bluuebunny/crossref_metadata_2025 huggingface dataset:
Ohio River Navigation Investment Model: Requirements and Model Design
Authors: Bronzini Michael S. , Curlee T. Randall , Leiby Paul N. , Southworth Frank , Summers Michael S.
Published: April 2007

Oak Ridge National Laboratory is assisting the U.S. Army Corps of Engineers in improving its economic analysis procedures for evaluation of inland waterway investment projects along the Ohio River system. The context and design of an integrated approach to calculating the systemwide benefits from alternative combinations of lock and channel improvements, providing an ability to project the cost savings from proposed waterway improvements in capacity and reliability for up to 50 years into the future, is described. The design contains an in-depth treatment of the levels of risk and uncertainty associated with different multiyear lock and channel improvement plans, including the uncertainty that results from a high degree of interaction between the many different waterway system components.
Monetary Cost of a Modal Shift
Authors: Lambert Richard F.
Published: April 2007

Placing an economic dollar value on the environmental impacts of shifting products from the waterway mode to a land mode is presented. Since the original study, completed in 1991, two of the three modal shift examples discussed have taken place. What caused the modal shifts to take place and their merits are also examined. The fuel cost efficiency of the water mode is compared with that of land modes and the air emission results of burning additional fuel to move the same product tonnage. Freight rate variations between the modes are not discussed because the focus is on environmental impact cost. When comparable, waterborne transportation has an environmental cost impact of one-fifth that of rail and one-tenth that of truck transport. Accident rates on a per ton-mile basis are also discussed, but no dollar figures are available for comparison purposes at this time.
High-Speed Sealift/Agile Port Operational Concept
Authors: Wykle Kenneth R. , Maya Isaac , Myers Richard A. , Remus Thomas A. , Williams J. Richard
Published: April 2007

How might emerging High-Speed Sealift (HSS) operating in conjunction with Agile Ports (AP) enhance Department of Defense (DOD) power-projection capability? The goal is to develop a concept for how a combination of HSS ships and Agile Ports, operating in concert with complementary technologies, focused logistics, and advanced management information systems, may be applied by the DOD to accelerate the movement of high-priority cargo to crisis and conflict locations. The capability sought is rapid entry into a theater of operations in support of missions requiring the projection, employment, and sustainment of forces across the entire spectrum of military operations: deterrence, Operations Other Than War (OOTW), or war. HSS ships can perform critical delivery tasks that will allow U.S. forces to increase their operational and logistical flexibility. For example, an appropriately configured HSS ship has the potential to assist the halting and build-up phase by transporting cargo that is normally moved by air, but is prevented from doing so by aircraft shortages or in-theater airfield constraints; transporting equipment and materiel for an Airborne Battalion Task Force (BTF) to an Intermediate Staging Base (ISB), or transporting to the theater of operations the equipment and cargoes of a Light Infantry BTF or an Air Assault BTF; or transporting during surge critical resupply items with early Required Delivery Dates (RDDs), such as Class V (ammunition), Class VIII (medical), or Class IX (repair parts). The incorporation of AP technologies into the coordinated commercial and defense transportation systems provides a superb complement to the overall value of HSS. In addition, Agile Ports significantly enhance and supplement conventional sealift by providing a conduit for the incorporation of next-generation technologies supporting both DOD mobility and the general efficiency of commercial shipping.
Sealift Overhead Rapid Delivery System Concept
Authors: Paris Bradley E. , Vickerman M. John , Seiberlich Carl
Published: April 2007

The logistics support of any military operation demands rapid and continuous delivery of equipment, munitions, and supplies. A small portion of this cargo is delivered by air, but the majority arrives by sea. Many of the sealift vessels currently used by the military are non-self-sustaining containerships and roll-on/roll-off vessels. The use of such vessels can encounter serious obstacles when the necessary cargo-handling equipment and facilities are either damaged or not present. This problem is further compounded in sea states of three [wave height of 1.5 to 3.6 m (5 to 12 ft)] and higher. The system presented outlines a cost-sensitive solution to the problem described above. The Sealift Overhead Rapid Delivery System (SORDS) represents a viable concept worthy of further study because it uses existing technologies and approaches the problem from a systems perspective. In addition, SORDS could be incorporated into the Department of Defense’s Rapid Deployment Concept or Maritime Prepositioning Force.
Effects of Age and Congestion Information Accuracy of Advanced Traveler Information Systems on User Trust and Compliance
Authors: Fox Jean E. , Boehm-Davis Deborah A.
Published: April 2007

Advanced traveler information systems (ATIS) are computer-based in-vehicle systems that provide travel-related information to automobile drivers. It is important for user acceptance to occur quickly because ATIS performance is optimized when many automobiles are equipped with the systems. One important factor in user acceptance is how much users trust the technology. Previous studies on this topic revealed that inaccurate congestion information reduced the users’ trust in ATIS and limited compliance with ATIS advice. The previous research is extended by the evaluation of both trust in ATIS and compliance with ATIS advice in a high-fidelity driving simulator. Participants drove through a simulation with the goal of avoiding congestion. A simulated ATIS recommended which way to go to avoid congestion. Participants drove through four trials of ten intersections each. In one trial, ATIS provided accurate information at 100 percent of the intersections. In the other three, the information was 80, 60, or 40 percent accurate. The four trials were presented to the participants in one of three orders. Dependent measures included ( a) how much participants trusted ATIS advice, ( b) how many times they complied with ATIS, and ( c) how accurate they thought the system was. The results show that 40 percent accuracy would not support user trust and compliance, but that 60 percent accuracy probably would. Also, the order in which participants experienced the trials significantly affected both trust and compliance; the effects of accuracy order were similar for both trust and compliance.
Network Model of Urban Taxi Services: Improved Algorithm
Authors: Wong S. C. , Yang Hai
Published: April 2007

A mathematical model is proposed to describe how vacant and occupied taxis will cruise in a road network to search for customers and provide transportation services. The model assumes that a taxi driver, once having picked up a customer, will move to the customer’s destination by the shortest path; and that a taxi driver, once having dropped a customer, will try to minimize individual expected search time required to meet the next customer. The probability that a vacant taxi meets a customer in a particular zone is specified by a logit model by assuming that the expected search time in each zone is an identically distributed random variable due to variations in perceptions and the random arrival of customers. The whole movement of all empty and occupied taxis is formulated as an optimization model, from which a gravity-type distribution of empty taxis is derived. Consequently, the taxi movement model can be solved efficiently by the established iterative balancing method and can be incorporated into any standard transportation planning packages.
Discrete Choice Elasticities for Elderly and Disabled Travelers Between Fixed-Route Transit and Paratransit
Authors: Franklin Joel P. , Niemeier Debbie A.
Published: April 2007

In the current practice of mode-choice modeling, models typically focus on the more traditional choices, such as those between automobile, transit, and nonmotorized transportation. For most travelers these are, indeed, the most relevant modes. However, for some segments of the population, particularly the elderly, the choice is more limited. This study investigates the factors that affect the elderly and disabled travelers’ choice between public transit and paratransit. Data collected from the public transit service, Sacramento Regional Transit, and the paratransit service, Paratransit, Inc., in Sacramento, California, were used to develop a mode-choice model and to calculate elasticities of significant factors. Age was found to have an elastic effect, whereas the difference in fare had an inelastic effect.
Benefits of Transit in Small Urban Areas: A Case Study
Authors: Skolnik Jonathan , Schreiner Richard
Published: April 2007

Although the value of transit subsidies is debated at the national level, local decision makers must decide whether it is economically worthwhile to operate transit given the federal and state subsidies currently in place. This issue is examined with respect to a recent study of the economic impacts of the Housatonic Valley Regional Transit District (HART) based in Danbury, Connecticut. The study methodology combined several recently developed benefit classification systems and benefit estimation methodologies. Like many similar studies, the methodology compares current service with the null hypothesis, the discontinuation of transit services. A survey of transit patrons was conducted to examine trip purpose, economic expenditures, and alternatives to HART services. The cost and benefits of local public transportation are examined and quantified. Issues include costs for transit users switching to alternative modes, economic and social costs of forgone trips, accidents, air pollution, congestion, and HART employment, purchases, and capital expenditures. This analysis indicates that publicly operated transit provides significant benefits to a local community compared with costs contributed by the community. The methodologies could be employed using a state or federal perspective to examine the economic efficiency of the transit funding decisions made at those levels of government.
Development of an Intermodal Transit Simulation and Its Application to the Frankford Transportation Center
Authors: Whitney Dudley E. , Brill Joseph C.
Published: April 2007

A summary is presented of the design and application of a discrete event simulation model and animation of the proposed Frankford Transportation Center (FTC), an intermodal transportation facility being developed by the Southeastern Pennsylvania Transportation Authority. Combining bus, trackless trolley, automobile, train, and pedestrian movements in an integrated model, the simulation provided designers and the client with a tool for evaluating the effectiveness of the proposed design on surface transit operations and traffic flow both in and around the facility. Distinguishing features of the model architecture are discussed in the context of its application to the FTC. Results of the study, and their applicability to intermodal facilities, are presented.
CTA’s Recent Experience with Major Rail Rehabilitation Projects: Construction Efficiency Versus Ridership Retention
Authors: Abrams Steven H.
Published: April 2007

The Chicago Transit Authority’s (CTA) rail transit system contains many kilometers of old elevated structure. Speed restrictions have been imposed on substantial lengths of track, slowing down scheduled service. As the condition of the infrastructure continues to worsen, methods other than spot repairs must be investigated. Recently, CTA closed the Green Line for reconstruction over a 2-year period. Before the suspension of service, there had been a precipitous decline in ridership, which was coincident with the deteriorating state of the line’s infrastructure. Attempting to reverse this trend, restoration of the line to a state of good repair became a top priority. Although the Green Line project has been successful in restoring track speeds to design standards, the lengthy closing of the line has had long-term negative effects with respect to ridership. Given that aging structures must be repaired, the issue facing transit operators is how to achieve an optimal balance between construction economies and accommodation of a line’s riders. A number of recent projects will be compared, noting their impact on ridership. Experience has shown that to ensure success, careful planning is vital when formulating the construction work itself, as well as the complementary alternative service for the line’s passengers. Performing an options analysis will assist in determining the optimal approach to undertaking such major work. In all cases, passengers must be given an alternative means of transportation comparable to the existing service.
NJ Transit’s MidTOWN Direct Service: Are Customers Satisfied?
Authors: Pepper Janice , Ray Ana
Published: April 2007

NJ TRANSIT routinely sets service quality goals, monitors them, and uses the results to improve service. To support this business practice, NJ TRANSIT conducts customer satisfaction surveys of rail customers to understand customers’ needs and their level of satisfaction. On June 10, 1996, NJ TRANSIT initiated new rail service on its Morris and Essex rail lines called MidTOWN DIRECT. To assess the regional impacts of this major transit investment and to gain a better understanding of customers’ response to the new service, NJ TRANSIT conducted a survey of riders that included a customer satisfaction component. This study provided an opportunity for NJ TRANSIT to test the impact on customer satisfaction of introducing a new service option in a corridor that had well-established rail service. The study also provided insights into designing customer satisfaction measurement techniques for application during and after the implementation of significant new service offerings. To determine satisfaction levels of customers regarding the new service on the Morris and Essex Lines, and to determine whether the key drivers of satisfaction had changed, several statistical analyses were conducted. Several significant findings resulted from this customer satisfaction study. Several components of the MidTOWN DIRECT rail service required fine-tuning, especially with regard to frequency, on-time performance, and mechanical reliability. Although the satisfaction ratings were lower than initially expected, the availability of key driver satisfaction data can provide fast, targeted direction for service improvements that will pay the greatest dividends with customers.
Karlsruhe 1975–1995: A Case Study of Light Rail Transit Development
Authors: Brandl P. G. , Axhausen K. W.
Published: April 2007

The public transport system of Karlsruhe, Germany, in particular its innovative services on jointly used heavy rail lines, has received substantial attention throughout the last 2 decades. The discussion of the system and of its development was rather limited in the past, mostly highlighting technical aspects. An overview is provided of the development, including the urban development of the region, and of the funding system. The ridership and financial development of the operator is documented in detail. Case studies focus on the integration of the system development in the general political process of the region and demonstrate the limitations of the operator under its current ownership structures.
Seismic Retrofit of Vincent Thomas Suspension Bridge
Authors: Baker George , Ingham Tim , Heathcote Dan
Published: April 2007

The Vincent Thomas Bridge in Los Angeles, California, is a major suspension bridge with a total length of 1848 m (6,060 ft), including approaches, and a main span bridge 766 m (2,513 ft) long, whose center span is 458 m (1,500 ft). The bridge, built in the 1960s, used the seismic codes of the time. The site conditions and tall, slender towers and bents have resulted in vulnerabilities that are particular to suspended bridges. This paper focuses on the suspended spans. The bridge is located within the Port of Los Angeles in a vicinity that has a legacy of earthworks associated with such projects as dock expansion, fuel lines, and rail lines. Geotechnical conditions include an active fault running between the main towers with a potential for liquefaction, fault rupture, and lateral spreading. A nonlinear time history analysis of the main suspended bridge was performed, using ADINA. The model included the effects of geometric stiffness of the cables and of multiple-support excitation of the bridge. The critical vulnerabilities detected in this study, arising from large predicted longitudinal motions, indicated distress in the towers, in the cable bents near the anchorages, in the short midspan suspenders, and in the stiffening trusses. During the retrofit study the nonlinear behavior was further developed, including tower rocking and uplift, the postyield deformations of the tower, and the optimization of the damper properties. Retrofit measures include releasing of the side-span trusses at the cable bents, creating fused hinges in the stiffening trusses, the installation of dampers at these locations and between the stiffening trusses and the towers of the bridge, stiffening of the bridge towers to prevent plate buckling, and cable and suspender modifications.
Testing of High-Performance Concrete Single-Span Box Girder
Authors: Miller R. , Shahrooz B. , Baseheart T. M. , Long E. , Jones J. , Knarr R. , Sprague R.
Published: April 2007

As part of a multistate research program on use of high-performance concrete (HPC) in highway bridges, a bridge originally designed as a three-span adjacent box girder bridge was converted to a single-span bridge by using 70-MPa HPC and 15-mm strands. As part of the research, a test beam was constructed and tested. Instruments placed in the beam before casting were used to measure transfer length, which was found to be approximately 1.22 m, larger than the 50-bar diameters usually used in the American Association of State Highway and Transportation Officials (AASHTO) Standard Specifications but consistent with recent studies. After the beam concrete reached the required compressive strength, it was tested to destruction. The beam was able to resist the required AASHTO ultimate moment without failure. It was found that the AASHTO cracking load was conservative for this beam, mostly because the measured modulus of rupture greatly exceeded the value assumed in the AASHTO specifications. The behavior of the beam was successfully predicted using a section analysis.
Full-Scale Tests of a Railway Bridge
Authors: Maragakis E. Manos , Douglas Bruce M. , Chen Qingbin , Sandirasegaram U.
Published: April 2007

Full-scale resonance and ultimate load tests of the Strawberry Park Underpass were conducted in March 1995. This bridge was typical of many railway bridges around the country—a two-span, 45.2-m (148-ft) long ballasted through plate girder railway bridge. It was located in Los Angeles and scheduled for removal in spring 1995. This fact allowed failure tests to be performed with the pushing loads applied at the bridge abutments. The main objectives of this experiment were to measure the dynamic properties of the bridge with and without the rails and to begin to identify the extent to which the unique railway bridge components, consisting of the rails, ties, ballast, and ballast pan, help strengthen it during a seismic event. It was found that the removal of the rails alone resulted in a slightly softer system and that the railway elements increased the ultimate capacity of the bridge significantly.
Laboratory Testing of Low-Volume Road Bridge Alternative
Authors: Phares B. M. , Wipf T. J. , Klaiber F. W.
Published: April 2007

In Iowa there are over 20,000 bridges on the secondary road system. The majority of these bridges are under the jurisdiction of county engineers with limited budgets; therefore many county engineers design and construct their own short-span bridges with their own labor force. The objective of this research is to perform laboratory testing on a bridge alternative that counties can design and construct. This concept involves the fabrication of precast units composed of two steel beams connected by a thin concrete deck. The concrete deck thickness is limited so that the units can be fabricated at one location and then transported to the bridge site. The number of units required is obviously a function of the width of bridge desired. After the precast units have been connected, an additional concrete deck is placed. The concrete surface of the units is scarified so that the two layers of concrete are bonded together, thus providing the required deck thickness. Since this bridge replacement system is primarily intended for use on low-volume roads, the precast units could be constructed with new or used steel beams. The laboratory testing program consisted of a series of small-scale tests on different types of precast deck connections, “handling strength” tests of the precast units, a series of tests on the model bridge with only the precast portion of the deck in place, and a series of tests on the fully constructed model bridge. For the bridge model tested [ L = 9750 mm (32 ft), W = 6400 mm (21 ft)], five precast connectors gave the desired lateral load distribution; the addition of the cast-in-place deck significantly improved the load distribution characteristics of the bridge system. The units developed and tested result in a simple-span bridge for low-volume roads that is relatively easy to construct.
Long-Span Reinforced Steel Box Culverts
Authors: McCavour Thomas C. , Byrne Peter M. , Morrison Timothy D.
Published: April 2007

A comprehensive investigation of soil–metal structure interaction for long-span deep-corrugated reinforced steel box culverts was carried out in a project sponsored by the National Research Council of Canada in 1996. Two 12-m span box culverts were erected at a Dorchester, New Brunswick, test site using two backfill densities, one structural steel plate thickness, and a minimum cover of 300 mm. These structures are the largest steel box culverts erected to date. One structure was reinforced using continuous deep-corrugated crown stiffeners, and the other was intermittently reinforced using composite concrete metal-encased stiffeners. Strain and deflection of the structure were monitored in response to static axle loads positioned at six locations on the test surface. A finite element model was then used in numerical simulations of the soil–metal structure system. The measured culvert response was then compared with results from the finite element model. A nonlinear soil-structure interaction program (NLSSIP) was used to analyze the two long-span box culverts. NLSSIP was developed specifically for long-span soil–metal culverts and has been used for structures with and without stiffeners. The box culvert test provided a definitive relationship between soil stiffness and metal structure stiffness. The test was the first that evaluated intermittently reinforced composite concrete metal-encased stiffeners relative to conventional continuous reinforcement. The performance of the two types of stiffeners is evaluated and recommendations are made for future design and installation of long-span deep-corrugated steel box culverts.
Boundary Effects on Response of Polyethylene Pipe Under Simulated Live Load
Authors: Conard B. E. , Lohnes R. A. , Klaiber F. W. , Wipf T. J.
Published: April 2007

The objective of this paper is to evaluate the deflection response of polyethylene pipes when loaded near their ends. Tests were conducted on pipes loaded at the center and near their ends to simulate loading of a vehicle at the center of a roadway and on the shoulder. The tests were performed on 900-mm (36-in.) and 1200-mm (48-in.) diameter polyethylene pipes with 610-mm (2 ft) cover and a variety of backfills. Loads were applied through a 93 025-mm2 (1-ft2) plate that provides very severe loading conditions. At high contact stresses, the load test plate punched into the soil cover so that the crown of the pipe was subjected to stresses in excess of those that would have occurred if the soil surface were paved or stabilized or a less severe loading condition better representing a truck tire had been used. At contact stresses equivalent to moderate highway tire pressures, pipe deflections are slightly higher near the ends of the pipes than at the center. Except for low-density till, the percent deflections are not excessive and the pipe-soil systems have adequate stiffness. For contact stresses near the upper limit of truck tire pressures and when loaded near the ends, the pipes with sand and till backfills fail by local wall bending. For flowable-fill backfill, the ultimate capacity of the pipes is nearly twice that for the soil backfills.
Construction of Daytime Activity Profiles from Household Travel Survey Data
Authors: Roddis S.M. , Richardson A.J.
Published: April 2007

The perception of population as the number of people living in a region is entrenched firmly in the minds of many urban planners and transport professionals. In the past, the use of such a residential or home-based description of population would have suited most local area planning and transportation modeling needs. In light of this, the use of a daytime distribution of population to locate services and facilities forms a radical departure from conventional practice. However, there is a clear need to consider the location of people across the day in planning for the provision of facilities that will be used during the day. Data from the Victorian Activity and Travel Survey were used to develop methods by which daytime population behavior can be examined. Specifically, two measures were developed. A population profile provides an estimate of population within any region at any time of the day. A visitation curve supplements the population profile by monitoring the number of people using a region across the day. Further disaggregation of the population to reveal behavioral and demographic characteristics constitutes an important component of the methodology.
Spatial and Statistical Analysis of Commercial Vehicle Activity in Metropolitan Atlanta
Authors: Ross Catherine , Guensler Randall , Stevens Paula
Published: April 2007

The next generation of air quality models demands a better understanding of medium- and heavy-duty vehicle activities and the relationship between these activities and emissions. Understanding fleet characteristics and their associated impact, therefore, is critically important. Data collected in a 1996 commercial vehicle trip survey for the Atlanta region are presented and analyzed. A survey data collection effort undertaken in 1996, which included the collection of data related to spatial, temporal, cargo, land use, and vehicle characteristics, is described. The results of a series of statistical analyses are reported and discussed. The results of geographic information systems analyses, which provide a spatial picture of commercial vehicle activity, are presented. The spatial analysis combines vehicle, cargo, and land use characteristics with spatial and temporal data within the study area. The results of this study provide a compelling snapshot of commercial vehicle activity in the Atlanta area.
Aspects of Functional Analysis of Mitigated Wetlands Receiving Highway Runoff
Authors: Yu Shaw L. , Earles T. Andrew , Fitch G. Michael
Published: April 2007

The wetland mitigation and storm water management provisions in the 1987 Clean Water Act significantly affect transportation agencies. A common requirement of these federal storm water management provisions and state storm water regulations is the use of best-management practices (BMPs). The Virginia Department of Transportation has constructed more than 200 wetlands and many storm water BMPs, such as detention basins. A potentially cost-effective approach to satisfying wetland mitigation requirements and storm water regulations is to use mitigated wetlands as storm water BMPs. A multifunctional evaluation of two mitigated wetlands receiving highway runoff is presented to examine the feasibility of using mitigated wetlands as storm water BMPs. Influent and effluent water quality and quantity were monitored at the sites during storm events. Vegetation density and diversity and wetland wildlife were examined as functional indicators because they were believed to be the most likely to be impaired by highway runoff. Data collected were stored in a geographic information system, which was developed to serve as a database for current and future monitoring of mitigated wetland sites. Both sites had peak reductions in excess of 40 percent, with attenuation of greater than 90 percent for a system combining a detention basin and a mitigated wetland in series. Removal rates were as high as 90 percent for total suspended solids, 65 percent for chemical oxygen demand, 70 percent for total phosphorus and orthophosphate, and 50 percent for zinc. Despite having highway runoff as a primary water source, both sites support apparently healthy and diverse vegetative communities and provide habitat for a variety of wildlife.
Innovative Concepts for Preventive Maintenance
Authors: Galehouse Larry
Published: April 2007

The Michigan Department of Transportation is committed to the successful implementation of a preventive maintenance program to protect pavement and bridge structures, slow the rate of deterioration, and correct minor pavement deficiencies using surface treatments that primarily target pavement surface defects caused by the environment and deficiencies in pavement materials. Structural deficiencies of the pavement structure caused by traffic-loading are generally not corrected by this program. Many innovative concepts were incorporated in the Michigan Preventive Maintenance Program. The business processes were simplified, and more responsibility was given to the private sector. All preventive maintenance projects used standard specifications and contained a limited number of pay items. But perhaps the most substantial concept was the introduction of warranty specifications for all surface treatments. The implementation of warranty specifications involved mutual trust and cooperation between the department and private enterprise. All contracting industries, suppliers, and bonding and insurance companies were invited to participate in this innovative venture. Introducing new and untested concepts required significant hours of discussion and negotiation by all groups represented. The final results gave the contractors greater flexibility in selecting the materials and application methods used for warranted surface treatments. The department gained higher quality and longer-lasting surface treatments with a smaller workforce.
Laboratory Investigation of Factors Affecting Bond Strength in Joint Sealants
Authors: Gurjar Ashok , Kim Hyung B. , Moody Eric , Buch Neeraj J.
Published: April 2007

An experimental program was carried out to study the factors that affect the bond of joint sealants to concrete substrate. The factors investigated included the preparation technique, aggregate type in concrete substrate, temperature and humidity during curing period, and sealant type. A series of analysis of variance (ANOVA) tests were conducted to analyze the data. This study clearly demonstrated that not all sealants are affected by the same factor and that the influence depends on the material type and interactions among the variables studied. Silicone-based sealants were found to be highly influenced by preparation type and curing temperature, whereas asphaltic-based material was significantly influenced by the aggregate type used in the concrete substrate. This suggests that the additional cost of priming may be justified because of gain in bond strength for silicone sealants. Higher substrate temperature was found to be beneficial to the asphaltic sealant materials.
Pavement Pressure Generation: Neglected Aspect of Jointed Pavement Behavior
Authors: Burke Martin P.
Published: April 2007

A number of recent rigid pavement research reports and papers and new pavement research projects either ignore effects of contraction joint behavior on the generation of pavement pressure or recommend the retention of high pavement pressures to protect contraction joints. In either case, research methods appear to be inappropriate, and conclusions suspect or counterproductive. It also appears that some researchers have completely lost sight of one of the primary reasons for sealing and resealing contraction joints in the first place. In addition, these reports either ignore entirely or significantly underestimate the effects that generating pavement pressure can have on the integrity of bridges that abut such pavements. Consequently, pavement maintenance engineers who uncritically implement the recommendations given in some of these reports and papers may, during the extreme heat of some distant summer, find themselves dismayed by structures (pavements and bridges) subject to destructive pressures and stresses, widespread structural damage, massive repair costs, restrictive traffic flow at structure repair sites, vehicular accidents, and the personal injuries that usually accompany such restrictions. Based on a brief introductory description of the pavement pressure generation phenomenon, a critique of some of the statements and recommendations given in these reports is provided. Recommendations for basic replicable research to clarify this phenomenon, and for subsequently qualifying future pavement joint research with respect to the effect of design, maintenance, and environmental factors on pavement pressure levels, are also provided. Ultimately, such pressure-generation-focused research will give less subjective and more reliable direction for achieving cost-effective structural designs, more durable structures, more effective maintenance practices, and a safer, more dependable highway environment.
Road Snow Removal and the Snowfall Information System in the City of Sapporo
Authors: Kanemura Naotoshi
Published: April 2007

The city of Sapporo has a high snow-removal capability due to a system that allows for effective operation and management of snow removal. The system relies on the city’s meteorological observation facilities and the snowfall information system. During the winter of 1995/1996, which had snowfalls of record depths, the implementation of this system resulted in expedient recovery of the urban functions of the city without human injury.
Mexican Driver Comprehension of U.S. Traffic Control Devices
Authors: Hawkins H. Gene , Picha Dale L. , Lopez Carlos A.
Published: April 2007

The Mexican border areas of Texas possess many unique characteristics that are not present in other parts of the state. One of the most obvious is the prevalence of Spanish as the primary language. Another characteristic is the large number of drivers from Mexico. These two factors may limit the ability of border area drivers to understand traffic control devices. The research study was conducted to determine how well drivers from Mexico understand 33 of the more significant traffic control devices used in the United States and Texas. The survey utilized flash-cards with open-ended questions to assess comprehension levels. It was administered to northbound traffic with Mexican license plates at international bridges in two Texas border cities. Driver responses were recorded on audiotape and later separated into several categories, including “correct” and “partially correct.” The analysis of the responses indicate that, of the 45 questions that were asked about the 33 traffic control devices, approximately half (23) had correct and partially correct response rates of over 80 percent. Approximately a third (15) had correct response rates of over 80 percent. Many of the devices with lower comprehension levels among Mexican drivers are the same devices that have lower comprehension levels among Texas drivers.
Evaluation of Prototype Highway Tourist Signs for Ontario
Authors: Smiley Alison , MacGregor Carolyn , Dewar Robert E. , Blamey Chris
Published: April 2007

Information load and comprehension of new tourist signs for Ontario highways were evaluated. In a laboratory study involving 288 subjects, drivers searched for target destinations on timed sequences of slides of signs and identified whether their target was present, and, if so, its direction and distance. Performance was assessed in relation to number of names, number of signs in a sequence, arrow shapes, pictograph effectiveness, and sign organization. Signs used a letter height of 19 cm (7.5 in.). Subjects were allowed reading time equivalent to that available to drivers driving at 80 km/h (50 mph), who must time-share sign reading and vehicle control tasks. The results showed that with four or five names per sign, approximately one in eight subjects reported an incorrect direction for their target destination. Thus, a maximum of three names per sign was recommended. Results showed that a 70-degree chevron was as effective as a gerber arrow, that the number of signs in a sequence (two, three, or four) did not affect performance, and that having left followed by right destinations on a single sign resulted in equivalent performance to signs with left and right destinations on separate signs. The presence of pictographs increased the number of incorrect responses. Comprehension of 11 pictographs was assessed for 150 subjects. For 5 of 11 pictographs, comprehension was less than 85 percent.
Study of Load Transfer Parameter in AASHTO Design Guide for Concrete Pavement
Authors: Kuo Chen-Ming
Published: April 2007

Some of the design parameters in AASHTO’s Guide for Design of Pavement Structures require experienced engineering judgment to obtain adequate designs. The load transfer parameter for concrete pavements in the AASHTO Guide is reviewed. A set of equations was developed to assist in choosing a J-factor for various pavement conditions. With three-dimensional finite element analysis, factorial runs were conducted to find the relationships between the critical stresses and joint design parameters—that is, joint width, diameter, length, and spacing of dowel bars. Extended procedures that incorporate dowel parameters into the J-factor were proposed. Conclusions were made to clarify the load transfer concept in the current AASHTO Guide and the effects of joint parameters on pavement performance.
Transverse Cracking Distress in Long-Term Pavement Performance Jointed Concrete Pavement Sections
Authors: Moody Eric D.
Published: April 2007

Transverse cracking is one of the more common distress manifestations in jointed concrete pavements. While the extent of transverse cracking is largely related to the specified joint spacing, there are several other primary design variables and distress mechanisms that can cause varying degrees of transverse cracking. These primary mechanisms and their associated variables are well-documented in the literature. However, all of these mechanisms often work on the pavement simultaneously over many years and, as a result, it has historically been difficult to calibrate prediction models with field data. The Strategic Highway Research Program’s Long-Term Pavement Performance (LTPP) program has collected a significant amount of condition survey data on more than 110 jointed plain concrete pavements (JPCP) and 65 jointed reinforced concrete pavements (JRCP) throughout North America over the last 7 years. The occurrence of transverse cracking in these sections is one of the principal distresses documented in the condition surveys and therefore provides an excellent data source for examining the relationships between the various primary distress mechanisms and the actual occurrence of distress in the field. Although it is premature to develop or calibrate purely “mechanistic” models based on the LTPP data, enough data have been collected to begin analyzing this distress and its association with the numerous prediction variables in the LTPP database. A complete analysis of the transverse cracking that has occurred in these LTPP test sections, along with their respective relationships with the primary prediction variables found in the primary distress mechanisms, is provided.
Axle Load Distribution Characterization for Mechanistic Pavement Design
Authors: Kim Jong R. , Titus-Glover Leslie , Darter Michael I. , Kumapley Robert K.
Published: April 2007

Proper consideration of traffic loading in pavement design requires knowledge of the full axle load distribution by the main axle types, including single, tandem, and tridem axles. Although the equivalent single axle load (ESAL) concept has been used since the 1960s for empirical pavement design, the new mechanistic-based pavement design procedures under development by various agencies most likely will require the use of the axle load distribution. Procedures and models for converting average daily traffic into ESALs and axle load distribution are presented, as are the relevant issues on the characterization of the full axle load distributions for single, tandem, and tridem axles for use in mechanistic-based pavement design. Weigh-in-motion data from the North Central Region of the Long-Term Pavement Performance study database were used to develop the models for predicting axle load distribution.
Nonlinear Analysis of Jointed Concrete Pavements
Authors: Asghar Bhatti M. , Molinas-Vega Idelin , Stoner James W.
Published: April 2007

A finite element model for nonlinear analysis of jointed concrete pavements is presented. The model allows for nonlinear representation of the properties of concrete, both in compression and in tension. It also accounts for the behavior under cyclic loading considering the nonlinear fatigue damage accumulation in concrete. An improved model accounting for the relative deformation between the dowel bars and the concrete slabs is presented to analyze pavement slabs connected with dowels. The sub-grade model is capable of representing pumping of the fine material with repetitive loading. Limited validation of the model is presented using data available in the literature.
Validation of Three-Dimensional Finite Element Modeling Technique for Joints in Concrete Airport Pavements
Authors: Hammons Michael I.
Published: April 2007

A rational, three-dimensional (3D) finite element modeling technique was developed to predict the structural response of a jointed concrete airport pavement system. Model features include explicit 3D modeling of the slab continua, load transfer capability at the joint, explicit 3D modeling of the base course continua, load transfer capability across the cracks in the base course, and contact interaction between the slabs and base course. Environmental effects were not explicitly included in the model development. The model was applied to predict the response of an instrumented pavement at the Denver International Airport (DIA) to a test vehicle driven over the instrumented pavement under day and night conditions. The DIA pavement was modeled as a three-layer system with the presence of cracking in the base course as well as a variety of interface conditions between the slabs and base course considered. Complex response patterns caused by environmental factors were observed in the data from DIA, making separation of load-induced and environmentally induced response difficult. The general shape and form of the deflection- and stress-based load transfer efficiency predictions from the finite element models match those observed at DIA. Model predictions of stress-based load transfer efficiencies were generally more accurate than predictions of deflection-based load transfer efficiency. The model developed represents a significant advancement in the state of the art and features innovations that are compatible with the FAA’s advanced pavement design model requirements.
Calibration of Performance Models for Jointed Plain Concrete Pavements Using Long-Term Pavement Performance Database
Authors: Bustos Marcelo , De Solminihac Hernáan E. , Darter Michael I. , Caroca Andres , Pablo Covarrubias Juan
Published: April 2007

A methodology for calibrating performance models for jointed plain concrete pavements (JPCP) is presented; it is based on statistical analysis of data from the Long-Term Pavement Performance (LTPP) database. The methodology provides calibration factors to pavements in four climatic regions (dry-freeze, dry-nonfreeze, wet-freeze, and wet-nonfreeze) for the JPCP performance models in HDM-4: joint faulting, transverse cracking, joint spalling, and roughness. The procedure allows calculation of global calibration factors, which does not affect significantly the quality of the prediction compared with the quality achieved through the use of regional factors.
Calibration of Mechanistic-Empirical Rutting Model for In-Service Pavements
Authors: Ali Hesham A. , Tayabji Shiraz D. , La Torre Francesca
Published: April 2007

Rutting is a major failure mode for flexible pavements. Pavement engineers have been trying to control and arrest the development of rutting for years. Many models are available to relate pavement rutting to design features, traffic loading, and climatic conditions. These models range from purely empirical to mechanistic models. Mechanistic-empirical models (the Asphalt Institute and Shell) were used to predict the development of rutting for 61 Long-Term Pavement Performance (LTPP) test sections. The rutting damage, calculated using these models, did not appear to be a good predictor of the observed rutting depth. A new rutting model was developed and calibrated using the data from the 61 LTPP sections. The model accounts for the plastic deformation in all pavement layers and allows the use of actual axle load and type, rather than the equivalent single axle load, in characterizing traffic.
Effects of Spot Diamond Grinding on Performance of Portland Cement Concrete Pavements
Authors: Wenzel Thomas H. , Vazir Abadi Fariborz , Shober Stephen F. , Schmiedlin Robert
Published: April 2007

A study was initiated by the Wisconsin Department of Transportation to investigate the effects of spot diamond grinding on the performance and material properties of concrete pavement. A field survey was conducted to assess the conditions of selected spot-diamond-ground PCC pavement sites. Pavement distress data were collected on control and spot-ground sections on 22 highways and 34 locations in Wisconsin. In addition, microsurveys were completed for each of the spot-ground sections. Utilizing the pavement distress index, values and results of the microsurvey comparisons are made between sections that were spot-ground and those that were not. Conclusions are drawn concerning the effects of spot grinding on the performance of the concrete pavements; no practical differences were found between the spot-ground and control sections.
Pavement Distress and Selection of Rehabilitation Alternatives: Michigan Practice
Authors: Wotring Donald C. , Baladi Gilbert Y. , Buch Neeraj , Bower Steve
Published: April 2007

The Michigan Department of Transportation (MDOT) practice regarding the preservation, rehabilitation, and preventative maintenance actions for rigid, flexible, and composite pavements is presented and discussed. For each pavement type, the causes of distress and the corresponding MDOT fix alternatives are also presented. Examples of the MDOT practice regarding the selection of maintenance and rehabilitation alternatives for rigid, flexible, and composite pavements are also presented.