bluuebunny/crossref_metadata_2025 huggingface dataset:
History and Future Challenges of Gyratory Compaction: 1939 to 2001
Authors: Harman Thomas , Bukowski John R. , Moutier Francis , Huber Gerald , McGennis Robert
Published: April 2007

History is a dynamic tapestry of facts and perceptions, dates and personalities. This work attempts to capture the events and rationale of those who contributed significantly to the use of gyratory compaction in the design and field management of hot-mix asphalt and discusses the challenges ahead. Throughout the evolution of asphalt mix design several different types of laboratory compaction devices have been developed. In general, the goal of these laboratory devices is to fabricate a specimen for volumetric or physical characterization, or both. Depending on the system, specimens can be cylindrical, trapezoidal, or rectangular and compaction can be achieved through impact, kneading, or vibration. Gyratory compaction applies a kneading effort to fabricate cylindrical specimens. The evolution of gyratory compaction has resulted in several unique devices and a variety of methods.
Target and Tolerance Study for Angle of Gyration Used in Superpave Gyratory Compactor
Authors: AI-Khateeb Ghazi , Paugh Chuck , Stuart Kevin , Harman Thomas , D’Angelo John
Published: April 2007

Five companies offer eight models of the Superpave® gyratory compactor (SGC) in the United States. Each model uses a unique method of setting and inducing the specified angle of gyration. However, all angles are set externally relative to the mold and none of the manufacturer’s calibration systems can be universally applied to all models. The specified external angle of gyration (α) is 1.25° FHWA, in partnership with Test Quip, Inc., developed a dynamic angle validation kit that measures the dynamic internal angle (DIA) of gyration during loading. The DIA accounts for equipment compliance issues, such as bending of the platens during compaction, which is not apparent when the angle is measured externally. Differences in specimen density produced by different compactors have been attributed to differences in compliance. Thus, the SGC test method needs to be revised to obtain uniformity. However, it would be inappropriate to assign the external angle of 1.25° to the DIA because the internal angle is always lower than the external angle. Use of a 1.25° internal angle would result in an increase in the compactive effort applied by all SGCs, which would invalidate the Ndesign table. FHWA investigated the DIA by using the original two SGC models. These models were used to refine the Ndesign table that is in use today. The study found that the DIAs for these original SGCs were 1.176° and 1.140°, which resulted in a proposed DIA of 1.16° The proposed tolerance is ±0.03°.
Electronic Marketplaces for Transportation Services: Shipper Considerations
Authors: Lin Iris I. , Mahmassani Hani S. , Jaillet Patrick , Michael Walton C.
Published: April 2007

Electronic marketplaces for transportation services in the context of their usage by shippers are examined. Shippers, carriers, and logistics providers come together at these marketplaces to provide and receive information about each other’s needs. The use of electronic marketplaces has promised to lower transaction costs, provide greater visibility of freight movement, and reduce inefficiencies in the current transportation and logistical processes. Although the efficiencies of these virtual hubs are promising, this promise will not materialize without the support of these interactive actors and agents of the transportation system. A study was performed of the adoption of this technology on the shipper side, primarily using a survey approach. The survey, designed for online administration, is aimed at studying the attitudes of shippers toward Internet technology and the subsequent development of electronic commerce. The results of this survey characterize the shippers’ awareness level of these marketplaces and the extent to which the marketplaces will be used. Furthermore, this survey also captures the roles that marketplaces will play in meeting the current and future needs of shippers.
E-Business Challenges for Intermodal Freight: Some International Comparisons
Authors: Smith Nariida , Chow Garland , Ferreira Luis
Published: April 2007

Separate Canadian and Australian government-sponsored studies, both reporting in mid-2001, have investigated expected impacts of rapid growth in e-business on transportation infrastructure and services. The different viewpoints of these two studies allow consideration of implications for freight transportation in general and intermodal freight in particular. The findings reported, relating to supply chain changes, special challenges for rail- and sea-freight carriers, and changes in requirements for freight warehousing and interchange, have international relevance, which leads to suggested policy responses. The importance of e-business in affecting freight transportation should not be underestimated. Transportation experts interviewed in the Australian study unanimously considered this the issue of most consequence for transportation over the next 5 to 10 years. Both studies point to freight transportation having significant potential to aid economic growth from e-business and conversely to a lack of appropriate infrastructure to accommodate that growth.
Integrating Freight Transportation with Intelligent Transportation Systems: Some European Issues and Priorities
Authors: Giannopoulos G. A.
Published: April 2007

Europe faces major challenges when it comes to formulating its transportation policy. Information and communication technologies (ICT) are considered a key tool to create the intelligent transportation systems (ITS) that Europe needs. In freight transportation, ICT is seen as playing a crucial role in providing efficiency in freight transportation operation and in integrating it within the overall ITS that are now being put in place in Europe. The issues and priorities for freight transportation integration with the European ITS are presented, with concentration (as one such priority) on the issue of linking freight transportation management systems with the advanced traffic-management systems of the European ITS. Also covered are the results so far of the thematic network THEMIS, which concertrates on the relation between freight transportation and ITS. A thematic network is a special type of research project, financed by the European Union’s Directorate General of Transport and Energy in order to review and synthesize the results of research in a specific field, in this case freight transportation. The efforts made at the European level toward the formulation of a common, ITS-based freight transportation systems architecture are also reviewed. In this respect, there is a report on work done within project THEMIS.
Development of a Nonaccident-Release Risk Index
Authors: “Skip” Elliott H. R. , Thomas Mitchell R.
Published: April 2007

Nonaccident releases (NAR) are the unintentional releases of a hazardous material while in transportation not resulting from a train accident. NARs are of significant concern to the shipping community due to their frequency, preventability, and cost. The North American Nonaccident Release Reduction Program was initiated in 1996 to help address the underlying causes of NARs and seek a substantial reduction in their frequency. Although the NAR Reduction Program showed significant gains initially, lately, NAR frequency, as measured by incidents per 1,000 tank-car originations, has held nearly steady. A new tool was therefore required to help the industry analyze the frequency, severity, and individual causes of NARs. In response, a working group consisting of all Class I railroads and several other interested parties developed the Non-accident Release Risk Index (NARRI). The NARRI sought to assign a numerical score to represent the severity of any given NAR based on its preventability, the potential risk involved considering the type and quantity of hazardous material involved, and the consequences of the NAR. Significant effort was devoted to the project to ensure that the measures employed were based on objective criteria to the maximum extent possible. Significant effort was also devoted to verify the consistency of the measure across different NARs and the repeatability of the measure for an individual NAR across various scoring individuals.
Modeling Approach for Transit Signal Preemption
Authors: Bhaskar Agrawal Bhuwan , Waller S. Travis , Ziliaskopoulos Athanasios
Published: April 2007

A simulation/assignment-based approach is introduced for evaluating the regionwide effect of signal preemption strategies for bus transit operations. The model addresses both the propagation and interaction of traffic with the bus operations as well as the routing behavior of drivers in response to the introduced preemption control. Furthermore, the need and feasibility of conducting this evaluation at the systemwide level is discussed and demonstrated. An example traffic network that includes Cermak Road in Chicago, Illinois, is used to demonstrate the applicability of the modeling approach.
Analysis of Florida Transit Bus Crashes
Authors: Rey Joel R. , Hinebaugh Dennis , Fernandez Jose
Published: April 2007

Through its National Center for Transit Research, and under contract with the Florida Department of Transportation, the Center for Urban Transportation Research (CUTR) was tasked with reviewing a sample of data on transit bus crash occurrence from selected Florida transit systems. The purpose of this review is to analyze changes in crash occurrence over time in relation to the effectiveness of training programs and capital safety improvements in reducing bus crashes. To this end, CUTR conducted two case studies utilizing occurrence data from Hillsborough Area Regional Transit Authority in Tampa (which implemented a refresher training course for bus operators) and LYNX Transit in Orlando (which replaced standard rear-end brake lights and turn signal and emergency flasher lights with high-density LED lights). The case studies examined the effect that these two particular safety campaigns had on postimple-mentation bus crash occurrence for the two properties. In addition to the promotion of safety, it is anticipated that this effort will be a preliminary step in the process of establishing a general list of safety campaigns, along with related costs and “rule of thumb” occurrence prevention effectiveness levels for each. A list of this nature will aid transit systems in Florida, the United States, and elsewhere in the selection of safety campaigns that will meet financial and safety goals.
Making Urban Transit Systems Sustainable Around the World: Many Birds with One Bus?
Authors: Schipper Lee , Fulton Lew
Published: April 2007

Urban transport in most cities around the world is developing in an unsustainable fashion, as reflected by rapid growth in traffic congestion and air pollution driven by individual motorization. Strengthened bus systems, built on rapid bus corridors, and improved bus technologies could play an important role in putting cities on a more sustainable path. Results and some of the main messages are presented from a recent study at the International Energy Agency, Paris, which has assessed the situation in a number of the largest cities in the developing world, while also drawing on experience from several cities in the developed world. A principal finding is that buses tend to carry a large share of travelers but contribute only a small part of total traffic and pollution. Also, although bus ridership is declining in many cities, new types of bus systems are emerging that offer the potential to reverse these trends and have done so in several cities (e.g., Curitiba, Brazil, and Bogota, Columbia). Advanced bus propulsion systems, that is, fuel cell and hybrid buses running on a variety of fuels, could eventually provide substantial relief from busrelated pollution problems. However, in developing countries, spending scarce funds for cleaning up the emissions from present technologies, along with developing improved bus systems that enhance traffic flow, would provide far more relief in the near-term than spending on a few advanced technology buses. Both paths must be followed, but the latter must not obscure the former. Conditions necessary for bus systems to prosper are discussed and, in conclusion, recent promising developments are highlighted.
Effect of Computer-Assisted Scheduling and Dispatching Systems on Paratransit Service Quality
Authors: Pagano Anthony M. , Metaxatos Paul , King Mark
Published: April 2007

The few computer-assisted scheduling and dispatching (CASD) systems evaluated to date do not, in general, provide details on the effects of quality of service. An analysis of the quality-of-service effects of a CASD system in central Illinois is presented. The analysis finds that a variety of service attributes have been positively affected by CASD implementation. Passengers experienced greater on-time rates at both pickup and drop-off, overall satisfaction with the service increased, and customer reporting of ride denials was reduced. On the other hand, the use of CASD to promote higher vehicle productivity resulted in slightly longer ride times. In addition, callers to the system experienced being put on hold more often. On the whole, the conclusion is that quality of service has been positively affected by the implementation of the CASD system.
Planning and Design of Flex-Route Transit Services
Authors: Fu Liping
Published: April 2007

A theoretical investigation is presented of various issues involved in the planning and design of flex-route transit services. An analytical model is proposed for an idealized operating environment with the objective of determining the optimal slack time that should be allocated to a flexroute segment. The optimization objective is defined to minimize total operator and user cost, which enables a systematic examination of complex interactions among the system parameters. An equation is derived for the relationship between the number of feasible deviations and various system parameters such as slack time, zone size, and dwell time. Subsequent analysis shows that the analytical model is elaborate enough to provide substantial insights into various issues that may arise in designing a flex-route service. A simulation analysis is conducted to validate some of the conclusions drawn from the analytical model and to further analyze the implications of stochastic variation in passenger demand.
Network Design for Personalized Public Transit Service
Authors: Pashaie Behruz , Ardekani Siamak A.
Published: April 2007

Network design requirements for personalized public transit service are presented. This concept involves diverting buses from their fixed routes to pick up passengers in the vicinity of the route. The software developed for the Dallas Area Rapid Transit to implement this concept is also discussed. A Dallas bus route is used as the case study. The service corridor is defined to be one-third of a mile on each side of the route. The software uses the real-time bus location and the schedule adherence data from a satellite-based vehicle locator system. Once it is determined that a given service request can be filled, the program generates the best diversion path and the estimated time of arrival to the caller’s location. The software includes modules for logging incoming calls for service, identifying passenger locations, assessing feasibility of providing service, determining the best diversion path for passenger pickup, and assessing the effect of the diversion on the schedule. The network database includes street geometry (nodes and links); link volumes, capacities, and free-flow speeds; node turning prohibitions; bus stop and timepoint locations; and route schedule including available schedule slacks.
Bringing Fixed-Route Transit Service to Small Cities and Towns: Potential Contribution of Existing Demand-Response Brokerages
Authors: O’Connell Lenahan , Siria Bruce , Grossardt Ted
Published: April 2007

The possibility is suggested of adding fixed-route transit service to many of the nation’s small cities and towns by using some of the money currently devoted to the provision of client-oriented demand-response transit to fund the new service. This can be done, this study finds, with very little additional expense and no loss of necessary demand-response service. The creation of small fixed routes is feasible, when the demand-response system is organized across a region by a brokerage (i.e., an organization paid on a capitated basis that assigns eligible riders to transportation providers). Research shows that both brokerages and fixed routes tend to lower Medicaid transportation costs. The thesis is that these two efficiency enhancers can be combined effectively in some of the nation’s small towns and cities, whenever capitated brokerages can provide the administrative apparatus and much of the funding for the fixed route. This thesis is illustrated with the results of a study conducted in a Kentucky city of 27,000. It found that a substantial number of those currently riding in demand-response vehicles to which they are assigned by a broker could be shifted to a proposed fixed route. The new route would be operated by the broker with funds from the capitation payments. The study’s findings suggest that capitated brokerages may create an opportunity for many of the nation’s smaller cities to obtain a fixed-route bus service at a modest, or perhaps at even no, additional cost.
Simple Procedure for Creating Digitized Bus Route Information for Intelligent Transportation System Applications
Authors: Lin Wei-Hua , Padmanabhan Vijaybalaji
Published: April 2007

The development of procedures for creating bus route information is discussed as part of a Global Positioning System (GPS)–based bus inventory database in urban transit systems for intelligent transportation system applications. In the past, bus route information was usually entered into the database through geographic information system tools. Procedures involved in data entry were often very tedious. This study utilizes GPS technology to automate the process of generating data inventory for bus route information. An efficient algorithm was developed in this study for capturing the route information on the basis of a sequence of vehicle location data. The algorithm can be readily implemented with computer programs. The route information obtained from the algorithm is compared with the field bus trajectory data collected in Blacksburg, Virginia. In particular, comparison was made for different digitizing intervals and different bus routes. The results show that the route map created is sufficiently accurate for many applications. The route map information obtained from this study is particularly useful for the development of transit information systems to ( a) predict arrival time of the next bus and ( b) track schedule adherence of individual buses.
Quality Bus Corridors in Dublin
Authors: O’Mahony Margaret
Published: April 2007

Bus transport in Dublin has been and continues to be perceived as a poor alternative to the car. It is generally seen as the “poor person’s” mode of transport, with many people upgrading to a car as soon as they can afford to do so. The result has been a significant increase in traffic congestion fueled by the recent period of economic growth during which car ownership levels have risen from 238 per 1,000 in 1991 to 350 per 1,000 in 1999. One of the main difficulties facing the state-owned bus company is that buses compete with cars for inadequate road space. In 1995, the Dublin Transportation Initiative proposed a new public transport strategy incorporating light rail transit and what they described as quality bus corridors (QBCs). To date, 9 out of 11 QBCs have been implemented. The characteristics of a QBC include a dedicated lane between 0700 to 1900 in most cases, although some 24-hour bus corridors also exist. Although there is no physical separation between the bus lane and other lanes, enforcement by the police is strict and there is a relatively low level of noncompliance. The QBC concept is described in more detail and the effects since introduction in Dublin are discussed, particularly with regard to travel times, passenger numbers, and reliability of service frequency. Future plans for bus transport in Dublin are mentioned, highlighting the significant contribution buses will be expected to make in solving Dublin’s transport problems.
Automobile Ownership, Households Without Automobiles, and Urban Traffic Parameters: Are They Related?
Authors: Karlaftis Matthew , Golias John
Published: April 2007

Most research to date on automobile ownership has concentrated on establishing links between various socioeconomic factors and automobile ownership, without much regard to urban traffic parameters that may affect ownership rates. To address the issue of the effect of traffic parameters on ownership rates, the study takes a twofold approach. First, it investigates whether traffic characteristics and network efficiency parameters influence automobile ownership. Second, it investigates whether not having an automobile (autolessness) is also affected, and to what degree, by these parameters. The results clearly suggest that the variables affecting automobile ownership and autolessness are not the same. It further suggests that traffic network and efficiency parameters do not, on one hand, affect autolessness, but they do, on the other hand, affect the number of automobiles owned by a household. What this seems to imply is that a household’s decision to purchase the first automobile is primarily based on socioeconomic factors, whereas the decision to purchase a second automobile (or more) is largely based on traffic network, efficiency, and transit level-of-service parameters.
Trials and Successes of Covered Bridge Engineering and Construction: Hamden Covered Bridge, Delaware County, New York
Authors: Pierce Phillip C.
Published: April 2007

The rehabilitation of a historic covered bridge is confounded by numerous challenges. The engineering involves issues unfamiliar to many of today’s practicing engineers. The relatively few, and geographically dispersed, covered bridge construction projects in modern times often involve contractors with limited experience in the nuances of covered bridges. Three bridges in Delaware County, New York, have recently undergone extensive rehabilitation. Although work on the Hamden bridge predated funding available through the National Historic Covered Bridge Preservation Program as created by the Transportation Equity Act for the 21st Century, the work was performed to standards similar to those required by that program.
Tiered Environmental Studies in the National Environmental Policy Act Process for Highway Projects
Authors: Malley William G. , Dusenbury Angela M.
Published: April 2007

In recent years, there has been a renewed interest in the use of tiering and tiering-like procedures as techniques for managing the National Environmental Policy Act (NEPA) process for highway projects. However, experience with these procedures remains limited, and guidance materials are scarce. Thus, available information is brought together about tiering, the benefits and drawbacks of tiering are assessed, and general advice is offered about when to use tiering and what issues to consider in a tiered NEPA process. The effort consists of five parts. First is an introduction of NEPA and its processes, followed by information on regulatory authority and guidance, early experiences with tiering, recent developments in tiering, benefits and drawbacks of tiering, and issues to consider in preparing a tiered study.
Creating Synergy In and Around Stations: Three Strategies for Adding Value
Authors: Peek Gert-Joost , van Hagen Mark
Published: April 2007

Recommendations are presented for developing or redeveloping railway station areas by creating synergy between both identities of a station—as a node in a transport network and as an urban location. Station users want a reliable, safe, fast, easy, comfortable, and pleasant experience in transferring to different transport modes. Besides speed and safety, quality in the sense of comfort and experience are added values. Focusing on the traveler’s appreciation of faster travel leads to three strategies that can add value—( a) acceleration: making individual trips faster and eliminating hassle in transferring to other transport modes; ( b) concentration: concentrating origins and destinations near stations and improving the station environment; ( c) enhancement: adding facilities that enhance the comfort and experience of transfer points. To create this synergy, a station should be divided into three areas. First, travel-related services should be located at the center of transfer points; acceleration is the key word here. Second, business facilities central to transfer points would make transfer intervals more useful and pleasant; the emphasis is on enhancing comfort and experience. Third, less-travel-related activities and attractions should be concentrated in a particular location, thus reducing travel time and hassle and enhancing the urban environment. Synergy in station development or redevelopment can result if both transportation and real estate factors are considered.
Encouraging Kiss-and-Ride at Commuter Railroad Stations
Authors: Schank Joshua L.
Published: April 2007

Providing parking for commuter rail passengers can be difficult. Commuter railroads want to accommodate as many riders as possible at their suburban stations, but it is often impossible to provide enough parking to satisfy demand. Railroads would rather not charge a marginal fee for parking because this would likely decrease ridership. Local communities usually oppose large parking structures, and space for additional surface parking is often limited. To alleviate some of the parking demand, a possible strategy is to promote kiss-and-ride, or passenger drop-off. This method of station access requires no parking spaces, yet attracts additional riders. Although commuters accessing stations in this way usually choose to do so because of the particular characteristics of their commute, station and parking lot design might also influence their decision. Commuter rail stations in the New York City metropolitan area were studied to help determine the role of parking lot design and regulation in encouraging or discouraging the use of kiss-and-ride as a station access mode. Stations on the Metro-North Railroad and Long Island Rail Road were examined relative to their access and parking statistics and also by site visits. The demographics of the areas surrounding the stations were also considered. The results show that parking lot design and regulation may have an effect on kiss-and-ride usage. Parking lots with larger, more-accessible drop-off points tended to have greater kiss-and-ride percentages. Lots with illegal-parking problems, particularly prevalent on Long Island, tended to have lower kiss-and-ride percentages because it was often impossible to find a place to drop someone off.
Washington State Ferries’ Travel Demand Model Development and Forecasting Analysis Programs: A 10-Year Perspective
Authors: Dehghani Youssef , Adury Murli K. , Bradley Mark , Gihring Celine K.
Published: April 2007

Recent Washington State Ferries (WSF) origin–destination travel survey data collection and model development activities are described. WSF performed similar activities in 1993. The lessons learned from the initial project helped to develop a better survey design and sampling plan. The overall survey response rate was 37%, about 28% higher than the response rate for the 1993 travel survey. The improved survey design and sampling plan also provided a richer data platform from which to establish more representative observed baseline ferry travel patterns, by boarding method and access and egress mode combinations. Compared with 1993, the 1999 travel survey results reflect a significant increase in the systemwide use of transit for access to and egress from ferry terminals. This increase was primarily attributed to improved transit service, timed ferry-bus connections, and ferry-bus passes implemented by Kitsap Transit and other transit agencies. In addition to the 1999 travel survey, WSF conducted a stated preference survey. The combined data from these two surveys provided information on ferry users’ revealed and stated preferences, which allowed a more rigorous statistical mode and route choice estimation analysis to be performed. This analysis helped develop a more robust and internally consistent model, as reflected in model performance. For walk-on and automobile-boarding passengers, the updated WSF model has produced more accurate route-level validation results than the previous model. The results from the model estimation and validation analyses are presented. Specific improvements made in the updated model are highlighted.
Minimum Retroreflectivity for Overhead Guide Signs and Street Name Signs
Authors: Carlson Paul J. , Hawkins H. Gene
Published: April 2007

Research and recommendations were produced on the basis of a study on the development of minimum retroreflectivity values for overhead guide signs and street name signs. The research reviewed the literature and available photometric models. A photometric model was created to develop minimum retroreflectivity values for overhead guide signs and street name signs. One model input was the minimum luminance required for legibility. To obtain minimum luminance requirements for overhead guide signs and street name signs, a field evaluation was performed. Accommodating older drivers was specifically emphasized. After the minimum luminance values were determined, the minimum retroreflectivity model was used to study the impacts of (and determine appropriate values for) factors that affect retroreflectivity, such as distance, headlights, and vehicle speed. After the appropriate values were determined, the minimum retroreflectivity model was executed for the final runs. The recommended minimum retroreflectivity values were grouped into one table that includes overhead guide signs, postmounted street name signs, and overhead (mast-arm– or span-wire–mounted) street name signs. The values depend on type of sheeting, speed, and sign position.
Development of a Pavement Marking Management System: Measurement of Glass Sphere Loading in Retroreflective Pavement Paints
Authors: Rich Michael J. , Maki Robert E. , Morena Jill
Published: April 2007

Of critical economic importance to roadway management agencies is the retroreflectivity of edge lines and centerlines and the retention of retroreflectivity with exposure to weather, snowplowing, road salt and sand, and traffic density. This study evaluated factors affecting the performance and durability of painted edge lines and centerlines on specific Michigan roadway sections as part of a project to develop a practical pavement marking management system. An ill-defined aspect of retro-reflectivity is the relationship of glass sphere content and the decay of retroreflectivity over time and from seasonal maintenance. Two techniques were developed to quantify the glass sphere content of retroreflective pavement paints. In the first method, aluminum plates are fastened to the roadway and painted in the field as the painting crew applies the striping. The plates are retrieved and pyrolyzed at elevated temperature, with observations made on weight changes of the painted plate. A mass fraction of glass spheres can then be calculated. In the second method, the painted plates are photographed at low magnifications. The macrographs are converted to a binary image that is evaluated using image analysis software to determine the number of spheres per area, average size, and aerial percent. The glass sphere content, as determined by pyrolysis and image analysis, is correlated with retroreflectivity measurements collected on the same samples. These new methods will lead to a better understanding of factors related to the retroreflectivity loss of pavement paints and ultimately to improved products and maintenance practices.
Extracting Slipperiness Component from Weather and Traffic Data for Winter Maintenance Operations
Authors: Nakatsuji Takashi , Hamada Naoki , Kawamura Akira
Published: April 2007

Although traffic and weather information systems indicate existing air and road surface temperatures, many drivers want to know not the temperature but the degree of road slipperiness. The friction coefficient is the best index for snow and ice conditions, but it is difficult to calculate. Some weather condition data are closely correlated with the friction coefficient. In this study, the use of weather and traffic data to determine the degree of road slipperiness was examined quantitatively by analyzing field data obtained at an intersection on a trunk line. Two kinds of filters were effective in extracting the slipperiness component from the observed data—the Kohonen Feature Map (KFM) and principal component analysis (PCA). KFM kept the distribution of the observed data uniform by eliminating excessive data, and PCA eliminated multicollinearity among the observed variables. The first two principal components successfully represented the original observed data with an accumulated proportion of more than 0.85. A linear multiple regression model, in which the PCA score values were adopted as the explanatory variable, was also justified. The multiple correlation coefficient was satisfactory for many patterns, and the radiation-related data were effective in improving estimate precision.
Application of Jetting Technology to Pavement Deicing
Authors: Taggart David G. , Ibrahim Osama , Huston Milton
Published: April 2007

Winter maintenance of pavement surfaces consists of plowing and the application of corrosive deicing agents. These chemicals are hazardous to the environment, and thus their use should be minimal. More than 20 years ago, the Connecticut Department of Transportation (ConnDOT) investigated the use of 2.1 MPa (300 psi) pressurized salt brine jets to enhance deicing performance. Despite promising results from several field trials, technical difficulties led to abandonment of this technology in the early 1980s. Recent advances in high-pressure jetting technology suggest that the use of high-pressure jets in conjunction with improved chemical agents for pavement deicing may now be practical. In this study, the application of modern high-pressure jetting technology to deice pavement is explored. The proposed system removes ice and snow through the combined action of mechanical jetting forces and controlled use of deicing chemicals. Appropriate operating parameters and consumption rates are identified and compared with the ConnDOT system developed in the 1970s.
Economic Evaluation of Banning Studded Tires Because of Environmental Impact
Authors: Asano Motoki , Tanabe Shintaro , Hara Fumihiro , Yokoyama Shingo
Published: April 2007

The environs of Sapporo, Japan, including four cities and three towns, were designated “studded tire restriction areas” by the Studded Tire Regulation Law of 1990. As a result of the law’s enactment, the studded tire usage rate decreased drastically, and the dust pollution from vehicles and dust concentration progressively decreased. The use of studless instead of studded tires had positive effects, such as improvements in air quality and the roadside environment. However, traffic congestion and vehicle and pedestrian accidents increased on slippery roads. The effects of the studded tire regulation were examined with an economic assessment of the 10-year period since the law was enacted. The effects of using studless tires were also assessed for transportation service and the environment. Calculated using the contingent valuation method for environmental evaluation and the primary unit method for transportation service and air quality, the effects were analyzed using the benefit incidence matrix. Positive effects were observed, such as an improved roadside environment for residents and pedestrians and reduced road maintenance expenditures. Adverse road user effects, however, were also observed, including increased travel time and costs.
Integrating Pavement Preservation into a Local Agency Pavement Management System
Authors: Smith Roger E.
Published: April 2007

Pavement preservation has become an important topic in the pavement community in the last few years. Preventive maintenance is a vital part of pavement preservation. All state and most local agencies use pavement management systems to assist in making decisions about pavement maintenance and rehabilitation. If pavement preservation is to be used effectively in these agencies, their pavement management decision-making processes must support it. A description is given of how the Metropolitan Transportation Commission Pavement Management System used by several local agencies in California, Oregon, and other states incorporates pavement preventive maintenance and pavement preservation.
Kentucky Transportation Cabinet Moves Its Bridge Painting into the 21st Century
Authors: Meade Bobby W. , Hopwood Theodore , Palle Sudhir
Published: April 2007

The Kentucky Transportation Cabinet (KYTC) is rapidly evolving its bridge-painting operations to address the diverse challenges of the 21st century. At the forefront of this effort is the KYTC Paint Team, a multi-disciplinary task force of KYTC personnel representing the KYTC divisions involved in paint activities as well as researchers from the Kentucky Transportation Center (KTC) at the University of Kentucky. Key features of the Paint Team are its close interagency cooperation within KYTC on all facets of bridge painting and the total integration of KTC researchers’ work in Paint Team activities, including laboratory work and field testing. The Paint Team works to achieve incremental improvements on all painting projects. Current Paint Team goals to advance KYTC painting operations include enhancing environmental and worker safety compliance on all projects; improving contractor quality and KYTC field inspections; employing cost-effective bridge-painting options to better address project needs; testing and developing promising new coatings and related technologies; improving project delivery; sharing information with peer groups; and committing to context sensitivity on all bridge-painting projects. This innovative approach has enabled the KYTC to successfully progress and to grow its activities in a field that is beset with technical and regulatory impediments. It is a model that can be used to address highway issues and is amenable for adoption by other transportation agencies.
Phenomena and Conditions in Bridge Decks That Confound Ground-Penetrating Radar Data Analysis
Authors: Barnes Christopher L. , Trottier Jean-François
Published: April 2007

Ground-penetrating radar (GPR) has gained a reputation for providing a fast and generally effective means of assessing and prioritizing reinforced concrete bridge deck delamination repairs on a network level. A collaborative research project between Dalhousie University and the Nova Scotia Department of Transportation and Public Works studied the use of GPR for asphalt overlaid reinforced concrete deck condition assessment. In some instances, differences observed between the GPR-based predictions and the actual quantities of necessary repairs resulted in significant costs for deck repair projects studied during this research project. These differences were caused by phenomena and conditions typical of structures in service and may confound the GPR data analysis. These phenomena and conditions include properties and condition of the asphalt concrete overlay, environmental effects pertaining to moisture, deck structure, extent of deterioration, and the method of detecting and delineating repair areas on the exposed deck surface. When these conditions and effects are expected in survey results, GPR can provide a powerful tool for network-level management of deck repairs. This paper provides a discussion of these phenomena and their effects on the resulting GPR surveys.
Integration of Agency Rules with the Preservation Optimization Model in the Pontis Bridge Management System
Authors: Robert William E. , Marshall Allen R. , Lin Sandi S. , Shepard Richard W. , Aldayuz José
Published: April 2007

The Pontis® Bridge Management System was initially designed as a tool for performing network-level analyses of bridge needs and work. Although even the earliest versions of the system simulated conditions and work at the bridge level, activities such as model calibration and reporting were designed at the network level. The most recent Pontis version, Release 4, adds significant new capabilities for performing bridge-level analyses, including the ability to invoke agency rules that allow recommendations to simulate agency practices. The intent of the rules is to recognize agency practices and their effects on bridge-level recommendations, while preserving the system’s basic modeling approach. This paper describes the new components of the Pontis modeling approach and analyzes a case that illustrates the effects of applying bridge-level agency rules to both network-level and bridge-level results generated by the Pontis system. Five-year program simulations, with and without agency rules, were performed on a sample set of bridges. The analysis indicates that for the limited sample, applying a typical set of agency rules improved bridge-level recommendations qualitatively by triggering recommendations for less frequent but larger projects than those recommended in the absence of the rules. Further, the rules, particularly those designed to upscope Pontis recommendations on the basis of agency practice, increased the estimate of initial network-level needs by approximately 23%. However, the backlog growth or reduction at a given budget level was not significantly altered by the rules’ application.
Durability Evaluation of Concrete Crack Repair Systems
Authors: Tsiatas George , Robinson Joseph
Published: April 2007

Concrete cracking in highway bridges is a major problem because it not only accelerates the rate of deterioration, but it also can reduce the structural strength of the bridge. Crack repair systems have been developed to address this problem. For repairing structural cracks, six repair materials were evaluated for durability. The repair materials include one cementitious system, one modified cementitious system, two epoxy-based systems, and two high-molecular-weight methacrylate (HMWM) repair products. Each product was applied according to its manufacturer’s directions to repair beams with crack widths of 0.51 mm (0.02 in.), 6.35 mm (0.25 in.), and 12.70 mm (0.50 in.). The specimens are subjected to a standard freezing and thawing test followed by fatigue testing to failure. In general, epoxies and HMWMs performed the best. However, individual products varied significantly. Specimens repaired with the cementitious system were unable to resist any significant amount of fatigue-loading cycles.
Selection of Design Speed Values
Authors: Fitzpatrick Kay , Carlson Paul
Published: April 2007

A revised definition for design speed has been adopted by AASHTO and included in the 2001 Green Book. Although this revised definition addresses several concerns, it does not include guidance on how to select the most appropriate design speed value. A summary of AASHTO policy, state practices, and international practices with regard to design speed selection demonstrates substantial variation in the processes used to select design speed. An analysis performed using operating speed as the measure of effectiveness validates some of the AASHTO criteria used to select design speed. However, the analysis also indicates that terrain (one of the AASHTO criteria used to select design speed) may not be related to operating speed, and its inclusion in the design speed selection process is justified in roadway cost considerations. Four possible solutions are presented for selecting the most appropriate design speed value for a better relationship between design speed and operating speed.
Influence of Vertical Alignment on Horizontal Curve Perception: Phase I: Examining the Hypothesis
Authors: Bidulka Shaun , Sayed Tarek , Hassan Yasser
Published: April 2007

The importance of the driver’s receiving precise visual cues from the road environment cannot be overstated. If the visual cues are confusing or in any way cause the driver to incorrectly assess the approaching road environment, the crash risk of the driver may increase. Of particular concern are the perceptual problems induced by superimposing horizontal and vertical curves. To investigate the effect of overlapping vertical alignment on the perceived horizontal curvature, dynamic and static computer-generated three-dimensional presentations of the driver’s view of a road were created. In Phase I of the experiment, data were collected to test the hypothesis that overlapping crest curves made the horizontal curvature appear sharper and overlapping sag curves made the horizontal curvature appear less sharp. The results of both presentation methods (dynamic and static) were in agreement and showed that the hypothesis was valid. However, the hypothesis was more evident in the case of sag curves, which is a more serious issue with respect to safety. The probability of erroneous perception, as influenced by vertical curves, increases as ( a) the sight distance increases, ( b) the horizontal curve radius increases, and ( c) the length of vertical curve per 1% change in grade decreases. Driver characteristics did not appear to affect the horizontal curve perception.
Safety Evaluation Process for Two-Lane Rural Roads: A 10-Year Review
Authors: Lamm Ruediger , Psarianos Basil , Cafiso Salvatore
Published: April 2007

A practical procedure was developed that explicitly considers the driving behavioral and safety rules of a horizontal alignment for the evaluation of roadway new designs; redesigns; and projects of rehabilitation, restoration, and resurfacing. Design classes were developed to classify, from a traffic safety point of view, roadway sections as good, fair, or poor; these design classes are associated with three safety criteria to develop an overall quantitative safety evaluation procedure for two-lane rural roads. The safety criteria are introduced to analyze and evaluate by ( a) Safety Criterion (SC) I: the difference between design speed and actual driving behavior as expressed by variations in observed 85th percentile speed; ( b) SC II: the difference between observed 85th percentile speeds on successive design elements; and ( c) SC III: the difference between side-friction assumed and side-friction demanded at the 85th percentile speed level on curves. Furthermore, the issues discussed include design speed, operating speed, sound tangential, and side-friction factors, as well as the application of tangents in the design process. A comparative analysis of the actual accident situation with the results of the safety criteria reveals a convincing agreement. Thus, the great advantage of the new concept is that as early as in the design stages, safety criteria can predict the endangerment (low, medium, and high) for new alignments or allow statements about the safety conditions of existing (old) roadway sections or whole road networks.