bluuebunny/crossref_metadata_2025 huggingface dataset:
Do New Highways Attract Businesses?: Case Study for North Country, New York
Authors: Hodge Daniel J. , Weisbrod Glen , Hart Arno
Published: April 2007

A frequently heard argument for new highways, especially those to be located in rural regions, is that they will directly lead to new business attraction and expansion opportunities (i.e., expanding from a two-lane road to a four-lane expressway will be what is needed to jump-start lagging economic regions). The literature on industrial site location commonly cites transportation infrastructure and access to markets as key determinants of business location. Meanwhile, many prospective studies are undertaken (major investments studies, environmental impact statements, etc.) that include analyses to try to estimate the economic impacts of new highway investments. The problem is that most transportation-based analysis tools, such as travel network and user benefit models, are not designed to answer the question of the potential for a highway investment to lead to business attraction (which is inherently speculative). Rather, they focus on quantifying current and future traffic patterns and how they will be affected by a highway improvement. The North Country Transportation Study examined these traditional benefits but also, perhaps more importantly, carefully studied the potential for business attraction to the region. This effort provides a substantial advance in the economic development analysis of transportation investments because of the thoroughness of sources and methodologies undertaken to understand and quantify this impact in the relatively rural and isolated region of northern New York. Local interviews and surveys, state business attraction and retention trend analysis, and a specially designed business attraction model were used to transform a typically speculative concept into a tangible one.
Mobility Management Strategies for the Next Decades: Findings and Recommendations from Largest European Mobility Management Project
Authors: Wilhelm Astrid , Posch Karl-Heinz
Published: April 2007

Mobility Management Strategies for the Next Decades (MOST) was the largest European-funded project in the field of mobility management (MM). It is a 3-year research and demonstration project. MM has been applied and tested by more than 30 demonstrators in 13 European countries, and its impacts have been evaluated. MM is an innovative, demand-oriented approach to provide for a sustainable transportation system. It is based on information, coordination, and motivation and complements traditional (infrastructural) transport planning. In comparison with transport demand management, which focuses mainly on the way to work and the formation of car- and vanpools, MM is broader and is applied to manifold target groups. In MOST this is reflected in the six thematic fields of the demonstrations: educational institutions, tourism, health institutions, site development, temporary sites and events, and mobility centers and consulting. MOST provides evidence for the wide applicability of MM to very different thematic fields and target groups. Already in the short term, MM raises the quality of offered mobility-related services, improves accessibility, fosters changes in attitudes, and influences modal choice toward more sustainable modes. MM can often be started by implementing temporary services that, due to their success, become long-term institutions. The complexity of MOST contributed to the ability to generalize from the results and recommendations, hence preparing the way for future standardization and an increase in the quality of transportation systems.
Psychological and Behavioral Effects of Travel Feedback Program for Travel Behavior Modification
Authors: Taniguchi Ayako , Hara Fumihiro , Takano Shin’ei , Kagaya Sei'ichi , Fujii Satoshi
Published: April 2007

The effects of the Travel Feedback Program (TFP) on travel behaviors and psychological factors that may influence automobile use were investigated. TFP was proposed as a method of modifying travel behavior with automobile use into travel behavior without automobile use. In TFP, participants were asked to report their travel activity behavior, after which they received feedback on that behavior, including information about the amount of carbon dioxide emission resulting from the behavior, and comments or suggestions from the program coordinators on how to reduce automobile use. The behavioral and psychological effects produced by TFP were theoretically investigated on the basis of norm activation theory, which describes the psychological process of altruistic behavior proposed in social psychology. From the theory that automobile-use reduction or pro-environmental behavior is influenced by behavioral intention to reduce automobile use, it was hypothesized that behavioral intention is in turn influenced by moral obligation, and moral obligation is in turn influenced by awareness of the negative environmental consequences of automobile use. The psychological and behavioral data confirmed the set of hypotheses of causal relations, and the data indicated that TFP has a significant positive effect on pro-environmental behavior even 1 year after participation in TFP.
Empirical Approaches to Outlier Detection in Intelligent Transportation Systems Data
Authors: Park Eun Sug , Turner Shawn , Spiegelman Clifford H.
Published: April 2007

Novel methods for implementation of detector-level multivariate screening methods are presented. The methods use present data and classify data as outliers on the basis of comparisons with empirical cutoff points derived from extensive archived data rather than from standard statistical tables. In addition, while many of the ideas of the classical Hotelling’s T2-statistic are used, modern statistical trend removal and blocking are incorporated. The methods are applied to intelligent transportation system data from San Antonio and Austin, Texas. These examples show how the suggested new methods perform with high-quality traffic data and apparently lower-quality traffic data. All algorithms were implemented by using the SAS programming language.
Validation of FHWA Crash Models for Rural Intersections: Lessons Learned
Authors: Oh Jutaek , Lyon Craig , Washington Simon , Persaud Bhagwant , Bared Joe
Published: April 2007

A national-level safety analysis tool is needed to complement existing analytical tools for assessment of the safety impacts of roadway design alternatives. FHWA has sponsored the development of the Interactive Highway Safety Design Model (IHSDM), which is roadway design and redesign software that estimates the safety effects of alternative designs. Considering the importance of IHSDM in shaping the future of safety-related transportation investment decisions, FHWA justifiably sponsored research with the sole intent of independently validating some of the statistical models and algorithms in IHSDM. Statistical model validation aims to accomplish many important tasks, including ( a) assessment of the logical defensibility of proposed models, ( b) assessment of the transferability of models over future time periods and across different geographic locations, and ( c) identification of areas in which future model improvements should be made. These three activities are reported for five proposed types of rural intersection crash prediction models. The internal validation of the model revealed that the crash models potentially suffer from omitted variables that affect safety, site selection and countermeasure selection bias, poorly measured and surrogate variables, and misspecification of model functional forms. The external validation indicated the inability of models to perform on par with model estimation performance. Recommendations for improving the state of the practice from this research include the systematic conduct of carefully designed before-and-after studies, improvements in data standardization and collection practices, and the development of analytical methods to combine the results of before-and-after studies with cross-sectional studies in a meaningful and useful way.
Development of Crash Reduction Factors: Methods, Problems, and Research Needs
Authors: Shen Joan , Gan Albert
Published: April 2007

Crash reduction factors (CRFs) are used in highway safety studies to predict safety benefits due to reduced numbers of crashes. NCHRP Report 162 identified the need for the development of a national comprehensive set of CRFs for each state to evaluate safety improvements. However, this need has not been met. As a result, many states have developed their own CRFs or have adopted CRFs from other states. A synthesis of the CRF development methods, the associated problems, and the research needs are provided. The emphasis is placed on the before-and-after study method because it has been, and still is, the method of choice for CRF development. Three before-and-after study methods were introduced and reviewed: ( a) the simple before-and-after method, ( b) the before-and-after study with comparison group method, and ( c) the before-and-after study with the empirical Bayes method. The problems associated with the simple before-and-after studies, including regression to the mean, crash migration, maturation, and external causal factor, are discussed. Several research needs related to crash migration and general CRF development are also identified. The information presented in the synthesis will be useful to states that plan to develop or update their CRFs.
Development of a Procedure for Estimating Expected Safety Effects of a Contemplated Traffic Signal Installation
Authors: Persaud Bhagwant , McGee Hugh , Lyon Craig , Lord Dominique
Published: April 2007

The Manual on Uniform Traffic Control Devices contains warrants for traffic signal installation but cautions that satisfying a warrant does not in itself justify the decision to install a signal and that one should not be installed unless an engineering study indicates that this will improve the overall safety or operation of the intersection. The development of an easily implementable procedure, which is intended to be part of an engineering study, for estimation of the expected safety effects of a contemplated signal installation is reported. These effects can then be considered in conjunction with other impacts in a conventional economic evaluation. The development of the procedure by use of a multijurisdiction database is described, and a detailed illustration is presented. Use is made of the empirical Bayes methodology that of late has been recognized as the state of the art in safety estimation and of the most recent advances in that methodology. Substantial focus is placed on the application of that methodology and on the development of the accident prediction models required to support that application. The development of the procedure is part of an NCHRP project (NCHRP 17-16) that aims to improve the safety warrant for signal installation and, more generally, to determine how safety is considered in the decision to install or not install a signal.
Systemwide Optimization of Safety Improvements for Resurfacing, Restoration, or Rehabilitation Projects
Authors: Harwood Douglas W. , Kohlman Rabbani Emilia R. , Richard Karen R.
Published: April 2007

Highway agencies face a dilemma in determining the appropriate balance of resurfacing and safety improvements in their programs to maintain the structural integrity and ride quality of highway pavements. Highway agencies currently lack a tool that would allow them to determine which sites should be resurfaced without accompanying safety improvements and which sites should be resurfaced and improved in other ways that would enhance safety. A resource allocation process that maximizes the benefits from resurfacing and safety improvements within a specified improvement budget can provide such a tool. A resource allocation process that accomplishes this goal has been developed and implemented in a software tool known as the Resurfacing Safety Resource Allocation Program (RSRAP). RSRAP uses an optimization process based on integer programming to determine which improvement alternatives (or combinations of alternatives) would optimize the benefits for a specified set of improvement projects. RSRAP incorporates the best available estimates of the safety effectiveness of specific geometric and safety improvements. RSRAP also gives consideration to the potential effects of resurfacing on vehicle speeds and on safety. The goal of the optimization process is not to optimize safety at any particular site but to optimize systemwide safety for a given set of resurfacing projects while not exceeding a user-specified improvement budget.
Accident Count Model Based on Multiyear Cross-Sectional Roadway Data with Serial Correlation
Authors: Ulfarsson Gudmundur F. , Shankar Venkataraman N.
Published: April 2007

The use of the negative multinomial model to form a predictive model of median crossover accident frequencies with a multiyear panel of crosssectional roadway data with a roadway section-specific serial correlation across time was explored. The negative multinomial model specification is compared with previous research, which used the same database but which also used negative binomial and random-effects negative binomial count models. If there is no section-specific correlation in the panel, the negative multinomial model becomes equivalent to the negative binomial. The differences in the estimation results between those models show that such a correlation exists in the data. The results show that the negative multinomial significantly outperforms the negative binomial and the random-effects negative binomial in terms of fit, with a statistically significantly higher likelihood at convergence. The signs of the coefficients were similar in all models; when the signs differed, the negative multinomial model results were more intuitive. Overall, the analysis supports the use of the negative multinomial count model to estimate median crossover accident frequency models that are based on panel data.
Impact of Buses on Highway Infrastructure: Case Study for New Jersey State
Authors: Boilé Maria , Narayanan Preethi , Ozbay Kaan
Published: April 2007

Buses are classified as heavy vehicles, and research has shown that heavy vehicles are mainly responsible for pavement damage and costs incurred to rectify the damage. Transit agencies must consider the pavement damage caused by a bus when choosing among different types of buses for procurement for certain corridors and deciding on the type of transit service for a corridor. Also, bus contribution to pavement damage should be considered in determining the appropriate amount of taxes and fees to be paid by this vehicle class. Currently, no tool exists to support such decisions. Pertinent literature was reviewed to determine the availability of methods for allocating roadway maintenance costs to buses. Two broad areas of highway impact–related literature, highway cost allocation studies and methods to estimate pavement deterioration resulting from vehicle–pavement interactions, were examined. A review of several state cost allocation studies showed that either equivalent single-axle loads (ESALs) or ESALS weighted by vehicle miles traveled were used to allocate pavement maintenance cost to various vehicle classes. Those studies, however, either accounted for buses by grouping them with other vehicles or did not account for them at all. Currently, no bus–pavement interaction models are available, although several mathematical and simulation models are available for truck-pavement interaction. Buses differ from trucks in load distribution, suspension, and travel characteristics. From results of the literature search a methodology, which uses industry standards and is minimal in data requirements, has been developed. With the use of data available in New Jersey, the application of this methodology showed that the maintenance cost attributable to buses in the state is about 2.4% of the total maintenance cost.
From Rural Single-County to Multicounty Regional Transit Systems: Benefits of Consolidation
Authors: Cook Thomas J. , Lawrie Judson J. , Henry Andrew J.
Published: April 2007

A research study developed recommendations for activities to consolidate single-county rural public transportation systems into regional multicounty transit systems in North Carolina. The study identified opportunities from regionalization of public transit services, examined barriers to integration and consolidation of transit systems regionally, evaluated best practices from case study sites, and made recommendations for programmatic and legislative changes to facilitate the implementation of regional transit systems in both metropolitan and rural areas of the state. Emphasis is on the rural component of the study, in summarizing regionalization issues and recommendations for the consolidation of rural single-county into multicounty transit systems. Consolidation of rural public transportation systems into regional entities is another step in further coordinating public transportation services in the state. However, there is a public transportation system now operating in all 100 North Carolina counties. Therefore, the thrust of regionalization will be to consolidate existing rural transportation systems into regional entities. There are key programmatic and legislative aspects of interest to state departments of transportation, transportation planners, and policymakers. Case studies also gathered information from associated state department of transportation staff, to include both the state and local perspectives on regional rural transportation systems.
Developing Coordination Policies for Paratransit and the Transportation Disadvantaged
Authors: Schlossberg Marc
Published: April 2007

Many social service agencies, for example, those serving the elderly, people with mental illness, or those in poverty and looking for work, operate their own van service for their own clientele. That type of service, if viewed regionally, is often duplicative and inefficient. The duplicative approach toward serving transportation-disadvantaged people has led to coordination as a policy response. However, key elements that policy makers need to consider are usually not well understood or delineated. There are four key factors and six subfactors that should be addressed in the pursuit of statewide policies of transportation coordination. The four key factors are to explicitly define what coordination means, to pursue efforts of coordination at the state level, to understand the political climate within which coordination policy will be presented, and to promote decisions on local coordination support. Finally, a new model of service delivery, the Community Support Organization, is presented as one way to better achieve positive results when coordination is pursued as a strategy for improving the efficiency and reach of local services to the transportation disadvantaged.
U.S. Shared-Use Vehicle Survey Findings on Carsharing and Station Car Growth: Obstacles and Opportunities
Authors: Shaheen Susan A. , Meyn Mollyanne , Wipyewski Kamill
Published: April 2007

Shared-use vehicle services provide members with access to a vehicle fleet for use as needed, without the hassles and costs of individual automobile ownership. From June 2001 to July 2002, there was a survey of 18 U.S. shared-use vehicle organizations on a range of topics, including organizational size, partnerships, pricing, costs, and technology. Although survey findings demonstrate a decline in the number of organizational starts in the last year, operational launches into new cities, membership, and fleet size continue to increase. Several growth-oriented organizations are responsible for most of this expansion. Several factors were explored that challenge shared-use vehicle growth, such as high capital investment (or start-up costs), dramatic insurance rate hikes, and scarcity of cost-effective technologies. Although the findings of early niche markets are encouraging, the ability of this emerging sector to actualize its total environmental, economic, and social goals may be limited without the collective support of private industry (e.g., automobile manufacturers, insurance providers, technology producers); public agents (e.g., transit and governmental agencies); and shared-use vehicle programs. Indeed, public–private partnerships and cooperation among shared-use vehicle providers may play a key role in addressing insurance and technology costs and ensuring the long-term viability of this market.
Generating Transit Performance Measures with Archived Data
Authors: Bertini Robert L. , El-Geneidy Ahmed
Published: April 2007

Measuring the performance of a transit system is the first step toward efficient and proactive management. Since 1990, the use of performance measures for transportation planning and operations has gained a great deal of attention, particularly as transportation agencies are required to provide service with diminishing resources. In the past, it was very difficult and costly to collect comprehensive performance data. Thus, until recently, the transit industry has relied on limited, general, and aggregate measures for reporting performance to external funding and regulatory agencies. In Portland, Oregon, the local transit provider (TriMet) has developed a bus dispatch system (BDS) consisting of automatic vehicle location, communications, automatic passenger counters, and a central dispatch center. Most significantly, TriMet had the foresight to develop a system to archive all of its stop-level data, which are then available for conversion to performance indicators. It is demonstrated that there are powerful ways in which the data collected by the BDS can be converted into potentially valuable Transit Performance Measures (TPMs). These TPMs have been proposed in the past but were not implemented because of data limitations. It is envisioned that systematic use of TPMs can assist a transit agency in improving the quality and reliability of its service, leading to improvements for customers and operators alike.
Estimation of Bus Dwell Times with Automatic Passenger Counter Information
Authors: Rajbhandari Rajat , Chien Steven I. , Daniel Janice R.
Published: April 2007

The average passenger boarding and alighting times and bus dwell times at stops are important information for estimating transit service capacities. Bus dwell time directly affects vehicle travel time, and thus the fleet size required to provide service based on scheduled headway is affected. Research focused on estimating bus dwell time and the impact of boarding and alighting passengers on dwell time. In addition, the effect of standees, time of day, and service type on bus dwell time was investigated. The data were recently collected from an archived database, within which automatic passenger counter information was recorded. The dwell times and passenger counts were recorded daily during 2001 and the first 6 months of 2002. The bus dwell time and average passenger boarding and alighting time at stops are explained using descriptive statistics.
Florida Metropolitan Planning Organization Reports on Transit Capacity and Quality of Service: First-Year Evaluation
Authors: Perk Victoria A. , Foreman Chandra
Published: April 2007

As an application of the transit quality-of-service framework presented in the first edition of the Transit Capacity and Quality of Service Manual (TCQSM), the Florida Department of Transportation required all metropolitan planning organizations (MPOs) in the state where fixed-route transit service operates to analyze those services on the basis of the six measures identified in the TCQSM: service frequency, hours of service, service coverage, passenger loading, reliability (on-time performance and headway adherence), and transit versus automobile travel time. A first-year evaluation compiles the analyses provided by the participating MPOs and provides an assessment of the aggregate performance of the transit systems. A larger part of the study focused on the examination of the actual process used by the MPOs and transit systems to evaluate their services. Changes recommended to improve and refine the process for future years are presented, based on the first-time experiences of the MPOs. This evaluation serves as a model for other areas in the country interested in applying the customer-oriented assessment of transit based on the TCQSM.
Sales and Impact of Class 2b Trucks
Authors: Davis Stacy C. , Truett Lorena F.
Published: April 2007

Vehicles in the upper portion of the Class 2 weight range [6,000 to 10,000 lb gross vehicle weight rating (GVWR)] were identified and examined, and their impact was assessed. Class 2b vehicles (GVWR of 8,500 to 10,000 lb) include pickup trucks, sport utility vehicles, and large vans. Oak Ridge National Laboratory researched each individual truck model to determine which models were Class 2b trucks and developed four methodologies to derive sales volumes. Two methods were recommended for producing believable and reliable results. The results of the study indicate that in calendar year 1999, 521,000 Class 2b vehicles (6.4% of sales of all trucks under 10,000 lb) were sold; 82% of Class 2b vehicles sold were pickups, and one-third of Class 2b vehicles sold had diesel engines. In 2000, 5.8 million Class 2b vehicles (7.8% of all trucks under 10,000 lb) were on the road; 24% of the Class 2b vehicle population had diesel engines, and Class 2b vehicles accounted for 8% of annual miles traveled by trucks under 10,000 lb and 9% of fuel use. Data on Class 2b vehicles are scarce. As the Tier 2 standards (which apply to passenger vehicles in the 8,500 to 10,000 lb GVWR category) become effective, additional data—not only about emissions, but also about all areas—on Class 2b vehicles may become available. At the moment, distinguishing Class 2b vehicles from all Class 2 vehicles is a substantial task that requires individual model data.
Composite Exhaust Emissions Rates: Sensitivity to Vehicle Population and Mileage Accrual Assumptions
Authors: Kear Tom , Niemeier Deb
Published: April 2007

In the California Air Resources Board’s newest model of mobile-source emissions, EMFAC 2002, vehicle population and mileage accrual data have been revised such that regional vehicle miles traveled (VMT) are calculated from vehicle population and accrual data [rather than directly, using metropolitan planning organization (MPO) estimates]. Calculated VMT is forced to match the MPO VMT estimate by scaling the mileage accrual rates and altering vehicle population data. Vehicle population and mileage accrual data also determine how VMT is allocated across the vehicle model years present in the vehicle fleet; thus, modification of these data also changes the fraction of the VMT associated with each model year in the vehicle fleet. Composite emissions rates were estimated based on various vehicle population and mileage accrual data. Small perturbations in age distributions and accrual data have a larger-than-expected impact on the composite emissions rates for light-duty automobiles. For example, total organic gas emissions varied by nearly a factor of 3 between the lowest and highest estimated emissions rates, and either emissions rate could justifiably be used in an inventory. Recommendations for VMT and accrual data in subsequent release of EMFAC 2002 are provided, giving preference to the methods used by the U.S. Environmental Protection Agency.
Problem Driving Maneuvers of Elderly Drivers
Authors: Chandraratna Susantha , Stamatiadis Nikiforos
Published: April 2007

Older drivers, who are the fastest growing segment of the U.S. population, experience high crash rates. An analysis was performed to evaluate potential problem maneuvers that may lead to higher crash involvement. Left turns against oncoming traffic, gap acceptance for crossing non-limited-access highways, and high-speed lane changes on limited-access highways are identified as such maneuvers. Older and younger driver accident propensities are measured, using Kentucky crash data. The findings of the analysis show that older drivers are more likely to be involved in crashes related with these maneuvers compared with younger drivers; older male drivers are safer than older female drivers in left-turn crashes and gap acceptance–related crashes, and having a passenger beside the older drivers makes for a safer driving environment. Potential countermeasures aiming to reduce the accident rates of older drivers are discussed.
Dancing Diamonds in Highway Work Zones: Evaluation of Arrow-Panel Caution Displays
Authors: Turley Brent M. , Saito Mitsuru , Sherman Samuel E.
Published: April 2007

Arrow panels, consisting of a matrix of lights, symbolically convey additional warning to motorists. Nondirectional arrow-panel displays are designated as caution displays. Before 2001, literature lacked significant statistical support for any one type of caution display. A 2001 Oregon Department of Transportation (ODOT) study suggested that the “dancing diamonds” display performs in the field as well as, if not better than, other caution displays. ODOT also found that local citizens preferred the dancing diamonds to other caution displays. However, additional research was needed to confirm these findings. The Utah Department of Transportation has used the dancing diamonds display since June 1972. To evaluate the effectiveness of the dancing diamonds and “flashing box” displays, a field experiment was conducted. The results of this experiment show that the dancing diamond was associated with a statistically significant 3 km/h (2 mph) reduction in mean speeds, whereas the flashing box display was associated with no statistically significant reduction in mean speeds, indicating that the dancing diamonds prompt safety near highway work better than the flashing box. A comprehension–opinion survey was also conducted. Regardless of caution-display type, most of the 412 respondents would “slow down” upon seeing any one, and they understood the meaning of the display to be “use caution ahead.” Fifty-four percent of drivers thought that use of the dancing diamonds would best prompt safe driving, followed by the “flashing diamonds” (43%), and the flashing box (3%). For getting attention, 94% said the flashing box was the least effective.
Driver Understanding of Pavement Marking Colors and Patterns
Authors: Parham Angelia H. , Womack Katie N. , Hawkins H. Gene
Published: April 2007

Driver understanding of the current U.S. system of yellow–white pavement markings was assessed through a driver survey. The survey was used to evaluate drivers’ ability to describe the pavement marking color code, drivers’ reliance on pavement marking patterns when interpreting marking messages, and drivers’ reliance on pavement marking color when interpreting marking messages. Researchers surveyed 851 drivers in 5 states, with respondents representing 47 states, the District of Columbia, and Puerto Rico. The survey results indicate that drivers tend to use signs and other traffic as the primary cue to determine whether a road is one-way or two-way. A substantial proportion of respondents had an understanding of the use of marking color to differentiate between one-way and two-way roads, but this knowledge is not the primary tool that drivers use to distinguish the direction of travel on a road. Approximately 75% of the drivers surveyed understood the basic concept that a single broken yellow line separates opposing traffic on a two-lane road. The presence of a solid line (either double solid or solid and broken) in the centerline increases comprehension of directional flow to approximately 85%; more than 90% of the drivers surveyed understood that a solid line (either double solid or solid and broken) prohibits passing. Almost 95% of drivers indicated that passing is permitted with a broken line. The survey results indicate that the yellow–white pavement marking system is better understood than previously believed.
Legibility of Overhead Guide Signs with Encapsulated Versus Microprismatic Retroreflective Sheeting
Authors: Carlson Paul J. , Hawkins Gene
Published: April 2007

A study was conducted to determine the legibility impacts of freeway guide signs when encapsulated retroreflective sheeting is replaced with microprismatic retroreflective sheeting. The study included freeway guide signs mounted in an overhead position and exclusively illuminated with vehicle headlamps. A total of 60 subjects divided into three age groups participated in this nighttime study. All 60 subjects drove two vehicles, a modern sport utility vehicle (SUV) and a late-model passenger car. The findings show that microprismatic sheeting does provide statistically longer legibility distances than encapsulated sheeting. Overall, the improvement was 53 ft, or 9.5%. However, for the modern SUV, the improvement was much greater (78 ft) compared with the late-model passenger car (28 ft). The main differences are related to the evolution of vehicle design and specifications. Today’s United States citizens prefer large vehicles such as an SUV, pickup, and minivan. These vehicles also meet recently revised headlamp specifications. These two issues inherently reduce the amount of headlamp light retroreflected from the sign back to the driver. Unfortunately, these counterproductive trends show signs of continuing. Considering the increasing proportion of older drivers in the United States, it becomes even more critical that transportation agencies do all they can to increase overhead-sign luminance. The findings show that increasing overhead-sign luminance by switching from encapsulated retroreflective sheeting to microprismatic retro-reflective sheeting results in significantly longer legibility distances. The magnitude of the difference will continue to increase as long as the SUV-like proportion of the U.S. fleet continues to grow and headlamp specifications continue to direct less light toward overhead signs.
Forecasting Train Travel Times at At-Grade Crossings
Authors: Cho Hanseon , Rilett Laurence R.
Published: April 2007

The ability to accurately forecast train arrival times is essential for the safe and efficient operation of highway–railroad grade crossings (HRGCs). Trains in the United States are required to give a minimum of 20 s of warning time before arriving at an HRGC. With the recent development of new detection-equipment technology, detectors potentially could be employed further upstream of the HRGC, which would result in earlier detection times. This information would be particularly useful for preemption strategies at signalized intersections located near the HRGC (IHRGCs). For example, earlier warning times could be used to reduce or eliminate the risk of unsafe pedestrian movements at IHRGCs. In this study, a modular artificial neural network (ANN) was used to forecast the train arrival time at an HRGC. An ANN was adopted because there is a nonlinear relationship between the independent variables such as train speed profile and the dependent variable arrival time at an HRGC. A modular approach was used because the trains often have different characteristics depending on their cargo and the operational rules in effect at the time they are detected. Because the train detection is continuous, different models were developed for each separate data input. In this case, the prediction interval update was assumed to be 10 s and 24 models were developed. Approximately 499 trains were used for training the ANN and 183 trains were used for testing. It was found that a modular architecture gave superior results to that of a simple ANN model, standard regression techniques, and current forecasting methods for the entire detection time period. It was found that, with an increase in detection time, the forecast accuracy increases for all methods and the prediction interval tends to decrease.
Fundamental Flaws in the Appearance of Bridges
Authors: Burke Martin P.
Published: April 2007

Many papers on bridge aesthetics design focus almost exclusively on the importance of certain visual qualities (i.e., harmony, unity, balance) as necessary distinguishing characteristics of beautiful bridges. Although each of these papers has considerable merit, their required brevity and limited focus provide only a superficial view of an effective bridge design process. Also, for the elucidation of aesthetic subject matter for bridge design novices, these papers appear to be inappropriate for several other reasons. First, they imply that a vague abstraction such as “beautiful” is a legitimate goal for a design effort. Second, the emphasis on a structure’s primary visual qualities mistakenly presumes that the complete silhouette of a highway bridge will generally be seen and evaluated by distant observers. Finally, these papers generally fail to mention fundamental flaws due to design, construction, and maintenance neglect and carelessness that can spoil the appearance of a bridge, even one that has been well designed in most other respects. These issues are discussed, and it is suggested that, instead of attempting to achieve beautiful bridges by a preoccupation with abstract visual qualities, a highway bridge designer’s attention should be devoted first and primarily to the avoidance or prevention of well-defined and easily recognizable bridge aesthetic flaws, many of which are described and discussed here. Thereafter, designers’ attention can be devoted to the adjustment of a bridge’s structural characteristics and visible aspects to satisfy both functional requirements and cost limitations and to simultaneously improve a structure’s visual qualities to the extent that some observers may be provoked to exclaim “beautiful” when they first view a designer’s work.
Landmark Cable-Stayed Bridge over the Charles River, Boston, Massachusetts
Authors: Chandra Vijay , Ricci Anthony L. , Towell Paul J. , Donington Keith
Published: April 2007

Boston, in the forefront of the American Revolution two centuries ago, is now in the forefront of another revolution in the field of cable-stayed bridge technology. New technologies and innovations have become hallmarks of the Leonard P. Zakim Bunker Hill Bridge—a structure unique in the world. This crossing of the Charles River brought the community, engineers, and architects together to create a “signature bridge” and a “gateway” to the city. Located at a preeminent point where Paul Revere crossed in 1775, the bridge took on special meaning from a historical perspective. Numerous alternatives were studied for the crossing and the interchange configurations on both sides of the river. Based on significant community input and evaluation of costs for different alternatives, the option known as the “non-river tunnel” alternative was chosen, which required a 10-lane crossing of the river. The 10 lanes include 4 lanes each for I-93 northbound and southbound and a 2-lane ramp on the east side. Some impediments the bridge had to contend with included the Orange Line subway adjacent to and below the bridge; the close proximity of the Charles River lock and dam and the need to maintain navigation; a major water main in the area of the south tower footing; a cantilevered 2-lane ramp on only one side of the structure; the existing Storrow Drive ramps at the south end, dictating the arrangement of the stay cables in the back spans; and a new tunnel at the south end of the structure.
Measurement and Evaluation of Mooring Cable Forces During Storm Events on the Evergreen Point Floating Bridge: Lake Washington, Washington State
Authors: Peterson Scott T. , McLean David I. , Anderson Mark , Pollock David G.
Published: April 2007

On January 20, 1993, the Evergreen Point Floating Bridge incurred structural damage at two mooring cables and at various other locations during a storm event of approximately the 20-year return period magnitude. The two mooring cables damaged were the shorter and stiffer cables located at the ends of the bridge and were likely damaged because of load attraction issues. To improve the performance of the floating bridge during storms, special replacement cables were installed after the 1993 storm near the areas where cable distress was noted. Measurements of cable forces were made during the winter season of 2001–2002 to evaluate the effectiveness of the replacement mooring cables. From the experimental measurements, it was found that the special replacement mooring cables have reduced the load attraction at the shorter end cables with respect to cable tension values reported for the pre-retrofit analysis. However, the measurements indicate that the replacement cables continue to attract loads between 65% and 80% higher than those measured at the longer and more flexible cables located near the midspan of the floating bridge during storm events of approximately the 1-year return period magnitude.
Reliability-Based Optimal Inspection for Fracture-Critical Steel Bridge Members
Authors: Chung Hsin-Yang , Manuel Lance , Frank Karl H.
Published: April 2007

To prevent fatigue failure of members in steel bridges, one usually needs to perform frequent periodic bridge inspections and employ detailed inspection methods. This is especially true for fracture-critical members or details. Carrying out these inspections puts a large burden on a transportation agency’s bridge maintenance budget. A systematic reliabilitybased method for inspection scheduling is proposed to yield the most economical inspection strategy for steel bridges that, at the same time, guarantees an acceptable safety level through the planned service life. A methodology is presented for evaluating the fatigue reliability of a specified detail classified according to AASHTO fatigue categories. A Miner’s rule approach is used to evaluate the fatigue reliability. The inspection scheduling problem is modeled as an optimization problem with a welldefined objective function that includes the total expected cost of inspection, repair, and failure formulated on the basis of an event tree framework and appropriate constraints in inspection intervals and minimum (target) structural reliability. An optimal inspection-scheduling plan can thus be obtained for any specified fatigue details (fracture-critical details) in steel bridges. Examples presented demonstrate the advantage of the reliabilitybased optimal inspection scheduling in cost saving and structural reliability control over alternative periodic inspection plans. Two numerical examples for a steel bridge in Texas are presented to demonstrate the proposed reliability-based optimal inspection scheduling.
Effects of Distortion on Strength of Curved I-Shaped Bridge Girders
Authors: Davidson James S. , Yoo Chai H.
Published: April 2007

The curved I-shaped plate girders used in bridges with curved alignment are subjected to forces that cause significant distortion of the cross section during construction and during application of live loads after the deck has hardened. Furthermore, the addition of curvature reduces the vertical bending stiffness, increases deflection nonlinearities, and changes stability characteristics of behavior. Although the design equations of the AASHTO Guide Specifications for Horizontally Curved Highway Bridges are formulated to address these behavioral issues, design and construction engineers often are not familiar with the difficulties curvature introduces and do not understand the relationship between distortion and deflection amplification with the design equations. Analytical research conducted as part of the FHWA Curved Steel Bridge Research Project was used to highlight and describe the effects of curvature on the strength and stability of curved I-girder bridge superstructures. Issues described include the following: ( a) effects of cross-frame and diaphragm spacing on system behavior, ( b) effects of curvature on the lateral-torsional stability of curved I-shaped beams, ( c) effects of warping stresses on flange buckling, ( d) effects of curvature on web behavior, and ( e) effects of curvature on initiation and propagation of yield stresses in the girders of curved I-girder frames.
Examination of Response of a Skewed Steel Bridge Superstructure During Deck Placement
Authors: Norton Elizabeth K. , Linzell Daniel G. , Laman Jeffrey A.
Published: April 2007

The response of a 74.45-m (244-ft 0-in.) skewed bridge to the placement of the concrete deck was monitored to compare measured and predicted behavior. This comparison was completed to ( a) determine theoretical deflections and rotations with analytical models for comparison to actual deformations monitored during construction; ( b) compare the results of various levels of analysis to determine the adequacy of the methods; and ( c) examine variations on the concrete placement sequence to determine the most efficient deck placement methods. Two levels of analysis were used to achieve the objectives. Level 1 was a two-dimensional finite element grillage model analyzed with STAAD/Pro. Level 2 was a three-dimensional finite element model analyzed with SAP2000. These studies are discussed and findings are presented.
Comparative Bond Study of Stainless and High-Chromium Reinforcing Bars in Concrete
Authors: Ahlborn Theresa M. , DenHartigh Timothy C.
Published: April 2007

Concrete bridge decks in corrosive environments have used several methods to prevent corrosion of the reinforcing steel including the use of alternative steels as reinforcement. While research has been conducted on corrosion resistance, very little information is available about the bond strength of alternative metallic reinforcement such as solid stainless steels and high-strength, high-chromium (HSHC) alloys. Therefore, the tensile bond strengths of three alternative metallic steel reinforcements in concrete are compared with conventional A615 Grade 60 steel reinforcement. Two types of stainless steel were considered, 316LN and 2205 duplex. An HSHC microcomposite bar was also considered. A total of 250 bond tests were performed with beam-end specimens similar to the ASTM A944 specimen. Bonded lengths of 4 to 12 in. were used for No. 4 and No. 6 reinforcing bars. Concrete clear cover for all tests was 1½ in. to produce cracking bond failure. No transverse reinforcement was present. The normal strength concrete was typical of that used in Michigan bridge decks. Statistical comparisons of bond test results with predicted values for bond strength of A615 reinforcement revealed there was no reason to believe the bond strength of the alternative metallic reinforcing bars was less than predicted. The conservatism of the current development-length relationships generally predicted lower bond strengths than were observed. Therefore, no modifications are suggested when estimating the development length of these reinforcements as a one-to-one replacement for A615 Grade 60 reinforcement, No. 4 to No. 6 bars, using standard development-length relationships.
Recent Experience with High-Performance Concrete Jointless Bridges in Tennessee
Authors: Knickerbocker David J. , Basu Prodyot K. , Holloran Mark A. , Wasserman Edward P.
Published: April 2007

Experimental and analytical studies of two high-performance concrete (HPC) jointless bridges with integral abutments built in Tennessee as part of the FHWA’s nationwide initiative to implement HPC in bridge structures are presented. Performance of the two bridges is observed through all stages of construction and service to date, via material testing, bridge instrumentation for both short- and long-term performance monitoring, and live-load testing. The up-to-date observed performance of the bridges reveals the success of such bridge construction. Local contractors were found to be capable of producing concrete to meet increased requirements in strength and durability parameters. In addition, new insights were derived about HPC behavior in such applications, identifying the areas requiring updating of current practice. Load test data revealed that load distribution among the girders is in marked difference from codes of practice. Thermal response of the bridges indicated longitudinal flexibility offered by the jointless construction.