bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Cohesive Material Properties on Local Scour Around Piers
Authors: Molinas Albert , Jones Sterling , Hosny Magdy
Published: April 2007

Local pier scour has been the topic of numerous research studies on noncohesive alluvial materials. However, because of the complexities involved in cohesive-material scour, very little effort has been devoted to the study of scour around bridge piers situated in cohesive materials. The parameters that affect the scour mechanism at bridge piers located in saturated and unsaturated clayey soils are identified, and prediction equations for quantification of the effects of some of the cohesive properties on the resulting local scour are developed. The scour depth predictors developed from the analysis of the experimental data express pier scour in terms of the approach flow conditions, initial water content, compaction, and soil shear strength of the cohesive bed materials. These predictors are related to scour in noncohesive alluvial material to derive factors that express clay scour as a percentage of sand scour. At bridge locations where exact soil properties are unknown, these estimators may be used to provide bounds to scour estimations.
Efficacy of Safety-Related Investments To Reduce Fatalities on the East Japan Railway
Authors: Barnett Arnold I. , Martland Carl D. , Odoni Amedeo R. , Sussman Joseph M.
Published: April 2007

In any organization there is a limit on the amount of resources that can be used for risk reduction. By examining strategies for reducing the risk of fatalities on the East Japan Railway (JR East), a framework in which risk-reduction resources can be used well is described. Basic principles of risk assessment are introduced. Various analyses and models to study collisions, earthquake effects, level-crossing accidents, and operating policies regarding natural hazards are presented. The concept of a global risk assessment of JR East is included. The question of perceived versus objective risk is discussed in the context of safety-related investment.
Changeable Message Sign Messages for Work Zones: Time of Day, Days of Week, and Month Dates
Authors: Dudek Conrad L.
Published: April 2007

The New Jersey Department of Transportation initiated a research study designed in part to further the state of knowledge of changeable message sign message design with specific application to the needs in New Jersey. Laboratory studies of human factors are described here; the studies were conducted in New Jersey to evaluate shorter alternative messages than those currently used to display time of day, days of week, and calendar dates. These types of messages are often displayed on portable changeable message signs used in highway work zones. Among the findings were that a dash can be used instead of the term Thru to indicate roadwork for a range of successive days; the term Weekend is not a good descriptor for work that begins on Friday evening and ends on Monday morning; the term Days did not connote specific daytime, off-peak times for roadwork, but it may be satisfactory for certain time periods; likewise, the term Nights did not connote specific nighttime, off-peak times for roadwork, but it may be satisfactory for certain time periods; Nite is an acceptable substitute for Night; and calendar dates were not easily translated by drivers to specific days of the week.
Performance Comparison of Three Freeway Guide Sign Alphabets
Authors: Gene Hawkins H. , Picha Dale L. , Wooldridge Mark D. , Greene Francis K. , Brinkmeyer Greg
Published: April 2007

Modern fully retroreflective legends can create a blooming effect that reduces legibility. In this research project three alphabets were evaluated to determine whether the legibility of a white high-intensity legend on a green high-intensity background could be improved by reducing the blooming effect. The three alphabets were: Series E(Modified), Clearview, and British Transport Medium. Overhead and ground-mounted sign positions were evaluated in both daytime and nighttime conditions. There was no sign illumination for the nighttime conditions other than the vehicle headlights. Both legibility (unknown word) and recognition (known word) distances were measured. A total of 54 subjects participated in both daytime and nighttime trials. There was significant variability in the results of the various experimental conditions. In general, the results indicated that Clearview was slightly more legible than Series E(Modified) in the overhead position in both daytime and nighttime conditions. The extent of improvement over Series E(Modified) was generally in the range 2 to 8 percent. The greatest improvement was achieved for worst-case drivers. Clearview ground-mounted signs were less legible than Series E(Modified) in daytime conditions. In nighttime conditions, the ground-mounted Clearview signs did not demonstrate a consistently better performance than Series E(Modified). A greater degree of improvement was realized in the recognition of Clearview in the overhead position for both day and night conditions. British Transport Medium was generally less legible than Series E(Modified).
Influence of Pavement Surface Characteristics on Nighttime Visibility of Objects
Authors: Hasan Khan Mainul , Senadheera Sanjaya , Gransberg Douglas D. , Stemprok Roman
Published: April 2007

Vehicle headlights do not light enough of a roadway length for safe nighttime driving at higher driving speeds. Therefore, particularly on highways with high traffic levels, fixed roadway lighting enables safe nighttime driving conditions. Roadway lighting design has evolved over the years from the illumination method, which is based on the amount of light falling on the road surface, to the luminance-and visibility-based methods that are in use today. Visibility of an object on the roadway is directly related to the contrast between the object and its surroundings. In nighttime driving situations, the pavement acts as the background for most objects on the road. Therefore, reflectance characteristics of the pavement are important in visibility-based roadway lighting design processes. Currently, pavement reflectance characteristics are incorporated through four standard reflectance tables ( r-tables) developed to represent portland cement concrete, open-graded asphalt concrete, seal coat, and dense friction coarse asphalt pavements. In this research, the computer program STV developed by M. E. Keck, which calculates pavement luminance and visibility level, was used for a sensitivity analysis to evaluate how the pavement type and the standard r-tables influence these parameters. The analysis was conducted for fixed roadway lighting situations without the influence of vehicle headlights. Results from the sensitivity analysis indicated that standard r-tables are not sufficient to model the whole spectrum of pavement surfaces encountered in practice. An analysis of pavement reflectance data collected by the Road and Transportation Association of Canada revealed that asphalt-based pavements tend to increase their specularity and brightness with age, whereas portland cement concrete pavements display a decreasing trend.
Driver-Headlamp Dimensions, Driver Characteristics, and Vehicle and Environmental Factors in Retroreflective Target Visibility Calculations
Authors: Zwahlen Helmut T. , Schnell Thomas
Published: April 2007

The inputs that are necessary for comprehensive visibility models are discussed. Inputs required by visibility models may deal with the physical arrangement of the observer and headlamps in three-dimensional space, the headlamp characteristics in terms of candlepower output and efficiency, observer age, observation time, probability of detection, and minimum preview time. There are also a number of environmental and vehicular parameters such as horizon sky luminance, atmospheric transmissivity, and windshield transmission. One problem associated with using comprehensive visibility models is the lack of standards, guidelines, and recommendations for the required model inputs. Consequently, it is currently difficult or even impossible to duplicate visibility model runs reported by others. Standardized headlamp-observer-target scenarios, standardized observer characteristics, and standardized environmental parameters would greatly facilitate cross-validation of model outputs. Numerous model input dimensions and values that are based on the technical literature are provided here. However, because there are no comprehensive eye location percentile dimensions available for late-model automobiles and for recent anthropometric dimensions, an exploratory vehicle survey was conducted and the measured vehicular dimensions were combined with anthropometric dimensions extracted from the 1988 U.S. Army personnel survey. The result of this effort is a table that shows the driver eye locations as a function of the population percentile, observer gender, and vehicle class. Further results include data pertaining to the location of low-beam headlamps. The recommended model input values should be considered for adoption as a standard that would facilitate easier cross-validation of visibility model results.
Comparative Study of Rural Stop-Controlled and Beacon-Controlled Intersections
Authors: Pant Prahlad D. , Park Yongjin , Neti Subbarao V. , Hossain Akhter B.
Published: April 2007

The characteristics of traffic flow at rural, low-volume intersections controlled by stop signs and by intersection control beacons plus stop signs were examined. The measures of effectiveness included vehicular speeds, stop-sign violations, service delay, gap acceptance, and accidents. In addition, the effects of sight distance, traffic volume, and day and night conditions were also considered. It was found that intersection control beacons generally reduced vehicular speeds in the major directions, particularly at intersections with inadequate sight distance. The intersection control beacons had, in general, little or no effect on accepted or rejected gaps and on service delays. A large proportion of drivers (40 to 90 percent) violated stop-sign laws by not completely stopping at the intersections, which indicates that intersection control beacons were not effective in reducing stop-sign violations. Intersection control beacons did not appear to be effective in reducing accidents.
Adapting Safety Audits for Small Cities
Authors: Haiar Keith A. , Wilson Eugene M.
Published: April 2007

Research has developed a practical approach for identifying street safety needs for local governments, which are responsible for a large amount of street kilometers carrying relatively low traffic volumes. The improvement of safety on these streets is given only limited focus in most small cities. Due to the limited funding, manpower, and traffic engineering expertise available, traditional safety improvement programs generally are beyond the means of these agencies. An effective safety program needs to recognize the reality of local governments. A regional survey was conducted to examine the current methods and practices used by city traffic-safety programs. Results from this survey were used to develop a Street Safety Audit procedure. A set of simple checklists covering fundamental intersection and traffic sign issues also was developed. This procedure is a useful tool for small cities to begin addressing basic safety needs on their streets.
Safety Review of Highway 407: Confronting Two Myths
Authors: Hauer Ezra
Published: April 2007

It often is alleged that highways built to standards are safe and that roads do not cause crashes, only humans do. These two myths were at the center of a public debate when a new, fully electronic, toll freeway was built in Canada north of Toronto. Before it was opened for use, the police raised doubts about the safety of its design. The minister of transport asked for a professional safety review. The safety review committee had to confront the aforementioned two myths. Some of its arguments and conclusions are reviewed. Once the myths are recognized for what they are, one is led to useful conclusions. For transportation professionals, the main conclusion is that merely designing to standards is not a sufficient safeguard.
Recorded Traffic Offenses of Graduates of Traffic Safety School, Cook County, Illinois
Authors: Raub Richard A. , Wark Richard I. , Reischl Broderick E. , Lucke Roy E.
Published: April 2007

The retraining of drivers who have received their first traffic citation has been examined for effectiveness. Unlike most other driver-intervention programs that focus on problem drivers, this one focuses on all drivers the first time they violate a traffic law and are convicted. The measure used for assessment was subsequent violations of traffic laws. For the study of subsequent violations, potential students for a traffic safety school 4-h training course were divided into a control group and an experimental group. The former received a letter waiving them from having to attend because of “scheduling conflicts.” The latter attended the course. Examined were the number of traffic-law violations and the number of times drivers were stopped for a violation (because drivers may receive one or more traffic citations on a traffic stop), comparing both groups before and after the training. Also, survival analysis was applied to determine whether those receiving training were as likely to fail in the same period as the control group. Those who had the training received significantly fewer traffic citations after training up to the first 6 months. After that period, both groups received citations at approximately the same rate, although the gap between the experimental group and the control group continued to widen, even after 12 months. For traffic stops, the differences were not as pronounced, although the individuals in the control group continued to be stopped for violations at a higher rate than those in the experimental group. The survival analysis showed a strong difference for the first 90 days after training. As a result, the traffic safety school is going to experiment with a follow-up intervention at the 90-day period.
Impact of Passengers on Young Driver Safety
Authors: Aldridge Brian , Himmler Meredith , Aultman-Hall Lisa , Stamatiadis Nikiforos
Published: April 2007

An analysis of young driver accidents uses the quasi-induced exposure technique to disaggregate accidents by different characteristics or circumstances while making estimates of the relative travel exposure for those different circumstances. Relationships are developed to investigate the effect of passengers on young driver (age 16 to 20) accident propensity. Three passenger groupings are used: solo (no passengers), peer, and adult or child. The database contains 77,312 accidents involving young drivers in Kentucky in 1994, 1995, and 1996. The passenger-group variable was found to have a significant effect on young driver accident propensities. Young drivers have the lowest propensity to cause single- or two-vehicle accidents when traveling with either adults and/or children. They have an increased propensity for causing single-vehicle accidents when traveling with peers. The relative accident involvement ratios for both single- and two-vehicle accidents for young drivers traveling alone were close to 1.0, suggesting that they were at fault approximately the same percentage of the time that they were not at fault. Seven variables were considered for possible interaction with passenger group: driver gender, total occupant gender, time of week, time of day, highway type, vehicle age, and safety-restraint usage.
Investigation of Effectiveness of Media Advertising and Police Enforcement in Reducing Red-Light Violations
Authors: Tarawneh Tarek M. , Singh Virendra A. , Mccoy Patrick T.
Published: April 2007

Research was conducted to evaluate the effectiveness of an organized public information and education program coupled with targeted police enforcement in deterring red-light-running activity at signalized intersections. To achieve the objectives of this research, data were obtained for six signalized intersections, using video technology. The field data included seven variables that assess drivers’ behavior about the yellow and red signal indications. Data were collected before and after a public information and education program that was implemented for 1 month. The study results indicate that, generally, the combination of public information and education programs and targeted enforcement does have a significant impact on the behavior of drivers approaching an intersection after the onset of the yellow light. No significant differences were found between the effects of these two treatments, however. Therefore, it can be inferred that right-angle accidents resulting from red-light running possibly can be reduced through the implementation of public information and education programs. These changes among drivers indicate that such programs are effective in deterring red-light violations at signalized intersections. The implication of this result is that governmental agencies should consider allocating more funds toward traffic safety–oriented educational and enforcement programs. With video surveillance’s impact in this project taken into consideration, automated enforcement technologies, such as red-light-running surveillance cameras, should be evaluated for further use at signalized intersections.
Age and Gender as Predictors of Injury Severity in Broadside and Angle Vehicular Collisions
Authors: Mercier Cletus R. , Shelley Mack C. , Adkins Geneva H. , Mercier Joyce M.
Published: April 2007

Is age a factor in injury severity in the occurrence of broadside and angle collisions of automobiles on rural highways? The primary hypothesis is that older drivers and passengers would suffer more severe injuries than younger adults when involved in these types of collisions. Injury severity was chosen as the dependent variable, with nine independent or interaction variables tested. Independent variables were selected if they improved the model significantly, at a significance level of p < .05. Relationships were verified using Hierarchical Regression Analysis and Principal Components Regression. Findings varied, depending on the point-of-impact examined and the vehicle occupant gender. Age (linear and quadratic) proved to be a significant predictor of injury severity for all, but it was slightly greater for females than for males. Use of lap and shoulder restraints proved to reduce injury severity, but results are less certain for women. Air bags deployed were significant predictors when the vehicle was struck in the rear third, but only for females. One of the study’s surprises was the lack of strength of the variable of occupant position relative to the point-of-impact, except as part of interaction variables with age—both linear and quadratic. Position refers to the location of the occupant relative to the point-of-impact, with the position furthest from impact presumed as being the safest.
Tomorrow’s Older Drivers: Who? How Many? What Impacts?
Authors: Burkhardt Jon E. , Mcgavock Adam T.
Published: April 2007

Most older Americans travel by car, either as drivers or as passengers, to fulfill their local travel needs. The numbers of drivers 65 years old and older will at least double over the next 30 years. The proportion of older drivers on our streets also will increase significantly, and older drivers will be driving more (taking more trips and driving more miles) than before. The total amount of travel that older drivers will undertake will be much greater in 30 years, increasing 400 to 500 percent. The proportion of all driving done by older drivers will nearly triple by 2030, even according to conservative estimates. With no changes to current crash-related fatality rates, the number of fatalities involving elderly drivers in 2030 could be three to four times greater than in 1995. If this occurs, the number of elderly traffic fatalities in 2030 will be 35 to 71 percent greater than the total number of alcohol-related traffic fatalities in 1995—a fatality number now viewed by policy makers and the public as cause for serious concern. Additional public- and private-sector responses will be necessary to provide for the safe mobility of all our citizens, including new kinds of vehicles, new designs for roadways, and new forms of transportation services. The costs of not responding to these challenges will include the increasing isolation of our oldest citizens and the loss of their potential contributions to our society—and may include avoidable traffic injuries and fatalities.
Premature Reduction and Cessation of Driving: Preliminary Study of Women Who Choose Not To Drive or To Drive Infrequently
Authors: Wilkins Jean W. , Stutts Jane C. , Schatz Sally J.
Published: April 2007

Some senior women prematurely stop or markedly reduce their driving. Although not restricted by medical or financial limitations, they drive infrequently or not at all. Through focus groups, a sample of these women were asked why they limit their driving, how they feel about their current mobility, and whether they have considered a future when they might need to drive more. On-road driving evaluations assessed their driving abilities. This research suggests that some of these senior women want to drive more and can do so capably. On-road assessments and refresher lessons may be effective interventions for them.
Sensory and Cognitive Factors Affecting Automotive Head-Up Display Effectiveness
Authors: Gish Kenneth W. , Staplin Loren , Stewart Joseph , Perel Michael
Published: April 2007

Automotive head-up displays (HUDs) present virtual images that are focused beyond the standard instrument panel distance and that appear to be superimposed on the driver’s view of the road environment. The study assessed HUD benefits and interference potential with respect to performance of in-vehicle driving tasks and response to safety-critical roadway events under various ambient light levels by older versus younger drivers. The primary baseline against which HUD performance was evaluated was a head-down display with the same message format, content, brightness, and angular size. Performance with both visual displays was compared with auditory display (AD) performance to assess channel interference. Safety-critical road events were captured on video and were presented to observers seated in a fixed-base, part-task driving simulator. Single- and dual-task trials were presented randomly within a block of trials. Measures of response accuracy and time were obtained for in-vehicle and external targets. Eye and head movements were videotaped to assess changes in scanning behavior caused by the in-vehicle displays and external targets. The analyses revealed that performances with the HUD and the head-down display were similar, whereas performance with AD was typically more accurate and faster for both in-vehicle and external responses. HUD benefits were obtained for overall response times to external targets and responses to collision avoidance warnings. Evidence for contrast interference and “cognitive capture” with HUDs and “response capture” with AD was also obtained. Implications for HUD safety and design are discussed.
Driving and Using Mobile Phones: Impacts on Road Accidents
Authors: Koushki P.A. , Ali S.Y. , Al-Saleh O.I.
Published: April 2007

Despite multidimensional efforts to improve road traffic safety in Kuwait, traffic violations and road accidents have increased steadily in recent years. Official statistics, although incomplete, indicate that the rates of road accident and accident fatalities in Kuwait are three to four times those in the United States. It is argued that the rapidly growing use of mobile phones by drivers has added a new dimension to the complexity of the driving task and further contributes to the deterioration of road safety, particularly in undisciplined driving environments like Kuwait’s. A random sample of 2,000 drivers was surveyed. Data on socioeconomic traits and on mobile phone availability, frequency of use, and contribution to road accidents were obtained. Seventy-three percent ofthe sample drivers owned a mobile phone, had owned it for nearly 2.5 years, and had made 1.4 calls during an average daily trip. An average individual in the sample had been involved in 0.4 road accidents since acquiring a mobile phone; 0.21 accidents occurred while he or she or the other driver(s) was using a mobile phone. It is strongly recommended that driver mobile-phone use be banned while the driver’s vehicle is in motion.
Brake Pulsing as Haptic Warning for an Intersection Collision Avoidance Countermeasure
Authors: Lloyd Mary M. , Wilson Glenn D. , Nowak Chris J. , Bittner Alvah C.
Published: April 2007

Human factors issues involved in defining driver warnings for potentially hazardous situations at intersections are addressed. General issues include what information to present to drivers (warning content), when to present it (timing of warning), and how to present it (type of warning modality). The work reported is being conducted to assist in the design of a driver-vehicle interface (DVI) warning system for the Intersection Collision Avoidance Using Intelligent Vehicle Highway System Countermeasures (ICA) program. The ICA program is one of four collision avoidance system programs sponsored by the NHTSA Office of Crash Avoidance Research. Initially, the results of an on-road baseline study that examined driver behavior during approaches to intersections controlled by stop signs are reviewed with respect to the timing of driver warnings. Subsequently, haptic warning characteristics for an intersection collision avoidance system are defined, and DVI design guideline recommendations for implementing haptic warnings generated through vehicle brake pulsing are included. Vehicle brake system modifications required to achieve brake-pulsing parameters are described. Human factors test plans directed toward verification that physical properties generated through brake pulsing are readily recognized and accepted by drivers are delineated. As part of verification efforts, track tests will be performed with various intersection approach speeds and driving maneuvers. Effect of velocity on perception of haptic warning will be evaluated for ranges of magnitudes and duration of brake pulsing. The test results will support ICA test-bed development in the latter part of the ICA program.
Does Travel Information Influence Commuter and Noncommuter Behavior?: Results from the San Francisco Bay Area TravInfo Project
Authors: Khattak Asad J. , Yim Youngbin , Stalker Linda
Published: April 2007

Improved information received from public and private advanced traveler information systems can help travelers make more informed decisions, shorten times spent in traffic congestion, and reduce anxiety and stress. The behavioral responses of automobile and transit commuters as well as those of noncommuters to travel information received from radio, television, and telephone are analyzed. The influence of information has seldom been studied in terms of these different users. The data were collected through a computer-aided telephone interview conducted in the San Francisco Bay Area ( n = 947). The study analyzes the impacts of socioeconomic, context, and information variables on individuals’ decisions to adjust travel before beginning their trips; given an adjustment, the frequency of trip changes; and the type of most recent trip changes in terms of route, departure time, or mode shifts. The statistical analysis involves estimation of probit models with and without sample selectivity and a multinomial logit model. The results of the study indicate that a sample selectivity model is more appropriate for understanding respondents’ frequency of trip changes only when members of a subset of the sample population change their trips. Travel time uncertainty and travel information received from the electronic media increase the pretrip adjustment propensity. Furthermore, information from the most widely available and accessed medium, the radio, is highly likely to result in behavioral adjustments. Noncommuters have a high receptivity to canceling their trips in response to travel information. This has important implications for congestion relief in transportation networks.
Modeling Nonmotorized Transport Costs and Benefits in the Highway Development and Management System
Authors: Odoki J.B. , Kerali H.R.
Published: April 2007

Nonmotorized transport (NMT) modes such as bicycles, cycle rickshaws, animal carts, and pedestrians play a major role in moving passengers and freight in many countries. A formal method has been developed for calculating the operating costs incurred by NMT on roads and thereby for estimating the benefits derived by NMT from road improvements. This method has been incorporated in the Highway Development and Management system, the successor to the Highway Design and Maintenance Standards Model developed by the World Bank.
Nonmotorized Traffic Accidents in San Juan, Argentina
Authors: Osvaldo Fernández DE Cieza Arístides , Ortíz Andino Julio César , Ricardo Archilla Adrian , María Gómez Adriana , Guillermo González Carlos , Mengual Susana , Morrall John
Published: April 2007

Findings are presented for a recently completed exploratory study of nonmotorized accidents in San Juan, Argentina. The study was undertaken jointly by EICAM [Escuela de Ingenieria de Caminos de Montaña (School of Mountain Highway Engineering)] in San Juan and a visiting Canadian professor from the University of Calgary at the National University of San Juan. The study was funded by EICAM and represents the first study of traffic accidents in San Juan. Nonmotorized traffic fatalities are a disproportionately high percentage of all traffic fatalities in Argentina compared with more-industrialized countries. Pedestrian and bicycle traffic fatalities comprise almost one-half of all traffic fatalities in the Province of San Juan. The probable causes of nonmotorized traffic fatalities and injuries are explored, including vehicle speed, nighttime driving without headlights or with parking lights only, cyclist and pedestrian behavior, and aggressive driving. Recommendations to enhance pedestrian and bicyclist safety include the strict enforcement of recently enacted traffic laws; for example, proper illumination at night, speed limit enforcement, a driver education program, a bicyclist education plan, and a wide range of traffic engineering improvements (e.g., line markings and traffic control devices). Institutional responsibilities for traffic should be reviewed, because various institutions have overlapping jurisdiction, resulting in an inadequate traffic audit database.
Sustainable Urbanization in Megacities: Role of Nonmotorized Transportation
Authors: Daniere Amrita G.
Published: April 2007

A key aspect of urban sustainability lies in the relationship between the environment and transportation. In a majority of the world’s megacities, transportation infrastructure and patterns are at the root of many environmental problems, including air pollution, increased reliance on fossil fuels, and urban sprawl, which is often blamed for a concomitant increase in energy consumption and the haphazard development of suburban land. As such, it makes sense to include nonmotorized transportation in the web of options to help create and plan for sustainable megacities. The importance of nonmotorized transportation in creating sustainable urbanization in the megacities of the developing world is discussed. Topics include ( a) sustainability in theory and in application; ( b) fundamental differences between urban transportation patterns and possibilities in developed versus developing countries, highlighting the current role played by nonmotorized transportation; ( c) the potential of nonmotorized transportation to improve mobility and sustainability in the megacities of the future; and ( d) how these contributions might best be realized.
Effect of Nonmotorized Transport on Motorized Vehicle Speeds in China
Authors: Pan Yuli , Kerali H.R.
Published: April 2007

Research was conducted on the effects of nonmotorized traffic flow on motorized vehicle speeds on the basis of field observations of vehicle speeds on Chinese roads. A linear relationship was observed between motorized vehicle speeds and nonmotorized traffic flow under a range of motorized traffic flow volumes. By using the relationships of non-motorized flow effects obtained in this study, together with free speed and speed-flow relationships investigated in other studies, a general congested speed model for predicting vehicle speeds under various road characteristics and traffic flow volumes has been developed. The generalized speed-flow model can be incorporated into the three-zone speed model used in the Highway Development and Management (HDM-4) model.
Fatalities of Heterogeneous Street Traffic
Authors: Fazio Joseph , Mazharul Hoque M. , Tiwari Geetam
Published: April 2007

A unique feature of large South Asian cities is the composition of their urban street traffic. Because many different traffic entities of varying size continuously interact on the street, the traffic mixture is heterogeneous. Heterogeneous traffic increases street capacity. Homogeneous traffic prevails in most North American, European, and Australian cities. Two broad categories comprise heterogeneous traffic: namely, motorized vehicles and nonmotorized entities. After collecting geometric, composition, speed, and conflict data at 14 midblock sites, heterogeneous traffic was examined at a microscopic level. The best model shows that the high-fatality midblock sites correlate to unidirectional street widths at a +0.89 correlation coefficient. The degree of heterogeneity and motorized traffic flow had the strongest relationship with street width at a +0.99 correlation coefficient. Given constant motor vehicle flow, the analyses revealed that when the traffic heterogeneity index approached 1 (i.e., 50 percent motorized and 50 percent nonmotorized), fewer midblock fatalities occurred.
Bridge Aesthetics: Guidelines for the New Millennium
Authors: Svensson Holger S.
Published: April 2007

The design of attractive bridges does not happen by chance, nor does it exclusively depend on some elusive “feel” that is only given to a chosen few. Constant conscious examination of existing bridges to find out why they are beautiful or ugly educates aesthetic awareness. Aesthetic guidelines can help to find a good shape or to check the shaping of bridges. Important aesthetic criteria are clear structural statements; good proportions; order; compatibility with the surroundings, including coloring; and, above all, simplicity.
Special-Design Precast Concrete Beams for Sidney Lanier Bridge Replacement Project
Authors: Callicutt Edwin
Published: April 2007

The Sidney Lanier Bridge Replacement Project is a $100 million undertaking in Brunswick, Georgia, that will lead to the replacement of an existing 40-year-old steel lift-span structure. The approach bridges that lead to the project’s main-span unit consist of 16 spans of 54.9-m (180-ft), special-design, precast concrete beams as well as 14 spans of 36.6-m (120-ft) Type V AASHTO girders. The special-design beams are 2.3 m (7.5 ft) deep, are erected as simply supported members and are then made into two-span continuous units by longitudinal posttensioning, and are rigidly connected transversely with cast-in-place diaphragms. The riding surface is a cast-in-place concrete deck constructed on stay-in-place metal forms. The 54.9-m (180-ft) beams, supported by hollow tapered concrete piers with hammerhead caps, are founded on 1.2-m (48-in.) drilled shafts. Wet-hole construction methods with bentonite slurry were required for the drilled shafts. The bridge piers are over land and water, and large cofferdams were required to facilitate construction. Additionally, the sizes of the cast-in-place footings and hammerhead pier caps required mass concrete thermal considerations. The approach bridges lead to the main-span portion of the project, which will be a 762-m (2,500-ft) concrete, cable-stayed unit with a 381-m (1,250-ft) center span. The design, casting, and erection of these beams, and construction of the substructure, posed many challenges to the Georgia Department of Transportation designers and contractors. These beams are among the longest erected in Georgia.
Load Distribution and Shear Strength Evaluation of an Old Concrete T-Beam Bridge
Authors: Al-Mahaidi Riadh , Taplin Geoff , Giufre Armando
Published: April 2007

There are about 330 T-beam bridges in the Australian state of Victoria that were built before 1950. Australia-wide there are nearly 1,000 of these early T-beam bridges. The shear capacity of these bridges, when assessed in accordance with current codes of practice, is in some cases not adequate for the current design loading. In 1996, VicRoads, the Victorian state road authority, initiated a project to enable a more accurate assessment of the shear capacity of these bridges to be made so that decisions on load rating or replacement could be made. An analysis of an existing reinforced concrete T-beam bridge that had been identified for a load test to failure was commissioned. The purpose of the analysis was to predict the load distribution behavior and the ultimate strength and to advise on the testing and monitoring program. After successful load testing of the bridge, a comprehensive analysis of the observed behavior was carried out and compared with the theoretical models. The pre-and posttesting analysis, which was undertaken with linear and nonlinear finite element analysis and with the modified compression field theory, are described and the analysis results are compared with the real behavior of the tested bridge. In particular, the load distribution in the elastic range and the ultimate shear strength of the reinforced concrete T-beams are discussed. The consequences of these findings on the load rating procedures are discussed, and a strategy for rating old reinforced concrete T-beam bridges is outlined.
In-Service Response of an Orthotropic Steel Deck Compared with Design Assumptions
Authors: Connor Robert J. , Fisher John W.
Published: April 2007

To minimize the possibility of fatigue cracking on the new orthotropic deck of the Williamsburg Bridge, laboratory tests with a full-scale prototype panel were conducted. During the study, recommendations for improving fatigue resistance of the welded rib-diaphragm connection detail were made before construction. In addition, load testing and long-term remote monitoring of the orthotropic deck were conducted. The field data suggest that actual truckloads are greater than the standard truck-loads assumed in the AASHTO Load and Resistance Factor Design (LRFD) Specifications. They also suggest that modifications to the fatigue design of deck elements may be required because the maximum stress range exceeds twice the stress range provided by the fatigue truck (i.e., twice the fatigue truck assumed by the AASHTO LRFD Specifications).
Influence of Hydration Temperature on Durability and Mechanical Property Performance of Prestressed and Precast High-Performance Concrete Beams
Authors: Myers John J. , Carrasquillo Ramon L.
Published: April 2007

Concrete technology has continued to advance throughout the years to meet the demands of designers and innovative structural systems. With the advent of high-performance concrete (HPC), which contains large amounts of cementitious materials, the investigation of the impact of concrete temperature development during hydration on concrete performance is of keen interest. Match-curing technology was used to investigate the influence of concrete temperature development during hydration on the mechanical and material property performance of prestressed and precast HPC beams. These members were fabricated for use in two recently constructed HPC bridges in Texas. The investigation was conducted in conjunction with the design, instrumentation, and construction of the Louetta Road Overpass in Houston, Texas, and the North Concho River US-87 and South Orient Railroad Overpass in San Angelo, Texas. FHWA and the Texas Department of Transportation cosponsored these projects as part of the Strategic Highway Research Program to stimulate the use of HPC and to demonstrate the suitability of HPC in highway structures. The results of the study indicated that for HPCs that contain large amounts of cementitious materials, the concrete temperature during hydration can have a dramatic impact on both the mechanical and the material (durability) performance of the concrete. Temperature recommendations are provided to avoid less than optimal concrete performance on the basis of the member shapes and mix designs investigated in the study.
Bridge Safety Assurance Measures Taken in New York State
Authors: O’Connor Jerome S.
Published: April 2007

A description of New York State’s Bridge Safety Assurance (BSA) Program is given, and specific examples of interim countermeasures that can be taken to lessen the risk of failure due to hydraulic scour, overload, steel details, collision, concrete details, and earthquakes are provided. The BSA program was adopted to provide a systematic means of identifying situations that pose a threat to the structural integrity of bridges. A traditional bridge inspection program ascertains the condition of various bridge elements. This information is typically used to drive an agency’s capital and maintenance bridge programs. New York’s BSA program supplements this condition-based evaluation by taking a slightly different perspective. It assesses and rates the degree of risk that is associated with certain design details and circumstances. The program is used to evaluate a bridge by using current design practice as a reference, whereas the inspection procedures are used to rate each element of a bridge only according to its condition and ability to function as intended in the original design. Rating all bridges according to their ability to remain safe under current conditions by using today’s design philosophy provides an ability to evaluate structures by using a common reference regardless of when they were built. Specific examples of retrofit work that has been undertaken as a result of the adoption of New York’s BSA policy in 1992 are given.
Areas of Uncertainty in Bridge Management: Framework for Research
Authors: Das Parag C. , Onoufriou Toula
Published: April 2007

Bridge maintenance activities, from inspection and assessment to fund allocation and execution of the work, involve many uncertainties. If the predictably increasing future requirements for bridge maintenance are to be met in a cost-effective manner, these uncertainties must be identified and reduced as much as possible. Past research in bridge engineering has mostly concentrated on the engineering aspects of the activities. Many countries are now conducting considerable research and development efforts to produce better materials, innovative forms of construction, improved inspection and monitoring techniques, and better evaluation procedures and criteria. Now is the time to examine the uncertainties found in bridge management. To address these deficiencies, it is necessary to determine the focus of future research. Clearly, the level of resources that is used in different areas of research should reflect the accuracy that is warranted by the end use. On the basis of experiences gained from bridge management as well as from similar activities in the field of offshore structures, the areas of uncertainty, such as method sophistication, operator expertise, and human and sampling errors, are identified. In addition, a possible methodology is outlined that could provide bridge authorities, researchers, and industry with an overview of the currently perceived problems and their relative importance so that resources could be used in a cost-effective manner. The process of breaking down management into component activities by the use of flow diagrams and the representation of individual uncertainties through probabilistic distribution are also presented.
Seohae Grand Bridge
Authors: Tang Man-Chung , Jang Dennis J. , Ahn Kookjoon
Published: April 2007

The Seohae Grand Bridge, located about 65 km south of Seoul, Korea, is currently under construction and, when complete, will be the longest bridge in Korea. The total length of the bridge is 9.4 km from Pyongtaek on the north to Dangjin on the south, carrying three lanes of traffic in each direction across the Asan Bay. The center span provides a 62-m-high navigation clearance above the high sea level of +4.65 m. The main bridge is composed of three cable-stayed spans of 200, 470, and 200 m and two 60-m-long side spans, one at each end. The center span will form the entrance to the harbor and will be built in the future. The bridge deck is supported by two longitudinal steel edge girders that are spaced 34 m apart and by transverse steel floor beams at 4.10 m on centers. The majority of the bridge deck is composed of precast panels and cast-in-place joints. The bridge superstructure is restrained in the transverse direction at the two pylons and end piers. The bridge longitudinal displacement due to live load, temperature variation, and creepshrinkage is restrained at one pylon with longitudinal shear keys. Lockup devices are installed on the other pylon and are mobilized only for longitudinal earthquake loading.
Current State of the Quebec Bridge
Authors: Sweeney Robert A. P. , Oommen George
Published: April 2007

The Quebec Bridge has the longest cantilever span in the world and is a monument to early railway bridge engineering. It opened 83 years ago to railway traffic. It has carried roadway traffic since 1928. A brief history of the bridge is presented. Its modifications and politics, the present condition of the bridge, details of the railway’s recent assessment strategy, and the current $60 million rehabilitation scheme are also examined.
Steel Bridges with Double-Composite Action: Innovative Design
Authors: Stroh Steven L. , Sen Rajan
Published: April 2007

Bridge engineers are continually faced with the challenge of providing efficient and cost-effective structures. In particular, the Florida Department of Transportation has recognized the need to develop economical bridge configurations in the medium-span range of 200- to 400-ft (60.96-to 121.92-m) spans and authorized a research project at the University of South Florida to identify and develop innovative design concepts within this span range. The study identified the concept of a steel bridge with double-composite action as an innovative bridge concept with the potential for significant cost savings compared with conventional modes of construction. This bridge type has been used with good success in Europe, but to the authors’ knowledge it has not been used in the United States. In addition to a composite concrete top slab, the double-composite bridge concept utilizes a composite concrete bottom slab in the negative moment regions. The result is provision of a design meeting compact requirements throughout, increased stiffness with corresponding decrease in fatigue stress range and deflections, savings in cross frames, and savings in flange material. The design implications of this system are examined, including redistribution effects due to creep and shrinkage, implications of different construction sequences, and strength and serviceability issues. Trial designs are presented, including both plate and box girder type structures, and design considerations are discussed. A prototype structure is identified for further development of the double-composite concept.