Son H.T.,Metropolitan Washington Council of Governments |
Kweon Y.-J.,Virginia Center for Transportation Innovation and Research |
Park B.T.,University of Virginia
Transportation Research Part C: Emerging Technologies | Year: 2011
Typical engineering research on traffic safety focuses on identifying either dangerous locations or contributing factors through a post-crash analysis using aggregated traffic flow data and crash records. A recent development of transportation engineering technologies provides ample opportunities to enhance freeway traffic safety using individual vehicular information. However, little research has been conducted regarding methodologies to utilize and link such technologies to traffic safety analysis. Moreover, traffic safety research has not benefited from the use of hurdle-type models that might treat excessive zeros more properly than zero-inflated models.This study developed a new surrogate measure, unsafe following condition (UFC), to estimate traffic crash likelihood by using individual vehicular information and applied it to basic sections of interstate highways in Virginia. Individual vehicular data and crash data were used in the development of statistical crash prediction models including hurdle models. The results showed that an aggregated UFC measure was effective in predicting traffic crash occurrence, and the hurdle Poisson model outperformed other count data models in a certain case. © 2011 Elsevier Ltd.
Goodall N.J.,Virginia Center for Transportation Innovation and Research
21st World Congress on Intelligent Transport Systems, ITSWC 2014: Reinventing Transportation in Our Connected World | Year: 2014
The act of driving always carries some level of risk. With the introduction of vehicle automation, it is probable that computer-driven vehicles will assess this changing level of risk while driving, and make decisions as to the allowable risk for itself and other road users. In certain situations, an automated vehicle may be forced to select whether to expose itself and its passengers to a small risk in order to protect other road users from an equal or greater amount of cumulative risk. In legal literature, this is known as the duty to act. The moral and legal responsibilities of an automated vehicle to act on the behalf of other road users are explored.
Goodall N.,Virginia Center for Transportation Innovation and Research
Transportation Research Record | Year: 2014
Automated vehicles have received much attention recently, particularly the Defense Advanced Research Projects Agency Urban Challenge vehicles, Google's self-driving cars, and various others from auto manufacturers. These vehicles have the potential to reduce crashes and improve roadway efficiency significantly by automating the responsibilities of the driver. Still, automated vehicles are expected to crash occasionally, even when all sensors, vehicle control components, and algorithms function perfectly. If a human driver is unable to take control in time, a computer will be responsible for precrash behavior. Unlike other automated vehicles, such as aircraft, in which every collision is catastrophic, and unlike guided track systems, which can avoid collisions only in one dimension, automated roadway vehicles can predict various crash trajectory alternatives and select a path with the lowest damage or likelihood of collision. In some situations, the preferred path may be ambiguous. The study reported here investigated automated vehicle crashing and concluded the following: (a) automated vehicles would almost certainly crash, (b) an automated vehicle's decisions that preceded certain crashes had a moral component, and (c) there was no obvious way to encode complex human morals effectively in software. The paper presents a three-phase approach to develop ethical crashing algorithms; the approach consists of a rational approach, an artificial intelligence approach, and a natural language requirement. The phases are theoretical and should be implemented as the technology becomes available.
Winter K.,Virginia Center for Transportation Innovation and Research
Transportation Research Record | Year: 2014
In 2012 the Virginia Department of Transportation (DOT) Research Library conducted a trial of the electronic book database of EBSCO Information Services (EBSCO). The goals of the trial were to determine the level of interest by Virginia DOT employees in accessing e-books, to observe usage patterns and preferences of users in accessing content (EBSCO offered three access options for viewing onscreen or downloading to a personal device), to observe and gather usage statistics during the trial, to survey users on their experience and preferences for e-book devices, and to learn whether patrons used the library's subscriptions to the Books24x7, Knovel, or ASCE databases, which contain onscreen-only e-books. Usage statistics revealed high levels of interest in the e-book database. During the trial, 959 user sessions occurred, with 2,702 searches taking place, 694 e-books read onscreen, and 130 e-books checked out and downloaded to Adobe Digital Editions. Of the 32 respondents to a user satisfaction survey, 93.75% indicated that they would use e-books for their work or professional development; 39% found them somewhat easy or very easy to use; 63% read e-books onscreen; and 37% read from a portable e-book reader. Ninety percent of respondents had used other library full-text databases; 69% had purchased or received an e-book as a gift; and 40% had borrowed an e-book from another library. Research indicates that the EBSCO e-books database is a viable resource for Virginia DOT, provided that the proper content can be licensed and that adequate user education is provided.
Miller J.S.,Virginia Center for Transportation Innovation and Research
Journal of Urban Planning and Development | Year: 2012
Using Virginia's statewide multimodal plan as a case study, this paper outlines an approach to evaluating policies that coordinate the transportation-related efforts of individual agencies. The approach entails identification of seven potentially promising multimodal policies, a case study quantification of impacts for two such policies, and recommended steps for implementation. The case policies evaluated were (1) using cost per kilogram of emissions eliminated to select among eight alternatives and (2) increasing density to reduce CO 2 emissions. The case study demonstrates the feasibility of the outlined approach: Policy 1 increases efficacy by a factor of up to 3.7, and Policy 2 reduces annual CO 2 by 1.5 million metric tons, showing that a comparison of diverse multiagency policies at a sketch planning level is productive. The paper shows that a multimodal planner's role includes explicit identification of assumptions and quantitative methods that enable a comparison of diverse transportation investments given the typical lack of hard data early in the transportation planning process. © 2012 American Society of Civil Engineers.
Kweon Y.-J.,Virginia Center for Transportation Innovation and Research
Journal of Safety Research | Year: 2015
Introduction Virginia saw a 20% reduction in traffic fatalities in 2008, an unprecedented annual reduction since 1950, and safety stakeholders in Virginia were intrigued about what caused such large a reduction and more generally what affects traffic safety from a macroscopic perspective. Method This study attempted to find factors associated with such a reduction using historical data of Virginia. Specifically, the study related 18 factors to seven traffic safety measures. Results In terms of annual changes, the study found that typical crash exposures were not generally associated with the seven measures, while two economic indicators (unemployment rate and U.S. Consumer Price Index [CPI]) were strongly associated with most of them. Conclusions Annual changes in the CPI and unemployment rate account for about half of the annual changes in total and fatal crash counts, respectively. On average, a 1 point increase in CPI and a 1% increase in the unemployment rate are associated with about 2,500 fewer traffic crashes and about 40 fewer fatal crashes annually in Virginia, respectively. © 2015 National Safety Council and Elsevier Ltd. All rights reserved.
Miller J.,Virginia Center for Transportation Innovation and Research
Transportation Research Record | Year: 2011
The Code of Virginia requires that goals relating to jobs-to-housing ratios be considered when projects are selected for the state's transportation program. Because the code does not specify the relative importance of the jobs-housing balance, this paper examines its influence on average jurisdiction commuting times. After regional differences were controlled for, the correlations between shorter commuting times and higher jobs-labor force ratios were from-.71 to-.76 for 1980, 1990, 2000, and 2006 data sets. A 20% increase in the 2000 ratio led to travel times being decreased by 5.3 min (about 18.5% of the statewide average). However, higher ratios may be associated with better transit service or other variables. Correlations alone do not prove causality and are potentially misleading. Consequently, a longitudinal model was developed that predicted changes in commuting time from 1990 to 2000 for each urban Virginia jurisdiction examined. This model estimated that the average impact of a given urban jurisdiction improving its balance by 20% was a reduction in commuting time of 2.2 min (7% of the average urban value). This effect is evident only if several factors, such as the manner in which the region is defined, are carefully controlled for. Otherwise, commuting time is not significantly affected by a change in balance. This finding suggests that the jobs-housing balance has a statistically significant impact on commute-related travel, but that the impact is more modest than a correlation-only analysis would suggest. Modifications necessary to apply this approach at a census tract level of analysis are discussed.
Diefenderfer B.,Virginia Center for Transportation Innovation and Research |
Apeagyei A.,Virginia Center for Transportation Innovation and Research
Transportation Research Record | Year: 2011
Innovative pavement rehabilitation techniques, such as in-place recycling, are becoming more prevalent as highway agencies face an ever-increasing list of pavement maintenance needs and declining or stagnant budgets. Full-depth reclamation (FDR) has been shown to be a cost-effective alternative to deep milling and repaving to rehabilitate deteriorated flexible pavements. The results of previous FDR studies that investigated pavement structural capacity through the use of deflection testing suggest that long-term strength gain may be achieved through curing; however, such a strength gain has not been well quantified. This study documented the in situ structural testing, with a falling weight deflectometer, of three FDR projects constructed in 2008. Deflection testing was performed periodically at the project sites in the first 2 years after reclamation. This study showed that an accurate estimation of the final structural capacity of an FDR project may not feasibly be achieved immediately after the project has been completed and that it could vary greatly depending on the stabilizing agent used. If data from early-age testing are used to calculate design parameters for future projects, the parameters may be too conservative and result in the loss of potential cost savings through the use of unnecessary overlay materials. A cost analysis, based on data collected in this study, showed that these potential cost savings could approach $37,000 per lane mile. Further mechanisticbased studies of the time-dependent structural response of FDR materials are recommended.
Apeagyei A.K.,University of Nottingham |
Diefenderfer B.K.,Virginia Center for Transportation Innovation and Research
Journal of Materials in Civil Engineering | Year: 2013
During the 2011 construction season, the Virginia Department of Transportation (VDOT) completed a major pavement recycling project that marked the first time full-depth reclamation (FDR), cold in-place recycling (CIR), and cold central-plant recycling (CCPR) were used together on a single project on the US interstate system. The CIR and CCPR mixtures were produced by using foamed asphalt and hydraulic cement as the stabilizing agents. After completing the pavement rehabilitation project, engineering properties of the CIR and CCPR mixtures were determined in the laboratory from field-cored specimens. VDOT conducted this study because the agency was considering using a single set of construction specifications for both CIR and CCPR materials if the engineering properties of the two processes were found to be similar. This project offered a unique opportunity to evaluate the two recycling methods by using materials from the same location. Laboratory tests included gradation, binder content, density measurements, indirect tensile strength (ITS) measurements, and resilient modulus (MR) testing. ITS and MR were selected because ITS has traditionally been used for the design and acceptance of recycled mixtures, whereas MR testing offers a step toward mechanistic pavement design in its use in Mechanistic Empirical Pavement Design Guide/DARWin-ME software. The results demonstrated that differences in the engineering properties of the recycled materials, as produced by CIR and CCPR, are not statistically significant. Previously, information was limited in the literature to support designs using pavement recycling, or using CCPR in particular, as another option for highway agencies seeking to use a more environmentally friendly option to rehabilitate pavements. The results presented in this study will also help pavement engineers to better recognize the range of material properties possible with recycled mixtures. © 2013 American Society of Civil Engineers.
Ohlms P.B.,Virginia Center for Transportation Innovation and Research
Transportation Research Record | Year: 2014
Several Virginia localities have used local funding and financing sources to complete major street improvement projects when state or federal funding was not available. Many other localities have combined local funding sources with state or federal funds or both to accelerate a project of importance to the locality. In addition to lessons learned, this research documented through case studies what local governments have been able to accomplish under Virginia statutes that enabled various types of funding and financing tools in addition to the lessons learned. As cities, counties, and towns in Virginia increasingly fund and administer their own roadway projects because of scarce state funds, the experience of Virginia localities becomes more and more transferrable to localities in other states.