bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistical Procedure Using an Expert Panel for Procurement of Emerging Transportation Technologies
Authors: Roberts Craig A. , Poppe Mark J. , Chalmers Seth W.
Published: April 2007

State departments of transportation (DOTs) rely on established standards and open and competitive bidding to procure materials and technologies. This process hinders the implementation of new technologies until such standards are developed. A time lag occurs between the commercial introduction and implementation of new technologies, often delaying deployment of safety and cost improvement items by many years. One solution to this time lag is to prequalify products and technologies and use competitive bidding for procurement. The task is to develop a workable prequalification procedure that will satisfy acceptable standards of fairness. A procedure is proposed and is illustrated with a case study. The procedure uses an expert panel performing blind evaluations of prospective products and technologies. A longitudinal repeated measures design on two factors was developed. Pass-fail criteria were established. Evaluation test questions and a measurement scale were developed. Analysis-of-variance models were used for two rating response variables and a ranking response variable. Model assumptions were checked and departures were noted. The DOT involved in the study will use the procedure as a prototype for future testing of new technologies.
Optimizing Aggregation Level for Intelligent Transportation System Data Based on Wavelet Decomposition
Authors: Qiao Fengxiang , Wang Xin , Yu Lei
Published: April 2007

Appropriate aggregation levels and sampling frames of real-time data in intelligent transportation systems (ITSs) are indispensable to transportation planners and engineers. Conventional techniques for the retrieval of aggregation levels are normally based on statistical comparison of the original and the aggregated data sets. However, it is not guaranteed that errors and noise will not be transmitted to the aggregated data sets and that the desired information will be reserved. Wavelet decomposition is a new technique that can be applied to the determination of aggregation level. An optimization process that can provide the optimized aggregation level of ITS data for different applications was developed. To illustrate the proposed technique, ITS data archived by the TransGuide Center in San Antonio, Texas, were used for a case study. Aggregation levels for different days of a week and different time periods over the whole year of 2001 were obtained through the proposed approach.
Real-Time Crash Prediction Model for Application to Crash Prevention in Freeway Traffic
Authors: Lee Chris , Hellinga Bruce , Saccomanno Frank
Published: April 2007

The likelihood of a crash or crash potential is significantly affected by the short-term turbulence of traffic flow. For this reason, crash potential must be estimated on a real-time basis by monitoring the current traffic condition. In this regard, a probabilistic real-time crash prediction model relating crash potential to various traffic flow characteristics that lead to crash occurrence, or “crash precursors,” was developed. In the development of the previous model, however, several assumptions were made that had not been clearly verified from either theoretical or empirical perspectives. Therefore, the objectives of the present study were to ( a) suggest the rational methods by which the crash precursors included in the model can be determined on the basis of experimental results and ( b) test the performance of the modified crash prediction model. The study found that crash precursors can be determined in an objective manner, eliminating a characteristic of the previous model, in which the model results were dependent on analysts’ subjective categorization of crash precursors.
Macrolevel Accident Prediction Models for Evaluating Safety of Urban Transportation Systems
Authors: Hadayeghi Alireza , Shalaby Amer S. , Persaud Bhagwant
Published: April 2007

A series of macrolevel prediction models that would estimate the number of accidents in planning zones in the city of Toronto, Ontario, Canada, as a function of zonal characteristics were developed. A generalized linear modeling approach was used in which negative binomial regression models were developed separately for total accidents and for severe (fatal and nonfatal injury) accidents as a function of socio-economic and demographic, traffic demand, and network data variables. The variables that had significant effects on accident occurrence were the number of households, the number of major road kilometers, the number of vehicle kilometers traveled, intersection density, posted speed, and volume-capacity ratio. The geographic weighted regression approach was used to test spatial variations in the estimated parameters from zone to zone. Mixed results were obtained from that analysis.
Identification of Accident Causal Factors and Prediction of Hazardousness of Intersection Approaches
Authors: Kumara S. S. P. , Chin H. C. , Weerakoon W. M. S. B.
Published: April 2007

Safety improvements were evaluated at signalized intersection approaches, where about 30% of road crashes occur in Singapore (in Singapore, vehicles are driven on the left side of the road). Identification of accident causal factors and prediction of hazardousness are essential tasks before safety treatments can be prescribed and prioritized. Statistical methods were used as a novel method for the identification of causal factors affecting accident frequencies, while nonparametric regression techniques were used for the prediction of intersection approach hazardousness. The statistical methodology used, the random-effect negative binomial model, indicates that uncontrolled left-turn slip roads, sight distances of less than 100 m, large numbers of signal phases, the use of permissive right-turn phases, the existence of horizontal curves, and total and left-turn volumes may increase the likelihood of accident occurrence. By nonparametric regression, the subtractive clustering methodology in fuzzy logic was used to derive an efficient and effective data set from the original data, which exhibited a high level of noise. This clustered data set was used to predict hazardousness. The prediction model, a generalized regression neural network, showed reasonable prediction accuracy. The model was capable of predicting hazardousness of about 65% for the total production data set, with a difference between the actual and the predicted values of less than 0.1. Moreover, the results suggest that the nonparametric regression network works well in multidimensional measurement spaces, in which hazardousness is assumed to be a function of several geometric, traffic, and traffic control measures.
Safety Effectiveness of Intersection Left- and Right-Turn Lanes
Authors: Harwood Douglas W. , Bauer Karin M. , Potts Ingrid B. , Torbic Darren J. , Richard Karen R. , Rabbani Emilia R. , Hauer Ezra , Elefteriadou Lily , Griffith Michael S.
Published: April 2007

The results of research involving a well-designed before-and-after evaluation of the safety effects of providing left- and right-turn lanes for at-grade intersections are presented. Geometric design, traffic control, traffic volume, and traffic accident data were gathered for a total of 280 improved intersections as well as 300 similar intersections that were not improved during the study period. The types of improvement projects evaluated included installation of added left-turn lanes, added right-turn lanes, and extension of the length of existing left- or right-turn lanes. An observational before-and-after evaluation of these projects was performed by using several alternative evaluation approaches. Three contrasting approaches to before-and-after evaluation were used: the yoked comparison or matched-pair approach, the comparison group approach, and the empirical Bayes approach. The research not only evaluated the safety effectiveness of left- and right-turn lane improvements but also compared the performances of these three alternative approaches in making such evaluations. The research developed quantitative safety effectiveness measures for installation design improvements involving added left-turn lanes and added right-turn lanes. The research concluded that the empirical Bayes method provides the most accurate and reliable results. Further use of this method is recommended.
Human Fatalities in Animal-Related Highway Crashes
Authors: Khattak Aemal J.
Published: April 2007

Recent national and statewide trends in the relatively uncommon animalrelated highway crashes that involve human fatalities were reviewed. Highway crashes in which animals are struck by vehicular traffic regularly occur throughout the United States. Invariably, such crashes are most damaging to the struck animals, while injuries to humans are usually not as severe. As such, significant research has focused on the plight of animals involved in traffic crashes. However, over the past decade animal-related crashes in the United States have claimed 1,353 human lives, costing the nation well over $1 billion in losses. The research reported focuses on recent national and statewide trends in fatality-producing animal-related vehicular crash frequencies and rates. Additionally, the temporal aspects of these crashes and trends in human and vehicle involvement in these crashes were investigated. The analysis used Fatality Analysis Reporting System data from 1991 to 2000, which were combined with data from other sources in a geographic information system. Analysis of the integrated data indicated that fatality-producing animal-related crashes are increasing nationally and that this trend is attributable to increasing vehicle miles traveled. The rate for fatality-producing animal-related crashes is holding steady at the national level. Human fatalities in such crashes occur at times when animals are more active, and unrestrained persons are more often killed than restrained persons. The information presented is suitable for agencies assessing the issue of human fatalities in animal-related crashes and for driver education and awareness programs.
Automated Accident Detection in Intersections via Digital Audio Signal Processing
Authors: Bruce Lori Mann , Balraj Navaneethakrishnan , Zhang Yunlong , Yu Qingyong
Published: April 2007

A system for automated traffic accident detection in intersections was designed. The input to the system is a 3-s segment of audio signal. The system can be operated in two modes: the two-class and multiclass modes. The output of the two-class mode is a label of “crash” or “noncrash.” In the multiclass mode of operation, the system identifies crashes as well as several types of noncrash incidents, including normal traffic and construction sounds. The system is composed of three main signal processing stages: feature extraction, feature reduction, and classification. Five methods of feature extraction were investigated and compared; these are based on the discrete wavelet transform, fast Fourier transform, discrete cosine transform, real cepstral transform, and mel frequency cepstral transform. Statistical methods are used for feature optimization and classification. Three types of classifiers are investigated and compared; these are the nearest-mean, maximum-likelihood, and nearest-neighbor methods. The results of the study show that the optimum design uses wavelet-based features in combination with the maximum-likelihood classifier. The system is computationally inexpensive relative to the other methods investigated, and the system consistently results in accident detection accuracies of 95% to 100% when the audio signal has a signal-to-noise-ratio of at least 0 decibels.
Measuring Unmet Needs of Intercity Bus Transportation
Authors: Pagano Anthony M. , Metaxatos Paul , Holeman Eric A. , Mora Victor , Morreale Alicia , Stanis Kate
Published: April 2007

Federal funding for intercity bus programs is available to states under Section 5311 (f) of the Federal Transit Act. The act requires that 15% of all federal funding for public transportation in nonurbanized areas be expended for intercity bus transportation, unless the state governor certifies that the intercity bus service needs are adequately met. A demand-supply-deficiency analysis was undertaken to assess whether intercity bus needs are being met in Illinois. The analysis indicates that some larger city-to-city routes could use additional service. In addition, many smaller urban places have no access to rail or bus service, especially in southern Illinois, and many of these have no Section 5311(f) recipients. Without state support for intercity bus programs, it is unlikely that people in these places will have access to such service in the foreseeable future.
Client Referral, Ridership, and Financial Tracking [CRRAFT] Transit Management System: CRRAFTing a Bridge to Coordinated Interagency Transportation
Authors: Espinosa Judith M. , Baca Matthew R. , Estelle Amy D. , Bennett Nancy , Knoebel Geri , White Mary E. , Lucero Josette P.
Published: April 2007

From the 1990s on, a growing number of federal and state human service programs have identified transportation as an allowable, often vital, support service for clients. State human services agencies in New Mexico are improving clients’ transportation options either by funding the expansion of local transit operators’ service areas and hours, or the starting up of new transit systems. Agencies providing this new transportation funding require specific reports based on the human service delivery model. Because services are client-based, the reports include the number of unique clients served, number of trips provided to each client, trip purposes, and costs. For New Mexico rural transit systems that operate under FTA Section 5311 guidelines, services and reports are trip based. To bridge the gap between human service agency and rural transit system cultures, the Alliance for Transportation Research Institute of the University of New Mexico developed a web-based software program, the Client Referral, Ridership, and Financial Tracking (CRRAFT) Transit Management System. The software integrates human service client transportation referral and service delivery with daily rural public transit operations, provides passengers with increased seamlessness in transportation service, and generates financial and client tracking reports that meet each funding agency’s criteria, including those required by FTA. The CRRAFT lessens the burden on small transit systems that have limited administrative staff of two to three people. The software also provides funding agencies with tools to facilitate planning and to maintain administrative and fiscal accountability.
Analytical Model for Paratransit Capacity and Quality-of-Service Analysis
Authors: Fu Liping
Published: April 2007

An analytical model could potentially be used by paratransit service planners to predict fleet requirements, system capacity, and quality-of-service measures for specific operating conditions. The model has a sound theoretical origin and was calibrated using data from a large number of simulated cases representing a wide range of operating conditions and quality of service. This model was shown to have a strong explanatory power, capable of capturing the complex relationship between fleet size, travel demand, quality-of-service measures, and other operating condition variables. With this model, analytical procedures similar to those provided in the Highway Capacity Manual and the Transit Capacity and Quality of Service Manual for other transportation facilities and services could be developed for paratransit systems.
Intelligent Transportation Technology Elements and Operational Methodologies for Shared-Use Vehicle Systems
Authors: Barth Matthew , Todd Michael , Shaheen Susan
Published: April 2007

There has been significant interest and activity in shared-use vehicle systems as an innovative mobility solution. Shared-use vehicle systems, that is, carsharing and station cars, consist of a fleet of vehicles used by several different individuals throughout the day. Shared-use vehicles offer the convenience of a private automobile and more flexibility than public transportation alone. From the 1990s to today, varying degrees of intelligent transportation system technologies have been applied to shared-used systems, providing better manageability and customer service. Many shared-use vehicle service providers today include some degree of advanced technologies (online reservations, vehicle tracking, smart card access) in their operations. Currently, there is a developing need for interoperability among shared-use vehicle service providers (e.g., smart card access among carsharing organizations) and transit operators (e.g., transit fare collection via smart cards). Interoperability will likely result in higher customer satisfaction and use, leading to greater market penetration. Similarly, some standardization will likely unfold for overall operational techniques (online reservations and insurance policies), customer interactions, and to some degree vehicle interfaces. Because shared-use vehicles systems are still a relatively new mobility concept, an industrywide standardization approach is still premature. Nevertheless, there are attempts to identify many of the important issues that will play a significant role in interoperability discussions among shared-use vehicle providers and the development of industry standards in the future. There are key elements in intelligent shared-use vehicle system operations and trade-offs encountered during the pioneering stage of shared-use vehicle system developments. Topics to discuss include vehicles, user–system interactions, user–vehicle interactions, and system operations.
Microscopic Modeling of Vehicle Start Emissions
Authors: Rakha Hesham , Ahn Kyoungho , Trani Antonio
Published: April 2007

A microscopic framework for estimating instantaneous vehicle start emissions for light-duty vehicles and trucks is developed. The framework assumes a linear decay in instantaneous start emissions over a 200-s time horizon. The initial vehicle start emissions rate is computed by using the soak time function of the U.S. Environmental Protection Agency’s MOBILE6 model, assuming a 200-s decay time interval. The use of the MOBILE6 soak time function ensures that the microscopic procedures that are developed produce start emissions that are consistent with the MOBILE6 model. The validity of the framework was demonstrated using independent trips that involved cold-start and hot-start impacts with vehicle emissions estimated to within 10% of the test in-laboratory measurements.
Effect of Arterial Signalization and Level of Service on Measured Vehicle Emissions
Authors: Unal Alper , Rouphail Nagui M. , Frey H. Christopher
Published: April 2007

The effect of arterial traffic signal timing and coordination on vehicle emissions is studied. Traffic signal timing improvement is one of the most common practices for congestion management in the United States. Although the benefits of improved signal timing for reduced fuel consumption are well documented, its effectiveness as a transportation control measure for emissions has not been clearly investigated. An empirical approach based on real-world, on-road vehicle emissions measurements was used. A total of 824 one-way runs representing 100 h and 2,020 vehicle miles of travel were conducted involving four drivers and eight gasoline-fueled light-duty vehicles on two signalized arterials in Cary, North Carolina: Walnut Street and Chapel Hill Road. Modal analyses of the data indicate that emissions rates were highest during acceleration and tend to decrease (in descending order) for cruise, deceleration, and idle. A modal approach is used to quantify the effect of arterial traffic signal timing and coordination on emissions. A key result is that signal coordination on Walnut Street yielded measurable improvements in arterial level of service and emissions reduction. For Chapel Hill Road, emissions were substantially lower under uncongested conditions [level of service (LOS) A/B] than under congested conditions (LOS D/E) for travel in the same direction at different times of day. Findings confirm the utility of signal coordination and congestion management as effective tools for controlling emissions.
Induced Travel and Emissions from Traffic Flow Improvement Projects
Authors: Stathopoulos Fotis G. , Noland Robert B.
Published: April 2007

Two scenarios for improving traffic flow are simulated and analyzed using the VISSIM microsimulation model and the Comprehensive Modal Emissions Model. Short-run and long-run emissions of CO, HC, NOx, and CO2 and fuel consumption are estimated. In the short run, with traffic volumes held constant, results demonstrate that the smoothing of traffic flow will result in reduced emissions. Long-run emissions are simulated by synthetically generating new trips into the simulated networks to represent potential induced travel. This is done until a “break-even” level of emissions for each pollutant and fuel consumption is reached that is equivalent to the base level before the traffic flow improvement was added. By also calculating short-run changes in travel time from the improvement, the travel time elasticity equivalents for each pollutant are calculated. These values are compared with travel time elasticities in the literature to evaluate whether long-run emissions benefits are likely to endure. Simulations are conducted using different assumptions of vehicle soak time to simulate cold-start and hot-stabilized operating modes. Results indicate that, in most cases, long-run emissions reductions are unlikely to be achieved under the two scenarios evaluated.
Reducing the Impacts of Transportation on Global Warming: Summary of New York Greenhouse Gas Task Force Recommendations
Authors: Winkelman Steven , Dierkers Greg
Published: April 2007

Global climate change is fundamentally caused by fossil fuel combustion. The transportation sector generates more than one-third of greenhouse gas (GHG) emissions in New York and represents the fastest-growing source of GHG emissions in the state. A summary of the recommendations of the New York Greenhouse Gas Task Force for reducing GHG emissions from the transportation sector is provided. Using a bottom-up analytical approach, the Center for Clean Air Policy—with advice from the task force—determined that New York can reduce transportation-sector emissions by 1.64 million metric tons of carbon equivalent (MMTCE) in 2010 (total emissions 20.9% above 1990 levels) and by 5.23 MMTCE in 2020 (total emissions 16.5% above 1990 levels) by implementing the task force’s recommendations. Achieving significant reductions in GHG emissions from transportation requires a comprehensive package of complementary measures, including shifting funding to more GHG-efficient alternatives such as transit and smart growth, adopting GHG emissions standards for light-duty vehicles (upon implementation in California), creating an indigenous biofuels program, and considering policy mechanisms to increase freight efficiency and high-speed rail options. To facilitate the implementation of these measures, the establishment of a state entity for reducing transportation-sector emissions is recommended with a goal of reducing transportation GHG emissions to 20% above 1990 levels by 2010, 10% above 1990 levels by 2020, and 1990 levels by 2030.
Mobile-Source Emissions: Analysis of Spatial Variability in Vehicle Activity Patterns and Vehicle Fleet Distributions
Authors: Malcolm Carrie , Younglove Theodore , Barth Matthew , Davis Nicole
Published: April 2007

Accurately estimating mobile-source emissions requires a good understanding of vehicle activity and the characteristics of the on-road vehicle fleet. Spatial variability in vehicle activity patterns and vehicle fleet composition can have significant effects on the overall emissions inventory. Simply determining total vehicle miles traveled is insufficient for emissions inventory calculations from the new-generation models of mobile-source emissions. Improvements in emissions-control technology over the past 20 years have led to large decreases in the emissions of light-duty cars and trucks, resulting in large variations in vehicle emissions depending on model year and technology type. In addition, research indicates that the accurate characterization of vehicle activity is necessary in conjunction with better spatial resolution of vehicle fleet characteristics because of the differing modal behavior of the vehicles within various vehicle and technology groups. Vehicle activity and vehicle fleet data were collected in the South Coast Air Basin in southern California. Vehicle activity was characterized primarily using a large second-by-second speed and acceleration data set collected from probe vehicles operated within the flow of traffic. In addition, three sets of vehicle fleet data were collected and used for spatial comparison. The results of the analysis show spatial and temporal differences in vehicle activity patterns and vehicle fleet characteristics; differences in speed and congestion affect the speed–acceleration profiles as well as associated emissions.
Characteristics and Emissions of Heavy-Duty Vehicles in Tennessee Under the MOBILES Model
Authors: Miller Terry L. , Davis Wayne T. , Reed Gregory D. , Doraiswamy Prakash , Fu Joshua S.
Published: April 2007

Heavy-duty vehicle (HDV) classifications used for modeling emissions in the MOBILE6 model have been expanded from 2 classifications in MOBILE5 to 16 classifications in MOBILE6. The new classifications are based on vehicle weight and fuel used (i.e., gasoline or diesel). The heavier vehicles have higher emissions, so it is important to use correct vehicle weight distributions. Tennessee’s HDV registration data show a distribution very similar to the national defaults, but with more vehicles in the heaviest weight category (HDV8B). More than 50% of Tennessee’s HDVs fall in the lightest vehicle category (HDV2B). The biggest difference in truck characteristics in Tennessee versus national defaults in MOBILE6 is the higher HDV fraction on Tennessee rural Interstates. Also, the ratio of single-unit trucks to trailer trucks varies considerably by facility type. The emissions of volatile organic compounds and carbon monoxide per mile of travel of gasoline-fueled single-unit trucks can be 2.5 to 5 times higher than those of heavy-duty diesel trailer trucks. The emissions of nitrogen oxides per mile of travel of diesel-fueled tractor–trailer trucks can be five times higher than those of gasoline-fueled single-unit trucks. For these reasons it is important to accurately characterize the HDV fleet. The characteristics of the Tennessee HDV fleet are compared with national defaults used in MOBILE6, and a new scheme for classifying vehicles by road type is presented.
Sensitivity Analysis of CAL3QHC Roadway Intersection Model
Authors: Patel Irfan , Kumar Ashok , Manne Gopi
Published: April 2007

Emissions from vehicular sources are a major contribution to air pollution in every country. Air quality models are being used to study the impact of such emissions. The CAL3QHC emissions model was developed by the U.S. Environmental Protection Agency based on California’s CAL3Q model. One area of concern with modeling results is uncertainty in input data, in model calculations, and in natural atmospheric processes. The focus of the study is uncertainty in input data for the CAL3QHC roadway model. Two practical methods—the ASTM approach and the least rigid approach—are used to perform the sensitivity analysis on the input parameters. The two important areas in which CAL3QHC requires sensitivity discussions are the emissions source strength of the vehicles in the queue and the link length (which represents the number of vehicles in a queue). The variability of these two parameters results in a nonlinear relationship between the source strengths and the predicted concentrations. Sensitivity analysis of the CAL3QHC model is carried out for a simple roadway intersection with two traffic lanes and two receptor locations (at the corner of the intersection and midblock). With results from the ASTM method, sensitivity indices are calculated for signal timing, traffic volume, number of traffic lanes, and wind speed. Among all indices, wind speed shows the maximum sensitivity on predicted carbon monoxide concentrations. The model needs no calibration because none of the parameters studied show Type IV sensitivity using ASTM results.
Markets for Fuel-Cell Auxiliary Power Units in Vehicles: Preliminary Assessment
Authors: Lutsey Nicholas , Brodrick Christie-Joy , Sperling Daniel , Dwyer Harry A.
Published: April 2007

Fuel cells are widely expected to replace internal combustion engines in vehicles. However, their high initial costs preclude their introduction into the mass market for some time. A new approach is needed that focuses on niche markets. The potential use of fuel cells in auxiliary power units (APUs) on board various types of automobiles and trucks— in luxury passenger automobiles, law enforcement vehicles, contractor trucks, specialized utility trucks, recreational vehicles, refrigerated trucks, and line-haul heavy-duty trucks—is explored. Power requirements, volume and weight targets, costs, market sizes, and potential benefits for several fuel cell technologies and fuels are analyzed. The attributes of market applications are matched with fuel cell attributes to assess the market potential of fuel-cell APUs. Although data are insufficient and more analysis is needed, several market applications apparently could play key roles in introducing fuel cell technologies to the transportation sector.
Driver Distraction: Evaluation with Event Detection Paradigm
Authors: Greenberg Jeff , Tijerina Louis , Curry Reates , Artz Bruce , Cathey Larry , Kochhar Dev , Kozak Ksenia , Blommer Mike , Grant Peter
Published: April 2007

The effects of eight in-vehicle tasks on driver distraction were measured in a large, moving-base driving simulator. Forty-eight adults, ranging in age from 35 to 66, and 15 teenagers participated in the simulated drive. Hand-held and hands-free versions of phone dialing, voicemail retrieval, and incoming calls represented six of the eight tasks. Manual radio tuning and climate control adjustment were also included to allow comparison with tasks that have traditionally been present in vehicles. During the drive the participants were asked to respond to sudden movements in surrounding traffic. The driver’s ability to detect these sudden movements or events changed with the nature of the in-vehicle tasks that were being performed. Driving performance measures such as lane violations and heading error were also computed. The performance of the adult group was compared with the performance of the teenage drivers. Compared with the adults, the teens were found to choose unsafe following distances, have poor vehicle control skills, and be more prone to distraction from hand-held phone tasks.
Characteristics of Cell Phone–Related Motor Vehicle Crashes in North Carolina
Authors: Huang Herman F. , Stutts Jane C. , Hunter William W.
Published: April 2007

Computerized crash narratives for the period January 1, 1996, through August 31, 2000, were searched to identify 452 cell phone crashes that occurred in North Carolina. The characteristics of these crashes were compared with about 1,080,000 non-cell-phone crashes during the same period. Cell phone crashes were ( a) less likely to result in a serious or fatal injury, ( b) nearly twice as likely to be rear-end crashes, and ( c) somewhat more likely to occur during the mid-day or afternoon hours. Moreover, cell phone crashes were more likely to occur in urban areas, on local streets, and on roads with “no special feature.” Drivers who were talking on a cell phone at the time of the crash were more likely to ( a) have committed a driving violation, ( b) be driving sport utility vehicles, and ( c) be going straight. They were more likely to be male and under age 55. All of these cell phone versus non-cell-phone differences were statistically significant. As cell phones continue to proliferate, the number of cell phone crashes will probably increase. The challenge is to minimize the risks associated with cell phone use and driving, while allowing drivers to enjoy the benefits of cell phones.
Viewing Ground-Mounted Diagrammatic Guide Signs Before Entrance Ramps at Night: Driver Eye Scanning Behavior
Authors: Zwahlen Helmut T. , Russ Andrew , Schnell Thomas
Published: April 2007

The driver eye scanning study is part of a larger study conducted for the Ohio Department of Transportation to evaluate the effectiveness of ground-mounted diagrammatic guide signs placed before entrance ramps at highway freeway interchanges. This nighttime study investigated driver eye scanning behavior while approaching ground-mounted diagrammatic guide signs placed before entrance ramps. Six highway-freeway interchanges were selected in the Greater Columbus, Ohio, area for placement of the diagrammatic signs in the field. Subjects were six unfamiliar drivers, between the ages of 22 to 42. Two diagrammatic signs were located at each of the six interchanges, .5 mi (805 m) and .25 mi (402 m) before the last point of the gore, where a driver can still gain access to the correct freeway entrance ramp. Driver eye scanning behavior measurements were recorded at night to determine if the presence of the diagrammatic signs elicited an excessive number of eye fixations or was visually distracting to the drivers or both. The results indicate that the diagrammatic signs are not looked at excessively often or excessively long. The average look numbers and average look duration times indicate a normal and reasonable level of information acquisition processing employed by the drivers. These values agree with those previously obtained for regular traffic signing determined in previous eye scanning studies. Ground-mounted diagrammatic signs on multilane arterials in advance of highway freeway interchanges were not demonstrated to unduly distract drivers and detrimentally affect a driver’s looking behavior.
Effectiveness of Ground-Mounted Diagrammatic Advance Guide Signs for Freeway Entrance Ramps
Authors: Zwahlen Helmut T. , Russ Andrew , Roth James M. , Schnell Thomas
Published: April 2007

This study investigated the effectiveness of ground-mounted diagrammatic signs in the context of urban multilane arterials leading to freeways. Six highway-freeway interchanges were selected in the greater Columbus, Ohio, area for installation of the diagrammatic signs in the field. The primary measure of effectiveness was the distance at which unfamiliar drivers driving in the wrong lane changed lanes. A total of 21 and 19 test drivers unfamiliar with Columbus roads were recruited for an evaluation before and after installation of the diagrammatic guide signs. This evaluation with unfamiliar test drivers showed that drivers were able to execute a needed lane change earlier when diagrammatic signs were provided. Combining all six sites and looking at the 50th (377 m before, 819 m after) and 85th percentile (203 m before, 601 m after) lane change distances, an increase by a factor of 2.2 to 3.0 between the after and before condition was observed. In addition, a panel of 13 Ohio Department of Transportation and FHWA evaluators visited the six interchange sites and provided their input and opinions on the use of diagrammatic signs. The majority of the evaluators fully embraced the idea of diagrammatic signs. It is suggested that such signs should be used on multilane arterials in advance of highway–freeway interchanges in addition to preexisting guide signs (trailblazer assemblies), in cases in which the cost of overhead span-type sign bridges cannot be economically justified and additional advance guidance information to motorists is highly desirable.
Driver En Route Guidance Compliance and Driver Learning with Advanced Traveler Information Systems: Analysis with Travel Simulation Experiment
Authors: Chen Wan-Hui , Jovanis Paul P.
Published: April 2007

If real-time driver en route guidance advice does not meet driver preferences (e.g., preference for taking the freeway) or the advice is not correct, drivers are very likely to ignore the information, and the guidance system becomes ineffective in their route choice no matter how advanced the system. There is a need to investigate the factors affecting driver compliance with en route guidance advice. A travel simulation experiment was used to investigate significant factors affecting driver route choice behavior. A linear mixed model was developed for describing the factors affecting driver compliance with guidance advice using the compliance rate over several simulated trips as a dependent variable. The issue of repeated observations is addressed. The system accuracy and subjects’ learning experience in their spatial experience at the same intersection and temporal experience in the same day are also taken into account. The model results show that significant factors are involved: freeway advice, turning advice, congestion occurrence, incident occurrence, subjects’ spatial experience, subjects’ temporal experience, and subjects’ education level; there are several important interactions as well.
Better Transportation Services for Older Persons
Authors: Burkhardt Jon E.
Published: April 2007

Improvements to public transportation services are being made, or can be made, to offer better public transportation services for older travelers. Communities in which some of the most forward-looking ideas have been applied were examined. A number of short-term, low-cost improvements have been shown to be beneficial, but new perspectives are also needed. In the long run, multiple types of services, offered at varying prices, are needed to replace the “one size fits all” approach to public transportation with options that riders could choose on their own to fit the specific demands of individual days and trips. Shared-ride, demand-responsive services, dispatched and controlled through advanced technologies, could provide higher levels of service than now available and at higher levels of productivity and cost-effectiveness. Frequent, comfortable, affordable, spontaneous service to a wide variety of origins and destinations over a wide range of service hours is what seniors desire. A serious challenge for the public transportation industry will be finding ways of providing such services while collecting revenues that cover their costs. A key finding of this research is that the transportation service attributes most highly valued by older riders are not markedly different from those valued by other transit riders, so that improvements that would best serve older riders will also attract significant numbers of other riders.
Relative Luminance of Retroreflective Raised Pavement Markers and Pavement Marking Stripes on Simulated Rural Two-Lane Roads
Authors: Molino John A. , Opiela Kenneth S. , Andersen Carl K. , Moyer M. Joseph
Published: April 2007

The FHWA Turner-Fairbank Highway Research Center is undertaking a research program to study the visibility of retroreflective raised pavement markers (RRPMs). The focus of the initial effort is to determine the relative luminance of RRPMs and pavement markings (PMs) needed to produce adequate guidance on rural two-lane roadways at night. A driving simulator was used to test 36 research participants as they drove simulated roadways containing various combinations of RRPMs and PMs. The luminance of the simulated roadway delineation ranged from 0.07 to 4.1 cd/m2. The primary driver performance measure was curve-recognition distance. For the various RRPM and PM luminance conditions, mean curve-recognition distances ranged from 19.0 m (62.3 ft) to 68.4 m (224 ft), with a grand mean of 43.0 m (141 ft). Regression analyses produced predictive equations to estimate the mean curve-recognition distance from the luminance of RRPMs acting alone or of PMs acting alone. Trading ratios were computed for PM luminance with and without RRPMs present on the road. A conservative empirical estimate of 0.52 was computed for such a trading ratio based on the data from the current experiment. This value compared favorably with independent estimates of 0.54 and 0.55 based on an earlier analytical approach. Thus, the current experiment confirmed, with empirical data, earlier estimates that it might be possible to reduce the luminance of PMs on rural two-lane roads by about 45% when appropriate RRPMs are installed.
Wind Load Provisions in 2001 AASHTO Supports Specifications
Authors: Fouad Fouad H. , Calvert Elizabeth
Published: April 2007

The AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals (Supports Specifications) has been revised in its entirety through a major research project conducted under the auspices of the National Cooperative Highway Research Program (NCHRP Project 17-10). The new document was approved in 1999 by all state departments of transportation for adoption by AASHTO and was published in 2001. A major part of the revisions included new provisions and criteria for wind loads. These provisions differ considerably from those in previous editions of the specifications. A review of the changes in the wind load provisions of the 2001 Supports Specifications is presented. These changes, which are primarily due to the adoption of a new wind speed map based on a 3-s gust, could result in a significant increase in the magnitude of wind pressure in hurricane areas and a decrease in inland areas depending on location and structure type.
Finite Element Study of Distortion-Induced Fatigue in Welded Steel Bridges
Authors: Zhao Yuan , Roddis W. M.
Published: April 2007

Out-of-plane distortion-induced fatigue cracking is caused by relative rotation and displacement between longitudinal girders and transverse members framing into these girders. Procedures for determination of secondary stresses are not specified in the design or rating process. Appropriate finite element method procedures to analyze distortion-induced fatigue behavior are presented. A multigirder bridge developed web gap cracks near the girder bottom flange in a positive moment region. The affected diaphragm–girder connections were repaired by installing additional reinforcing splice plates to the web and attaching connection stiffeners to the flanges. Because no structural modifications were made to similar details in the bridge that had not developed fatigue cracks, concerns remain that these details may also be subjected to high-magnitude fatigue stresses that may lead to future cracking. By using finite element submodeling techniques, potential crack initiation sites in the bridge were identified and the corresponding distortion-induced stresses were determined. The most stressed detail reached yielding with an out-of-plane displacement of only a few thousandths of an inch. On the basis of the analytical results, a linear stress–displacement correlation was established for prediction of the secondary stresses. Repair analysis indicated that web gap stresses can be significantly reduced if a rigid stiffener-to-flange attachment is used. Thus, a bolted repair is recommended for the positive moment region connections, and a welded repair is recommended for the transition and negative moment region connections.
Live-Load Test Results of Missouri’s First High-Performance Concrete Superstructure Bridge
Authors: Yang Yumin , Myers John J.
Published: April 2007

For its significant economical savings and greater design flexibility, high-performance concrete (HPC) is becoming more widely used in highway bridge structures. High-performance bridges with HPC and large-diameter prestressed strands are becoming attractive to designers. Bridge A6130 is the first fully HPC superstructure bridge in Missouri. The bridge has HPC cast-in-place deck and high-strength concrete girders reinforced with 15.2-mm (0.6-in.) diameter strands. The bridge was instrumented with embedded strain gauges and thermocouples to monitor the early-age and later-age behavior of the structures from construction through service. To investigate the overall behavior of the bridge under live load, a static live-load test was developed and carried out. During the live-load test, 64 embedded vibrating wire strain gauges and 14 embedded electrical-resistance strain gauges were used to acquire the changing strain rate in the bridge caused by the varying live-load conditions. Girder deflections and rotations were also recorded with external sensors and a data acquisition system. Based on the test results, the load distribution to the girders was studied. The AASHTO specifications live-load distribution factor recommended for design was compared with the measured value and found to be overly conservative. The AASHTO load and resistance factor design live-load distribution factors recommended for design were found to be comparable to measured values. Two finite element models were developed with ANSYS and compared with measured values to investigate the continuity level of the Missouri Department of Transportation interior bent detail.
Live-Load Response of Alabama’s High-Performance Concrete Bridge
Authors: Barnes Robert W. , Stallings J. Michael , Porter Paul W.
Published: April 2007

Results are reported from live-load tests performed on Alabama’s high-performance concrete (HPC) showcase bridge. Load distribution factors, deflections, and stresses measured during the tests are compared with values calculated using the provisions of the AASHTO LRFD Bridge Design Specifications and AASHTO Standard Specifications for Highway Bridges. Measured dynamic amplification of load effects was approximately equal to or less than predicted by both specifications. Distribution factors from both specifications were found to be conservative. Deflections computed according to AASHTO LRFD Bridge Design Specifications suggestions matched best with the measured deflections — overestimating the maximum deflections by 20% or less. Bottom flange stresses computed with AASHTO distribution factors were significantly larger than measured values. AASHTO LRFD Bridge Design Specifications provisions suggest a special procedure for computing exterior girder distribution factors in bridges with diaphragms. When two or more lanes were loaded, this special procedure did not reflect the actual behavior of the bridge and resulted in very conservative distribution factors for exterior girders. Further research is recommended to correct this deficiency.
How Accurate Is Ground-Penetrating Radar for Bridge Deck Condition Assessment?
Authors: Shin Heejeong , Grivas Dimitri A.
Published: April 2007

As ground-penetrating radar (GPR) is increasingly used for assessing the condition of bridge decks, quantifying and controlling the quality of GPR measures becomes an important challenge. A methodology developed to assess the accuracy of deck condition measures is presented, and its use in a case study involving real data is demonstrated. The latter are generated during GPR applications on a large bridge deck and are processed with a commercial image-processing algorithm. The measures extracted from the processed GPR data are the rebar reflection amplitude and the dielectric constant of the deck material. The accuracy of the GPR assessments is evaluated by comparing core data (ground truth) with the GPR measures. The methodology uses appropriate statistical characteristic curves for quality control. It is based on a use of data to plot the probabilities of true detection versus false detection. Image interpretation requires using a threshold value (typically established from experience) selected to optimize true and false detection rates. The results of the case study indicate that rebar reflection data detect defects of the bridge decks at a 75% true detection rate with a 15% false detection rate. The dielectric data generated during field testing appear not to adequately represent the condition of the bridge deck because of the presence of latex-modified concrete overlay. The details of this finding and important conclusions are presented and discussed.