bluuebunny/crossref_metadata_2025 huggingface dataset:
Cooperative Effort To Promote Economic Development and Maintain Low-Volume Road Safety and Operations: Intermodal Case Study
Authors: Beachy Kevin T. , Eck Ronald W.
Published: April 2007

The principal function of low-volume roads is to provide access to land uses adjacent to the road. The roads are important to industry for hauling raw materials and to local residents. Low-volume roads often intersect railroads, creating a grade crossing. This creates the potential for conflicts between modes and introduces delays for motorists when long trains occupy a crossing. These conflicts can reach unacceptable levels. Presented is a case study of one such situation. The George’s Creek area in Maryland is a significant producer of bituminous coal. A local coal operator wanted to ship coal via train to the port of Baltimore. Clearly, this would be a boost to the local economy. A rail line already served the area; however, there were no coal-loading facilities. The quantity of coal produced did not justify construction of such facilities. Thus it was decided to load the train by using mobile equipment. This required the train to block a low-volume road grade crossing for significant periods on a quarterly basis. Residents were concerned about access to their homes, emergency vehicle access, and grade crossing safety. Through communication, coordination, and cooperation among the mine operator, the railroad, and the local jurisdiction, a plan was developed wherein the mine was able to ship its coal by rail and local residents had safe access to their homes and emergency vehicle service. Implementation of the solution is detailed. Critical issues are identified and their resolution discussed. Lessons learned and suggestions for other locations facing similar problems are included.
Small-Scale Intelligent Transport System Applications for Low-Volume Roads: Some Experiments and Experiences from the North European VIKING Project
Authors: Leviäkangas Pekka , Pilli-Sihvola Yrjö
Published: April 2007

The Euroregional VIKING program includes several projects that have potential as intelligent low-volume road applications. In Finland, traffic volumes are on average very low and therefore the telematic applications often are designed to fit into low-volume traffic conditions as well. Some relevant projects are introduced. The projects include applications such as weather-controlled variable message signs and speed limits, local ferry traffic management, animal detection and warning system, cross-border data exchange in rural areas, and some ideas for the future such as managing the forest harvest traffic and low-cost road weather monitoring. Some of the experiences gained are encouraging but a lot of research needs to be done in future years. Although the applications described are evaluated as potential low-volume road solutions, many other applications may become available as the real prices of telematic equipment and systems fall over time. Recent estimates of the fall of real prices suggest that prices may decrease significantly, perhaps within 1 decade.
Toward a Low-Cost Structures Design Manual for Rural Roads in Developing Countries
Authors: Larcher Paul
Published: April 2007

Numerous road construction projects in developing countries have aimed to provide low-cost roads. A major component of these road networks is the structures required to cross streams and rivers. On these projects little attention has been paid to the use of local resources and indigenous skills such as masonry, brick, or manufactured blocks for the construction of highway structures instead of reinforced concrete. A wealth of information is available to designers of highway structures in high-income countries, primarily on the design of large steel and reinforced concrete structures. However, these design guides and textbooks do not address the design of simple water crossings such as drifts, vented fords, or small bridges. There is a clear need for a design manual that provides information and guidelines for highway engineers who are designing structures on low-cost roads in developing countries with limited resources. The findings of desk and field studies for the preparation of a manual for road engineers, technicians, and supervisors in developing countries are discussed. The problems typically encountered in the design, construction, and subsequent use of highway structures are highlighted, and how the manual addresses these problems is discussed.
Laboratory Studies on Cement-Asphalt Emulsion Composite
Authors: Li Guoqiang , Zhao Yi , Pang Su-Seng , Wei Lianyu , Deng Xuejun
Published: April 2007

An experimental investigation was conducted on a three-phase cement-asphalt emulsion composite (CAEC), in which asphalt was introduced as a cushion layer in between coarse aggregates and cement mortar matrix by dispersing asphalt emulsion-coated coarse aggregates into cement mortar matrix. Laboratory tests on fatigue, strength, rigidity, temperature susceptibility, and stress-strain relationship were studied to evaluate the mechanical properties of the CAEC. The test results showed that CAEC possesses most of the characteristics of both cement and asphalt—namely, the longer fatigue life and lower temperature susceptibility of cement concrete and the stronger toughness and higher flexibility of asphalt concrete. It is expected that CAEC can be an alternative for semirigid base-course material. However, it slightly reduced the strength compared with control cement concrete.
Continuous Intrusion Miniature Cone Penetration Test System for Transportation Applications
Authors: Kurup Pradeep U. , Tumay Mehmet T.
Published: April 2007

The electronic cone penetrometer is an important investigation tool of choice for in situ site characterization. Application of this proven concept of the cone penetration test (CPT) to transportation applications is described. A miniature cone penetrometer with a projected cone area of 2 cm2 has been developed and implemented in a continuous intrusion miniature CPT system (CIMCPT). This device may be used for rapid, accurate, and economical characterization of sites as well as to determine engineering soil parameters needed in the design of pavements, embankments, and earth structures. The miniature CPT (MCPT) gives finer details than the standard 10-cm2 cross-sectional area reference cone penetrometer, which makes it attractive for subgrade characterization, quality control assessment, compaction control of embankments, and assessment of ground improvement effectiveness for transportation infrastructure. In situ calibration of the CIMCPT system was conducted at a highway embankment site in Baton Rouge, Louisiana. MCPT penetration profiles were compared with those obtained with the standard cone penetrometer at the same site. The tip resistance of the MCPT was 10 percent higher than that of the reference CPT. The sleeve friction and friction ratio of the reference CPT were higher than that of the MCPT by 12 and 23 percent, respectively. Calibration was also performed to determine empirical cone factors required for estimating undrained shear strength from MCPT data.
Utilization of Municipal Solid Waste Combustion Bottom Ash as a Paving Material
Authors: Zhang Xishun , Gress David , Karpinski Stanley , Eighmy T. Taylor
Published: April 2007

A multiyear research project was conducted to investigate the potential of using municipal solid waste combustion bottom ash as a paving material. Characterization of the ash physical properties, development of the asphalt mix designs, and the bottom ash demonstration project in Laconia, New Hampshire, are discussed here. Laboratory results suggest that the physical properties of the ash are consistent with its use as a substitute for conventional aggregate in asphalt mixtures, the properties of ash are typical of a lightweight aggregate, and the 50 percent ash-asphalt mixture design meets New Hampshire Department of Transportation specifications. An ash demonstration project at 50 percent substitution was successfully placed in Laconia in May 1993. A 5-year period of field performance evaluation indicates that the ash section performs as well as the control section.
North Dakota Gravel Road Management: Alternative Strategies
Authors: Smadi Ayman , Hough Jill , Schulz Lance , Birst Shawn
Published: April 2007

Gravel roads account for a large portion of the total 5.1 million km (3.2 million mi) of rural roads in the United States. These roads support the movement of farm families, rural residents, school buses, mail carriers, tourists, and agricultural commodities. In recent years, these roads have been affected by several trends. First, agricultural states are experiencing population shifts from farming areas to urbanized centers as farm sizes continue to grow, further reducing population densities and traffic levels. Second, some states such as North Dakota are experiencing a shortage in quality gravel supplies. Third, more rural road users perceive a lower level of service on gravel roads and demand better services, specifically more paved roads. Finally, the reduction in transportation budgets limits the number of gravel road kilometers that can be properly maintained. Several research efforts that examined alternative approaches to reduce gravel road maintenance costs are summarized here. These strategies may generally be classified into ( a) modifying gravel road surface for high traffic roads (i.e., paving or using chemical additives), ( b) reducing maintenance on gravel roads with lower traffic volumes, and ( c) closing unneeded gravel roads. These options require careful economic and legal analysis before they would be implemented. The results of a case study that investigated the feasibility of paving gravel roads with various traffic levels and a brief overview of a survey of chemical soil additives in Colorado, Montana, North Dakota, South Dakota, Utah, and Wyoming are reported.
Analytical Design Criteria for Village Roads in India
Authors: Das Animesh , Mohanty S. K. , Reddy K. S. , Pandey B. B.
Published: April 2007

Pavement condition data collected from several sections of village roads were correlated with analytical structural response of pavements for developing a performance-based rutting criterion. Laboratory tests were carried out to obtain the design parameters, and a computer program was used for layered elastic analysis of pavement structure. Charts were prepared for design of village road pavements with a reliability level of 50 percent.
Predicting Subgrade Moisture Content for Low-Volume Pavement Design Using In Situ Moisture Content Data
Authors: Hall Kevin D. , Rao Shreenath
Published: April 2007

Subgrade soil strength and/or stiffness are major factors in the design and performance of pavements, particularly low-volume pavements. A practical method of realistically estimating in situ moisture content significantly improves the determination of the appropriate resilient modulus to be used for pavement design. Because of the variability in soil properties and soil behavior under repeated traffic loads, environmental factors, geometric factors, and site conditions, and because of the complexity of moisture movement in soils, the prediction of subgrade moisture content has been unreliable and complicated. In a study of subgrade moisture changes with time, temperature, precipitation, and depth at 18 sites across Arkansas, five general trends in subgrade moisture variation are identified. In addition, upper and lower equilibrium limits for subgrade moisture contents are estimated. These equilibrium values are independent of environmental factors and are solely dependent on soil properties and site conditions. Regression equations to predict upper and lower equilibrium values from soil properties are developed. It is shown that reasonable predictions of in situ moisture content may be developed, given the range of subgrade moisture content variation for a given soil type and the trends of moisture variation with temperature, precipitation, and depth. In addition, guidelines and issues to be considered when establishing a subgrade moisture content monitoring program are given. The information presented could provide agencies with responsibility for lowvolume roads valuable tools for obtaining reasonable estimates of subgrade moisture conditions without the need for extensive (and expensive) soil sampling and testing programs.
Flexible Portland Cement Concrete Pavement for Low-Volume Roads
Authors: Visser Alex T. , Hall Sally
Published: April 2007

One of the challenges of South African civil engineers is to develop techniques for infrastructure provision appropriate to local conditions and suitable for creating employment. Local technology, consisting of welded plastic cells known as Hyson-Cells, is identified as a potential solution. After tensioning the cells, coarse aggregate is placed and compacted, after which a sand-cement grout is vibrated into the voids in the coarse aggregate. Alternatively, ready-mixed concrete can be used. The design catalogue for geocell pavements for low-volume roads is presented, and the suitability of the catalogue is demonstrated by evaluating streets that had been in service for more than 5 years. The catalogue of pavement structures was developed from the results of a laboratory study and field trials. An evaluation of eight road projects that had been in service for more than 5 years supported the structural design but also showed that construction control was important to ensure good performance. An economic analysis demonstrated that it was competitive with other pavement types normally used on access streets.
United Kingdom Study of Minor Road Deterioration and the Development of Maintenance Strategies
Authors: Duffell Roger
Published: April 2007

The highway maintenance scene in the United Kingdom is presented with respect chiefly to the minor (low-volume) road network. A 10-year study of the causes, consequences, and resulting maintenance options is presented based on observations in five highway authorities, at research sites of 100-m length at the worst end of the condition range. Edge- and non-edge-supported roads are featured, with or without positive and natural drainage. A pavement condition index (PCI) was developed comprising structural, surface, and edge indexes from manual surveys. Some correlation was achieved between PCI and profile from machine-based surveys. The concept of a time-independent relationship between rate of change in a number of condition indicators and absolute condition is advanced. Deterioration rates for eight conditions, as well as their variation in relation to causal factor “pairings” and between lost and remaining sites, are included. Some comparisons are made with the annual National Road Maintenance Conditions Survey of all road categories in the range of conditions found in practice.
Maintenance of the Austrian Rural Road Network: Organization and Financial Aspects
Authors: Litzka Johann , Haslehner Wolfgang
Published: April 2007

After more than 35 years of construction, the Austrian rural road network is almost completed. The construction of new roads will decrease within the next decade due to finalization of the development plans. Thus, the maintenance of the rural road network has been the major task for the last 10 years, and will continue to be important. An overview of the organization of the maintenance plans in the different provinces and of the financing is provided. As no federal funds are available for maintenance costs—unlike the case with new construction—only small contributions from provinces are possible, while the road owners and communities cover the majority of costs. This requires the most cost-effective maintenance methods and a lean organization for performing maintenance, like district or province maintenance associations. Research for the Federal Ministry of Agriculture and Forestry has provided a practical model for the systematic maintenance of rural roads. Thus, a technical basis for systematic pavement management for rural roads is already available, including all steps for inventory, condition rating, maintenance-method choice, and prioritization.
Do North American Railroads Understand Their Costs?: Implications for Strategic Decision Making
Authors: Resor Randolph R. , Thompson Gregory L.
Published: April 2007

There is considerable evidence that railroads have misunderstood their own cost structures since before the turn of the 20th century. This persistent management failure to recognize costs led, in the early 20th century, to a failure to recognize that certain lines of business (e.g., long-distance passenger trains) were money losers and also led to excessive reliance on petitions for general rate increases instead of commodity- and service-specific rates. The downward rate trend since industry deregulation in 1981, the failure to recognize or profit from the value that shippers place on high-quality service, and a focus on cost-cutting rather than revenue growth suggest that the industry is still uncertain of the relationship between revenue, costs, and service quality. The result has been a loss of rail capacity, through reductions in the train and engine workforce and through abandonment of a large part of the national rail network. Reductions in the workforce and in track capacity have reduced net investment and the industry’s ability to compete for high-value commodities. Meanwhile, equipment productivity has risen far less than worker productivity, and equipment ownership and maintenance costs typically account for 40 to 60 percent of total direct movement costs. Returns must increase if investment in capacity is to be justified financially. Raising rates, the free-market response to capacity shortages, will raise public policy questions as additional traffic is diverted to the highways. A proper understanding of its cost structure will help the railroad industry make the right decisions for the future.
North American Free Trade Agreement Trucks on U.S. Highway Corridors
Authors: McCray John P. , Harrison Robert
Published: April 2007

The increasing number of trucks that transport U.S.–Mexico and U.S.– Canada trade on U.S. highways has stimulated a strong interest among state departments of transportation and federal highway officials in the location and truck densities along these highway corridors. In many cases, public advocacy groups seeking corridor-related economic development have been formed to promote one or more highway trade corridors. Most of these groups advocate a north-south route through the United States between Canada and Mexico that follows the alignment of an existing federal highway number. Because of the interest in and promotion of highway trade corridors in the United States, the Transportation Equity Act for the 21st Century includes authorizations for a discretionary program for the development, study, and construction of highway trade corridors. This places a serious burden on state and federal highway administrators to define, plan, and upgrade these corridors adequately. Earlier work that defined U.S. highway trade corridors for U.S.–Mexico trade is extended by including U.S.-Canada trade and total North American Free Trade Agreement (NAFTA) trade. Results indicate that U.S.-Mexico trade transported by truck primarily affects the highway corridors in southern border states such as Texas, California, and Arizona. U.S.–Canada trade primarily affects highway trade corridors in the northern border states of Michigan, New York, Ohio, Illinois, and the states along 1-80 from Salt Lake City to Chicago. Interestingly, there are no significant north-south NAFTA highway corridors with a single Interstate or U.S. Highway number.
Reduced Rehabilitation Cost from Use of Falling Weight Deflectometer
Authors: Zaghloul SAMEH M. , Kerr J. BRIAN
Published: April 2007

A network-level falling weight deflectometer (FWD) testing program was performed on a selected subset, approximately 533 centerline (CL) km (330 mi), of the National Highway Network of New Jersey. The main goals of this program were to identify the limits of structurally homogeneous sections, to assess pavement structural capacity, to estimate remaining pavement service life, and to predict future rehabilitation needs. A comparison was made between the FWD rehabilitation analysis results and those obtained from the Pavement Management System (PMS) network-level rehabilitation analysis, in which network-level distress, rut depth, and roughness measurements are considered. Results of the comparison show that (a) the PMS rehabilitation analysis results agreed with those obtained from the FWD rehabilitation analysis for 27 percent (146 CL km) of the total length considered in this project; (b) the PMS rehabilitation analysis results were found to be overdesigned for 32 percent (173.5 CL km) of the total length considered in this project (e.g., the PMS selected a strengthening rehabilitation activity, whereas the FWD showed that the pavement has adequate structural capacity and no need for any structural improvement); and (c) the PMS rehabilitation analysis results were found to be underdesigned for 41 percent (224 CL km) of the total length considered in this project (e.g., the PMS analysis did not select a strengthening rehabilitation activity, whereas the FWD analysis showed that the pavement had inadequate structural capacity and there was a need for structural improvement). Limited life-cycle analysis was performed to quantify the difference between the FWD and PMS rehabilitation analysis results. In this analysis, the differences in rehabilitation costs for the overdesigned sections (173.5 CL km) and for the underdesigned sections (224 CL km) were estimated to be $6.6 million and $11.35 million, respectively.
Pavement Roughness Data Collection and Utilization
Authors: Ksaibati Khaled , McNamara Ronald , Miley William , Armaghani Jamshid
Published: April 2007

The Florida Department of Transportation (FDOT) is in the process of evaluating the protocols for collecting and analyzing roughness data. As part of that evaluation, a nationwide survey was performed to identify the trends and practices of various departments of transportation with regard to roughness data collection and analysis. All responding states indicated interest in obtaining the results of the survey, which was mailed to all 50 state departments of transportation. The responses show that most states are using laser-type road profilers for roughness measurements. The international roughness index (IRI) is the most widely used roughness index. Highway Performance Monitoring System (HPMS) data from different states are collected by using different equipment, and the data are collected in various wheelpaths and filtered differently. Stricter guidelines should be developed to ensure the consistency of HPMS data.
Deterioration Model for Pavements in Frost Conditions
Authors: Doré Guy , Konrad Jean-Marie , Roy Marius
Published: April 2007

Pavements in cold climates are often subjected to transverse differential heaving. This phenomenon is the result of the more severe frost action under the unprotected road surface. It induces bending stresses in the pavement structure and ultimately causes longitudinal cracking at the pavement surface. A simple model to predict the initiation and the propagation rate of cracking induced by frost heave is proposed. The model is based on mechanistic principles and calibrated using field performance data. It can be used in designing and managing pavements in frost conditions.
Standard Installation Direct Design Trench Installations
Authors: Kurdziel John M.
Published: April 2007

A great deal of information has been published in recent years on the development and performance of the new standard installation direct design (SIDD) procedures for designing and installing concrete pipe. National standards organizations such as AASHTO, ASCE, and ASTM have developed new specifications to address these performance revisions necessitated by the new SIDD beddings. Most of the work by these organizations has concentrated on embankment installations. The challenge that currently exists is the practical application of these new standards by the specifying community, contractors, and manufacturers into common place installations, which are typically trenches. Guidelines on developing these new SIDD procedures for practical applications in trench conditions are provided.
Railing Systems for Use on Timber Deck Bridges
Authors: Faller Ronald K. , Ritter Michael A. , Rosson Barry T. , Duwadi Sheila R.
Published: April 2007

Bridge railing systems in the United States have historically been designed based on static load criteria given in the AASHTO Standard Specifications for Highway Bridges. In the past decade, full-scale vehicle crash testing has been recognized as a more appropriate and reliable method of evaluating bridge railing acceptability. In 1989, AASHTO published the Guide Specifications for Bridge Railings, which gave the recommendations and procedures to evaluate bridge rails by full-scale vehicle crash testing. In 1993, the National Cooperative Highway Research Program (NCHRP) published Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features, which provided criteria for evaluating longitudinal barriers. Based on these specifications, a cooperative research program was initiated between the University of Nebraska-Lincoln and the Forest Products Laboratory, and later the FHWA, to develop and crash test 11 bridge rails for wood deck bridges. The research that resulted in successful development and testing of 11 bridge railing systems for longitudinally and transversely laminated wood bridge decks in accordance with AASHTO Performance Level 1 and 2 (PL-1 and PL-2) requirements and Test Levels 1, 2, and 4 (TL-1, TL-2, and TL-4) requirements of NCHRP Report 350 are described here.
Traffic Flow Characteristics of the Late Merge Work Zone Control Strategy
Authors: Pesti Geza , Jessen Daniel R. , Byrd Patrick S. , McCoy Patrick T.
Published: April 2007

Conventional traffic control plans such as the one used in Nebraska (NDOR Merge) 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. The Late Merge is a merge-control concept developed by the Pennsylvania Department of Transportation to reduce the length of queues and reduce the road rage that often develops among drivers. The operational effects of the Late Merge were evaluated. The traffic flow characteristics determined from the field data indicate that the Late Merge is more effective than the NDOR Merge in terms of the safety and efficiency of merging operations in advance of lane closures on Interstate highways. The Late Merge has higher capacity and results in fewer traffic conflicts. However, it was also found that the concept might not be working as effectively as it is capable of. Based on the lane distribution data obtained during both free-flow and congested-flow periods, it can be concluded that some motorists did not follow the directions given by the traffic control signs, thus reducing the effectiveness of the merging operation. The potential benefits of the Late Merge will not be fully realized until drivers, particularly truck drivers, gain a better understanding and acceptance of the concept.
Laboratory-Accelerated Versus Outdoor Weathering for Retroreflective Sheeting Specifications
Authors: Ketola Warren D.
Published: April 2007

Laboratory-accelerated weathering tests are used instead of outdoor weathering tests in specifications for products intended for long-term outdoor use because they provide fast results. These accelerated tests are used as a measure of acceptable weathering performance for a material. Acceptance of results from laboratory-accelerated tests in product specifications is based on two major assumptions: (a) materials that pass the requirements of the laboratory-accelerated test meet outdoor durability requirements, and (b) results from laboratory-accelerated tests are much more consistent than those from outdoor exposures. Numerous examples illustrate the errors that occur when these assumptions are wrong. Material with good outdoor durability can fail to meet the requirements of a specified laboratory-accelerated test, or material with poor outdoor durability will pass the requirements of the specified laboratory-accelerated test. Between-lab variability can cause a product to be rejected by a specifier although the same test run by the supplier produced acceptable results. For retroreflective sheeting, outdoor exposures are actually more consistent than the laboratory-accelerated exposure most commonly used in specifications. To assure minimum acceptable durability, 36-mo outdoor exposures are recommended for most retroreflective sheeting specifications. However, results from these exposure tests do not predict the ultimate service life of retroreflective sheetings.
Field Surveys of Pavement-Marking Retroreflectivity
Authors: Migletz James , Graham Jerry L. , Bauer Karin M. , Harwood Douglas W.
Published: April 2007

Field surveys of pavement-marking retroreflectivity were conducted throughout the United States. Thirty-two state and local highway agencies participated in the study by identifying pavement-marking sites for measurement. The retroreflectivity of both white and yellow pavement-marking lines of six different marking materials—conventional paint, waterborne paint, epoxy, polyester, thermoplastic, and tape—was measured in the field. Field measurements of pavement-marking retroreflectivity for sites under the jurisdiction of all 32 participating agencies were made in the fall of 1994. Selected sites were remeasured in the spring of 1995 for six of the participating agencies. All field measurements were made with a Retrolux Model 1500 retroreflectometer. A comparison of the fall 1994 and spring 1995 results are presented. Data analyses were conducted to determine the mean, standard deviation, and distribution of the coefficient of retroreflected luminance (retroreflectivity) and the contrast ratio between the retroreflectivity of the pavement markings and that of the adjacent pavement surface by color of line and pavement marking material. However, it was difficult to state any definitive comparisons between material types without knowing the relative ages and manufacturers of the markings, and such data were unavailable. The economic implications of particular threshold values for replacement of pavement markings were also evaluated.
Little Falls, Gorham: Reconstruction to a Modern Roundabout
Authors: Gårder Per
Published: April 2007

Older American traffic circles can typically handle high traffic volumes, but they often have poor safety records. Modern roundabouts are similar to traffic circles in the sense that traffic “circles” around a central island, but many other design concepts differ. The first modern roundabout in Maine was opened to traffic in July 1997. The total accident rate after 16 months of operation is below that which would be expected if the junction had been signalized. There still has not been a single accident with injuries, and the injury rate is expected to stay significantly below that of a signalized intersection. The one-lane design will be able to handle traffic growth for years to come. Vehicle exhaust has been reduced, and delay on the minor approaches has been reduced by approximately 80 percent during morning and afternoon peak hours. In total, the reconstruction will save 5,000 to 10,000 h of travel time annually. This alone will pay for the investment within 5 years.
Relationships Between Ball Bank Indicator Readings, Lateral Acceleration Rates, and Vehicular Body-Roll Rates
Authors: Carlson Paul J. , Mason John M.
Published: April 2007

The objective of the current AASHTO criteria for horizontal curve design is to select the radius and superelevation so that the lateral acceleration perceived by the occupants of vehicles traversing horizontal curves is kept within comfortable limits. It is considered good design practice to provide roadways on which these comfortable lateral acceleration limits are not violated within an appropriate range of speed values. However, because of geometric constraints, some horizontal curves require significant speed reductions to maintain motorists’ comfort levels. The ball bank indicator has been used since the 1930s to measure the speed at which occupants become uncomfortable. Reported in degrees, the reading of the ball bank indicator is the sum of a vehicle’s lateral acceleration and the body-roll minus the roadway superelevation. Ball bank indicator readings and lateral acceleration levels are both indicators of safe speed based on vehicle occupants’ comfort levels. Both have been used for highway design since first being introduced, although they are related only theoretically. The criteria for using ball bank indicators have been modified only slightly in the last 50 years, while vehicle technology and societal changes have experienced significant changes. Ball bank indicator readings were correlated with lateral acceleration rates. Additionally, the influence of vehicular body-roll on ball bank indicator readings was investigated. Ball bank indicator readings and lateral acceleration values were found to be highly correlated. The influence of body-roll on ball bank indicator readings appears to be negligible when using typical passenger cars to determine safe speed on horizontal curves.
Speed Variability on Rural Two-Lane Highways
Authors: Collins Jon , Fitzpatrick Kay , Bauer Karin M. , Harwood Douglas W.
Published: April 2007

A better understanding of speed variance on rural two-lane highways may assist in addressing driver error associated with highway geometric elements. Previous research has identified a direct relationship between speed variance and accident potential. Speed variance increases are associated with an increase in accidents. Therefore, identifying relationships between speed distribution measures of free-flowing vehicles and roadway characteristics may identify inconsistent roadway features. Horizontal and vertical curves from four geographic regions were identified based on selected criteria, and speed data were collected at the midpoint of the preceding tangent and the curve. Four hypotheses were explored to determine if relationships between speed statistics and geometry could be used to identify design inconsistencies. Statistical tests were conducted to identify relationships between mean speed, speed variance (standard deviation), and roadway characteristics for tangents, horizontal curves, and vertical curves. The findings suggest that speed distribution measures do not appear to be useful in the evaluation of design consistency.
School Bus Design Vehicle Dimensions
Authors: Gattis J.L. , Howard M.D.
Published: April 2007

Research was conducted to generate design vehicle characteristics for large or full-size school buses. Characteristics that were measured include length, width, overhangs, and the turning radius and path for 90° and 180°turns. The researchers observed the paths of the inner rear tire, the outer front corner, the outer front tire, and the outer rear corner. The paths observed in the field were contrasted to those generated by computer-aided design software. The path of the outer rear corner was found to be a significant consideration during the initial part of a turn. The researchers recommended adoption of a more intuitive terminology to describe the various turning paths.
External Costs Associated with Interregional Transport
Authors: Heaney Quentin , O’Mahony Margaret , Gibbons Eithne
Published: April 2007

The environmental and social costs of transport are becoming an important issue in Europe as car ownership and usage levels continue to rise. A subject of current debate is the internalization of these external costs by means of road-use pricing in a fair and efficient way, particularly in urban areas. Similar theory can be applied in an interregional transport context, but little research has been conducted in this area to date. The TRENEN model has been developed under the European Union TRANSPORT Program to quantify the marginal external costs of transport. Case studies have been completed for several European cities, using the urban version of the model, and for Belgium, Ireland, and Italy, using the interregional version. The calibration of the interregional model and the related case study results for Ireland are presented. The conclusions suggest users of all transportation modes currently pay less than the marginal external costs of their transportation activities. Another finding is that traffic congestion is a major externality. The model allows comparison of different transportation policy options with a full optimum scenario (the external costs are internalized precisely). Typically, such a policy would be difficult to implement, given the sophisticated pricing instrumentation required. However, it serves as a good baseline for testing other policies. In the case of Ireland, when a congestion pricing policy—similar to that used for motorways in France—was compared with the full optimum case, it achieved 60 percent of the maximum achievable welfare.
Accuracy Issues with Route Choice Data Collection by Using Global Positioning System
Authors: Wolf Jean , Hallmark Shauna , Oliveira Marcelo , Guensler Randall , Sarasua Wayne
Published: April 2007

Advancements in global positioning system (GPS) technology now make GPS route choice data collection for travel diary studies and other transportation applications a reality. Opportunities abound for increased quantities of data, for improved quality of data, and for new data elements that were once considered too burdensome or expensive to capture. For example, automated travel diaries can electronically capture trip purpose, origin and destination location names, and driver and passenger names at the push of a button. An accompanying GPS receiver can accurately capture origin and destination locations, departure and arrival times, as well as trip lengths and travel routes. This wealth of data can be used to validate or calibrate travel demand models, for in-vehicle information systems analysis, and for modeling mobile source emissions across a given network. These data collection and processing advancements do have their costs, however. In fact, care and caution should be exercised when GPS technologies are selected and used to collect route choice data. The focus of this paper is on the accuracy issues related to route choice data collection and processing using GPS technology. Vendor specifications, observation techniques, data collection procedures, data postprocessing, and the importance of using a reliable and accurate geographic information system (GIS) database are examined in detail. Critical issues in the calculation of GPS accuracy are reviewed. Finally, recent experience in Atlanta is reported, and recommendations designed to reduce the introduction of error into automated route choice data collection are provided.
Prototype Internet Applications for Transportation System Management
Authors: Sathisan Nambisan Shashi , Pulugurtha Srinivas S. , Jensen Jeffery J. , Puterski Robert , Miller Thomas D. , Hwan Park Chang
Published: April 2007

Technologies for integrating, communicating, analyzing, and displaying spatial information interactively have been evolving in recent years. Although dissemination and analysis of information over the Internet are efficient and time effective in reaching a multitude of users, it is still difficult to perform these operations with transportation data in a graphical format using the Internet. The development of a prototype system for this purpose is described in this paper. The system specifications include the need for versatility in utilizing several forms of data such as spreadsheets, AutoCAD drawings, as well as coverage produced from various geographic information system (GIS) programs (e.g., ARC/INFO). These specifications were designed to ensure maximum utilization of existing data and to facilitate data sharing within and among various organizations. The prototype system is demonstrated using a case study of projects from the Clark County Department of Public Works in Nevada. The system was developed using an off-the-shelf suite of software programs (MapGuide). Using this software greatly reduced startup costs, time, and configuration management tasks and did not compromise the desired functionality. Through its web site, the system facilitates communications between elected officials, public works agency staff, management, stakeholders, and constituents using the Internet or intranets. Various applications were designed and developed to support project management, resource allocation, and internal or external communications as well as information storage, retrieval, analysis, and display and office automation. Because of the promise shown by the prototype system, a variety of transportation and public-sector agencies have expressed an interest in its full-scale deployment to address their emergent needs.
Toward National Indicators of Vehicle Travel and Traffic Congestion Based on Real-Time Traffic Data
Authors: Chin Shih-Miao , Greene David L. , Hopson Janet , Hwang Ho-Ling , Thompson Brad
Published: April 2007

Automated traffic data being posted on the Internet by an increasing number of cities are a potentially invaluable source of information on national vehicle travel and highway system performance. An experimental system is presented that demonstrates the feasibility of using these data to create national indicators of vehicle travel and traffic congestion. The experiment raises a number of critical institutional and technical issues that must be resolved before a complete national system can be realized. This paper represents a progress report on the initial phase of an ongoing study.
Empirical Analysis of Attrition and Underreporting in Mailback and Personal Interview Panel Surveys
Authors: Polak John
Published: April 2007

Panel data, in which the same observational units are surveyed at several points in time, offer a number of important advantages compared with more conventional cross-sectional or time-series data. However, panel data are also susceptible to specific forms of bias that do not affect cross-sectional or time-series data, for example, panel attrition, fatigue, and conditioning. If these sources of bias are not properly taken into account in the preanalysis of panel data, they may lead to serious distortion of the conclusions of substantive analyses. It is therefore important to seek a better understanding of the nature of these biases, how they arise, and how to deal with them. The objective of this paper is to explore these issues by presenting the results of the preanalysis of two different panel datasets collected in different countries at different times and using different survey approaches. The patterns of wave-to-wave attrition in the two datasets are compared, and various approaches to dealing with this problem are discussed.
Low-Temperature Physical Hardening of Hot-Mix Asphalt
Authors: Romero Pedro , Youtcheff Jack , Stuart Kevin
Published: April 2007

A study was conducted to determine if low-temperature physical hardening, which has been reported to be exhibited by asphalt binders, also affects hot-mix asphalt. Two asphalt binders, Designation AAM-1 and AAM-2 of the Strategic Highway Research Program, which are known to show the effects of physical hardening, were used to prepare asphalt mixtures with different mineral fillers. The asphalt mixtures were compacted into slabs from which cores were obtained and tested at low temperatures in the thermal stress restrained specimen test. Before testing, the cores were cooled unrestrained to –15°C and held isothermally for 1 h or 24 h. After conditioning, the specimens were restrained and held at a constant length while the temperature was dropped at a rate of 15°C per hour until the specimens fractured. The temperature at which the specimens fractured, the stress at the time of fracture, and the slope of the temperature-stress curve were measured and analyzed using several statistical techniques. The results showed that the mixture made with asphalt binder AAM-2 was affected by conditioning time. The mixture made with asphalt binder AAM-1 was not affected by conditioning time. Other factors, such as mineral fillers and air voids of the mixtures, had a greater influence on the results than did physical hardening.
Physical Hardening of Asphalt Binders Relative to Their Glass Transition Temperatures
Authors: Anderson David A. , Marasteanu Mihai O.
Published: April 2007

Physical hardening (physical aging) is a process that occurs below room temperature in asphalt binders. Physical hardening causes time-dependent isothermal changes in the rheological behavior and specific volume of asphalt binders. The process is reversible: when the asphalt binder is heated to room temperature or above, the effect of physical hardening is completely removed. Physical hardening for amorphous materials is generally reported as occurring below the glass transition temperature ( Tg), but this is not the case for asphalt binders, in which physical hardening is observed both above and below Tg. The glass transition temperature of asphalt binders is measured by using three different techniques: dilatometry, differential scanning calorimetry, and rheological considerations (peak in the loss modulus versus temperature). These three techniques give roughly equivalent estimates of the glass transition temperature. The behavior of physical hardening in asphalt binders is somewhat different than that reported for polymers and other organic materials. This difference is explained in terms of the presence of crystalline fractions in the asphalt binder. Techniques for modeling physical hardening are described, and possible explanations for the anomalous behavior of asphalt binders are given.
Effect of Oxidation Pressure on Asphalt Hardening Susceptibility
Authors: Domke Christopher H. , Davison Richard R. , Glover Charles J.
Published: April 2007

There are many methods to accelerate the aging process of asphalts to determine how susceptible the asphalt is to hardening. These tests use increased temperature, pressure, or both, and assume that the properties after the accelerated test match those if the asphalt is aged at lower temperature and pressure. However, the slope of the logarithm of viscosity versus carbonyl area, known as the hardening susceptibility, does not easily correlate from high-pressure to low-pressure aging conditions. The hardening susceptibility (HS) is a strong function of the oxygen pressure at which the test is run. HS is a function of pressure because the two terms that compose it—the asphaltene formation susceptibility, which determines how susceptible the asphalt is to the production of asphaltenes, and [Formula: see text], which determines how the asphaltenes are affecting the viscosity of the asphalt—are functions of pressure. The pressure dependency is hypothesized to be caused by oxygen diffusion on a molecular scale.