bluuebunny/crossref_metadata_2025 huggingface dataset:
Density and Captivity in Public Transit Success: Observations from the 1995 Nationwide Personal Transportation Study
Authors: Polzin Steve E. , Chu Xuehao , Rey Joel R.
Published: April 2007

The new millennium provides a good time to reflect on transportation-industry trends in some fundamental external factors that influence transportation behavior and planning response. In the public-transit industry, urban density and transit captivity have long been fundamental conditions driving transit planning and service and facility investment decisions. In light of demographic and economic changes, it is useful to revisit the issue of the importance of these factors to the transit market. Findings from a comprehensive analysis of the 1995 Nation-wide Personal Transportation Study (NPTS), which explored current transit-travel behavior, are reported. Two key findings reflect on two historical axioms in transit: ( a) the extent to which density influences transit use and ( b) the importance of the transit-dependent market. The research findings reiterate the significant influence that development density has on public transit mode share and bring to light some revealing data on the influence of urban-area size on transit use. The importance of transit dependency on transit use is documented, and trends in transit dependency over the past few decades are revealed. Finally, the implications of these trends for the public-transit industry are discussed.
Importance of Objectives in Urban Transit-Network Design
Authors: van Nes R. , Bovy P.H.L.
Published: April 2007

Stop spacing and line spacing are key design variables in urban transit-network design. They determine both the travel time and the operational costs. It is therefore essential to know what the main relationships are for these design variables. The question is, What are the optimal values for stop spacing and for line spacing in urban transit networks, given traveler preferences and supply-budget constraints? Possible objectives are discussed and analyzed using analytical models. The results of these analytical models for two typical city types are analyzed by comparing performance characteristics (i.e., travel time, operator costs, and patronage). Modeling outcomes are compared with actual data for urban transit networks in Europe. A supplemental analysis is made of the impact of considering different traveler groups. It was found that although many objectives may be formulated, only a few objectives are suitable for transit-network design. Currently applied stop spacings prove to be too short. Focusing the design to specific traveler groups might lead to a variation of stop spacing and line spacing ranging from −12 percent to +13 percent at most. Recommendations for urban transit-network design and for further research are given.
Kinematic Approach to Horizontal Curve Transition Design
Authors: Bonneson James A.
Published: April 2007

Research has shown that vehicles shift laterally in the traffic lane during their entry to (or exit from) a horizontal curve. In addition, research indicates that most drivers momentarily adopt a path radius that is sharper than that of the roadway curve. A study was undertaken to investigate the causes of lateral shift and sharp path radii and to determine if they can be minimized (or eliminated) by modifying the horizontal curve transition design. From a review of the driver–vehicle control process, it was concluded that lane shift is due to unbalanced lateral accelerations that act on the vehicle as it enters the curve. These accelerations result from gravity, as effected through roadway superelevation, and side friction, caused by the steer angle of the vehicle. Kinematic models of lateral acceleration, velocity, and shift were developed. The calibrated models were used to develop design guidelines for superelevation rate and superelevation runoff location.
Utilization of Auxiliary Through Lanes at Intersections of Four-Lane, Two-Way Roadways
Authors: Tarawneh Mohammed S.
Published: April 2007

To increase the capacity of through traffic at signalized intersections, additional lanes with limited length—called auxiliary lanes—are added to the roadway at the intersection. Because of their limited length, as well as other factors, these lanes are not as fully utilized as other continuous through lanes. Research was undertaken with two objectives: ( a) to observe and identify the level of use of auxiliary through lanes added at intersections of four-lane, two-way roadways; and ( b) to study the effects of auxiliary lane length, right-turn volume, and through/right-turn lane group delay on the level of their use. Lane-use data collected during 1,050 saturated cycles at eight signalized intersections with different auxiliary lane lengths were used to accomplish research objectives. All factors investigated—auxiliary lane length, right-turn volume, and stopped-delay—were found to contribute significantly to the use of auxiliary lanes at 0.01 level. The level of each factor’s contribution, however, was dependent on the level of the other two. Lane use of nearly one to seven straight-through vehicles per cycle, depending on levels of factors investigated, was observed at the study locations. Longer auxiliary lanes, lower right-turn volumes, and excessive approach delays encouraged the use of auxiliary lanes by straight-through vehicles. The range of lane utilization adjustment factors ( fLU-factors) calculated from field data was 0.73 to 0.82, which is lower than the 1997 Highway Capacity Manual default value of 0.91 for a three-lane through/right-turn group.
Natural Gas as a Marine Propulsion Fuel: Energy and Environmental Benefits in Urban Ferry Service
Authors: Farrell Alex , Glick Mark
Published: April 2007

Although transportation has major energy and environmental policy implications, not all sectors are treated equally, and ships often are overlooked. However, ships are a significant source of air pollution and account for a nontrivial portion of U.S. petroleum demand. Moderate emissions standards for new marine engines have been proposed by the Environmental Protection Agency, but these will take well over a decade to become effective once they are enacted, and there are no energy policy provisions for ships. Nonetheless, ships offer cost-effective options for both emissions reductions and the use of alternative fuels. Aware of these issues, the U.S. Department of Energy’s Office of Transportation Technologies and the Gas Research Institute sponsored a study of the potential use of natural gas as the fuel for passenger ferries as part of their Natural Gas Vehicle Technology Initiative. The results of the study are discussed, with a focus on the energy and environmental issues related to maritime operations in the United States. The challenges and opportunities of a specific project to design, construct, and operate several natural gas-powered ferries in Boston Harbor are discussed. A significant reduction in air pollution and a large increase in the use of natural gas as a transportation fuel are expected from this project, but the greenhouse gas emission impacts are ambiguous. Further, an emissions monitoring and analysis program is described that would greatly improve the accuracy of maritime emissions inventories and would enable ships to take part in existing emissions trading programs in port cities around the country. Such a development would create significant economic incentives to encourage ferry owners to invest in clean fuel technologies, which could have major implications for energy and environmental policy.
Effect of Cycle-Counting Methods on Effective Stress Range and Number of Stress Cycles for Fatigue-Prone Details
Authors: Najem Clarke Shima , Goodpasture David W. , Bennett Richard M. , Deatherage J. Harold , Burdette Edwin G.
Published: April 2007

Two important parameters in fatigue life evaluations of existing steel highway bridges are the number of stress cycles experienced and the effective stress range. The inaccuracies in predicting remaining fatigue life can be attributed to either one of these two parameters. However, the AASHTO guide specification has no provisions for the cycle-counting methods to be used to determine these two parameters. A sensitivity analysis that addresses the effects of cycle-counting methods on the effective stress range and the number of cycles for various fatigue-prone details in both main and secondary bridge members is described. A comparison of five cycle-counting methods (level-crossing counting, peak counting, simple-range counting, mean-crossing-peak counting, and rain-flow counting) by using a simple variable-amplitude strain-time history showed that both the stress range and the number of cycles are sensitive to cycle-counting methods. Two of the most commonly used cycle-counting techniques for highway bridge variable-amplitude loading are the mean-crossing-peak and the rainflow cycle-counting methods. A comparison of the two methods by using field data taken under normal traffic showed that the rainflow cycle-counting method is more conservative than the mean-crossing-peak method. The relationship between the mean-crossing-peak and the rainflow cycle-counting methods was determined in the form of a correlation coefficient and a linear regression line. There is a nearly perfect positive correlation between the two methods. Therefore, values obtained for the effective stress range and the number of cycles by the mean-crossing-peak method can be converted to values for the rainflow method.
Retrofit of Aerodynamic Cable Instability on a Cable-Stayed Bridge: Case Study
Authors: Telang Niket M. , Minervino Charles M. , Norton Paul G.
Published: April 2007

Elegantly poised over the Mobile River, the twin pylons and the semi-harped cable stays of the Cochrane Bridge subtly complement the vast and undulating landscape of the Mobile Bay as the bridge carries US Route 90 over the Mobile River in Alabama. In February 1998, light rain drizzled on the bridge, and a weather station nearby recorded wind speeds of about 48 km/h (30 mph). Under these seemingly mild weather conditions, the normally immobile cable stays started to vibrate, and within moments, these nascent vibrations reached amplitudes of more than 1.2 m (4 ft). Alarmed by this event, the Alabama Department of Transportation (ALDOT) took immediate action to ensure the continued safety and serviceability of the bridge. A team of consultants was selected by ALDOT to investigate mitigation measures for the large-amplitude cable-stay vibrations. The fast-tracked comprehensive program planned and implemented to inspect, test, document, and evaluate the effects of the large-amplitude vibrations and the recommendation of retrofit measures that would limit future occurrences of such cable-stay vibrations on the Cochrane Bridge are described in detail.
Asphalt Plug Joints: Refined Material Tests and Design Guidelines
Authors: Bramel Brian K. , Dolan Charles W. , Puckett Jay A. , Ksaibati Khaled
Published: April 2007

Highway builders and rehabilitators throughout the United States use asphalt plug joints (APJs) in bridge expansion joints according to manufacturers’ recommendations. Joint performance varies widely, as indicated in recent surveys. State departments of transportation are installing joints in unsuitable sites or are overlooking other sites where APJs may work well. Rational design guidelines for APJs have been developed. The research suggests suitable applications, material characterization, design guidelines, and validation procedures. Two critical material properties are required to qualify APJ material: relaxation and glass-transition temperature. Both properties may be obtained by using a slight modification of the AASHTO standard thermal specimen, restrained specimen asphalt test. This modified standard test was conducted, and the results were compared with those of the near-full-scale test. Design guidelines are based on field observations, material tests, near-full-scale testing, analytical evaluations, and a survey of the experiences of state departments of transportation. Design recommendations are provided, and joint design changes are proposed to help mitigate the present shortcomings.
Asphalt Surfaces on Steel Bridge Decks
Authors: Hicks R. Gary , Dussek Ian J. , Seim Charles
Published: April 2007

A variety of materials have been used for wearing surfaces on steel bridge decks. The requirements for these paving materials are identified, the various asphalt-based materials that have been used are described, a description of the construction process is provided, and the expected field performance and maintenance requirements for the most common materials used are discussed. The selection of the wearing surface should be based on life-cycle costs, not just initial construction costs. Life-cycle-cost calculations must include consideration of initial construction costs, expected life, maintenance and rehabilitation costs, and user delay costs associated with the removal and replacement of failed surfaces. The reliability, durability, and skid resistance of the wearing surface are very important to prolongation of the life of the surfacing and minimization of delays to users caused by frequent replacements.
Estimation of Second-Order Effects for Pole-Type Structures
Authors: Nunez Edgar , Fouad Fouad H.
Published: April 2007

The design of pole-type structures for highway supports requires computation of second-order effects induced by the interaction of vertical gravitational and transverse wind loads. The 1994 Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals provides two methods to account for those second-order effects. The first method uses a simplified approach by introducing a factor, CA, into the combined stress ratio equation. The second method requires the computation of the exact bending stresses by means of a nonlinear analysis. Most structural design codes specify simplified methods for the evaluation of second-order effects to facilitate the design of structural members by using the forces obtained in a first-order static analysis. Therefore, simplified methods must be accurate to be considered an adequate alternative to a more sophisticated analysis. The purpose of this study was to determine the accuracy of the simplified method by using the CA factor to estimate the second-order effects for pole-type structures. An analytical study that included 241 pole configurations was conducted to evaluate the CA factor. Exact solutions were computed by using a computer program capable of performing second-order analysis. The study indicated that for typical pole-type structures, the results obtained with the CA factor were highly conservative. On the basis of the results, a modified expression for the CA factor is proposed. Results obtained by use of the modified expression for the CA factor were within 10 percent of those obtained by use of the “exact” nonlinear analysis.
Abrasives and Salt: New Research on Their Impact on Security, Economy, and the Environment
Authors: Schlup Ulrich , Ruess Beatrice
Published: April 2007

Research was performed to obtain an integral view of the effects of salt and abrasives spreading on security, economy, and the environment. In addition, the research was to provide objective and practical strategies and decision-making aids for the improvement of efficiency and economy in road winter maintenance. Findings with regard to security were that spreading of salt contributes significantly to traffic safety in winter and can be considered an effective solution for road safety. Abrasives, on the other hand, have a limited and normally only short-term effect on slipperiness. The adhesion of tires to the road surface, crucial for the braking distance and stability of the vehicle, is limited. Spreading of abrasives suggests a false security and entices the road user to drive faster than advisable. The risk factor increases considerably. As to economy, existing studies and experience show that salt spreading is highly beneficial. For abrasives, limited data could be found. Tests carried out during two winters in the Swiss cities of Zurich, Baden, and Chur showed that the costs for the use of abrasives are six times higher than those for salt in normal winters and 10 times higher in severe winters. In the case of environmental effects, the impact of salt on soils, flowing water, and underground water was found trifling because of the locally and temporarily limited appearance. The impact on vegetation, especially on roadside trees in urban areas, must not be underestimated. Measures to reduce the salt load are recommended. The use of abrasives produces waste. The ecology balance shows that with respect to energy and water consumption, waste, and emissions in air and water, salt comes off distinctly better than do abrasives. However, further efforts are necessary to reduce the amount of both substances used in road winter maintenance.
Assessment of the Performance of Prewetted Salt for Snow Removal and Ice Control
Authors: Burtwell Marilyn
Published: April 2007

In the United Kingdom, the primary method of preventing ice from forming on road surfaces is to spread rock salt with purpose-built spreaders that regulate both the rate of spread and the spread pattern. British Standards Institution Standard BS3247 requires that the rock salt contain no more than 4 percent moisture by weight. Although salt is an effective deicing chemical, its extensive and intensive use on roads has been found to corrode vehicles, damage highway structures, cause detrimental effects to vegetation, and increase groundwater pollution. Prewetted salt is under trial on minor roads by local authorities in England and Scotland. The U.K. Highways Agency commissioned TRL Limited to review the use and to determine the potential benefits of prewetted salt. The use of prewetted salt has been compared with the use of dry rock salt in terms of their environmental effects as well as their cost. Factors such as salt loss due to trafficking and climatic conditions, potential hazards and damage to structures, and safety issues arising from the use of prewetted salt have been investigated. Field trials are in progress in the winter of 2000–2001 to determine the efficacy of prewetted salt as a precautionary treatment. The trials will be used to assess specifications for materials and equipment, the cost and method of retrofitting brine tanks to a spreader, the accuracy of spread width and pattern, and salt residue on the road and verge. The final results of this study will enable the Highways Agency and local authorities to determine whether to introduce prewetted salt on U.K. roads and, if so, the climatic conditions under which it should be used.
Recent Situation of Winter Road Management and Traffic Accidents in Hokkaido
Authors: Asano Motoki , Hirasawa Masayuki , Oikawa Shuichi
Published: April 2007

The 1990s may be described as the decade of conversion from studded to nonstudded tires (called “studless tires” in Japan). By 1993, studded tires had disappeared from Japan. Since a ban on the use of these tires went into effect, environmental benefits have been realized, such as a reduction in the amount of suspended particulate matter from tire-abraded roads. However, the roughness of snow- or ice-covered roads rapidly declined, and extremely slippery roads became common throughout Hokkaido. To address this problem, road administrators expanded measures for treating snow- or ice-covered roads, and the amount of antifreezing agents and abrasives applied to roadways has increased to several tens of times the amount applied a decade ago. Changes such as decreased traffic capacity and increased traffic accidents in winter have also been observed. The influences of the studded tire ban on the environment, changes in road surface management, changes in winter traffic characteristics, and trends in traffic accidents in the decade since the ban are summarized. Issues for future resolution are identified.
Information-Sharing Experiments for Better Winter Roads: Greater Sapporo WHITE-NET Experimental Project
Authors: Matsuzawa Masaru , Kajiya Yasuhiko , Konagai Nobuo , Kaneda Yasuhiro
Published: April 2007

In January 1996, record snowfall halted urban functions for 3 or 4 consecutive days in the Sapporo, Japan, area. The Civil Engineering Research Institute concluded that lack of cooperation among the road organizations and improper provision of information to citizens aggravated the disruptions. Experiments on appropriate methods of sharing information and providing information to road users were conducted and collectively named the Greater Sapporo WHITE-NET Experimental Project. Under the project, the road information–sharing experiment has been performed since the winter of 1997–1998. Information on road maintenance and road conditions during snowstorms is shared by using an e-mail mailing-list system. In a questionnaire survey, more than 60 percent of respondents indicated that sharing information by e-mail was more effective than sharing by fax or website. The car commuter monitoring experiment was carried out to understand how car commuters change their commuting methods according to road and weather information. During the 1999–2000 winter, 31 monitors who own mobile phones that can access the Internet participated. Weather and road information was provided at 6:00 p.m. and 7:00 a.m. As a result, on February 25, when 45 cm of snow fell from night until morning, more than 10 percent of the monitors changed their transportation mode to public transportation.
Evaluation of Methods for High-Speed Application of Road Salt
Authors: Perchanok Max S.
Published: April 2007

The operating speed for applying rock salt with conventional spreaders is limited by material loss caused by bouncing or sliding across the pavement. This results in excess salt loss to the roadside environment, traffic congestion during winter operations, and unnecessarily long spreading cycle times. Equipment designed to control the velocity at which material hits the pavement and to prewet winter materials has been developed to solve these problems. Tests were undertaken to examine the feasibility of high-speed material application on bare pavement by using traditional and newly developed methods and equipment. The study included measurement of spread patterns and material loss against operating speeds using ground-speed spreaders and using prewet materials, in comparison with conventional methods. Ground-speed spreaders and prewetting are recommended to permit high-speed spreading of salt in a windrow pattern on bare pavement.
Environmental Impact of Runoff from Highway Construction and Repair Materials: Project Overview
Authors: Huber Wayne C. , Nelson Peter O. , Eldin Neil N. , Williamson Kenneth J. , Lundy James R.
Published: April 2007

A study was conducted to identify the possible effects of highway construction and repair (C&R) materials on the quality of surface water and groundwater near the highway environment. The scope involved the development of a validated methodology to assess such effects in three phases. Phases 1 and 2 involved a survey of C&R materials, laboratory testing of the chemical and toxicological characteristics of a selected number of these materials, development and validation of a laboratory testing–based screening and evaluation methodology for highway C&R materials, and development of a mathematical model to simulate the fate and transport of water quality constituents, including toxicity, along surface and subsurface pathways in the highway environment. Phase 3 focused on 10 tasks designed to confirm the evaluation methodology, test various hypotheses of the model development, develop additional leaching and sorption data, compare ecotoxicological testing procedures developed during the project with standard Environmental Protection Agency procedures, refine laboratory protocols, enhance the model, and investigate the availability of field data for model testing.
Environmental Impact of Construction and Repair Materials on Surface Water and Groundwater: Screening and Evaluation Methodology
Authors: Nelson Peter O. , Williamson Kenneth J. , Azizian Mohammad F. , Thayumanavan Pugazhendhi , Huber Wayne C. , Eldin Neil N.
Published: April 2007

The 6-year NCHRP Project 25-9, titled Environmental Impact of Construction and Repair Materials on Surface and Ground Waters, concluded in March 2000. The main purpose of the study was to develop and demonstrate a methodology for identification of the possible impact of highway construction and repair (C&R) materials on the quality of surface water and groundwater in the immediate highway environment. The evaluation methodology consisted of an initial screening of a raw (unamended) C&R material leachate for aquatic toxicity by using bioassay tests and of further detailed testing and evaluation of those materials identified as potentially toxic. In the detailed evaluation, leaching source term tests were conducted to determine leachate composition under varying environmental conditions. Environmental tests were then conducted on the leachate to determine the effects of removal, reduction, and retardation (RRR) processes in the highway environment. The environmental processes included photolysis, volatilization, biodegradation, and soil sorption. The leaching and RRR tests identified interactions between specific environmental processes and leachate contaminants and yielded empirically derived functions for each process. The functions were coupled with selected reference environments in a computer model to simulate fate and transport for surface and subsurface pathways. Model results were reported as concentrations, loads, or fluxes of contaminants as a function of time at the highway boundary. Complete evaluation methodology results are presented for a standard asphalt cement concrete developed to serve as a reference asphalt concrete for interlaboratory comparisons.
Dynamic Late Merge–Control Concept for Work Zones on Rural Interstate Highways
Authors: McCoy Patrick T. , Pesti Geza
Published: April 2007

Conventional traffic control plans for lane closures of rural Interstate highways normally work well as long as congestion does not develop. However, when the traffic demand exceeds the capacity of the work zone, queues may extend back past the advance warning signs, often surprising approaching traffic and increasing the accident potential. Also, smooth and orderly merging operations may be lost as some drivers remain in the closed lane attempting to squeeze into the open lane at the head of the queue, while other drivers try to prevent drivers in the closed lane from passing them by straddling the centerline or traveling slowly in tandem with another vehicle in the closed lane. These maneuvers tend to reduce the capacity of the merging operation and increase the accident potential and road rage among drivers. Early merge and late merge are two forms of merge control designed to deal with these problems. However, these approaches have operational characteristics that limit their effectiveness under both congested and uncongested traffic flow conditions. The advantages and disadvantages of each approach are examined. A new concept called the dynamic late merge is described, which features the integration of the late merge and conventional lane-closure merge control on the basis of real-time measurements of traffic conditions in advance of the lane closure.
Evaluation of Speed Displays and Rumble Strips at Rural-Maintenance Work Zones
Authors: Fontaine Michael D. , Carlson Paul J.
Published: April 2007

An evaluation of the effectiveness of speed displays and portable rumble strips at reducing speeds in rural-maintenance work zones is described. Speed displays are radar-activated signs that dynamically display approaching vehicle speeds. The devices were tested on two-lane low-volume, high-speed rural roads where maintenance activities were completed in a single day. Speed and volume data were collected for cars and trucks as they traveled through four work zones. These data were collected when no work-zone traffic control was present, when normal work-zone traffic control was set up, and when the test treatment was installed. The results for the portable rumble strips were mixed, with passenger cars experiencing less than a 3.2-km/h (2-mph) reduction in mean speed approaching the temporary traffic-control zone. The impact of the rumble strips on trucks was more pronounced, with mean speed reductions approaching the temporary traffic-control zone of up to 11.6 km/h (7.2 mph) lower than normal traffic control. The percent of vehicles exceeding the speed limit in the advance warning area was also reduced when the rumble strips were used. The speed display was generally more effective than the rumble strips at reducing speeds in the advance warning area. Mean speeds were often reduced approaching the activity area, with speed reductions of up to 16.1 km/h (10 mph) being achieved. The percentage of vehicles exceeding the speed limit was also reduced in the advance warning area.
Development of Artificial Neural Network Models to Predict Driver Injury Severity in Traffic Accidents at Signalized Intersections
Authors: Abdelwahab Hassan T. , Abdel-Aty Mohamed A.
Published: April 2007

The relationship between driver injury severity and driver, vehicle, roadway, and environment characteristics was examined. The use of two well-known neural network paradigms, the multilayer perceptron (MLP) and fuzzy adaptive resonance theory (ART) neural networks, was investigated. The use of artificial neural networks can lead to greater understanding of the relationship between the aforementioned factors and driver injury severity. Accident data for 1997 for the Central Florida area, which consists of Orange, Osceola, and Seminole Counties, were used. The analysis focuses on two-vehicle accidents that occurred at signalized intersections. The MLP neural network has a better generalization performance of 65.6 and 60.4 percent for the training and testing phases, respectively. The performance of the MLP was compared with that of an ordered logit model. The ordered logit model was able to correctly classify only 58.9 and 57.1 percent for the training and testing phases, respectively. A simulation experiment was then carried out to understand the MLP neural network model. Results show that rural intersections are more dangerous in terms of driver injury severity than urban intersections. Also, female drivers are more likely to experience a severe injury than are male drivers. Speed ratio increases the likelihood of injury severity. Drivers at fault are less likely to experience severe injury than are those not at fault. Wearing a seat belt decreases the chance of sustaining severe injuries. Vehicle type plays a role in driver injury severity. Drivers in passenger cars are more likely to experience a greater injury severity level than are drivers of vans or pickup trucks. Finally, drivers exposed to impact at their side experience greater injury severity than those exposed to impact elsewhere.
Efficiency Gains from Value Pricing: Case Study of Sunol Grade
Authors: Kirshner Daniel
Published: April 2007

A case study of value pricing of a proposed capacity expansion for a major congested corridor in the San Francisco Bay Area known as the Sunol Grade is presented. A new high-occupancy vehicle (HOV) lane with a two-passenger-plus occupancy requirement is proposed to be added to the existing three southbound lanes to serve the morning peak period. The performance of the proposed HOV lane is compared with that of a value-priced express lane, which would provide unlimited, free access to vehicles with three-plus occupants and priced access to lower-occupancy vehicles. Compared with the proposed HOV lane, the express lane would reduce total vehicle-hours of delay—on both the general purpose and new lanes—by approximately two-thirds during the morning peak period, according to the queuing and high-occupancy mode-share models used here. These results are due to efficient throughout and increases in HOV mode share, made possible by the free-flowing conditions in the express lane compared with the expected congestion in a two-passenger-plus HOV lane.
Pedestrian Timing Alternatives and Impacts on Coordinated Signal Systems Under Split-Phasing Operations
Authors: Tian Zong Z. , Urbanik Tom , Engelbrecht Roelof , Balke Kevin
Published: April 2007

Split phasing can sometimes be more efficient in serving vehicular traffic under certain geometric and traffic flow conditions, such as the case in which a high volume of left-turning traffic is served from a sharedlane configuration. However, pedestrian crossing-time requirements can have a significant impact on intersection operations, especially in coordinated signal systems. Various alternatives for providing pedestrian timings under split-phasing operations are presented. The advantages and disadvantages, implementation strategies, and potential impact on intersection operations, especially on coordinated signal systems, are addressed with regard to each timing alternative. Further, the concept of the two-stage crossing design and the use of an exclusive pedestrian phase under split-phasing operations are investigated. The proposed model can be used to determine when exclusive pedestrian phasing can actually improve operational efficiency.
Construction and Performance of an Ultrathin Bonded Hot-Mix Asphalt Wearing Course
Authors: Hanson Douglas I.
Published: April 2007

In recent years, the need for preserving the investment in the U.S. highway system has received increased emphasis. An effective pavement preservation program includes several maintenance strategies that are applied in a cost-effective and efficient manner. Several new technologies have been developed to address these problems. One of the more promising technologies is the use of an ultrathin bonded hot-mix asphalt (HMA) wearing course (UTBWC). It consists of a layer of HMA laid over a heavy asphalt emulsion layer or membrane. The thickness of the ultrathin surface ranges from 9.5 to 19 mm (3/8 to ¾ in.). The system is placed on a structurally sound rigid or flexible pavement, which may exhibit minor surface distresses. The process was developed in France in 1986 and has been in use in the United States since 1992. Published experimental project reports and inspections of recently completed projects in many locations indicate good performance of the UTBWC. It provides a surface with excellent macro texture qualities, good aggregate retention, and excellent bonding of the very thin surfacing to the underlying pavement.
Thin Polysulfide Epoxy Bridge Deck Overlays
Authors: Stenko Michael S. , Chawalwala Arif J.
Published: April 2007

Over the past decade, polysulfide epoxy overlays have emerged as a cost-effective solution for protecting steel orthotropic and concrete bridge decks. The low modulus of the polysulfide epoxy resin, combined with its excellent bonding characteristics and easy application, makes it a suitable material for bridge deck overlays. More recently, epoxy overlays also have been successfully used on fiber-reinforced plastic (FRP) composite and timber bridge decks. Two major case studies on the use of polysulfide epoxy overlays as a wearing surface for multiple bridge deck materials are reported. In the first study, the thermal and mechanical properties of polysulfide epoxy materials were evaluated in laboratory testing; tests were performed on both steel and FRP substrates. In the second study, applications of thin polysulfide epoxy overlay placed on a steel orthotropic deck and an FRP composite bridge deck were evaluated in the field.
Estimating Time-Dependent Origin-Destination Trip Tables with Trips Originating in Multiple Time Slices
Authors: Nambisan Shashi S. , Pulugurtha Srinivas S.
Published: April 2007

Intelligent transportation system initiatives, such as travel information systems and travel demand management systems, have been used to ameliorate problems with congestion due to increasing travel demand. The success of these initiatives depends on the ability to accurately estimate the temporal variations in travel demand. A modeling framework based on arrival patterns of trips at workplaces and travel times in urban areas is presented. The peak period is divided into short, discrete intervals of time called time slices. Origin-destination trip tables for each time slice are estimated on the basis of when a trip with a certain travel time must have started to arrive at the destination in a specified time slice. There are two possibilities for the time slice in which a trip might have originated: ( a) starting in time slice k - 1 and ending in time slice m and ( b) starting in time slice k and ending in time slice m ( m ≥ k). A model is presented to estimate the probability that the trip might have originated in time slice k - 1 and time slice k. On the basis of these probabilities, the performance of the model is tested using data for the Las Vegas metropolitan area.
Multimodal Trips in the Netherlands: Microlevel Individual Attributes and Residential Context
Authors: Krygsman Stephan , Dijst Martin
Published: April 2007

Multimodal passenger transportation has received renewed attention in industrialized countries as a more sustainable and environmentally sensitive alternative to the uncontrolled growth in car travel. As a result there has been a diverse range of policy and planning guidelines supporting, promoting, and evaluating seamless multimodal travel alternatives. Few attempts, however, have been made at quantifying the space-time implications of multimodal transportation on the travel behavior and activity patterns of individuals. This research is concerned with an analysis of multimodal trips to provide insight into the specific travel behavioral and sociodemographic characteristics of multimodal transportation users in the Netherlands. A conceptual overview of multimodal transportation is provided followed by a brief literature review that discusses some relevant research themes relating to multimodal transportation. This conceptual overview is quantified with travel data from the 1998 Dutch National Travel Survey. On the basis of the analysis, conclusions are drawn with regard to the most frequently occurring mode chain combinations, number of trips, trip duration, and mean trip and stage distance. Attention is also paid to each mode’s unique distance decay function for the different stages in a multimodal trip. Finally, a schematic framework of the typical multimodal trip characteristics is provided. The individual level attributes that influence multimodal transportation is explored with multivariate analysis. The results indicate some very distinct person characteristics associated with multimodal transportation.
Regional Transportation Program for Welfare to Work
Authors: Hunt Kim L. , Czerwinski David
Published: April 2007

In its first round of Welfare to Work (WtW) competitive grants, the Department of Labor awarded $3 million to the Mayor’s Office of Workforce Development for a regional public transportation program for the Chicago area. The proposal was submitted on behalf of the Chicago Transit Authority (CTA), which operates bus and rail service in the city of Chicago and 38 suburbs, and Pace, which operates the suburban bus service in the region. The service area for the program includes the following counties: Cook, Chicago, DuPage, Kane, Lake, McHenry, and Will. The program consists of three components, CTA/Pace 30-day passes, a regional vanpool program, and train-the-trainer workshops in which job developers and caseworkers learn about public transportation options in the region. Program participants are Temporary Aid to Needy Families (TANF) clients who are new to or reentering the workforce. The TANF population, like the general population, is diverse. However, there are common challenges that must be overcome by many of the people who qualify for the regional program. CTA and Pace automated fare collection equipment data were used to examine ridership of WtW passes compared with the ridership of regular 30-day passes.
Integrating Geographic Information Systems with Transit Survey Methodology
Authors: Barua Barnali , Boberg Jeff , Hsiao Shirley , Zhang Xiaobo
Published: April 2007

Literature demonstrating how to use geographic information systems (GIS) effectively for transit origin-destination (O-D) data analysis is rather inadequate to date. Other than geocoding O-D survey data to point locations, not much attention has been accorded GIS as either a tool for checking survey data quality or for validation of data analysis. The purpose here is to demonstrate how the Orange County Transportation Authority applied GIS technology effectively to project transit passengers’ mobility patterns with greater accuracy and consequently strengthen the validation database for travel demand forecasting analysis with respect to transit planning. In addition to the use of traditional statistical methods for weighting procedures, this study relied on analytical GIS functions to achieve the following two objectives: ( a) incorporation of the spatial element while expanding the weighting factors, and ( b) validation of the weighted O-D survey returns with passenger counting data derived from other independent data sources. This project demonstrates both the usefulness of GIS technology in its ability to improve the quality of travel survey data and its value in combination with weighting-factors expansion methodology. In addition to the traditional statistical weighting methodology, a spatial component was incorporated as a criterion for enhancing the expansion results of the O-D data. Furthermore, comparative analysis with transit passenger counts and transfer data volumes were used to validate the findings of the weighting methodology. The results support the conclusion that GIS can greatly improve O-D data quality and statistical representation.
Dynamic Vehicle Dispatching at the Intermodal Transfer Station
Authors: Chowdhury Md. Shoaib , I-Jy Chien Steven
Published: April 2007

Transfer time is one of the most important service quality indicators for evaluating intermodal transit systems. In the advent of advanced public transportation systems, vehicle arrival times and transfer demand can be obtained in real time. Thus, the decision of dispatching vehicles at transfer stations can be optimized to reduce the transfer cost. A time-varying total-cost function, including connection delay and missed-connection costs incurred by transfer passengers and vehicle holding cost, is formulated as a function of holding times for vehicles that are ready to be dispatched at transfer stations. A procedure is developed to dynamically optimize the dispatching time for each ready vehicle by minimizing the time-varying objective function. A transit network consisting of four routes connecting at a transfer terminal is designed in this study to demonstrate the application of the dispatching model. The proposed method can be used to advance transit vehicle dispatching strategies and reduce the transfer time.
Human Factor Constraints on Transit Faregate Capacity
Authors: Weinstein Aaron , Lockhart Robert , Scalici Steven P.
Published: April 2007

Factors that affect faregate transaction times and hence the capacity of transit station faregates are described. These include both technological factors, such as the type of ticket processing mechanism (e.g., swipe readers versus ticket transport systems), and human factors, such as the extent of a customer’s interaction with information displayed at the faregate. Fieldwork conducted at the Bay Area Rapid Transit (BART) and New York City Transit systems has provided empirical data. The purpose of the research was to help BART assess alternative technologies for modernization of its 30-year-old fare collection system. As part of this assessment, BART was interested in obtaining higher throughput per faregate to minimize the number of new faregates that would be needed to meet expected increases in demand. The research suggests that although swipe readers are ultimately capable of higher throughput rates than ticket transport systems, human factors limit the actual throughput that can be obtained with either of these systems.
Fare Variable Construction and Rail Transit Ridership Elasticities: Case Study of the Washington, D.C., Metrorail System
Authors: Petitte Ryan A.
Published: April 2007

Two contributions are provided to the economic and transportation literature on rail transit ridership fare elasticities. First, several fare variables are constructed with controls for the decentralized nature of metropolitan employment; this relaxes the traditional assumption that railtransit patrons commute to a central city station. Second, rail transit demand elasticities are estimated using data from the Washington, D.C., metropolitan area rail transit system; research on this system has been absent from the literature on demand elasticities. Analysis of the extensive data shows that restricting rail patron travel patterns according to the monocentric urban model underestimates by 35 percent to 68 percent the responsiveness of ridership to fare increases.
Brightness and Color of Fluorescent Yellow and Fluorescent Yellow Green Retroreflective Signs: Comparison of Laboratory and Field Measurements
Authors: Burns David M. , Donahue Timothy J.
Published: April 2007

There is a growing body of traffic engineering research indicating that fluorescent-retroreflective signing can promote safer driver behavior on the road. However, missing from these studies are quantitative evaluations of the field performance of fluorescent-retroreflective materials on the roadway. How do the properties of fluorescent signs differ from those with ordinary colors? Information on the photometric performance of fluorescent-retroreflective signs under daytime and nighttime driving conditions relative to conventional signing is of interest to both researchers and practitioners. Laboratory measurements of the photometric and colorimetric properties of signing materials are commonly used in standard material specifications as surrogates for the field performance properties of traffic signs. Yet there are few data in the literature illustrating the relationship between laboratory testing of sign materials using standardized test methods and the photometric performance of signs on the road. Consequently, measurements were made of the photometric properties of a series of fluorescent and ordinary (nonfluorescent) retroreflective signs in both the laboratory and the field. The results show that laboratory testing does correlate to some extent with field measurements of the same properties. However, the data point toward a need for improvements in the current laboratory test methods to make them correspond more directly to what is observed by the driver.
Analysis of Railroad Horn Detectability
Authors: Rapoza Amanda S. , Raslear Thomas G.
Published: April 2007

The Acoustics Facility of the Volpe National Transportation Systems Center (part of the Research and Special Programs Administration of the U.S. Department of Transportation), in support of the Federal Railroad Administration, is conducting safety research to evaluate the effectiveness of various methods of reducing the number of accidents and resulting casualties at highway-railroad grade crossings. As part of this research, the effort reported here evaluates the probability of detecting railroad horn systems used as audible warning for motorists at highway-railroad grade crossings. To evaluate the detection probability, three sets of acoustic data were collected: ( a) acoustic characteristics of railroad horns, including sound level and directivity; ( b) insertion loss of motor vehicles; and ( c) baseline interior noise levels of motor vehicles. These data were used to determine the warning-signal-level-to-interior-noise-level ratio inside the motor vehicle at the minimum distance that would give the motorist sufficient time to react and avoid a collision. Signal detection theory, which incorporates the motorist’s prior expectations of encountering a train, is then applied to estimate the probability of detecting three currently used railroad horn systems at active and passive grade crossings.