bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Properties and Durability of Bonded-Concrete Overlays and Ultrathin Whitetopping Concrete
Authors: Delatte Norbert , Sehdev Anshuman
Published: April 2007

Concrete overlays have been used for pavement and bridge-deck rehabilitation for many years. The mechanical properties and durability of several plain and fiber-reinforced concrete-overlay mixes were analyzed. Eight different concrete-overlay mix designs were investigated. The materials properties investigated were compressive and splitting tensile strength, modulus of elasticity, bond to concrete (with three different surface roughness characteristics), and durability. Freeze-thaw tests were performed to determine the durability of the concrete mixtures used. Strength and stiffness were investigated from 1, 3, 7, and 14 days. Laboratory tests on the strength and stiffness development of eight candidate concrete-overlay designs showed that high-strength concrete was appropriate for opening overlays to traffic in 24 h or less, but normal-strength concrete may be used if traffic loading may be delayed for 48 or 72 h. For larger projects, where paving continues over several days, normal-strength mixtures may be used when 48 to 72 h or more of curing can be achieved before traffic loading begins, with high-strength mixtures used for the last day's construction. All the high-strength concrete overlay-mixture designs tested appear to have satisfactory strength, stiffness, bond properties, and durability for use in bonded overlay construction. The normal-strength concrete is more economical than the high-strength concrete but develops its design properties more slowly.
Quantifying Early-Age Stress Development and Cracking in Low Water-to-Cement Concrete: Restrained-Ring Test with Acoustic Emission
Authors: Hossain Akhter B. , Pease Brad , Weiss Jason
Published: April 2007

Early-age cracking has been found to occur in some concrete bridge decks, slabs, and pavements when the volumetric changes associated with drying, hydration, and temperature reduction are prevented. While free-shrinkage tests can quantify length change, they may not always be sufficient for detecting materials that are prone to cracking, since the potential for cracking is influenced by complex interactions of strength gain, stiffness development, creep, shrinkage, the degree of restraint, and toughness. The simplicity of the ring test enables it to be used as a comparative test to screen potential mixture designs. From the use of this test, AASHTO developed a provisional standard ring test that establishes specimen geometry; however, the provisional standard does not provide an approach for quantifying stress development or indicating how close a specimen may be to failure. Described is a simple stress solution for quantifying the results of the ring test. Issues related to ring and free-shrinkage specimen geometries are discussed to improve the fundamental understanding of the information provided by the ring test. Also described is how elastic stress and actual stress can be compared to measure the stress relaxation in a material. To better illustrate the microcracking and visible-crack development process, acoustic-emission testing was performed. These experiments indicated that specimens with a higher level of restraint exhibited more microcracking as a part of the stress relaxation process.
Development of Performance Specifications for Shrinkage of Portland Cement Concrete
Authors: Mokarem David W. , Weyers Richard E. , Stephen Lane D.
Published: April 2007

During its service life, concrete experiences volume changes. One of the types of deformation experienced by concrete is shrinkage. There are four main types of shrinkage associated with concrete: plastic, autogenous, carbonation, and drying shrinkage. The volume changes in concrete from shrinkage can lead to the cracking of the concrete. In the case of reinforced concrete, cracks in the cover concrete provide a direct path for chloride ions to reach and corrode the reinforcing steel. The development of concrete drying-shrinkage performance specifications with an associated test procedure was assessed for concrete mixtures purchased by the Virginia Department of Transportation (VDOT). Five existing shrinkage-prediction models were also assessed to determine the accuracy and precision of each model as it pertains to the VDOT mixtures used in this study. The five models are the ACI 209 Code model, CEB90 Code model, Bazant B3 model, Gardner–Lockman model, and Sakata model. The percentage length change limits for the portland cement concrete mixtures were found to be 0.0300% at 28 days and 0.0400% at 90 days. The CEB90 Code model was judged as the best prediction model for the VDOT portland cement concrete mixtures.
Development of Some Performance-Based Material Specifications for High-Performance Concrete Pavement
Authors: Rangaraju Prasada Rao
Published: April 2007

In collaboration with FHWA, the Minnesota Department of Transportation (Mn/DOT) has successfully completed its first experimental high-performance concrete pavement (HPCP) project under the Testing and Evaluation Program (TE-30). This project is one of the 22 projects funded under the TE-30 Program. With a structural design life of 60 years, this HPCP is unique in that it incorporates significant changes to the existing Mn/DOT specifications on concrete materials. Some of the new materials-related specifications developed as a part of this project are based on performance criteria that influence long-term durability of the pavement structure. The background and considerations for selecting the new performance measures are discussed, and test results are presented that evaluate the practical feasibility of establishing and achieving the performance specifications.
Comprehensive Process for Evaluating Existing and New Transit Services: San Diego Metropolitan Transit Development Board
Authors: Cheung Conan , Daney Michael
Published: April 2007

Just as public transit services must be adjusted periodically to efficiently and effectively respond to the opportunities and constraints of changing operating environments, so do the policies and procedures that govern service planning and development. The Metropolitan Transit Development Board’s (MTDB) Policy No. 43, originally adopted by the board in 1993, outlines methodologies for evaluating existing services and new service proposals. This policy was most recently revised in 2002 to reflect regional transportation goals and objectives, provide flexibility in prioritizing new services for implementation, and position MTDB for developing service reductions during times of fiscal constraints. The revision changed the process for evaluating service proposals and established a lifeline service plan. The original process for evaluating service proposals was limited to a quantitative evaluation based on calculated measures of productivity that did not account for qualitative merits of the proposals. Therefore, the process was revised to include qualitative criteria and the adoption of an annual investment strategy to help prioritize new services for implementation. The revised process results in a more comprehensive evaluation of service proposals and adjusts to the constantly evolving service development goals and objectives. Because of the current budget deficit faced by all MTDB area transit operators, criteria for developing a lifeline service plan were also included in the policy revision. The plan provides a policy framework for service provision in years of major fiscal constraints and establishes a “footprint” of minimum geographic coverage of transit services that would be retained in the event of major service reductions.
Transit Use and Proximity to Rail: Results from Large Employment Sites in the San Francisco, California, Bay Area
Authors: Dill Jennifer
Published: April 2007

Survey data from more than 1,000 large employment sites in the San Francisco Bay Area are used to examine the link between transit use and proximity to rail stations. The data were collected as part of an employer trip-reduction rule. Findings show that sites within one-quarter mile of a rail station have significantly higher rates of transit use than sites between one-quarter and one-half mile from stations. Transit use drops even further one-half mile from stations. That relationship holds true for all three rail systems in the Bay area. A closer look at 20 work sites near two light rail stations in Santa Clara County reveals that actual walking distance is also an important factor related to transit use. However, site design often lengthens walking distance unnecessarily. In addition, certain types of employers have higher rates of transit use than others.
Multiuser-Class Urban Transit Network Design
Authors: van Nes Rob
Published: April 2007

In transit network design it is common to use characteristics of the average traveler to describe travel behavior, while in reality different traveler groups can be distinguished that react differently with respect to transport service quality. A study is conducted of the possible consequences of basing the design of urban transit networks on the preferences of specific traveler groups. To that end, an analytical network optimization model is developed that considers a mix of different traveler groups simultaneously. Results from the analyses show that focusing on specific traveler groups leads to clearly different network design characteristics. However, the optimal network design developed for the average traveler proved to be the best network for all traveler groups. Furthermore, it was found that focusing on traveler groups having good transport alternatives led to very low values of consumer surplus and social welfare. Optimizing transit networks while considering different traveler groups simultaneously results in networks that are similar to those using the traditional single-user-class approach based on the average traveler. Differences in preferences for traveler groups are balanced by the size of the resulting transit patronage. Apparently, a more realistic description of the demand side is not essential for urban transit network design.
Implementing Zurich’s Transit Priority Program
Authors: Nash Andrew
Published: April 2007

Transit priority is an excellent way of improving transit system productivity and attractiveness although it is often neglected in favor of larger investments. Transit priority techniques and implementation are outlined, Zurich’ss transit priority program is described, eight transit priority implementation lessons from Zurich are presented, and Zurich’s innovative traffic-signal transit priority system is summarized. A longer report that fully describes research results is the basis. Transit priority improvements are relatively low-cost ways to make transit systems work better by speeding up transit vehicles. Specific improvements include four categories: roadway improvements and traffic regulations, traffic signal priority, transit system operations, and separate right-of-way. These improvements may be implemented individually or in a comprehensive program. Comprehensive implementation is optimal but politically and institutionally difficult. Zurich has been successful in implementing a comprehensive transit priority program with impressive results. Implementation lessons from Zurich were identified through interviews and a survey of public officials. Key findings were the importance of support from public and elected officials (and the common underestimation by elected officials of their constituents’ transit support), smart implementation techniques (not alienating the public), government organization to deliver projects, careful traffic engineering, simultaneous implementation of complementary programs (such as traffic calming), careful systems-level thinking, and leveraging needed organizational change through capital improvement funding. Zurich’s traffic-signal transit priority system is an interesting example of reducing opposition to transit priority through technical innovation. The system provides transit priority without significantly affecting private vehicle traffic by adjusting signal timing and phasing to provide the right amount of green time for transit when needed.
Automatic Passenger Counter Evaluation: Implications for National Transit Database Reporting
Authors: Kimpel Thomas J. , Strathman James G. , Griffin David , Callas Steve , Gerhart Richard L.
Published: April 2007

Findings from a study assessing the accuracy and precision of automatic passenger counter (APC) technology at Tri-County Metropolitan Transportation District of Oregon (Tri-Met) are presented. Video surveillance cameras, rather than ride checkers, were used to establish reference values for determining APC accuracy and precision. Analysis of data collection, processing, and reporting methods at Tri-Met indicates that APC data, along with a properly designed sampling plan, can be used for internal monthly ridership reporting and annual national transit database (NTD) reporting. Presently, NTD sampling plans require that bus trips be randomly selected before manual data collection efforts. The sampling methodology developed for this analysis allows APC data to be matched with a random selection of bus trips following automated data collection. This was made possible by the widespread deployment of APC technology at Tri-Met. For transit properties with limited APC resources, other sampling approaches are preferred.
Understanding Transit Ridership Growth: Case Studies of Successful Transit Systems in the 1990s
Authors: Yoh Allison C. , Haas Peter J. , Taylor Brian D.
Published: April 2007

During the economic boom of the late 1990s, transit ridership increased nationwide, but not all transit systems added riders in equal proportions. To examine agencies that were especially successful at increasing patronage during the late 1990s, in-depth, open-ended interviews were conducted with managers from 12 agencies that substantially increased ridership between 1995 and 1999. The transit agency managers reported a wide variety of factors that they believe influenced patronage on their systems. While it was initially hypothesized that transit managers would tend to cite factors internal to the transit system, such as policy changes or managerial initiatives, in explaining ridership growth, they actually most often cited factors external to their transit systems, such as population or employment growth, as the primary determinants of increased ridership. When reported, the internally developed programs most frequently cited were changes in fare structure and new transit pass programs.
Converting a Large Region to a Multimodal Pulsed-Hub Public Transport Network
Authors: Maxwell Ross R.
Published: April 2007

Applicability of the cost-effective strategy used in Switzerland that successfully integrates all public transport for the entire country into a multi-hub timed-transfer system (pulsed-hub network) is investigated using the greater San Francisco Bay Area as an illustrative case study. For the existing and proposed Bay Area rail service routes, the study investigates the optimal repeating (clock-face) base headway for the pulsed-hub network, hub spacing, and locations (ideally adjacent to dense and diverse land uses providing destinations within walking distance, preferably a downtown), and hub station design to minimize transfer walk times. A pulsed-hub network schedule, because of the repeating schedule, can be shown as a schedule map that represents typically a 1-h schedule module. The schedule map, showing the routing and travel times between hubs and the pulse timings by means of a clock face at each hub, becomes a tool to develop the multihub system and to communicate with all stakeholders, including policy makers and the public. The illustrative pulsed-hub network uses existing and proposed rail services and express buses on high-occupancy vehicle lanes. These include the two publicly owned regional rail systems, Bay Area Rapid Transit and the Peninsula Commute Service (Caltrain); the intercity Amtrak-operated Capitol Corridor trains between San Jose, Oakland, and Sacramento (assuming that reliable passenger service can be maintained by freight railway by providing schedule windows for both passenger and freight trains); the proposed Sonoma-Marin Area Rail Transit and Dumbarton Rail Bridge routes; and the proposed California high-speed trains, currently in environmental review.
Application of Light Detection and Ranging Technology to Highway Safety
Authors: Khattak Aemal J. , Hallmark Shauna , Souleyrette Reginald
Published: April 2007

An application of light detection and ranging (LIDAR) technology to highway intersection safety is presented. LIDAR can be used to collect information about a surface by reflecting thousands of light beams per second off the surface and measuring the return time of the beams. The surface profile is collected as a digital signature that can be used in a variety of applications. Collection of information on the surface profile of the earth in the form of elevation data is one of several LIDAR applications that have been used for mapping and contouring. The focus of the described application is use of LIDAR elevation data to obtain information on intersection geometry that can lead to the discovery of potential obstructions in driver sight lines. After appropriate transformations, LIDAR elevation data were used in line-of-sight analysis to obtain information on sight-line obstructions at six intersections on the IA-1 corridor in Iowa. Intersection crash frequency and data availability were considerations in the selection of the six intersections. Results from the line-of-sight analysis were validated by visits to the intersections in the field and verification of the existence of obstructions detected during the analysis. Sixty-six lines of sight were blocked during the line-of-sight analysis, of which 62 (89.8%) were confirmed during the validation process. Four (5.8%) sight-line obstructions were not confirmed during the validation. At least three (4.4%) potential sight-line obstructions discovered during validation were not detected during the line-of-sight analysis. The intersection with the highest crash frequency was correctly found to have obstructions located within the intersection sight triangles. It can be concluded that LIDAR elevation data can be used successfully for identifying potential sight-distance problems at intersections. Identified potential problems can be verified and rectified in the field. LIDAR is a relatively costly data source, and a single application, such as this one, cannot justify the high cost of LIDAR data acquisition. Other potential highway safety enhancing applications of LIDAR must be investigated to offset the high data-acquisition cost. Suggestions for other highway safety applications are provided.
Bilevel Formulation for Optimal Traffic-Information Dissemination
Authors: Yang Fan , Liu Henry X. , He Rachel R. , Ban Xuegang , Ran Bin
Published: April 2007

With the fast-growing telematics market and maturing traffic-information services, telematics devices provide a feasible means with which to manage traffic more efficiently. The provision of traffic information to travelers usually involves different parties that have distinctive objectives: travelers are concerned with benefits of travel-time savings at an affordable service charge, private information service providers (ISPs) seek to provide marketable information services from which they can derive a profit, and traffic management centers (TMCs) have the responsibility to maintain and improve system performance, especially to minimize the total system travel time. How transportation system managers can analyze the trade-offs among these objectives and adjust this new traffic-information flow diagram to improve system performance remains an open question. The trade-offs needed among the conflicting multiple objectives of different parties are studied, and traffic system performance is analyzed. The complex traffic network is formulated as a bilevel program. The upper level can be formulated by using various objective functions, such as the objectives for ISP and TMC. The lower level is a multiclass dynamic traffic-assignment model, which determines dynamic traffic flows in the network by considering the information dissemination strategies provided by the upper-level model. Numerical results of a small network are provided to illustrate the behavior of this model, and they prove that when there is congestion in the dynamic transportation network, appropriate subscribed rates benefit both all travelers and system performance, while the ISPs’ information influences little without congestion in the transportation network.
Learning a Causal Model from Household Survey Data by Using a Bayesian Belief Network
Authors: Torres Francisco J. , Huber Manfred
Published: April 2007

A Bayesian belief network (BBN) is a modeling and knowledge-representation structure used in artificial intelligence that consists of a graphical model depicting probabilistic relationships among variables of interest. This graphical model is a valuable tool for representing the causal relationships in a given set of variables. Because the number of possible BBNs for a given data set is exponential with respect to the number of variables, learning a BBN from data is a difficult and resource-consuming task. A greedy algorithm that automatically constructs a BBN from a data set of cases obtained from a household survey was implemented. The resulting BBN shows the dependencies among key variables that are associated with the trip-generation process.
Modular Artificial Neural Networks for Solving the Inverse Transportation Planning Problem
Authors: Sadek Adel W. , Mark Charles
Published: April 2007

Because major capacity-expansion projects are very unlikely in the coming years, transportation planners need to view the existing infrastructure as fixed and to start thinking about how much development the current system can sustain. This line of thinking, which involves deriving land use limits from infrastructure capacity, requires solving the inverse of the typical transportation planning problem. Modular artificial neural networks (ANNs) were developed for solving the inverse transportation planning problem. ANNs were designed to predict zonal trip ends, given the traffic volumes on the links of the transportation network. Computational experiments were performed to study the effect on ANN accuracy of three factors: transportation network size, variability in training data, and ANN topology. ANNs were shown to be quite capable of capturing the relationship between link volumes and zonal trip ends for both small and medium-sized transportation networks and for degrees of variability in the training data. Modular ANNs with one or two hidden layers appeared to outperform other ANN topologies.
Optimization of Dynamic Neural Network Performance for Short-Term Traffic Prediction
Authors: Ishak Sherif , Kotha Prashanth , Alecsandru Ciprian
Published: April 2007

An approach is presented for optimizing short-term traffic-prediction performance by using multiple topologies of dynamic neural networks and various network-related and traffic-related settings. The conducted study emphasized the potential benefit of optimizing the prediction performance by deploying multimodel approaches under parameters and traffic-condition settings. Emphasis was placed on the application of temporal-processing topologies in short-term speed predictions in the range of 5-min to 20-min horizons. Three network topologies were used: Jordan–Elman networks, partially recurrent networks, and time-lagged feedforward networks. The input patterns were constructed from data collected at the target location and at upstream and downstream locations. However, various combinations were also considered. To encourage the networks to associate with historical information on recurrent conditions, a time factor was attached to the input patterns to introduce time-recognition capabilities, in addition to information encoded in the recent past data. The optimal prediction settings (type of topology and input settings) were determined so that performance was maximized under different traffic conditions at the target and adjacent locations. The optimized performance of the dynamic neural networks was compared to that of a statistical nonlinear time series approach, which was outperformed in most cases. The study showed that no single topology consistently outperformed the others for all prediction horizons considered. However, the results showed that the significance of introducing the time factor was more pronounced under longer prediction horizons. A comparative evaluation of performance of optimal and nonoptimal settings showed substantial improvement in most cases. The applied procedure can also be used to identify the prediction reliability of information-dissemination systems.
Adjusting Trip Rates in the Cross-Classification Table by Using the Fuzzy Optimization Method
Authors: Kikuchi Shinya , Rhee Jongho
Published: April 2007

Trip-production rates presented in cross-classification tables are essential data for the planner’s understanding of the travel characteristics of a region. Trip rates obtained from surveys, however, often show a pattern that is not consistent with what is expected by the analyst; for example, the greater the household size and auto ownership, the greater the number of trips generated. This pattern may not be found in the trip rates that are obtained directly by the survey. In such cases, analysts commonly adjust the irregularities manually. The way in which the values are adjusted affects the credibility of the trip table and, ultimately, the forecast travel demand. A method that adjusts the values of the trip table systematically is presented. The process uses the fuzzy linear programming method. The objective is to make the adjusted value as close to the observed value as possible. The constraints are to make the adjusted values adhere to the analyst’s general expectations about the pattern of the values in the table, and to match the number of trips estimated from the adjusted trip table with the actual number of trips surveyed. An application example that uses real-world data is given.
Building and Maintaining a Statewide Transportation Framework
Authors: Dueker Kenneth J. , Bender Paul
Published: April 2007

Creating and maintaining up-to-date, sharable, geographic information systems–transportation data are challenging. Many states are working on transportation framework efforts to build a complete, consistent, and current transportation data layer in conjunction with the National Spatial Data Infrastructure and Geospatial One-Stop efforts. An effort was made to systematically reexamine transportation data-sharing issues as part of the development of a transportation framework for the state of Washington. Business needs were assessed for spatial and temporal accuracy needs of stakeholders and users of a statewide transportation framework. A conceptual model was developed for a transportation framework with emphasis on data flows to update and maintain it and other transportation databases. An update clearinghouse is proposed to collect and disseminate data about new and modified road features. A synthesis of issues is presented, including determining the desired robustness of the transportation framework and cost-allocation principles for possible add-on enhancements.
Exploring Imputation Techniques for Missing Data in Transportation Management Systems
Authors: Smith Brian L. , Scherer William T. , Conklin James H.
Published: April 2007

Many states have implemented large-scale transportation management systems to improve mobility in urban areas. These systems are highly prone to missing and erroneous data, which results in drastically reduced data sets for analysis and real-time operations. Imputation is the practice of filling in missing data with estimated values. Currently, the transportation industry generally does not use imputation as a means for handling missing data. Other disciplines have recognized the importance of addressing missing data and, as a result, methods and software for imputing missing data are becoming widely available. The feasibility and applicability of imputing missing traffic data are addressed, and a preliminary analysis of several heuristic and statistical imputation techniques is performed. Preliminary results produced excellent performance in the case study and indicate that the statistical techniques are more accurate while maintaining the natural characteristics of the data.
Rough Sets and Probability Masses for Dempster-Shafer Data Fusion at a Traffic Management Center
Authors: Yi Ping , Lu Huapu , Zhang Yucheng
Published: April 2007

The Dempster–Shafer data-fusion technique as affected by probability masses as a result of sensor selection and probability masses distribution is investigated. Dempster–Shafer inference is a statistically based data-classification technique for detecting traffic events that affect normal traffic operations. It is used when data sources contribute discontinuous and incomplete information such that no single data source can produce a predominantly high probability of certainty for identifying the most probable event. To help in the selection of appropriate sensors and probability masses, a rough-sets data-mining technique in support of Dempster–Shafer inference was proposed and tested. The basic rough-sets technique is introduced, and a numerical example is given to explain its applications. Field testing of the rough-sets technique showed that it can reasonably and systematically process a large amount of traffic information, as an alternative to relying on the intuition of traffic operators and system managers. Because it allows easy maintenance and update of estimated probability masses, this technique is suitable for large-scale applications at the traffic management center.
Engineering Behavior of Stabilized Soils
Authors: Parsons Robert L. , Milburn Justin P.
Published: April 2007

Stabilization of soils is an effective method for improving soil properties and pavement system performance. For many soils, more than one stabilization agent may be effective, and financial considerations or availability may be the determining factor on which to use. A series of tests was conducted to evaluate the relative performance of lime, cement, Class C fly ash, and an enzymatic stabilizer. These products were combined with a total of seven different soils with Unified Soil Classification System classifications of CH, CL, ML, and SM. Durability testing procedures included freeze–thaw, wet–dry, and leach testing. Atterberg limits and strength tests also were conducted before and after selected durability tests. Changes in pH were monitored during leaching. Relative values of soil stiffness were tracked over a 28-day curing period using the soil stiffness gauge. Lime- and cement-stabilized soils showed the most improvement in soil performance for multiple soils, with fly ash–treated soils showing substantial improvement. The results showed that for many soils, more than one stabilization option may be effective for the construction of durable subgrades. The enzymatic stabilizer did not perform as well as the other stabilization alternatives.
Estimation of the Compressive Strength and Modulus of Elasticity of Cement-Treated Aggregate Base Materials
Authors: Lim Seungwook , Zollinger Dan G.
Published: April 2007

Experimental study on the development of strength and modulus of elasticity of cement-treated aggregate base (CTAB) materials was undertaken. Unconfined uniaxial compression tests were conducted with 189 samples for 16 CTAB mixtures at different ages. Two different aggregates, conventional crushed limestone base and recycled concrete materials, were used in the test program. Using the test results, equations were proposed to estimate the development of compressive strength and modulus of elasticity of CTAB materials with time. Test results indicated that the relationship between the compressive strength and elastic modulus of CTAB materials could be expressed in a single equation regardless of aggregate type and mixture proportions.
Validated Model for Predicting Field Performance of Aggregate Base Courses
Authors: Tutumluer Erol , Little Dallas N. , Kim Sung-Hee
Published: April 2007

The International Center for Aggregates Research Project 502 focused on pavement layers of unbound aggregate proper representation in mechanistic pavement models. The research team developed models for resilient and permanent deformation behavior from the results of triaxial tests conducted at the Texas Transportation Institute and the University of Illinois. The studies indicate that the unbound aggregate base (UAB) material should be modeled as nonlinear and cross-anisotropic to account for stress sensitivity and the significant differences between vertical and horizontal moduli and Poisson’s ratios. Field validation data were collected from a full-scale pavement test study conducted at Georgia Tech. The validation of the anisotropic modeling approach was accomplished by analyzing conventional flexible pavement test sections using the GT-PAVE finite element program to predict responses to load in the UAB layer and comparing these predicted responses to the measured values. Laboratory testing of the aggregate samples was conducted at the University of Illinois, and characterization models were developed for the stress-sensitive, cross-anisotropic aggregate behavior. With nonlinear anisotropic modeling of the UAB, the resilient behavior of pavement test sections was successfully predicted for a number of response variables. In addition, the stress-sensitive, cross-anisotropic representation of the base was shown to greatly reduce the horizontal tension computed in the granular base compared with a linear isotropic representation.
Micro-Deval Testing of Aggregates in the Southeast
Authors: Cooley L. Allen , James Robert S.
Published: April 2007

Aggregate used in hot-mix asphalt (HMA) must be tough and durable, not only to withstand the effects of HMA production, transportation, and construction but also to resist the effects of traffic and the environment. Historically, the Los Angeles abrasion and impact test has determined the toughness of aggregates. The long-term durability characteristics of aggregates are generally determined using a soundness test: sodium or magnesium sulfate. During the National Cooperative Highway Research Program’s Project 4–19, the micro-Deval test, in conjunction with the magnesium sulfate soundness test, were recommended in lieu of the Los Angeles abrasion and impact test and other soundness tests. Therefore, a study was needed within the southeastern United States to evaluate the range in micro-Deval results that could be expected. This research characterized the toughness and durability of aggregates with respect to their micro-Deval test results. Seventy-two aggregate sources from eight different states were included in this research. These aggregates were rated as good, fair, or poor with respect to performance by the contributing state. On the basis of the results of this study, some large differences were found in micro-Deval test results within a given performance category. There was no relationship between Los Angeles abrasion and impact and micro-Deval test results.
Spatial Multimedia Representation of Chicago Transit Authority Rail Infrastructure
Authors: Shiffer Michael , Chakraborty Arnab , Donahue Beth , Garfield Graham , Srinivasan Ramakrishnan , McNeil Sue
Published: April 2007

When key decisions are made on capital infrastructure programs at the Chicago Transit Authority (CTA), it is often necessary to relate maps to mental or physical images of the built environment. Multimedia tools have evolved so that such queries can be addressed using off-the-shelf software combined with innovative development techniques to achieve powerful results. A spatial multimedia system was developed for CTA. Such spatial multimedia technologies can integrate spatial representations of existing or proposed urban environments with qualitative descriptions by linking maps to static and dynamic images.
MAGLEV 2000 Urban Transit System
Authors: Powell James , Danby Gordon , Morena John , Wagner Thomas , Smith Charles
Published: April 2007

The MAGLEV 2000 (M2000) of Florida Corporation has designed magnetic levitation (maglev) and propulsion technology for high-speed intercity transportation systems capable of operating at speeds in excess of 300 mph. This high-speed technology can be adapted for slower-speed urban transit operations with operating speeds of 30 to 120 mph. M2000 preliminary baseline urban transit designs and essential criteria for a maglev technology to operate safely and efficiently in an urban transit environment are discussed. M2000 uses superconducting magnets on the vehicle, interacting with aluminum coils in the guideway for levitation, stability, and propulsion. The coils are completely encapsulated in polymer concrete panels, which are attached to the sides of a narrow-beam guideway. The vehicle straddles the beam with a 6-in.gap between the guideway surface and vehicle. Propulsion is provided through the linear synchronous motor coils and powered by alternating electrical current. The large clearance between vehicles and guideway with the superconducting M2000 magnet system ensures low-cost guideway construction because of more leeway with construction tolerances. These large clearances allow system operations under snow and ice conditions. The magnetic switch also allows for efficient off-line stations and permits increased train frequencies and operation of express trains without delays from locally stopping trains. Most of the components for a M2000 operating system have been constructed. A review is presented of manufacturing techniques, operating requirements, and performance results for a maglev transit project.
Agricultural Off-Road Fuel Tax: Midwestern Comparative Analysis and Assessment
Authors: Eger Robert J. , Knudson Deborah A. , Marlowe Justin , Verbos Amy Klemm
Published: April 2007

During the past several years, state governments across the United States have engaged in a variety of new efforts to curb motor fuels tax evasion. Unlike the income tax, which is typically evaded through a simple reporting error or other manipulation, motor fuels tax evasion often occurs because potential evaders are able to exploit the complexity of the audit, collection, and exemption processes. Estimates of annual revenue losses related to this sort of evasion are substantial, ranging from $1.5 billion to $2.5 billion. In response to these estimates, FHWA and a number of state governments have implemented changes designed to streamline the administration of this often-overlooked but critical revenue source. The potential for evasion that results from the fuel tax exemptions that Wisconsin provides for agricultural "off-road" uses was examined. The investigation began with a statistical analysis of recent tax-exempt fuel consumption and monthly rebate figures for all midwestern states. These results indicate that Wisconsin consumes significantly higher quantities of tax-exempt fuel for off-road agricultural purposes than other midwestern states. A comparative analysis was also conducted of Wisconsin's Motor Vehicle Fuel Tax law and equivalent laws throughout the Midwest. The statistical and comparative results provide statistical and legal-analytical evidence that Wisconsin's current law is vulnerable to evasion. With these findings in mind, policy options to improve the enforcement of Wisconsin's Motor Vehicle Fuel Tax law were developed.
Financing Transport Infrastructure in Developing Country Cities: Evaluation of and Lessons from Nascent Use of Impact Fees in Santiago de Chile
Authors: Zegras Christopher
Published: April 2007

The potential for and limitations to the use of impact fees to finance urban transport infrastructure in developing country cities are assessed, drawing from the specific case of Santiago de Chile. The current state of urban transport infrastructure financing and its inherent complications are first presented. Principles of appropriate impact fee use are then derived from the U.S. experience. These principles are then applied to the recent use of transportation impact fees in Santiago, leading to preliminary recommendations for improvement, including the following: establishing proper overarching legal guidance for their use; taking a uniform approach to their application; clarifying the relationship of impact fees to other user fees and other forms of development exactions; answering the question of who bears the ultimate burden of impact fee costs; and improving the understanding of the effects of transportation impact fees on other public policy goals. From this assessment of the Santiago experience, lessons for other developing country cities are presented.
Using Public Consultation in Developing Edinburgh’s Congestion-Charging-Based Transport Strategy
Authors: Cain Alasdair , Jones Peter
Published: April 2007

The City of Edinburgh Council is developing a transport strategy based on the introduction of a congestion-charging scheme, linked to the implementation of a major package of transport improvements. A phased consultation approach is being used to allow public views to form a major input into the transport strategy design process. The overall objectives of the consultation in relation to the major project milestones are discussed. The results of each of four completed consultation phases are presented, along with how these results have been used to narrow the range of potential transport strategy options to one preferred congestion-charging scheme design and associated transport improvement package. The results of the completed consultation phases have shown that public views on different elements of the transport strategy design range from a high degree of consensus to a considerable degree of diversity. It has been found that the level of charge is the most significant factor in determining the level of public support for a particular congestion-charging scheme, with the lowest charge levels invariably receiving the greatest level of support, even when this is associated with a smaller transport investment package. In general, the consultation results have shown that there is significant in-principle support for a congestion-charging-based transport strategy but that support tends to decline as the strategy becomes more accurately defined. A major challenge appears to exist in retaining in-principle support through to project implementation.
Provisional Typology of Highway Economic Development Projects
Authors: Weiss Martin H. , Figura Roger
Published: April 2007

Past efforts to analyze and select promising highway economic development projects for implementation and to evaluate implemented projects for effectiveness have not progressed as much as they could partly because not all projects are the same type. Projects that improve local access to employment sites are inherently different from those that improve connectivity between two cities (sometimes called corridor improvements) and will properly merit different analysis and evaluation. The different types of projects were categorized, and the methods that will be required in analysis, evaluation, and selection are discussed.
Evaluating Economic Benefits of Newly Opened Expressways in China
Authors: Liu Louie Nan
Published: April 2007

In the past decade, expressways have been developed rapidly in China. It is evident that a number of opened expressways generated promoting effects on regional economic development. Most existing studies tend to assess the effects in a qualitative way. The purpose of this study was to develop quantitative methods to evaluate the economic benefits of expressway projects during the operational period. The benefits discussed include user benefits (reduced vehicle operating costs, time savings, and safety benefits), which are the direct effects of the expressway projects. The estimation of user benefits is carried out on the basis of well-defined quantitative methods. Development benefits, which are the indirect effects of the expressway projects, were also examined. Their indirect nature makes them inherently more difficult to analyze quantitatively. A comparative analysis method was developed to tackle the problem. These methodologies were applied to a case study of the Hangzhou-Ningbo Expressway in Zhejiang Province, one of the fastest-growing provinces in China in economic activity. The estimation results show that, since its opening in December 1996, the expressway has generated significant user benefits in the region. Statistical data have provided some evidence that the expressway promoted the region's economic development by improving the investment environment, promoting exchange and circulation of commodities, providing convenient transportation for tourists, and promoting development in small towns and urbanization.
City CarShare: First-Year Travel Demand Impacts
Authors: Cervero Robert
Published: April 2007

Nine months into the introduction of car sharing in San Francisco, California, an estimated 7% of members' trips and more than 20% of vehicle miles traveled were by shared-use vehicles. Evidence suggests that access to shared cars is stimulating motorized travel. Most members do not own cars, and many appear to be leasing vehicles in lieu of walking and biking. Car-share vehicles are used more for personal business and social-recreational travel than for nondiscretionary, routine travel such as to work or school. Shared cars are generally not used during peak periods or to dense settings well served by transit, such as downtown. In this sense, car sharing appears to be stimulating a resourceful form of judicious automobility. Users are accruing substantial travel-time savings and willingly pay market prices for these benefits.
Estimating Price and Service Elasticity of Urban Transportation Demand with Stated Preference Technique: Case in Korea
Authors: Lee Sungwon , Lee Yeong Heok , Park Jee Hyung
Published: April 2007

Price and service elasticities of passenger car travel are estimated using stated preference and sample enumeration methodology. Moreover, the effects of hypothetical travel demand management policies are analyzed by changes on modal share using the elasticity estimates. The elasticity of passenger car travel with fuel price is estimated to be within the range of −0.078 to −0.171. The parameter estimate of the fare variable is estimated to be statistically insignificant in every subgroup of car users. This finding suggests that fare policies are relatively ineffective for increasing transit modal shares in Korea. Meanwhile, car users' responsiveness to changes in parking costs is estimated to be much higher than for fuel cost. This suggests that parking regulations or pricing policies may be effective in reducing travel by passenger car. The elasticity with in-vehicle time, which is a key attribute of public transport amenities, is estimated to be particularly high, implying that policy measures such as introducing express buses or express urban trains could be effective in reducing passenger car travel. The demand elasticity of service levels of mass transit represented by the degree-of-crowdedness proxy turns out to be very high. Reducing crowdedness in public transit can be very effective in attracting more passengers, or at least in retaining current patronage.