bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating New Transportation Technologies with Tiered Criteria: Rail Case Study Approach
Authors: Miller John S.
Published: April 2007

New transportation technologies, such as magnetic levitation (maglev), offer promise and risk as they move through the successive stages of research, development, demonstration, and deployment. The Virginia General Assembly’s initial financial contributions to a low-speed, 3,400-ft (1,037-m), maglev-based people mover being constructed by the private sector illustrate the opportunities for potential reward and failure. Requests for additional funding to refine and deploy the prototype motivated the Virginia Department of Transportation (VDOT) to seek a structured decision process. VDOT did not want to spend taxpayers’ money frivolously on a technology not yet in commercial service anywhere in the world, or to impede an affordable, new approach that could effectively reduce congestion. To help VDOT evaluate the prototype maglev system, the Virginia Transportation Research Council developed a set of broad-based performance measures applicable to different rail systems including maglev. This study links the standards of credibility, reliability, performance, safety, and cost to the types of detailed performance measures that should be obtained during an operational test. A strong link between technical data and broad-based metrics enables persons of disparate backgrounds to jointly evaluate the results of a new technology and establish reasonable expectations for what that technology should accomplish. This is a better approach than making decisions on the sole basis of preconceived notions of whether a technology is good or bad. These performance measures, therefore, offer a promising method for evaluating new transportation products. Although the concept of technology-blind criteria has received renewed emphasis over the past decade, this study highlights challenges and suggestions for using such criteria in a relatively political setting, which is less than ideal but common.
Policy Versus the Market: Transportation’s Battleground
Authors: Deen Thomas B.
Published: April 2007

The American transportation system is large, pervasive, decentralized, and an enormously important part of the economy. The public demands that it be efficient, available, reliable, and safe, and expects the government to ensure that these demands are met. For more than two decades we have also sought to reduce its highway dominance, reduce its consumption of energy, and reduce its negative environmental impacts. The fact that many of these efforts have failed raises the question of why the system seems so resistant to policy intervention. Americans believe that industry, including transportation, should be left to the private sector, subject to market principles, and competitive economics. Despite this, transportation has some special characteristics that have resulted in government's ownership of most of the fixed infrastructure, while the manufacture, ownership, and operation of vehicles (the big expense) are left in private hands. Government charges the private sector for the use of its facilities to maximize productivity and deal fairly with users. But determining these charges is complex and is necessarily the product of philosophy as well as sophisticated costing. It is the source of endless squabbling between modes and special interests. This tension-combined with the huge size of the system, the dominance of the private sector, its decentralization, and other factors-makes government intervention into the system on behalf of societal goals often challenging and sometimes unsuccessful.
Results of Driver Survey Investigating Intersection Queue Jumps
Authors: Burris Mark W. , Byers Margie W. , Swenson Chris R.
Published: April 2007

An intersection queue jump (IQJ) can be defined as an elevated ramp or side lane that can be used by motorists normally stopped in traffic at an intersection to bypass the intersection and traffic congestion. The feasibility and ultimately the success of an IQJ depend on several factors, including the traveling public's willingness to use the queue jump. Road pricing theory and the results of a recent stated preference survey to gauge the willingness of drivers in Lee County, Florida, to pay for the use of an IQJ are examined. It was found that approximately 54% of surveyed drivers indicated a willingness to pay at least a small amount to use the IQJ. The appropriate toll level is likely between $0.25 and $0.40 per trip. Using the survey data, it was also found that the respondents' stated value of travel-time savings was approximately $5.21 per hour. The toll-price elasticity of IQJ was approximately −0.2 when the toll increased from $0.10 to $0.25, and approximately −0.4 when the toll increased from $0.25 to $0.50. Using logit modeling, it was found that certain driver characteristics, including being married with children and having a household income of less than $16,000 or more than $75,000, increased the likelihood that a driver would use the IQJ. Other characteristics, including being on a shopping trip, being more than 65 years old, and being male, decreased the likelihood that the driver would use the IQJ.
Acceptability of Transport Pricing Measures Among Public and Professionals in Europe
Authors: Link Heike , Polak John
Published: April 2007

Transport pricing has been an actively debated topic in the European Union for a number of years. This debate has been stimulated both by the European Commission policy and by a multitude of national policy initiatives. A central theme in this debate is the issue of the public and (linked to this) political acceptability of pricing measures. Indeed, concerns about acceptability now constitute the most significant single barrier to implementation, especially in the road transport sector. The results of recent research undertaken on behalf of the European Commission into the acceptability of different transport pricing measures to professionals and citizens and the factors influencing their acceptability are reported.
Dynamic Value Pricing on I-15 in San Diego: Impact on Travel Time and Its Reliability
Authors: Supernak Janusz , Kaschade Christine , Steffey Duane
Published: April 2007

Selected results are presented of the Traffic Study, one of 12 studies conducted by San Diego State University for the I-15 Congestion (Value) Pricing Project in San Diego, a 3-year demonstration. The focus is on the project's impact on travel times and their distribution on both the main lanes and the express lanes of I-15 for both ExpressPass and FasTrak phases of the project. Specifically addressed is the issue of reliability of on-time arrival enjoyed by the FasTrak subscribers and the high variability of travel times for the I-15 travelers who use only main lanes of I-15 for their commute. Examination of the ramp and freeway delays shows that in the worst-case scenario, FasTrak subscribers who use express lanes can save up to 20 min avoiding delay on the I-15 main lanes. This finding agrees with the drivers’ perceptions about their time savings when using FasTrak. Travel-time changes during the duration of the project also are examined. There were substantial year-to-year changes in travel times along the I-15 main lanes and the I-8 lanes used as control. The travel-time profile along the I-15 main lanes differed significantly from the profile along I-8, the control corridor, in both a.m. and p.m. peak periods.
Evaluation of Toll Options with Quick-Response Analysis Tools: Case Study of the Capital Beltway
Authors: DeCorla-Souza Patrick
Published: April 2007

Analysis tools in current use in transportation decision-making processes are not well suited for evaluating toll highway alternatives against more traditional free highway alternatives. How existing analysis tools might be used in evaluating toll options was examined. A case study demonstrates that relatively simple analytical procedures may be used to estimate the impact of pricing alternatives and to generate information for use by local decision makers. The case study also demonstrates that pricing alternatives often can accomplish the purpose of a major highway project more efficiently and more effectively than conventional alternatives that exclude pricing, while generating revenue to support bonds for project construction or to fund improved transit and paratransit services. With toll revenue to back bonds, project delays due to constrained funding can be avoided, and the public can be provided with superior mobility earlier and at lower public cost.
Industrial Diversity, Economic Development, and Highway Investment in Louisiana
Authors: Horst Toni , Moore Anne
Published: April 2007

Studies examining the link between transportation investment and economic development typically measure development by job and income gains or productivity growth. For some economies, however, stabilization or diversification of the existing economic base is a desired outcome that needs to be attained even as traditional development goals are targeted. This is particularly the case for the rural and persistently poor economies of the Mississippi River Delta region of the United States. Small populations and remoteness are especially acute, constraining the number and kind of employers who will locate or expand in these markets, limiting the job opportunities for residents, and perpetuating the out-migration of younger and better-educated workers. Using information from the Economic Development Highways Initiative that was directed by Congress and administered by the Federal Highway Administration, this study analyzes the linkage between highway investment and economic diversification in Louisiana to evaluate whether this type of investment can play a role in stabilizing these weak and deteriorating economies. Using two-digit employment data, a summary index of industrial diversity is calculated for each parish (county) in Louisiana for the period 1977 to 1997. This diversity index is then correlated with the type of road present in the parish-Interstate, divided highway, and major thoroughfare. Results indicate that highway quality is associated with industrial diversification, even controlling for the size of the economy.
Transportation and Tourism in Hawaii: Computable General Equilibrium Model
Authors: Konan Demise Eby , Kim Karl
Published: April 2007

Using data from the state of Hawaii input-output (I-O) table, the economic impact of the transportation sector in Hawaii was described, modeled, and forecast under a number of alternative scenarios. Transportation is compared with the key economic sectors in the state in output, exports, household consumption, visitor spending, number of employees, and compensation of employees. Next, the overall transportation sector was disaggregated into key activities and functions to present a more complete picture of the important role of transportation in Hawaii. A computable general equilibrium (CGE) model of the economy with a special focus on transportation is developed. Because tourism is the state's leading sector, the effects of both an increase and a decrease in visitor expenditures were modeled. Both measuring the economic importance of transportation in Hawaii and estimating probable consequences of potential economic changes are of interest. The visitor industry dominates Hawaii's economy, with small increases in visitor expenditures contributing significantly to the gross state product. Transportation industries, along with restaurant and accommodation services, account for a disproportionately large share of this growth. Key residential transportation sectors (transit and motor vehicles) contract in response to cost increases generated by a growth in visitor demand. The use of the I-O table and CGE modeling provides a useful analytical and planning tool for evaluating economic scenarios within a region such as Hawaii. The increased availability of both data sets and new modeling techniques offers opportunities to planners, engineers, and transportation policy makers.
Modeling Traffic Crash-Flow Relationships for Intersections: Dispersion Parameter, Functional Form, and Bayes Versus Empirical Bayes Methods
Authors: Miaou Shaw-Pin , Lord Dominique
Published: April 2007

Statistical relationships between traffic crashes and traffic flows at roadway intersections have been extensively modeled and evaluated in recent years. The underlying assumptions adopted in the popular models for intersections are challenged. First, the assumption that the dispersion parameter is a fixed parameter across sites and time periods is challenged. Second, the mathematical limitations of some functional forms used in these models, particularly their properties at the boundaries, are examined. It is also demonstrated that, for a given data set, a large number of plausible functional forms with almost the same overall statistical goodness of fit (GOF) is possible, and an alternative class of logical formulations that may enable a richer interpretation of the data is introduced. A comparison of site estimates from the empirical Bayes and full Bayes methods is also presented. All discussions and comparisons are illustrated with a set of data collected for an urban four-legged signalized intersection in Toronto, Ontario, Canada, from 1990 to 1995. In discussing functional forms, the need for some goodness-of-logic measures, in addition to the GOF measure, is emphasized and demonstrated. Finally, analysts are advised to be mindful of the underlying assumptions adopted in the popular models, especially the assumption that the dispersion parameter is a fixed parameter, and the limitations of the functional forms used. Promising directions in which this study may be extended are also discussed.
Level of Service of Safety: Conceptual Blueprint and Analytical Framework
Authors: Kononov Jake , Allery Bryan
Published: April 2007

While some initial and significant progress has been made in the development of a highway safety manual, much remains to be done in the areas of conceptual development and the diagnostics of safety problems. The concept of level of service of safety (LOSS) in the framework of safety performance function is introduced, and the problem of diagnostics is addressed. LOSS reflects how the roadway segment is performing in regard to its expected accident frequency and severity at a specific level of annual average daily traffic. It provides a comparison of accident frequency and severity only with the expected norms; it does not, however, provide any information related to the nature of the safety problem itself. If the safety problem is present, LOSS will describe only its magnitude. The nature of the problem is determined through diagnostic analysis by direct diagnostics and pattern recognition techniques, which are also discussed.
Empirical Investigation of Interactive Highway Safety Design Model Accident Prediction Algorithm: Rural Intersections
Authors: Lyon Craig , Oh Jutaek , Persaud Bhagwant , Washington Simon , Bared Joe
Published: April 2007

One major gap in transportation system safety management is the ability to assess the safety ramifications of design changes for both new road projects and modifications to existing roads. To fulfill this need, FHWA and its many partners are developing a safety forecasting tool, the Interactive Highway Safety Design Model (IHSDM). The tool will be used by roadway design engineers, safety analysts, and planners throughout the United States. As such, the statistical models embedded in IHSDM will need to be able to forecast safety impacts under a wide range of roadway configurations and environmental conditions for a wide range of driver populations and will need to be able to capture elements of driving risk across states. One of the IHSDM algorithms developed by FHWA and its contractors is for forecasting accidents on rural road segments and rural intersections. The methodological approach is to use predictive models for specific base conditions, with traffic volume information as the sole explanatory variable for crashes, and then to apply regional or state calibration factors and accident modification factors (AMFs) to estimate the impact on accidents of geometric characteristics that differ from the base model conditions. In the majority of past approaches, AMFs are derived from parameter estimates associated with the explanatory variables. A recent study for FHWA used a multistate database to examine in detail the use of the algorithm with the base model-AMF approach and explored alternative base model forms as well as the use of full models that included nontraffic-related variables and other approaches to estimate AMFs. That research effort is reported. The results support the IHSDM methodology.
Profiling of High-Frequency Accident Locations by Use of Association Rules
Authors: Geurts Karolien , Wets Geert , Brijs Tom , Vanhoof Koen
Published: April 2007

In Belgium, traffic safety is one of the government's highest priorities. The identification and profiling of black spots and black zones (geographical locations with high concentrations of traffic accidents) in terms of accident-related data and location characteristics must provide new insights into the complexity and causes of road accidents, which, in turn, provide valuable input for governmental actions. Association rules were used to identify accident-related circumstances that frequently occur together at high-frequency accident locations. Furthermore, these patterns were analyzed and compared with frequently occurring accident-related characteristics at low-frequency accident locations. The strength of this approach lies with the identification of relevant variables that make a strong contribution toward obtaining a better understanding of accident circumstances and the discerning of descriptive accident patterns from more discriminating accident circumstances to profile black spots and black zones. This data-mining algorithm is particularly useful in the context of large data sets for road accidents, since data mining can be described as the extraction of information from large amounts of data. The results showed that human and behavioral aspects are of great importance in the analysis of frequently occurring accident patterns. These factors play an important role in identifying traffic safety problems in general. However, the accident characteristics that were the most discriminating between high-frequency and low-frequency accident locations are mainly related to infrastructure and location.
Configuration Analysis of Two-Vehicle Rear-End Crashes
Authors: Abdel-Aty Mohamed A. , Abdelwahab Hassan T.
Published: April 2007

Light truck vehicles (LTVs), including light-duty trucks, vans, minivans, and sport-utility vehicles, are generally larger than common passenger cars and are able to take on additional tasks. LTVs usually ride higher than other common passenger cars, which likely affects the visibility of passenger car drivers. The role of LTVs in rear-end crashes was investigated. The use of statistical models of unordered multiple categories was attempted, including multinomial logit (MNL), heteroscedastic extreme value (HEV), and bivariate probit (BVP) models. Four different rear-end crash configurations (lead and following vehicles) were defined on the basis of the type of the two vehicles involved (LTV or regular passenger car). General Estimates System (GES 2000) traffic crash data were used to calibrate the three suggested models (the MNL, HEV, and BVP models). Modeling results showed that there are sight distance and discomfort problems when a driver in a regular passenger car is driving behind an LTV. The probability of a rear-end crash involving a regular passenger car striking an LTV increases when the driver of the following vehicle is distracted. The analysis also illustrates that the probability of a regular car striking an LTV increases when the driver of the following vehicle has an obscured view.
Are SUVs “Supremely Unsafe Vehicles”?: Analysis of Rollovers and Injuries with Sport Utility Vehicles
Authors: Khattak Asad J. , Rocha Marta
Published: April 2007

With increasing speed limits and more light trucks penetrating the market, concern over their rollover risk is growing. In particular, the general public and automobile manufacturers would like to know if the increasingly popular sport utility vehicles (SUVs) are indeed safer than other vehicle platforms. The influences of various vehicle platforms on rollovers and driver injuries were investigated. Specifically, ( a) the rollover intensities of SUVs vis-à-vis those of other vehicle types in single-vehicle crashes and ( b) the severity of the resulting driver injury were explored. Data from a good-quality federally maintained database were used for crash analysis. The database contains a relatively clean stratified sample of police-reported tow-away crashes nationwide, and it contains detailed information about vehicle rollovers. Rollover intensity, captured by the number of quarter turns, was investigated by using weighted negative binomial models; injury severity, measured on the abbreviated injury scale, was examined by using weighted ordered logit models. New insights emerged about the factors that increase rollover intensity and injury severity. As expected, SUVs are more likely to roll over and therefore injure their occupant drivers more severely. However, SUVs also protect their drivers during collisions because of their greater crashworthiness. In fact, the SUV crashworthiness effect exceeds the rollover effect, on average. The implications of these findings are discussed.
Study of Farm Vehicle Crashes in North Carolina
Authors: Lacy J.K. , Hunter William , Huang Herman
Published: April 2007

Crashes involving farm vehicles on the public roads in North Carolina have remained basically the same for 30 years. However, as the population continues to increase, some farmland near urban centers is developed into residential neighborhoods, which increases the likelihood that a farm vehicle will encounter other vehicles. This study provides a descriptive analysis of more than 3,000 farm vehicle crashes reported in North Carolina from 1991 through 1999. The study also includes a summary of 69 clinical examinations of farm vehicle crash sites and provides recommendations to decrease the frequencies of these crashes. A primary finding of the study is that rear-end and left-turn crashes make up more than 50% of the crashes. Other findings include the fact that the roadway and operation characteristics on primary highways are noticeably different from those on secondary roads. Because of the relatively small number of annual events and the potential effects on the agricultural industry, countermeasures need to be targeted. Recommendations include the following: a learner’s permit to operate a farm vehicle on the public highways should be required, all farm vehicles operating on public highways should be required to display the “Slow Moving Vehicle” emblem, the costs and benefits of requiring all new farm vehicles to have flashing beacons permanently fixed to the vehicle should be researched, and brochures that inform farmers on specific strategies to reduce farm vehicle crashes should be developed and distributed. These strategies include information on how to perform a wide two-point left turn and voluntary adoption of more stringent standards for their vehicle operators and equipment.
Bus Rapid Transit: Synthesis of Case Studies
Authors: Levinson Herbert S. , Zimmerman Samuel , Clinger Jennifer , Gast James
Published: April 2007

Bus rapid transit systems have grown in popularity in recent years. Spurred by federal initiatives, the spiraling cost of rail transit, and market realities, a growing number of cities have installed or are planning bus rapid transit (BRT). There is a synthesis of current experience, drawing on ongoing research conducted in a project for TCRP. The nature of BRT is described; where it operates; key features, such as running ways, stations, vehicles, intelligent transportation systems, and service patterns; performance in ridership, travel times, and land development; and the emerging implications for new systems. It is important to match transit markets to rights-of-way; achieve benefits in speed, reliability, and identity; minimize adverse impacts to street traffic, property access, and pedestrians; and obtain community support throughout an open planning process.
Data Challenges in Development of a Regional Assignment: Simulation Model to Evaluate Transit Signal Priority in Chicago
Authors: Chang Elaine , Ziliaskopoulos Athanasios
Published: April 2007

Recent years have seen major advances in the field of simulation-based dynamic traffic assignment (DTA), resulting in the development of DTA software packages capable of simulating real-world networks. However, simulation of such networks requires not only sophisticated algorithms and software, but also large and detailed data sets. Although algorithmic and software-related issues in large-scale DTA development have received considerable research attention, there is little reported experience with the data-related challenges in real-world applications of large-scale simulation models. There were challenges in using a large-scale simulation-assignment model for evaluation of transit signal priority (TSP) in the Chicago, Illinois, region. Relevant impacts of TSP are described, to provide a framework for comparing simulation approaches and data sets. The practice of using microsimulation models to evaluate TSP impacts on short corridors is compared with that of using regional assignment-simulation approaches, with an emphasis on TSP impacts that can be captured and observed with each one of the approaches. The data sets used for the regional Chicago TSP study are then described, along with assumptions made to adapt each data set to the task of regional time-dependent simulation.
Evaluation of Service Reliability Impacts of Traffic Signal Priority Strategies for Bus Transit
Authors: Chang James , Collura John , Dion François , Rakha Hesham
Published: April 2007

Recent progress in technology has facilitated the design, testing, and deployment of traffic signal priority strategies for transit buses. However, a clear consensus has not emerged about the evaluation of these strategies. Each agency implementing these strategies can have differing goals, and there are often conflicting issues, needs, and concerns among the various stakeholders. To assist in the evaluation of such strategies an evaluation framework and plan was developed that provides a systematic method to assess potential impacts. The use of this framework and plan is illustrated on the Columbia Pike corridor in Arlington, Virginia, with the use of the INTEGRATION simulation package. In building on previous efforts on this corridor, the work presents a method of simulating conditional priority to late buses to investigate the impacts of priority on service reliability. By using the measures developed in this research, a conditional priority strategy designed to increase bus service reliability without resulting in severe traffic-related impacts was tested. Simulation results indicated statistically significant improvements of 3.2% in bus service reliability and 0.9% for bus efficiency, whereas negative traffic-related impacts were found in the form of increased overall delay to the corridor of 1.0% on a vehicle basis or 0.6% on a person basis. These results are also comparable and consistent with the results of other research.
Fuel Consumption of Heavy-Duty Trucks: Potential Effect of Future Technologies for Improving Energy Efficiency and Emissions
Authors: Saricks Chris , Vyas Anant D. , Stodolsky Frank , Maples John D.
Published: April 2007

The results of an analysis of heavy-duty truck (Classes 2b through 8) technologies conducted to support the Energy Information Administration’s long-term projections for energy use are summarized. Several technology options that have the potential to improve the fuel economy and emissions characteristics of heavy-duty trucks are included in the analysis. The technologies are grouped as those that enhance fuel economy and those that improve emissions. Each technology’s potential impact on the fuel economy of heavy-duty trucks is estimated. A rough cost projection is also presented. The extent of technology penetration is estimated on the basis of truck data analyses and technical judgment.
Analysis of Alternative Forms of Automotive Fuel Economy Standards for the United States
Authors: Greene David L. , Hopson Janet L.
Published: April 2007

Nations around the world have used fuel economy standards, voluntary or mandatory, to control greenhouse gas emissions and oil consumption. Although the literature on fuel economy standards is extensive, little attention has been paid to analyzing the efficiency and equity of alternative forms and levels of standards. A mathematical programming model is developed and applied to measuring the effects of alternative fuel economy regulations in terms of economic efficiency and differential impacts on manufacturers in the United States. Fuel economy improvements of 20% to 33% would appear to provide net economic benefits to U.S. consumers. Unfortunately, none of the alternatives tested is clearly more equitable than the others. The uniform percentage increase (UPI) and corporate average fuel economy (CAFE) metrics disadvantage different sets of manufacturers. An industrywide, voluntary fuel economy standard [such as that of the European Union or l’Association des Constructeurs Européens d’Automobiles (European Car Manufacturers’ Association)] has the potential to be most economically efficient and to avoid transfer payments among manufacturers as well. A weight-based metric would be more expensive than CAFE or UPI metrics for the same level of fuel economy increase but might be less likely to restrict manufacturers’ future marketing options. The analysis has many limitations that should be addressed in future research.
Regulating Transportation in New Nonattainment Areas Under the 8-Hour Ozone Standard
Authors: Makler Jonathan , Howitt Arnold M.
Published: April 2007

The U.S. Environmental Protection Agency promulgated a new National Ambient Air Quality Standard for ground-level ozone in July 1997, beginning a process that (after some litigation-induced delays) will soon lead to the designation of new nonattainment areas that will be subject to the transportation conformity regulations. The history of the 8-h ozone standard is reviewed, the process of designating the boundaries of new nonattainment areas is described, and the types and geographic locations of the new nonattainment areas are suggested. Drawing on previous research, the institutional challenges that will face the new and expanded nonattainment areas are explored. The experiences of Georgia, North Carolina, and Oklahoma in preparing for implementation of the new standard are presented. Finally, several recommendations for transportation agencies involved in implementing the new standards are given.
Vehicle Activity–Based Procedure for Estimating Emissions of Heavy-Duty Vehicles
Authors: Weinblatt Herbert , Dulla Robert G. , Clark Nigel N.
Published: April 2007

A new procedure for estimating the emissions of heavy-duty vehicles (HDVs) is presented. This procedure combines second-by-second data on actual in-use speed and acceleration of HDVs with data on average emissions rates of HDVs operating at corresponding speeds and acceleration rates. The initial implementation of this procedure used a limited amount of newly collected emissions data and a somewhat larger amount of previously collected HDV activity data. Validation tests provide a reasonable level of confidence about the validity of the nitrogen oxide (NOx) emissions factors produced using this initial implementation. However, these tests also indicate that the small amount of emissions data used in the initial implementation is insufficient to produce meaningful estimates of emissions factors for carbon monoxide or particulate matter. The research, the procedure that was developed, the validation tests, the results for NOx emissions, and NOx speed correction factors derived from these results are briefly described. The speed correction factors are of particular interest. The minimum values for these factors occur at speeds higher than those currently used by the U.S. Environmental Protection Agency, and the factors grow more slowly at higher speeds than do the factors generated by MOBILE.
Transitions in Light-Duty Vehicle Transportation: Alternative-Fuel and Hybrid Vehicles and Learning
Authors: Leiby Paul N. , Rubin Jonathan
Published: April 2007

New vehicle technologies and alternative fuels are believed to be key factors in increasing energy security, improving air quality, and reducing greenhouse gas emissions. Proposed legislation (Energy Policy Act of 2003) would extend significant tax credits to fuel-cell vehicles and promote hybrid vehicle use through credits toward other federal requirements (i.e., for alternative fuel use). Analyses using single-period equilibrium models and multiple-period scenario analyses are often used to demonstrate the feasibility of technology to attain policy goals. These analyses typically assume mature markets, large-scale vehicle production, and the widespread availability of alternative fuels at retail stations. These conditions are not currently attained and may or may not be realized in a market economy. The Transitional Alternative Fuels and Vehicles model is used to simulate market outcomes for the use and cost of alternative-fuel vehicles (AFVs) and hybrid electric vehicles (HEVs) over a 20-year period, considering possible transitional barriers related to infrastructure needs, production scale, and technological learning. Without subsidies, no substantial penetration by HEVs is projected, based on their prospective fuel efficiency gains and costs. Hybrid subsidies (on the order of $2,000/vehicle) can induce substantial hybrid penetration and gasoline demand displacement under the U.S. Energy Information Administration’s 2001 oil price projections. This result is quantitatively different from that achieved for AFVs. Temporary HEV subsidies are effective at inducing hybrid vehicle penetration but do not have long-term effects once they are removed unless costs are reduced due to learning-by-doing.
Risky Driving: Relationship Between Cellular Phone and Safety Belt Use
Authors: Eby David W. , Kostyniuk Lidia P. , Vivoda Jonathon M.
Published: April 2007

The main purpose of the study was to explore the relationship between cellular phone and safety belt use. Rates of safety belt use of drivers using and drivers not using handheld cellular phones were compared. All data for safety belt and handheld cellular phone use were collected through direct observation while vehicles were stopped at intersections and freeway exit ramps in Michigan. Data were weighted to be representative of drivers during daylight hours in Michigan. Analyses included statistical comparisons of safety belt use rates and a logistic regression model to determine the effects of handheld cellular phone use on safety belt use. The study found that safety belt use for drivers using a handheld cellular phone was significantly lower than for drivers not using cellular phones. This same significant relationship was found within nearly all demographic categories analyzed. The logistic regression model showed that the odds of a handheld cellular phone user not using a safety belt were 1.77 times that of a driver not using a cellular phone. These results stress the importance of the public health issue posed by cellular phone use; not only are those who are conversing on cellular phones potentially more likely to be in a motor vehicle crash, they are also more likely to sustain greater injury because of the lack of safety belt use.
Sensory Cause of Railroad Grade-Crossing Collisions: Test of the Leibowitz Hypothesis
Authors: Cohn Theodore E. , Nguyen Tieuvi
Published: April 2007

Railroad crossing collisions are costly in both lives and property damage and are a principal limitation preventing meaningful increases in train speed. At a recent TRB workshop on means of minimizing the frequency of these events, it was agreed that a major hypothesis aimed at explaining the collisions had never been tested. That hypothesis, attributed to Leibowitz, is that the speed of larger objects, like trains, is underestimated by observers owing to a normal deficiency of visual processing. The elements of this hypothesis have begun to be tested in a laboratory setting. While there are numerous aspects to the judgment of speed of approach, studied has been one narrow aspect of the problem that relates to the rapidity with which a gradual increase in the size (starting size 3.7°, 5.3°, and 7.6° side) of a square is perceived by normal human observers. The object is a light gray rectangle set either in a dark gray surround or with no surround. The time required to react to the gradual change averages around 280 milliseconds (ms) after onset. In a significant number of tests on six individuals across conditions ranging from day to night light intensities, expansions in either width or height, and proportional increases in size or fixed increases, the time required to render the judgment increased with the starting size. The rate of increase was approximately 3 ms divided by the degrees of angle subtense (360° = full circle). Apparently, the initial approach of larger objects is seen more slowly or later than that of smaller ones. If so, this can be shown to translate to a more slowly perceived object speed. Leibowitz may have been correct.
Evolution of an Enhanced Rear Signaling System
Authors: Lee Suzanne E. , Wierwille Walter W. , DeHart Maryanne C.
Published: April 2007

Rear-end crashes are the most frequently occurring type of crash, making up approximately 25% of all crashes. Crash analysis has revealed a need to detect stopped and slowing lead vehicles with peripheral vision, as well as to detect stopped and slowing lead vehicles with foveal vision more quickly. Two experiments were conducted in an effort to develop systems that have these properties, yet do not have too much discomfort glare. Both experiments used the same four dependent measures: attention-getting rating, discomfort-glare rating, horizontal peripheral detection angle, and diagonal peripheral detection angle. Experiment 1 examined 17 candidate systems, all using white light and clear lenses. The results showed that the TCL, a lamp with a motorized reflector that moves in an M-sweep pattern, was the top candidate for an imminent crash warning signal, while a pair of centrally located alternating halogen lamps would be optimal for a stopped or slowly moving vehicle signal. Experiment 2 examined the effect of colored lenses for the top four configurations identified from Experiment 1. The results showed that TCL is superior to the alternating pair configurations in attention getting and peripheral detection for an imminent crash warning signal, with glare reduced by the use of tinted lenses in either red or amber. The high-output halogen alternating pair with either amber or red dispersive lenses represents the best available configuration for the stopped or slowly moving vehicle signal.
Toward More Realistic Driving Behavior Models for Autonomous Vehicles in Driving Simulators
Authors: Al-Shihabi Talal , Mourant Ronald R.
Published: April 2007

Autonomous vehicles are perhaps the most encountered element in a driving simulator. Their effect on the realism of the simulator is critical. For autonomous vehicles to contribute positively to the realism of the hosting driving simulator, they need to have a realistic appearance and, possibly more importantly, realistic behavior. Addressed is the problem of modeling realistic and humanlike behaviors on simulated highway systems by developing an abstract framework that captures the details of human driving at the microscopic level. This framework consists of four units that together define and specify the elements needed for a concrete humanlike driving model to be implemented within a driving simulator. These units are the perception unit, the emotions unit, the decision-making unit, and the decision-implementation unit. Realistic models of humanlike driving behavior can be built by implementing the specifications set by the driving framework. Four humanlike driving models have been implemented on the basis of the driving framework: ( a) a generic normal driving model, ( b) an aggressive driving model, ( c) an alcoholic driving model, and ( d) an elderly driving model. These driving models provide experiment designers with a powerful tool for generating complex traffic scenarios in their experiments. These behavioral models were incorporated along with three-dimensional visual models and vehicle dynamics models into one entity, which is the autonomous vehicle. Subjects perceived the autonomous vehicles with the described behavioral models as having a positive effect on the realism of the driving simulator. The erratic driving models were identified correctly by the subjects in most cases.
Variable Response Time Lag Module for Car-Following Models: Development and Structuring with Fuzzy Set Theory
Authors: Hatipkarasulu Yilmaz , Wolshon Brian
Published: April 2007

The car-following process consists of a stimulus-response relationship between vehicles in which the driver of the following vehicle reacts to the actions of the lead vehicle after a time lag. Since the 1950s, the car-following phenomenon has been studied and analyzed, resulting in various models and algorithms. Throughout this period, driver response time lag has always been assumed to be a constant value for the driver at all times, regardless of the approach and level of detail of the model. The primary shortcoming of a constant time lag is that it introduces a number of strong assumptions that do not concur with human nature. To address the problems associated with constant time lag, an independent response time lag module was developed that can be used in any car-following model or algorithm without changing its fundamental mathematical structure. One of the most appealing aspects of this module is its flexible and transparent structure that can easily be adapted to and calibrated for any model or simulation algorithm. The development and structure of the module are described, including the fuzzy definitions of driving states, fuzzy rule extraction, and fuzzy time lag assignment. Statistical and graphical evaluations of the module performance are also included by integrating the module to a proportional car-following model. In the graphical evaluation, the module improved the model performance significantly by providing more precise timing for the driver response. Both Kolmogorov–Smirnov and root-mean-square error tests confirmed that the use of the module improves the car-following model performance.
Consequences of Driving Reduction or Cessation for Older Adults
Authors: Harrison Ayodele , Ragland David R.
Published: April 2007

The purpose of this study was to understand the adverse consequences of driving reduction or cessation among elderly adults. A comprehensive literature search was conducted for studies that ( a) included information on driving by an elderly population, ( b) included results from a qualitative or quantitative (or both) study of the elderly and driving cessation, and ( c) provided information to evaluate consequences surrounding driving reduction or cessation. The selected subjects of the studies included men and women over the age of 55 years. Driving reduction or cessation is associated with a number of adverse consequences, including reduced activity out of the home and decreased life satisfaction. However, determining causality of the associations is difficult because of unidentified third variables (such as health). Understanding the adverse consequences will aid researchers and policy makers to develop better strategies to help people anticipate and prepare for reduced driving and to develop and improve transportation alternatives.
Improving Dilemma-Zone Protection of Advance Detection with Advance-Warning Flashers
Authors: McCoy Patrick T. , Pesti Geza
Published: April 2007

Two methods of dilemma-zone protection were compared. One was a conventional design with advance detectors at multiple locations. The other was a new design with advance detection at only one location and advance warning flashers on signs, with the legend “Prepare to Stop when Flashing,” which are interconnected to the traffic signal. The flashers are activated at a predetermined time before the onset of yellow. Field studies indicated that the performance of both designs depended on the probability that vehicle speeds are in the speed range of their dilemma-zone protection when the green terminated by gap-out. The primary advantage of the new design was its shorter maximum allowable headway, which greatly reduced the probability of max-out and loss of dilemma-zone protection at higher volumes. However, this advantage is diminished at low volumes by the limited speed range for which it provides dilemma-zone protection. The new design was modified to reduce the effects of this limitation and improve the level of dilemma-zone protection it provides.
Supplemental Pavement Markings for Improving Safety at Railroad–Highway Grade Crossings
Authors: Stephens Burton W. , Long Gary
Published: April 2007

An evaluation was performed of special X-box pavement marking configurations at railroad–highway grade crossings, originally used in several European countries. The intent is to provide motorists with supplemental visual cues about whether sufficient space is available for safe storage of a vehicle beyond the track for a motorist to proceed across. It is intended for application where nearby intersections can cause queues to back up to the track. These conspicuous markings, configured as an X in a box, were tested at two Florida locations, one in an urban area and one in a rural area, over a 1 ½-year period. The rates of cars hazardously stopping on or closely adjacent to the railroad tracks at the crossings were compared under pre- and postinstallation conditions. Results at the rural location showed a decline of more than 60% in hazardous stoppage rates over an extended period. No significant differences were found between the pre- and postinstallation tests at the urban location. A control site was utilized near the crossing in the urban location, and it showed no significant differences between the two test periods that were concurrent with the analysis at the treated site. Recommendations are provided for application of these markings at grade crossing sites in rural and urban locations.