost overruns.
Performance Measures for Evaluating Transportation Systems: Stakeholder Perspective
Authors: Falcocchio John C.
Published: April 2007

This study provides a conceptual discussion on the use of performance measures in transportation. Performance measures are needed to assist decision makers in setting priorities, generating financial resources, and allocating funds. They are also required for assessing needs, evaluating system performance, and simply communicating with customers and other stakeholders. To be effective in their purpose, performance measures need to be linked to the goals and objectives that guide transportation decisions. The goals and objectives of transportation systems are inherently an expression of the various stakeholders affected by the system. This includes not only the providers of transportation but also the customers and the communities that house the transportation infrastructure. Therefore, performance measures must include metrics that address the interests of all stakeholders. In response to federal mandates and guidelines of the last decade, much research has been done on this subject, and a lot of information has been disseminated through the various professional media. This study investigates the key aspects of performance measurement, recommends a framework for the application of performance measures, and highlights some of the major issues that need to be resolved in implementing performance measures for decision making.
Calibration of Mechanistic-Empirical Performance Model for Continuously Reinforced Concrete Pavement Punch-Outs
Authors: Rao Chetana , Selezneva Olga , Darter Michael I. , Titus-Glover Leslie , Khazanovich Lev
Published: April 2007

The field calibration of a mechanistic-empirical (M-E) continuously reinforced concrete pavement (CRCP) punch-out prediction model developed under NCHRP Project 1-37A is presented. The model elaborates on the procedure adopted to obtain a national calibration curve for punch-outs, the quantity and extent of data used, and the development of a reliability design procedure based on the calibration data. The model was based on a national database of pavement performance data and advanced mechanistic CRCP structural evaluation and damage accumulation concepts presented in earlier works by other authors. Sensitivity plots are also presented to illustrate how the model responds to changes in key design features considered in the design of CRCP pavements. The model presented can be used to perform M-E design of CRCP pavements.
Mechanistic-Empirical Model to Predict Transverse Joint Faulting
Authors: Khazanovich Lev , Darter Michael I. , Yu H. Thomas
Published: April 2007

A summary is presented of the procedures used to model the effects of transverse joint faulting in the design of jointed plain concrete pavements in the 2002 Design Guide, which was developed under NCHRP Project 1-37A, Development of the 2002 Guide for Design of New and Rehabilitated Pavement Structures. The mechanistic-empirical 2002 guide procedure for rigid pavement design incorporates several key features that are expected to offer significant improvements in design accuracy. The 2002 Design Guide faulting model identifies the differential energy of subgrade deformation as the mechanistic parameter governing joint faulting development. This parameter reflects total pavement flexibility and the level of load transfer efficiency. The 2002 design procedure uses the incremental damage approach. It allows for direct consideration of changes in many factors throughout the entire design period and joint load transfer, including material properties (concrete strength and modulus), seasonal climatic conditions, traffic loadings, subgrade support, and others. Each analysis increment represents a specific combination of the preceding factors over a distinct period (month, season, etc.). The main concepts are described, the model overview presented, and the results of the model calibration provided. Several examples illustrating sensitivity of the 2002 Design Guide faulting prediction to the key design parameters (dowel diameter, slab width and edge support, built-in temperature gradient, and others) are also provided.
Fatigue-Transfer Functions: How Do They Compare?
Authors: Pellinen Terhi K. , Christensen Donald W. , Rowe Geoffrey M. , Sharrock Mark
Published: April 2007

The primary objective of this work was to investigate which of several fatigue-transfer functions predict the failure of mixtures and expected fatigue life most accurately. A second objective was to study existing fatigue models and how they relate to mixture volumetrics. This work was done by employing layered elastic analysis to obtain stresses and strains in the pavement under monthly temperature variations. The calculated tensile strains were then used in the fatigue-transfer functions to predict the fatigue life of the pavement. The mix and distress data were obtained from the WesTrack project. In general, all fatigue-model predictions were poor to fair; even the locally calibrated models (WesTrack) yielded at best 57% accuracy in predicting failing or surviving mixtures. The Strategic Highway Research Program (SHRP) model predicted failures with 72% accuracy; the Asphalt Institute model, 39%; Medani and Molenaar's model, 31%; and the Shell models, 28% accuracy. The SHRP and Asphalt Institute models used suggested field shift factors (FSFs). The fatigue models studied were originally developed for predicting crack initiation in the laboratory. In using these models to predict fatigue life in actual pavements, crack propagation is usually addressed through an empirically determined FSF. An attempt was made to calibrate and recalibrate the fatigue-transfer models using the WesTrack data. This analysis indicates that there is a trade-off in predicting failing or surviving mixtures correctly and the accuracy of the predicting fatigue life compared with the applied traffic loading. Because the nonfailed mixtures were trafficked with only 5 million traffic repetitions, the error associated with the fatigue-life predictions was unknown. Therefore, the overall improvement of the model accuracy through this calibration process cannot be assessed. For several reasons, this study recommends using the Asphalt Institute fatigue-transfer equation in layered elastic analysis to evaluate the fatigue-cracking potential of asphalt mixtures.
Multilayer Boundary-Element Method for Evaluating Top-Down Cracking in Hot-Mix Asphalt Pavements
Authors: Sangpetngam Boonchai , Birgisson Bjorn , Roque Reynaldo
Published: April 2007

Cracking in hot-mix asphalt (HMA) pavements is a major mode of premature failure. Recent work at the University of Florida has led to the development of a new viscoelastic fracture mechanics-based crackgrowth law called the HMA fracture mechanics law, which is capable of fully describing both initiation and propagation of cracks in asphalt mixtures. The successful simulations of crack growth for generalized pavement conditions depend largely on how well the state of stress can be predicted in and around existing cracks in pavements. Previous work has focused on the adaptation of a displacement-discontinuity boundary-element method for predicting stresses in the Superpave® indirect tensile test (IDT), which then were subsequently used to predict the crack initiation and crack growth in simulated IDT tests that used HMA fracture mechanics. The previous displacement-discontinuity boundary-element formulation is here extended into layered materials. Homogeneous layers are stitched together numerically in "welded" contact. The ability of the new numerical formulation to model the effects of temperature-induced stiffness gradients on tensile stresses at the top of two cracked pavement sections in Florida is demonstrated. These pavement sections were modeled with and without temperature-induced stiffness gradients. The introduction of stiffness gradients into the HMA layer is shown to increase the magnitude of tensile stresses at the top of the pavement, which is consistent with previous observations.
Laboratory, Prototype, and In-Service Accelerated Pavement Testing to Model Permanent Deformation
Authors: Sivasubramaniam Sivaranjan , Galal Khaled A. , Noureldin A. Samy , White Thomas D. , Haddock John E.
Published: April 2007

State departments of transportation began using the Superpave® mixture design system and the associated material specifications without long-term validation. This design system is based on the Strategic Highway Research Program performance models, which need further calibration. Within this context, the National Center for Asphalt Technology built and tested several test sections on a full-scale oval test track in Opelika, Alabama. One purpose of the track was to provide validation of the Superpave mixture design method. The test track also provided a unique opportunity to verify the relationships among the PURWheel laboratory wheel tracker, the Indiana Department of Transportation/Purdue University accelerated pavement tester (APT), and the in-service track performance. The verification was accomplished by replicating eight hot-mix asphalt mixtures from the test track in the APT. Samples were also taken from the APT facility and the test track and tested in the PUR-Wheel. A simple power model was used to relate the rutting performance in both the APT and the PURWheel. The results demonstrate a strong correlation between the two and their capabilities to predict the in-service rutting performance at the test track. The effect of initial density and varying in-service temperatures on rutting performance is also presented and explained.
Chaos Theory and Transportation Systems: Instructive Example
Authors: Frazier Christopher , Kockelman Kara M.
Published: April 2007

Chaos theory is used to analyze highly complex systems and thus may be useful for transportation applications. A series of analyses with which to find and exploit chaos is outlined, including time delays and embedding dimensions, Fourier power series, the correlation dimension, the largest Lyapunov exponent, and predictions. As an example, traffic flow data are analyzed and found to be chaotic, although it is shown that this could be the result of high-frequency noise. When used with a low-pass filter, predictions based on chaos theory are shown to have greater predictive power than a nonlinear least-squares method.
How Best to Rank Sites with Promise
Authors: Hauer Ezra , Allery Bryan K. , Kononov Jake , Griffith Michael S.
Published: April 2007

The starting point for a program of local safety improvements is the preparation of a list of sites with promise at which to conduct a detailed engineering study, by which cost-effective projects can be identified. Inclusion on the list depends on the criteria used for ranking sites. Five alternative ranking criteria were compared by the cost-effectiveness of the projects to which they lead. It was found that sites at which most accidents or most severity-weighed accidents are expected lead to most cost-effective projects.
Safety Models for Urban Four-Lane Undivided Road Segments
Authors: Hauer Ezra , Council Forrest M. , Mohammedshah Yusuf
Published: April 2007

A statistical model was estimated for the frequency of nonintersection accidents on urban four-lane undivided roads. The model was based on electronic data from the state of Washington as supplemented by information from videologs. Modeling emphasized the selection of appropriate functional form for each variable. Results point to three principal lessons. First, the fit depends mostly on variables such as annual average daily traffic, number of commercial driveways, and speed limit, and the fit depends only weakly on variables such as vertical alignment or lane and shoulder width. Second, although some results are in line with common beliefs, many are not. This raises the important question of whether or when results of multivariate models can be assumed to indicate cause and effect. Third, relationships that hold for two-lane rural roads may not hold for urban four-lane roads. In particular, on four-lane roads, horizontal curves of moderate degree may be safer than tangent road sections.
New Approach for Including Traffic Volumes in Crash Rate Analysis and Forecasting
Authors: Ivan John N.
Published: April 2007

A critical part of any risk assessment is identifying the appropriate measure of exposure to the risk in question. Incorporating vehicle miles traveled per year into highway crash analysis was an important step forward for identifying truly hazardous locations, as opposed to locations with high volumes but a low number of crashes per vehicle. This exposure measure is now ubiquitous in highway crash reporting, although it has not been proved to be the most accurate representation of highway crash risk. Research results demonstrate that the relationship between traffic volume and crash count is more complex than this and that it relates to quantities such as the distribution of traffic through the day and the types of crashes experienced. A proposed specification for models of crash count incorporates all these considerations in a form that is accessible to most highway crash analysts and permits comparison of crash rates between various highway locations in a way that accounts for the nonlinearity of the crash rate for traffic volume.
Marginal Impacts of Design, Traffic, Weather, and Related Interactions on Roadside Crashes
Authors: Shankar Venky N. , Chayanan Songrit , Sittikariya Sittipan , Shyu Ming-Bang , Juvva Naveen K. , Milton John C.
Published: April 2007

A multivariate model that incorporates the effects of design, traffic, weather, and related interactions with design variables on reported roadside crashes is presented. By providing for a framework that accounts for all measurable effects, the model minimizes the impact of omitted variable effects. Furthermore, the presented framework accounts for partial observability effects that stem from fluctuations in environmental conditions as well as unobserved effects that contribute to heterogeneity in the traffic safety network. A sample of 318 sections 1 mi long was used for the study. These sections represent the state highway network in the state of Washington on the basis of environmental and road classification factors and therefore were used for the collection of detailed precipitation, snowfall, and temperature data in addition to roadway and roadside design and traffic parameters. The resulting model suggests that the marginal impact of weather is both in main effects and interactive form, and that even after controlling for unobserved heterogeneity and partial observability, weather effects play a statistically significant role in roadside crash occurrence. In particular, it was found that in addition to precipitation, average monthly snowfall exceeding 4 in. and interactions between snow depths and horizontal curves were found to have a statistically significant effect on roadside crash frequency probabilities. The marginal effects of these variables were also statistically significant; furthermore, the contribution of weather and related interactions to the likelihood of roadside crash frequencies was approximately 19%, design main effects contributed to 33%, and traffic and design interactions contributed to 6%. Weather interactions with design contributed to approximately 6% of the overall likelihood. Traffic as a main effect contributed 36% to the overall roadside crash likelihood.
Revisiting the Influence of Crash Report Forms on Work Zone Crash Data
Authors: Ullman Gerald L. , Scriba Tracy A.
Published: April 2007

Researchers present an analysis of work zone fatal crashes nationwide to assess possible underreporting due to differences in how information about a work zone crash is captured on standard state crash reporting forms. The possible effects of differences in crash report forms on work zone crash statistics were first identified in the mid-1990s, by using data from the Highway Safety Information System. The influence of different crash report forms on work zone crash data contained in the Fatality Analysis Reporting System (FARS) is examined. An investigation of the data contained in FARS from 1998 to 2000 indicates a statistically significant dependence between the way in which work zones are denoted on a state's crash report form and the percentage of fatalities that are coded as occurring in a work zone. From this analysis, it appears that existing data may underreport the number of fatalities that occur in work zones nationally by as much as 10%.
Assessing Safety Benefits of Variable Speed Limits
Authors: Lee Chris , Hellinga Bruce , Saccomanno Frank
Published: April 2007

A method is suggested for evaluating the effectiveness of variable speed limits in reducing freeway crash potential. The real-time crash prediction model that was developed in earlier studies was used to estimate crash potential for different control strategies of variable speed limits. To mimic realistic responses of drivers to changes in speed limits, a microscopic traffic simulation model was used. The simulation results indicate that total crash potential over the entire freeway segment could be significantly reduced under variable speed limit control with a minimal increase in travel time compared to the fixed speed limit. The methodology for assessing safety benefits of variable speed limits is illustrated, and findings from the experiment that used a simple freeway segment are presented.
Departure-Time Choice and Mode Choice for Nonwork Trips: Alternative Formulations of Joint Model Systems
Authors: Tringides Constantinos A. , Ye Xin , Pendyala Ram M.
Published: April 2007

Modeling travel demand by time of day is gaining increasing attention in the practice of travel demand forecasting. The relationship between time-of-day (departure-time) choice and mode choice for nonwork trips is investigated. Two alternative causal structures are considered: one in which departure-time choice precedes mode choice and a second in which mode choice precedes departure-time choice. These two causal structures are analyzed in a recursive bivariate probit modeling framework that allows random error covariance. The estimation is performed separately for worker and nonworker samples drawn from the 1999 Southeast Florida Regional Household Travel Survey. For workers, model estimation results show that the causal structure in which departure-time choice precedes mode choice performs significantly better. For nonworkers, the reverse causal relationship, in which mode choice precedes departure-time choice, is found to be a more suitable joint modeling structure. These two findings can be reasonably explained from a travel behavior perspective and have important implications for advanced travel demand model development and application.
Activity-Travel Scheduling and Rescheduling Decision Processes: Empirical Estimation of Aurora Model
Authors: Joh Chang-Hyeon , Arentze Theo , Timmermans Harry
Published: April 2007

Predicting short-term activity-travel decisions is high on the research agenda because it constitutes a critical step in assessing the impact of policy decisions on daily traffic flows. The Aurora model was developed for predicting short-term activity scheduling and rescheduling decisions. Previous studies, using numerical simulations, have shown the potential of this model. The results of a study that estimated the model using empirical activity-travel diary data collected in the Amsterdam-Utrecht corridor, in the Netherlands, are reported.
Agent-Based Approach to Travel Demand Modeling: Exploratory Analysis
Authors: Zhang Lei , Levinson David
Published: April 2007

An agent-based travel demand model is developed in which travel demand emerges from the interactions of three types of agents in the transportation system: node, are, and traveler. Simple local rules of agent behaviors are shown to be capable of efficiently solving complicated transportation problems such as trip distribution and traffic assignment. A unique feature of the agent-based model is that it explicitly models the goal, knowledge, searching behavior, and learning ability of related agents. The proposed model distributes trips from origins to destinations in a disaggregate manner and does not require path enumeration or any standard shortest-path algorithm to assign traffic to the links. A sample 10-by-10 grid network is used to facilitate the presentation. The model is also appfied to the Chicago, Illinois, sketch transportation network with nearly 1,000 trip generators and sinks, and possible cafibration procedures are discussed. Agent-based modeling techniques provide a flexible travel forecasting framework that facilitates the prediction of important macroscopic travel patterns from microscopic agent behaviors and hence encourages studies on individual travel behaviors. Future research directions are identified, as is the relationship between the agent-based and activity-based approaches for travel forecasting.
Verifying Accuracy of Regional Models Used in Transportation and Air Quality Planning: Case Study in Sacramento, California, Region
Authors: Rodier Caroline J.
Published: April 2007

Model validation involves the comparison of model forecasts with observed data that are not used in model development to identify model prediction capabilities. In this study, the historical forecasting method of validation is applied to the original version of the Sacramento, California, regional travel demand model (estimated with 1991 data) with observed data obtained in 2000 to test the accuracy of the model over a 9-year period. Two simulations were used to test the model's accuracy and its representation of induced travel. The results indicate that the model's functional forms and parameters overestimate vehicle miles traveled, hours traveled, and hours of delay (by 5.7%, 4.2%, and 17.1%, respectively) and that the model captures about half of estimated induced travel (i.e., elasticity of 0.14 versus 0.22). It appears that if the model were used for air quality analyses in this region, its overestimation of daily vehicle travel would provide a relatively generous margin of error with respect to meeting emissions budgets. However, in environmental impact statements for new highway projects, the model's upward bias would tend to overestimate no-build travel demand and congestion and, thus, the need for the projects. Compared with the no-build alternative, the magnitude of change for the highway alternative would have to be greater than the model error to be considered significantly different.
Weighting Waiting: Evaluating Perception of In-Vehicle Travel Time Under Moving and Stopped Conditions
Authors: Levinson David , Harder Kathleen , Bloomfield John , Winiarczyk Kasia
Published: April 2007

Experiments are described in which traditional computer-administered stated-preference (SP) data are compared with virtual experience SP data to ascertain how people value stopped delay compared with stop-and-go or free-flow traffic. The virtual experience SP experiments were conducted by using a wraparound driving simulator. The two methods produced different results: the traditional computer-assisted SP data suggested that ramp delay is 1.6 to 1.7 times more onerous than delay on freeways, whereas the virtual experience SP data based on the driving simulator suggested that freeway delay is more onerous than ramp delay. Several factors are advanced to explain the differences, including recency, simultaneous versus sequential comparison, awareness of public opinion, intensity of the stop-and-go traffic, and the goal-directed nature of driving in the real world. However, without further research, it is unclear which, if any, of these factors will eventually prove to be the right one. What is clear is that a comparison of the computer-administered SP data with virtual experience SP data produces different results, even though both procedures strive to find the same answers in nominally identical sets of conditions. Because people experience the world subjectively and make decisions on the basis of those subjective experiences, future research should be aimed at better understanding the differences between these subjective methodologies.
TRESIS: Application of Transport and Environmental Strategic Impact Simulator to Sydney, Australia
Authors: Hensher David A. , Stopher Peter R. , Bullock Philip , Ton Tu
Published: April 2007

An integrated microsimulation urban passenger transport model system, TRESIS (Transport and Environmental Strategic Impact Simulator), for evaluating the impact of a large number of interrelated policy instruments on urban travel behavior and the environment is presented. The model system has four integrated modules defining household location and automobile choices, commuter workplace and commuting travel choices, noncommuting travel activity, and worker-distributed work practices. The demand model system, estimated as a set of discrete and continuous choice models, is combined with a set of equilibrating criteria in each of the location, automobile, and commuting markets to predict overall demand for passenger travel in various socioeconomic segments, automobile classes, and geographic locations. The current version was developed to operate at a high level of aggregation for the Sydney, Australia, region, including a 14-zone system with a spiderweb network, and is designed to explore the impacts of broad strategic directions. The model system is embedded within a decision support system to make it an attractive suite of tools for practitioners. The usefulness of TRESIS is illustrated by its application to a major investment option in Northeast Sydney to replace a bottleneck created by the raising of a bridge either with bridge improvements together with improvements to a number of intersections on the roads serving the region or with several possible tunnel options, including different levels of tolls for the tunnels. The application of TRESIS to this case was considered a success: TRESIS provided a comprehensive regional view of the likely outcomes of the alternatives.
Parking Management and Downtown Land Development in Berkeley, California
Authors: Deakin Elizabeth , Bechtel Ally , Crabbe Amber , Archer Mary , Cairns Shannon , Kluter Andrew , Leung Kamshing , Ni Jason
Published: April 2007

Findings are presented from a study of land use, parking, mode choice, and housing and jobs development in downtown Berkeley, California, a medium-sized city with 4 decades of experience with parking management and transit-oriented development. The multiple roles that parking management, including reduced parking requirements and parking pricing, can play in a downtown area are explored, as is the performance of transit-oriented development in smaller cities. Originally developed as a streetcar suburb, Berkeley has long supported high-quality transit, restricted parking, and walking and biking facilities. These practices have resulted in transit, walk, and bike usage far higher than U.S. averages. Nevertheless, in downtown Berkeley, traffic is heavy, parking is full, and concerns about infill development persist. Merchants are also concerned that parking constraints may limit economic development. Surveys of downtown shoppers, workers, and residents show that relatively few drive downtown. Workers and downtown residents make up a large share of downtown commercial enterprises' customers. Residents have intentionally chosen to live in a transit- and pedestrian-friendly area and own and use cars far less often than average. Parking shortages are caused in large part by overtime parking, facilitated by broken meters and by meter feeding by employees. Overall, transit-oriented development has been successful in reducing auto ownership and use, but it is accompanied by tight parking and a certain amount of congestion. Parking enforcement and better use of off-street spaces would relieve the former problem.
Modifiable Areal Units: Problem or Perception in Modeling of Residential Location Choice?
Authors: Guo Jessica Y. , Bhat Chandra R.
Published: April 2007

The sensitivity of spatial analytic results to the way in which the areal units are defined is known as the modifiable areal unit problem (MAUP). Although a general solution to the problem does not yet exist, it has been suggested in the literature that the effects of the problem may be controllable within specific application contexts. This line of inquiry is pursued, and MAUP is addressed in the context of residential location choice modeling. Previous residential location choice analysis typically involved the representation of alternative locations by areal units and the measurement of residential neighborhood characteristics based on these areal units. The vulnerability of such an approach to effects of the MAUP is demonstrated. It is contended that the fundamental issue is the inconsistency between the analyst's definition of areal units and the decision maker's perception of residential neighborhoods. An alternative approach of using a multiscale modeling structure is proposed to mimic the notion of a neighborhood being a hierarchy of residential groupings. The proposed approach allows the spatial extent of choice factors to be determined endogenously. The authors show that the multiscale approach produces richer and more interpretable results than its single scale counterpart.
Decentralization in the Hartford, Connecticut, Metropolitan Region, 1900-2000
Authors: Baird Brian A. , Garrick Norman W.
Published: April 2007

Decentralization, the intrametropolitan movement of people and activity away from dense centers toward less developed suburbs, occurs when dispersive forces are greater than agglomerative forces for any metropolitan area. Two mathematical tools, the regional dispersion index and the Hoover index, are used to measure the movement of population, employment, and retail activity in the Hartford, Connecticut, metropolitan region from 1900 to 2000. The approach used differs from other research in that it does not assume a parametric density function, and it allows decentralization for a multicentered region to be measured. Between 1900 and 1930, population concentrated toward Hartford and other regional centers. The trend reversed around 1940, and for the remainder of the century population decentralized away from both Hartford and regional centers. Economic activity bore the same overall pattern with a lag. The results presented here are consistent with existing theories of decentralization and previous empirical work.
Discrete Choice Model with Structuralized Spatial Effects for Location Analysis
Authors: Miyamoto Kazuaki , Vichiensan Varameth , Shimomura Naoki , Páez Antonio
Published: April 2007

The discrete choice modeling paradigm and in particular the logit model are research topics that have been continuously developed and refined for years in the field of transportation applications. Modeling locational choices, however, differ from modeling transportation choices in that geographically referenced data are used and thereby give specifically spatial choices. A discrete choice model with a systematic specification of the spatial influences in the choice process is presented. The utility function of the model is specified with autoregressive expressions for the deterministic and error components, and the model is evaluated with reference to three alternative models: the standard logit model, a logit model with an autoregressive deterministic term, and the mixed logit model with autoregressive error terms. Two applications are presented: one with simulated data and another with real data for the analysis of location choice in Sendai, Japan. The proposed model shows an improved performance over the three reference models.
Empirical Analysis of Travel and Housing Expenditures in the Greater Toronto, Canada, Area
Authors: Miller Eric J. , Roorda Matthew J. , Haider Murtaza , Mohammadian Abolfazl
Published: April 2007

An empirical investigation of household annual travel and housing expenditures within the greater Toronto area (GTA), Canada, during the period 1986-1996 is presented. The analysis is based on data obtained from local travel surveys, the Canadian census, and the Toronto Real Estate Board, which were combined with transportation network assignment models and travel cost models for the GTA to compute average annual travel and housing expenditures by zone within the region. Key findings include the following: ( a) both travel and housing expenditures tend to increase as one moves away from the city center; ( b) the city of Toronto is much more "efficient" than the surrounding suburban regions in that it has lower combined average travel plus housing expenditures; and ( c) combined housing plus travel expenditures have increased over time within the region (principally because of increased housing expenditures), with the result that GTA households on average spent just over a third of their total income on travel plus housing in 1996.
Transportation Needs, Location Choice, and Perceived Accessibility for Businesses
Authors: Kawamura Kazuya
Published: April 2007

Results from a survey of businesses were analyzed with both descriptive and inferential statistical techniques to investigate how the businesses used the transportation system and how access could affect site location decisions. Most of today's businesses rely heavily on automobiles for all facets of business activities. The only exception is the central business district, where rail transit is heavily used for employee commutes. In addition, more than 90% of the businesses enjoy at least a "somewhat convenient" level of overall access. The perceived level of overall access of a site is statistically correlated with the automobile access and parking but not with the transit access. Analyses indicate that the locational advantage of the sites that are situated close to transportation facilities is minimal. Based on the complex and changing nature of transportation needs uncovered by the survey and on market research, an approach is recommended for inclusion in the transportation planning process.
Use of Intelligent Transportation System Data to Determine Driver Deceleration and Acceleration Behavior
Authors: Haas Robert , Inman Vaughan , Dixson Andrew , Warren Davey
Published: April 2007

Data gathered during a 1996 Intelligent Cruise Control (ICC) Field Operational Test conducted in Michigan and sponsored by NHTSA were analyzed. The purpose was to evaluate driver deceleration and acceleration behavior at stop sign–controlled intersections on rural highways when the driver is unimpeded by a leading vehicle. A novel trip analysis technique was developed to scan the ICC data and identify 299 deceleration and 214 acceleration events at appropriate intersections, and a new mathematical model was used to evaluate those events. This model was used to compute the average rates of deceleration and acceleration for each of these events, and these average rates were compared for different subgroups (e.g., subgroups based on initial speed, final speed, driver gender, and type of street). The results indicate a strong and statistically significant dependence of the deceleration rate on the initial speed but little dependence of these rates on any of the other factors studied. The data indicate that there is a large, random component in the rate of deceleration or acceleration initiated by a driver. This result demonstrates the stochastic nature of driver deceleration and acceleration behavior, which may indicate a need to revisit how deceleration and acceleration rates are treated in common traffic calculations.
Assessing Driving with the Global Positioning System: Effect of Differential Correction
Authors: Porter M. M. , Whitton M. J. , Kriellaars D. J.
Published: April 2007

The Global Positioning System (GPS) offers new opportunities for the assessment of driving. GPS receivers acquire signals from a constellation of satellites to determine position. By logging position and time data, other kinematic parameters, such as velocity and acceleration, can be derived. Until recently, errors were intentionally introduced to reduce positional accuracy. Without the intentional degradation, it may be possible to use uncorrected data for assessment of driving. Differential correction can be performed by using a reference station to correct errors. GPS was used to determine the position, velocity, and acceleration of a vehicle. The main objectives were to compare corrected and uncorrected positions, velocities, and accelerations. Bland–Altman plots showed about two times as much error in the north–south position or velocity than in the east–west position or velocity when uncorrected data were compared with corrected data. Acceleration data showed no systematic differences between corrected and uncorrected data. Most errors between data sets could be explained by satellite geometry, transitions in the satellites being used, and the direction of travel. The greatest effect of differential correction was on position. Most uncorrected velocity and acceleration data would be acceptable for the assessment of driving. However, if positional information is needed, then correction should be done.
Field Study of Gap Acceptance by Left-Turning Drivers
Authors: Davis Gary A. , Swenson Tait
Published: April 2007

To complete a permitted left turn successfully, a driver must first correctly assess the adequacy of a gap in the opposing traffic stream. A tendency to reject physically adequate gaps can lead to needless delay, while acceptance of an inadequate gap can lead to a conflict or a collision with an opposing vehicle. Traditional gap acceptance models use time to arrival as the main (and often only) determinant of whether a driver accepts a gap. Human factors research, however, suggests that drivers have difficulty in accurately perceiving time to arrival and that other variables, such as the distance to an oncoming vehicle, may be more salient. In the present study, video extraction methods were used to collect speed, separation distance, and time-to-arrival data for 74 drivers making permitted left turns at an urban intersection. Logit modeling of the drivers’ gap choices indicated that distance to the opposing vehicle was the variable most reliably associated with gap selection, with speed and time to arrival making weaker contributions. All of the best models implied that the probability that a driver will accept a gap of a given duration increases as the speed of the oncoming vehicle increases.
Impact of Video Advertising on Driver Fixation Patterns
Authors: Smiley Alison , Smahel Thomas , Eizenman Moshe
Published: April 2007

To assess driver distraction because of video advertising signs, eye fixation data were collected from subjects who passed four video advertising signs, three at downtown intersections and one on an urban expressway. On average, drivers glanced at the signs on 45% of the occasions on which the signs were present. When drivers looked, they made 1.9 glances, on average, with an average duration per glance of 0.48 s. The distribution of eye fixations on intersection approaches where video signs were visible was compared with that on approaches on which video signs were not visible. No significant differences were found in the number of glances made at traffic signals or street signs. On the video approach, a greater proportion of glances were made at the speedometer and rearview mirrors. Glances were made at short headways and occasionally in unsafe circumstances. In the downtown area, glances at static commercial signs were made at larger angles and at shorter headways than was the case for video signs. A comparison of the results with those of other studies showed that video signs were less likely to be looked at than traffic signs (about half the time versus virtually every time, respectively) and that individual average glance durations and total durations were similar to those found for traffic signs in rural environments. These results apply to particular video signs in particular environments. Another on-road study indicates that a video sign on a curve that is close to the line of sight and visible for an extensive period is particularly distracting.
Effects of Passenger and Cellular Phone Conversations on Driver Distraction
Authors: Laberge Jason , Scialfa Charles (Chip) , White Cale , Caird Jeff
Published: April 2007

The distracting effects of a simulated conversation with passengers and those of a conversation over a hands-free cellular phone were compared. The conversation was also analyzed to determine if passengers modulated their conversations as driving demands changed. Eighty participants were randomly assigned to one of three conditions: driving alone, driving with a passenger, and driving with a cellular phone. Drivers drove through residential and urban traffic environments in a fixed-based driving simulator in which a variety of events occurred, such as pedestrian activity, oncoming vehicles, and intersections. The results indicated that lane and speed maintenance were influenced by increased driving demands. Response times to a pedestrian incursion increased when the driver was driving and talking compared with those detected when the driver was not talking at all. Contrary to what some researchers have assumed, there was little practical evidence that passengers adjusted their conversations to changes in the traffic environment. The workload was rated higher when the driver was driving and talking and was also rated higher by drivers than by nondrivers. The discussion focuses on future research and implications for driver safety and training.
Back Disorder and Ergonomic Survey Among North American Railroad Engineers
Authors: Johanning Eckardt , Landsbergis Paul , Fischer Siegfried , Luhrman Raymond
Published: April 2007

Railroad engineers are exposed to whole-body vibration and sedentary postural stress while operating locomotives. A self-administered 200-item health survey was distributed nationwide to a randomly selected group of active railroad engineers ( n = 2,546) and a comparison group (civil engineers; n = 798). The response rate was 47% for railroad engineers ( n = 1,195) and 41% for controls ( n = 323). Back pain lasting more than 1 day per week within the past year was reported by 75% of railroad engineers, whereas it was reported by 41% of the controls [crude odds ratio (OR) = 4.32; 95% confidence interval (CI) = 3.31 to 5.64]. In a logistic regression model, by adjusting for age, gender, race, smoking, and non-job-related vibration exposure, the adjusted OR was 4.24 (95% CI = 3.20 to 5.62). The adjusted OR for sciatic pain (a back condition with neurological complications) was 2.17 (95% CI = 1.33 to 3.56). The rates of neck and shoulder problems were also higher among railroad engineers. In conclusion, the survey suggests that railroad engineers have higher rates of back disorders and other health problems than the controls, who have lower levels of exposure to shock and vibration and fewer ergonomic complaints. Better vibration control and ergonomics are probably important factors in preventing back disorders among railroad engineers.
Real-Time Environmental Visualization with Web3D
Authors: Huang Bo , Li Hongga , Chandramouli Magesh
Published: April 2007

A project that uses a real-time web-based visualization approach for environmental modeling by integrating a geographic information system (GIS) with virtual reality modeling language and Java was explored. A new technique, the server push approach, is developed to “push” only up-to-date data from the remote server to the client and consequently reduce network traffic across the Internet. A fat client model is adopted to host the GIS environmental data model on the Internet. Online data hosting boosts interactivity, swift and transparent communication, user access, and cost-efficiency. These data can be analyzed online by using a GIS and the numerical functions embedded in Web3D-based Java applets. The spatially distributed GIS-based model used to generate data on catchment hydrology and runoff (the topography-based hydrological model; TOPMODEL) accepts incoming information and facilitates real-time simulation.
Stringline Effects on Concrete Pavement Construction
Authors: Rasmussen Robert Otto , Karamihas Steven M. , Cape William R. , Chang George K. , Guntert Ronald M.
Published: April 2007

Modern concrete pavement construction typically uses slipform paving equipment, especially on major highways and airfields. This equipment commonly is guided by its sensing of a stringline set in advance by an engineering survey. Although use of stringline guidance has improved the smoothness of pavement, some limitations of this technique are known to exist. Three of these limitations are explored in detail. The effects on concrete pavement smoothness from the chord effect, the sag effect, and random survey error are described both conceptually and analytically. Of these three effects, random error introduced during the engineering survey is found to be the most pronounced. Furthermore, this analysis shows that contradictions exist within what is sometimes considered good practice for concrete pavement construction; the belief that improved smoothness can be obtained by simply using shorter spacing of the stringline stakes is not always correct. In fact, it is demonstrated that optimum stringline spacing can be realized by recognizing each of the effects described, including the associated costs of mitigation.
Active Crack Control for Continuously Reinforced Concrete Pavements
Authors: Kohler Erwin , Roesler Jeffery
Published: April 2007

Continuously reinforced concrete pavements (CRCP) traditionally have been allowed to crack naturally. This type of passive crack control has resulted in nonuniform crack spacing, which has led to premature distress development. Although the accuracy of the mean crack spacing prediction has greatly improved, punchout and spalling distresses on CRCP have been found to occur primarily at locations of small crack spacing, divided cracks, cluster cracks, and Y-cracks. The findings of previous research results on active crack control for CRCP in Texas are presented, along with the results from recent full-scale test sections constructed at the University of Illinois. The active crack control process used two systems: automated tape insertion and early entry saw cut. Active crack control was found to eliminate crack meandering, Y-cracks, divided cracks, and cluster cracking. The active crack control sections also propagated 90% of the cracks in the first month after construction, whereas the passive crack sections took 18 months to reach a similar number of cracks. Both active and passive cracks propagated only in the winter months. Crack opening measurements showed that active crack control resulted in slightly smaller movements relative to the natural crack sections. By using active crack control on CRCP, more uniform, straighter, and early-age transverse cracks result, which will increase the expected service life of CRCP.