bluuebunny/crossref_metadata_2025 huggingface dataset:
Roadway Widening Costs for Geometric Design Improvements To Accommodate Potential Larger Trucks
Authors: Harwood Douglas W. , Glauz William D. , Elefteriadou Lily
Published: April 2007

The substantial costs that could be required to accommodate potential future trucks on the existing roadway system are estimated. These costs have been shown to be sensitive to the size of the truck and the extent of the roadway system considered. Geometric requirements are considered for truck configurations that have greater offtracking and swept-path width than tractor-semitrailer combinations with a single 14.6-m (48-ft) trailer (longer combination vehicles). The truck configurations evaluated include larger tractor-semitrailers, Rocky Mountain doubles, B-train doubles, turnpike doubles, and triples. The extent and cost of roadway widening that would be necessary to accommodate the larger trucks are considered for horizontal curves on mainline roadways and interchange ramps and for ramp terminals and at-grade intersections. Potential costs also are included to provide staging areas to accommodate larger multitrailer trucks and the cost savings in geometric improvements that might be required if staging areas were provided. Tables illustrate both the estimated extent of geometric design improvements and the cost of those improvements to accommodate particular truck configurations on particular roadway networks. These costs have been estimated for truck configurations that are larger than the 14.6-m (48-ft) tractor-semitrailer combination that was used as the baseline vehicle for the study.
Private Financing of Road Infrastructure: The Portuguese Experience
Authors: Fernandes Carlos , Viegas José M.
Published: April 2007

A well-balanced road network is essential for promoting equity of chances across a territory; it allows the populations to make easy use of what increasingly is viewed as the fundamental right of mobility. Portugal has lagged behind in the standard of its roads with respect to most European countries, and it has been trying to reduce that difference. Traditionally, road financing has come either through state investment or mixed investment (e.g., BRISA’s tolled motorway). However, these alternatives might not be viable in the future. Therefore it was decided to bring private investment into the road construction market. The national road agency tendered six contracts under a design, build, finance, and operate (DBFO) model, for a total of 830 km of roadways. Under each contract, the private sector would build or upgrade a road and maintain it for 30 years. In return, the agency would pay the concessionaire according to the number of vehiclekilometers driven on the roads (i.e., shadow tolls). The Portuguese government has made preliminary and ongoing evaluations to support its choice of the DBFO model. The first impressions are that the initial judgments of the private sector’s interest in this business—as well as of the advantages for the public and for the population as a whole—are justified. A careful monitoring program allows continuous improvement of the decision model and the negotiation procedures.
Benefit-Cost Evaluation of the Electronic Toll Collection System: A Comprehensive Framework and Application
Authors: Li Jianling , Gillen David , Dahlgren Joy
Published: April 2007

Although electronic toll collection (ETC) technologies are fairly mature and many ETC systems have been implemented, there is a dearth of comprehensive and systematic assessment of their benefits and costs. Most previous studies have focused only on one or two short-term benefits or costs and have not translated the benefits into dollar values. A comprehensive framework is proposed, incorporating various benefit and cost components, and decomposing the benefits and costs by affected groups. The framework also is tested using data for the ETC system at the Carquinez Bridge in the San Francisco Bay Area. The results of the analyssis show that while the Carquinez ETC project would generate a benefit-cost ratio of 40 over the entire evaluation period, the distribution of costs and benefits would be uneven. Time saving is a major direct benefit of ETC. Other benefits include energy saving, emission reduction, and service improvement. Toll patrons would be the primary beneficiaries. However, cost savings to the agency would depend largely on the demand for use of the ETC system and the cost of transponders. Implications of the findings are discussed.
Attitudes Toward an Increase in Gasoline Taxes: Survey Results
Authors: Sööt Siim , Sternberg Trisha , Sen Ashish , Dijohn Joseph
Published: April 2007

Attitudes toward surface transportation funding—in particular, on the role of a gasoline-tax increase—are reported from a survey of about 1,200 randomly chosen individuals in Illinois. Slightly more than half of the respondents favor a gasoline-tax increase of 5 cents/gal (1.3 cents/L) to fund transportation improvements, and approximately 56 percent of these respondents would like the additional revenue spent on improvements for both transit and highways. Of those who do not favor a tax increase, more than 40 percent would like additional funding for surface transportation from other sources. Only about 3 percent of the residents stated that transportation “needs no improvement.” Opinions about a 5-cent tax increase exhibit regional variation, with Chicago residents showing the most support, downstate residents the least, and suburban respondents falling in between. Support of the tax increase also seems to decline with increasing household income—a counterintuitive result, given the somewhat regressive nature of the tax. Likewise, respondents who think traffic congestion is increasing are less likely to support higher taxes than those who believe traffic flow is improving. Lastly, those with the lowest education levels express the highest support for an increase in the gasoline tax.
Bottlenecks in Transportation Research: Understanding Behavior, the Alpha and Omega for the Applicability of Applied Research
Authors: Strand Sverre
Published: April 2007

There are some basic problems of transportation research that, for many reasons, should be termed bottleneck problems. The terms “behavioral relevance” and “prediction of behavior” indicate that a description of behavior must reflect actual behavior. This is necessary for a description that can contribute to predicting behavioral patterns. These predictions, in turn, are essential to most transportation studies that involve human behavior. The following bottleneck problems are discussed in detail: behavior-relevant private car costs; behavior-relevant time costs; generalized costs and cost-benefit analysis; attitude surveys and self-knowledgeability; forecasting history versus forecasting the future; and indirect effects and the perfect traffic forecast. All these problems are much too important to be solved by sweeping them under the carpet—which in many ways is what we are doing now.
Cost Functions for Optimizing Highway Alignments
Authors: Jong Jyh-Cherng , Schonfeld Paul
Published: April 2007

Optimizing highway alignments through complex environments is a difficult problem. Optimal alignment is influenced by many factors and should be based on trade-offs among various supplier and user cost components. Previous works on alignment optimization usually have neglected some important components of the total cost function that should influence the optimal solution. The formulations of different cost components for two-lane rural highways are presented. The proposed cost functions are based on the geometric features of both horizontal and vertical alignments. The cost formulations can be employed in models for simultaneously optimizing three-dimensional alignments. Possible methods for solving such optimization problems are provided. A numerical example also is presented to illustrate the optimization of three-dimensional alignments with the proposed cost functions.
Traveler Reactions to Congestion Pricing Concepts for New York’s Tappan Zee Bridge
Authors: Adler Thomas , Ristau Willard , Falzarano Stacey
Published: April 2007

The findings from a comprehensive evaluation of traveler reactions to congestion pricing concepts for the Tappan Zee Bridge in Westchester County, New York, are described. Central to the Tappan Zee Bridge Congestion Relief Study is an analysis of traveler reactions to congestion pricing concepts. The bridge is already tolled and the existing structure of steep commuter discounts for passenger vehicles runs directly counter to the pricing schemes that would be used to reduce peak-period delays. A comprehensive program of qualitative and quantitative survey research was specified to determine how corridor travelers felt about congestion pricing concepts and to determine how they would be likely to behave if the concepts were implemented. The focus groups conducted as part of the study have indicated—as had previous studies—that before travelers support congestion pricing concepts, they must understand the congestion benefits and believe that these benefits will accrue. The quantitative surveys found that many travelers have flexibility in the timing of their trips and would exercise that flexibility in response to tolls that varied by time of day. The surveys also found that when the congestion pricing concept and its potential benefits were explained, a slight majority favored it. Finally, the level of support did not appear to differ significantly across gender or income categories.
Effectiveness of the Katy Freeway HOV-Lane Pricing Project Preliminary Assessment
Authors: Woong Shin Sung , Hickman Mark
Published: April 2007

The QuickRide program, implementing priority-lane pricing on the Katy high-occupancy vehicle (HOV) lane in Houston, Texas, is described. The program allows two-person carpools to use the HOV lane for $2.00 during peak periods, when the lane has a three-or-more person restriction. The use of QuickRide during its first 6 months is reported, and an analysis of the program’s effectiveness is presented. QuickRide usage and data from before and after implementation are employed to analyze users’ travel patterns, observed travel time-savings, and changes in person-throughput in the Katy Freeway corridor. The results of this analysis show that the participation in the QuickRide program is too low to observe significant impacts on travel speeds and person-throughput in the general-purpose lanes and the Katy HOV lane. Also, the analysis indicates that use of the QuickRide program reached a plateau about two months after start-up. Participants seem to be using QuickRide occasionally or infrequently, and a majority of the participants do not use it at all in any given week. Most of the QuickRide users appear to be previous two-person carpool commuters, with a substantial minority of single-occupant vehicle (SOV) drivers now forming carpools to participate. Higher vehicle-occupancy modes are not losing many patrons to the QuickRide program. An analysis shows that travel time-savings for participants are substantial and are worthwhile for two-person carpools, with a value of time exceeding $6.57/hr. However, the analysis also indicates that, at this initial stage, the observed changes in vehicle- and person-throughput are not statistically meaningful. To improve participation in the program, a lower fee is recommended, and marketing efforts should be enhanced, especially to SOV drivers.
High-Occupancy Toll Lane System: A Concept Plan for the Twin Cities
Authors: Lari Adeel Z. , Buckeye Kenneth R.
Published: April 2007

Critics of high-occupancy vehicle (HOV) lanes have cited what seems to be excess capacity as reason to abandon the lanes and open them to all users. HOV proponents argue that the lanes do their job, though with unused capacity needed for the future. As a means to stem some of the criticism of the unused capacity, the Minnesota Department of Transportation and the Metropolitan Council of the Twin Cities have undertaken a high-occupancy toll (HOT) system study. Under this concept, additional freeway capacity—primarily lane additions—would be implemented as HOV lanes with the option for solo drivers to use the facility by paying a toll. Users of existing roadway capacity on the regular-use lanes would continue to be able to use the freeways toll-free. The possible inclusion of ramp-meter bypass lanes as an option for HOT-lane users also was studied. Although the HOT-lane system concept is technically and financially feasible, serious challenges lie with public acceptance of any form of value pricing. Significant, ongoing value-pricing education efforts must continue and political champions must emerge before the public is willing to accept the HOT-lane concept. However, market research indicates that public acceptance increases when HOT lanes are presented in the context of the system, showing the other alternatives for reducing congestion that have been implemented or examined, along with their associated costs and benefits. Social and geographic equity issues begin to diminish when it is shown that HOT-lane revenues would be targeted to maintenance, debt service, and transit enhancements in the corridors where the fees are collected.
Accreditation of Programs in Transportation Engineering: The University of Arkansas Experience
Authors: Grimm Lewis G. , Elliott Robert P.
Published: April 2007

At its annual meeting on July 25, 1997, the Engineering Accreditation Commission (EAC) of the Accreditation Board for Engineering and Technology, Inc. (ABET), granted initial accreditation to an advanced-level program in transportation engineering at the University of Arkansas. Not only was this one of the first baccalaureate or advanced-level engineering programs accredited under EAC’s new outcomes-based Criteria 2000 process, but it also represented the first accredited program in transportation engineering at any college or university in the United States. With the passage of the Intermodal Surface Transportation Efficiency Act of 1991 and the establishment of the Mack-Blackwell Transportation Center at the University of Arkansas, the faculty of the department of civil engineering saw an opportunity to create a unique educational program. The program would address the multidisciplinary requirements of the transportation engineering profession in a more comprehensive manner than traditional programs oriented to civil engineering. Bringing together a mix of civil-engineering-oriented transportation planning, traffic engineering, and facility design courses along with requirements for exposure to private-sector transportation and logistics issues through the school of business, the University of Arkansas has created a model for an accredited program in transportation engineering. The development of this program is discussed, along with the manner in which the EAC Criteria 2000 were applied, and what should be considered the basic elements of an advanced-level program in transportation engineering.
Transportation Planning, Policy, and Data: Inextricable Linkages
Authors: Pisarski Alan E.
Published: April 2007

Transportation is a fascinating interaction of sociology, economics, and technology. It is so interwoven with the social and economic structure of all societies, and most conspicuously American society, that its connections and impacts are inextricable from the understanding of the society itself. We do not really understand it in any quantitative sense and are not capable of assessing its real value in our society. What we expect from transportation today has changed sharply from the past. Today there is a whole list of “musts” and “must nots” that define the context in which transportation functions. Transportation seems implicated in everything and is the universal lever for accomplishing public goals. We expect more of transportation today than ever; therefore we need more from our data sources and presumably from planning and policy. This lecture reflects on 35 years of practice and the lessons provided. It concludes that we need new mechanisms for evaluating and justifying transportation investments and policies. We need tools to transmit the basis for investment decisions to the public.
Estimation of Annual Average Daily Traffic for Nonstate Roads in a Florida County
Authors: Xia Qing , Zhao Fang , Chen Zhenmin , Shen L. David , Ospina Diana
Published: April 2007

A study was undertaken to develop a methodology to estimate annual average daily traffic (AADT) for nonstate roads in urbanized areas in Florida. The current practice related to the estimation of AADT for nonstate roads has been of great concern to the Florida Department of Transportation because of the potential lack of accuracy in the estimated data. For this study, a multiple regression model was developed for estimating AADT on nonstate roads. The model utilized a large sample size (data from 450 count stations in Broward County) and involved the investigation of up to 12 initial variables. Various methods, including geographic information systems (GIS), were explored to convert the current digital data and aggregate them into suitable forms for statistical analysis. Statistical tests were performed and the results showed that the most important contributing predictors are roadway characteristics, such as the number of lanes, functional classification, and area type. Socioeconomic variables, including population, dwelling units, automobile ownership, employment numbers, and school enrollment in the surrounding area, have an insignificant impact on AADT. Further analyses revealed the deficiency of traditional roadway functional classification, the need to improve the method of road classification, and the need for alternative methods to account for the impact of economic activities on AADT.
Travel Time Information Using Global Positioning System and Dynamic Segmentation Techniques
Authors: Quiroga Cesar A. , Bullock Darcy
Published: April 2007

The architecture and application of an updated methodology based on the Global Positioning System (GPS) for conducting travel time studies are described. The methodology is called Travel Time with GPS (TTG). TTG uses a general data model that includes a spatial model, a geographic relational database, and a procedure for linearly referencing GPS data using dynamic segmentation tools. This architecture allows users to conduct travel time studies at various levels of resolution (from regionwide studies down to studies of signalized intersections). The data reduction and data reporting for such a system are outlined. Data reduction is based on linear referencing of GPS data using highway links, where highway links are defined as vector representations of directional centerlines delimited by physical discontinuities. Data reporting is based on the use of dynamic segmentation tools to compute travel time and speed along highway corridors using any highway segmentation scheme. The resulting aggregated data can be used for the production of tabular reports and color-coded maps to document travel time, delay, and speed data. The database management system built into TTG allows users to handle many GPS data files using a centralized, structured procedure, which is critical for data archival purposes and the development of clientserver applications. In conclusion, quantitative values for data storage requirements and processing speeds are provided. Those values should be useful to practitioners currently designing travel time information systems.
Traffic Impact Analysis by Using Geographic Information System Technology
Authors: Sarasua Wayne , Simas de Oliveira Marcelo G. , Carroll Bradley , Troemel David
Published: April 2007

Several software tools are available to help the planner or engineer forecast the traffic impacts of site developments that are too small to effectively use transportation modeling software. Using these tools can provide numerous time-saving advantages. The tools include trip generation software that has built-in trip rates taken from the Institute of Transportation Engineers trip generation manual and manual pathencoding traffic impact software that will identify turn movements and link volumes (as well as intersection levels of service) given certain inputs. Manual path-encoding software such as TRAFFIX requires manually creating a network of project zones, critical intersections, and connecting road segments; inputting existing count data and trip generation information; manually describing the paths that traffic takes to get from a development to a gateway (trip assignment); and inputting the percentage of trips that go to each gateway from a development (trip distribution). Once these inputs have been made, traffic volumes that result from the developments are automatically applied to the intersections. Many of the manual path-encoding software packages will include intersection capacity analysis capabilities. A major benefit of manual path-encoding software is that different land use alternatives can be analyzed quickly. The drawback of these software packages is the extensive manual input required for even small networks. Described in this paper is a site impact tool based on geographic information system (GIS) technology that works on the same premise as the manual path-encoding tools. The major difference is that this approach makes heavy use of the network analysis and map manipulation tools of GIS to significantly enhance the process of doing traffic site impact analysis. An actual application is presented.
Accuracy of Linearly Referenced Data by Using Geographic Information Systems
Authors: Quiroga Cesar A.
Published: April 2007

Distance accuracy issues are identified that should be considered when linear referencing procedures based on geographic information system (GIS) technology are applied to map objects and events to highway networks. One of the most pressing issues is that of consistency among GIS functions to compute surface distances. Several GIS packages are compared using two sets of points: National Geodetic Survey geodetic control points for which independent estimates of distance were available and virtual points for measuring the effect of increasing distance between points. Results show a wide discrepancy in distances measured, and tools are provided to identify two groups of GIS packages: those that use a variable radius ellipsoidal model of the surface of the earth and those that use a less flattened, possibly spherical model of the earth’s surface. The accuracy associated with distance measurements varies according to the model of the earth’s surface used. Thus, transportation agencies need to be aware of their distance accuracy needs and the distance accuracy their GIS package can provide. Guidelines are provided that transportation agencies could use to determine distance accuracy requirements and to evaluate GIS distance accuracy capabilities. These guidelines could also be used as a foundation for the development of standardized GIS distance-measuring functions to facilitate distance and linear referencing data exchange across hardware and software platforms.
Linear Referencing System for North Carolina Department of Transportation
Authors: Kiel Don , Rasdorf William , Shuller Ed , Poole Ron
Published: April 2007

Linear referencing system (LRS) structures have been utilized by transportation agencies for many years to locate and graphically display data collected along linear features such as roads, railroads, and transit lines. Strategies for implementing a real-world LRS have always been dependent on technical, organizational, and cost factors. Large transportation agencies such as state departments of transportation are developing more sophisticated tools to support analysis of LRS-related information. Among these are geographic information system (GIS)-related display and analysis methods and database storage and manipulation systems. An increasingly common desire is for such agencies to link data in an enterprise system that can support efficient, effective management and retrieval and analysis using GIS technology. A continuing project at the North Carolina Department of Transportation involves design and implementation of a unified enterprise LRS solution to promote data sharing, reduction of redundant data, enhanced GIS capabilities, and development of state-of-the-art data management structures and tools. The project includes several units in the Statewide Planning Branch that have not traditionally been able to share LRS data effectively. The LRS model being implemented incorporates ARC/INFO GIS software and Oracle database management software to provide a solution to this problem. Sufficient flexibility in system design is also being included to promote data sharing with external agencies such as metropolitan planning organizations, counties, and municipalities. The experience of the authors during the design and implementation process of this project at North Carolina Department of Transportation is reviewed.
Self-Describing Data Transfer Methodology for Intelligent Transportation Systems Applications
Authors: Dailey D.J. , Meyers D. , Friedland N.
Published: April 2007

The wide variety of remote sensors used in intelligent transportation systems (ITS) applications (loops, probe vehicles, radar, cameras, etc.) has created a need for general methods by which data can be shared among agencies and users who own disparate computer systems. In this paper a methodology is presented that demonstrates that it is possible to create, encode, and decode a self-describing data (SDD) stream using existing data description language standards, parsers to enforce language compliance, a simple content language that flows out of the data description language, and architecture neutral encoders and decoders based on Abstract Syntax Notation One (ASN.1). Further, it documents a reference implementation of an SDD receiver.
Innovative Commuter Surveying Techniques Used in Advanced Transportation Management System Evaluation
Authors: Jacobson Marc , Henk Russell
Published: April 2007

Procedures and results associated with a unique approach for conducting commuter surveys in San Antonio, Texas, are presented. This approach was specifically developed in association with a before-and-after evaluation of Phase II of San Antonio’s advanced transportation management system (ATMS), known as TransGuide. The primary purpose of the surveys is to identify user understanding and utilization of ATMS components. The surveying approach used a geographic information system (GIS) application that would identify the appropriate group to survey on the basis of the location of the incident and the route information supplied by the survey panelists. This automated approach reduced the number of nonapplicable surveys that were distributed, was easy to use, and could identify the survey panel very quickly. Using the results of the GIS application, surveys were distributed in both paper and electronic formats. The electronic method consisted of sending via electronic mail a request to complete a survey that would guide the respondent to an on-line survey that they could use to answer the questions. The electronic survey significantly reduced the labor and materials costs associated with distributing the survey. The preliminary response rates indicate that, at a minimum, the electronic survey will provide the same response rate with a reduction in cost. Although issues concerning sample bias must be considered, the electronic survey method has the potential to be more effective and more efficient than most of the other surveying techniques commonly used in current practice.
Rheological Characteristics of Selected Polymer-Modified Asphalts Through Their Dynamic Compliances
Authors: Stastna J. , Liu C. , Zanzotto L.
Published: April 2007

In past decades polymer-modified asphalts have become commonly used materials for the construction of high-quality flexible pavement. Regardless of the commercial importance of these “modified asphalts,” little is known about the mechanisms of polymer-asphalt interaction, and polymer-asphalt production is purely empirically based. A better understanding of the molecular processes in polymer asphalts is necessary, not only to satisfy scientific curiosity, but also for economic reasons. An attempt is made to investigate the changes in molecular mechanisms after the addition of polymer into asphalt. To see these changes, the contribution of viscous flow to the rheological behavior of paving asphalts has to be mathematically eliminated because this phenomenon masks the more subtle behavior of asphalt materials. It is quite common to present viscoelastic data as components of the complex modulus, G*(ω) In linear viscoelastic theory these material functions, and the stress relaxation modulus, G( t), can generate a complete set of viscoelastic functions that are all mathematically equivalent. The experimental experience, however, does not support such equivalence. It was shown that what is sometimes identified as a plateau or shoulder by the dynamic storage modulus G′(ω) or the stress relaxation modulus G( t) is an artifact of the viscous deformation, which can be subtracted from some compliance functions but not from the modulus functions. Thus, compliance functions can show more attributes of the actual structural dynamics of the studied materials than the dynamic functions. Several polymer-modified asphalts are studied in the terminal and at the beginning of the transition regions. The advantage of using the dynamic compliance functions for modified asphalts is discussed.
Comparison of Asphalt Extraction Procedures: Implications of Hidden Environmental and Liability Costs
Authors: Behrens Michael L. , Dvorak Bruce I. , Woldt Wayne E.
Published: April 2007

In the past, asphalt extractions were performed using toxic solvents; alternative, less polluting methods have been developed that can replace the traditional solvent extraction method. Accordingly, five potential asphalt extraction methods were compared for the Nebraska Department of Roads Bituminous Laboratory: solvent extraction using trichloroethylene (TCE), solvent extraction using an alternative solvent, solvent extraction using TCE and a solvent recovering reclaimer, ignition oven, and an ignition oven and solvent combination. To compare the total cost of each option, the direct capital costs, operating and maintenance costs, as well as the hidden environmental, health, and safety costs were considered. Because the hidden costs can be difficult to quantify, a total cost assessment approach was used. To represent the uncertainties in the cost and design data, fuzzy set theory was used. A traditional economic analysis, including only the capital, and operating and maintenance costs, found that the three least-cost options were within the range of uncertainty of the analysis; these three options were the ignition oven (most environmentally friendly option), ignition oven with solvents, and solvent reclaimer. However, when the hidden costs related to the environmental, health, and safety aspects for an asphalt extraction procedure were incorporated into the cost analysis, the cost comparison changed significantly; the most environmentally friendly option, ignition oven, was shown to be by far the least-cost option. Accordingly, the quantification of environmental, health, and safety costs that are difficult to assess is very important when evaluating environmentally friendly processes.
Low-Temperature Evaluation of Kentucky Performance-Graded 70-22 Asphalt Binders
Authors: Michael Anderson R. , Walker Dwight E. , Turner Pamela A.
Published: April 2007

A study was initiated to ascertain whether all performance-graded (PG) 70-22 binders would perform the same in an asphalt mixture in Kentucky, regardless of method of manufacture of the binder. Five PG 70-22 binders and one PG 64-22 binder (control) were incorporated into an asphalt mixture through a hot-mix asphalt plant. Test sections were placed for each binder. The mixture was sampled at the plant and returned to the laboratory for mechanical property testing. The mechanical property tests included repeated shear test at constant height, frequency sweep test at constant height, and indirect tensile creep (ITC) test. These tests were chosen to evaluate the high-, intermediate-, and low-temperature properties of the asphalt mixtures. Only low-temperature properties are discussed. Thermal stress analysis techniques permitted the critical mixture temperature for single-event thermal cracking to be compared with critical binder temperatures. Although the critical binder temperature [calculated from bending beam rheometer (BBR) stiffness] matched the critical mixture temperature reasonably well, the critical binder temperature calculated from the BBR m-value did not match as well. The m-value critical temperature is generally higher than indicated by the low-temperature ITC testing. Although not all PG 70-22 binders performed the same in mixture testing, the research did not clarify whether differences in mixture properties for the PG 70-22 binders are related to differences in binder stiffness, differences in method of manufacture, or both.
Effect of Hydrated Lime on Rheology, Fracture, and Aging of Bitumen
Authors: Lesueur Didier , Little Dallas N.
Published: April 2007

Hydrated lime (HL) is an active filler in some bitumens. Rheological models demonstrate that HL interacts with certain bitumens to develop an adsorbed (interactive) layer around the HL particles. The volume of this layer can be substantial, causing HL to have a much more substantial effect on the bitumen than inert fillers. The level of interaction between HL and bitumen is bitumen dependent. This interaction causes HL to strongly affect high-temperature rheology in certain bitumens, but it has less of an effect in others. The low-temperature stiffening effects of HL are less prominent, and a significant level of fracture toughening (at low temperatures) occurs through the addition of HL. The active nature of HL with certain bitumens is further verified by nuclear magnetic resonance. HL is considered a multifunctional additive with potential benefits to the binder and to the mixture that include resistance to deformation, low-temperature fracture toughening, and increased resistance to age hardening. HL may be competitive with some polymer additives.
Full Cost of Air Travel in the California Corridor
Authors: Gillen David , Levinson David
Published: April 2007

The theoretical and empirical literature on the cost structure of the provision of air transportation is reviewed, and cost functions for air travel in the California corridor are specified and estimated. A full cost model is developed; it identifies and measures key cost components—fuser, carrier, infrastructure, time and congestion, noise, accident, and pollution costs. Applying the models to data for domestic air travel in the California corridor, the total long-run average cost is estimated to be 11 cents per passenger km traveled. The single largest cost category is owning and operating a plane. In general, because of large fixed-cost components, the average cost of infrastructure exceeds the marginal cost.
Fundamentals of Airplane Accident Dynamics: Extracting Meaning from Fatal Accidents
Authors: Roberts William
Published: April 2007

Knowledge gained from fatal accidents improves the safety design of new vehicles and shows the need to control speed, upset, and overspeed in the existing fleet. Of the 13,000 fatal accidents that have been reported since 1970, 99 percent occurred in general aviation (GA). These accidents are examined, and the fundamentals of fatal accidents are defined. In transports, utilization has grown faster than accident rates have fallen. Thus, the number of fatalities has remained roughly constant for 28 years. In GA, however, the reduction in fatal accidents averages less than 3 percent per year. Fearing that the number of fatalities could actually increase, a White House Commission on Aviation Safety challenged engineers in 1996 to reduce the number of fatal accidents by 80 percent. Accomplishments included ( a) the concept of amplification of structural loads on close approach to an instability explained in-flightairframe-failure; ( b) the establishment of load and speed at the point of failure ( c) the finding that the most likely failure occurs slightly above design cruise speed if minimum strength and minimum stiffness were used in design; ( d) the correlation of accident rates with structural flexibility and speed; ( e) the finding that strong trends at high speed in four variables could not be intuitively separated until a math model of the failure process was created; ( f) the finding that the model matched the 10:1 difference in accident rates between GA and transports; and ( g) the finding that the model demonstrated that structural stiffness was more important than structural strength.
Limited Study of Flight Simulation Evaluation of High-Speed Runway Exits
Authors: Trani Antonio A. , Cao Jin , Tarragó Maria
Published: April 2007

The provision of high-speed runway exits is one of several alternatives to increase airport runway capacity through reductions in runway occupancy time. The Runway Exit Design Interactive Model developed at Virginia Tech proposes new geometric design standards for high-speed turnoffs and an algorithm to locate optimal runway exits. The results from a limited flight simulation study that was conducted to assess the operational suitability of high-speed runway exits developed at Virginia Tech are presented. The flight simulation experiments were conducted at the Mike Monroney Aeronautical Center in Oklahoma City in a Boeing 727-200, 6-degree-of-freedom, full-motion-base aircraft simulator. The study used six FAA pilots rated in the Boeing 727-200 aircraft to obtain information about the operational suitability of the proposed high-speed exits. Pilot responses were extracted from questionnaires that were administered during the flight-simulation experiments. Aircraft state variable time histories extracted from the flight simulator computer were analyzed to verify the dynamic behavior of the aircraft as high-speed runway exits were negotiated. Two statistical experiments were carried out to evaluate the acceptance of the high-speed exit designs: ( a) a two-factor analysis of variance test to verify differences in runway exit speeds and ( b) nonparametric tests of pilots questionnaire responses. The results suggest that a new generation of high-speed runway exit geometries could be used to increase runway exit speeds without compromising safety or inducing extra workload on pilots.
Tension Piles in Sand: A Method Including Degradation of Shaft Friction During Pile Driving
Authors: Alawneh Ahmed
Published: April 2007

Estimation of the shaft resistance component of the axial capacity of a driven pile into sand involves considerable uncertainty, and most of the current design methods are not consistent with the observed pile behavior during installation and axial loading. In this paper, a method for the estimation of the ultimate uplift shaft resistance of a single pile driven into sand was developed based on a database of 34 pullout pile load tests collected exclusively from the current geotechnical literature. The collected database comprises steel and concrete piles (open- and closedended) driven into loose to very dense sand with varying normalized penetration depth with respect to pile diameter. The developed method accounts for the degradation of shaft friction during pile installation. At any given location, the earth pressure coefficient is assumed to degrade from a maximum value (near the pile tip) to a minimum value as an exponential or as a power function of the length of pile driven past that location. The maximum earth pressure coefficient value has been linked to sand relative density, level of effective vertical stress, and pile diameter. The method is extended for the estimation of the compressive shaft resistance of a driven pile into sand by applying De Nicola and Randolph ( 1) correction for the direction of loading. Comparisons of measured and predicted shaft friction profiles of some field cases showed reasonable agreement and indicated that the method is useful in estimating shaft resistance of driven piles in sand and has sound physical meaning.
Applying Greenhouse Gas Emissions Trading to the Light-Duty Vehicle Sector
Authors: Salon Deborah , Dudek Daniel J.
Published: April 2007

The threat of global climate change induced by human production of greenhouse gases is becoming more intensely debated every year. With international agreement on the Kyoto Protocol in December 1997, nations are beginning to assess their options to meet the commitments that they have made. In terms of greenhouse gas emissions control, the passenger vehicle sector presents a significant challenge. Every liter of gasoline burned produces approximately 2.3 kg of carbon dioxide, the most common greenhouse gas. Although all known methods of greenhouse gas emissions control come with some associated costs, a properly designed emissions trading system is a promising policy tool to deal with this increasingly significant environmental problem in a costeffective manner. The issues involved with measurement of the greenhouse gases produced by passenger vehicles and their incorporation into an intersectoral emissions trading system were investigated. It is suggested that direct emissions measurement may not be necessary for these vehicles to participate in such a program, and an alternate emissions estimation methodology is described. Finally, an emissions trading implementation plan is discussed. By that plan vehicle manufacturers are given credit or responsibility for the greenhouse gas emissions of the vehicles that they sell, with the emissions annualized over the projected lifetime of the vehicles.
Modal-Based Intermediate Soak-Time Emissions Modeling
Authors: An Feng , Barth Matthew , Scora George , Ross Marc
Published: April 2007

A comprehensive modal emissions model for light-duty cars and trucks is being developed under the sponsorship of NCHRP Project 25-11. Model development has been described previously for vehicles operating under hot-stabilized conditions. A modal emissions model is presented for vehicles operated under incremental soak-time conditions. The Federal Test Procedure (FTP) measures vehicle emissions after a 24-h soak time during Bag 1 testing and vehicle emissions after a 10-min soak time during Bag 3 testing. Vehicle incremental soak-time emissions refer to vehicle emissions after intermediate variable soak times of between 10 min and 24 h. Recent research shows that most on-road vehicles experience soak times of between 10 min and 24 h during daily driving; thus, there is strong desire to model vehicle emissions under such circumstances. An intermediate soak emission model has been developed on the basis of second-by-second emissions measurements generated at the College of Engineering Center for Environmental Research and Technology, University of California–Riverside vehicle testing facility by using the FTP Bag 1 and Bag 3 test cycles. The modeling results are based on a composite vehicle concept in which more than 300 tested vehicles are composited into two dozen vehicle technology groups. The modeling approach is a fuel-based physical modal emissions model in which vehicles’ fuel use, engine-out emissions, air/fuel equivalence ratio, catalyst efficiencies, and tailpipe emissions are modeled individually as a function of variable soak time. Since the developed model is based on modeled vehicle fuel consumption under any given driving cycle, it not only is capable of predicting vehicle emissions under variable soak time for any given test cycle but also is capable of predicting emissions under different starting test cycles.
Empirical Bayes Procedure for Ranking Sites for Safety Investigation by Potential for Safety Improvement
Authors: Persaud Bhagwant , Lyon Craig , Nguyen Thu
Published: April 2007

The identification of sites requiring investigation for possible safety treatment is one of the most important aspects of infrastructure safety management and has been the subject of considerable research aimed at improving the efficiency of the process. The more recent techniques use the empirical Bayes (EB) method for estimating the safety of specific sites. A refinement of the EB method that is conceptually sound and inherently simple to apply is the focus of this research. With this refinement, the EB estimate of the safety of a site is compared with its expected safety to determine the potential for safety improvement, which forms the basis for ranking sites for safety investigation. A comparative evaluation is provided of the proposed method against other EB methods and the more conventional ones, with data for signalized intersections and two-lane rural highway sections. The refined EB method is shown to be comparatively efficient.
Safety Effects of the Conversion of Rural Two-Lane to Four-Lane Roadways Based on Cross-Sectional Models
Authors: Council Forrest M. , Richard Stewart J.
Published: April 2007

As congestion on two-lane rural roads increases, there is increasing interest in conversion to a four-lane undivided or four-lane divided facility within the same corridor. There is a surprising lack of research aimed at precisely estimating the safety benefits of these conversions. This lack is due in large part to the difficulty of conducting such research, because the best answer would result from analysis of a large sample of converted locations covering many different before-and-after configurations. The authors have attempted to estimate the benefits of such conversions by developing cross-sectional models producing crash rates for typical sections of two- and four-lane roadways in four different states. Predicted crash reductions for conversion from most typical two- to four-lane divided sections ranged from 40 to 60 percent. The reduction due to conversion to a four-lane undivided configuration is much less well defined, ranging from no effect to perhaps a 20 percent reduction. Continuing research needs include ( a) verification of the undivided four-lane results, ( b) additional information on the effects of driveways, ( c) estimates for higher levels of two-lane average daily traffic, ( d) expansion of the outcome variable to include crash severity, and ( e) verification of all results by before-and-after studies of actual conversions.
Using Origin-Destination Data and a Geographic Information System To Estimate Risk Exposure in Urban Areas
Authors: Andrey Jean C. , Lister Murray
Published: April 2007

The importance of exposure in explaining accident patterns has been recognized for at least 50 years. A method is outlined for using existing origin-destination data, in conjunction with a geographic information system, to estimate risk exposure for specific driver groups in urban areas. The method is developed for drivers age 60+ years in the region of Waterloo, Ontario, Canada. Results were validated by three criteria. First, comparisons of simulated trips with stated-preference routes showed a high degree of correspondence at the route/system level. Second, simulated travel patterns were fairly consistent with what would be expected given the spatial and temporal distribution of not-at-fault drivers. Third, the geographic information system results were combined with accident data to calculate involvement rates. These were then compared with estimates for the province of Ontario. Again, risk patterns were found to be similar at the aggregate level. In conclusion, geographic information system technology provides a novel and promising method for estimating risk exposure from origin-destination data.