The US currently has over 60,000 bridges over water with unknown foundations. This report presents a risk-based approach to managing these bridges in the absence of foundation information. The general framework in this report, which is primarily applied to scour failure, can easily be applied to other hazards such as earthquakes and tsunamis. The guidelines illustrate how to collect appropriate data, estimate risk of failure from an estimated failure probability and associated economic losses, and use risk in a structured approach to select an appropriate management plan. Risk analysis is specifically used to select appropriate performance standards for various bridge classifications and justify the costs of nondestructive testing of foundations, monitoring activities, and countermeasures. The scour guidelines were applied to sixty case studies in the US to validate the management plan that was selected for bridges with known foundations, and to illustrate the specific application of the guidelines in a variety of settings.
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Author: Houston, William N | Size: 2.67 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2009 | pages: 257 | ISBN: -
Performance objectives for achieving durable bridge deck concrete and the properties of locally available concrete raw materials, particularly supplementary cementitious materials (SCMs) like fly ash, GGBFS and silica fume, vary by geographic region. Because of this variation, the optimum concrete mixture proportions for a given application must be determined by experiment. Since durability-related experimental programs investigating the performance of concrete mixtures are expensive and time-consuming, a methodology for designing and conducting an investigation using statistical experimental design concepts has been developed to efficiently identify the optimum concrete mixture proportions for a specific set of conditions. The approach implemented is based on fractional orthogonal experimental design, which supports modeling for a large number of factors (input variables) based on a minimum number of tests. The Methodology, presented in NCHRP Report 566: "Guidelines for Concrete Mixtures Containing Supplementary Cementitious Materials to Enhance Durability of Bridge Decks," consists of six steps: (1) definition of performance requirements, (2) selection of durable raw materials, (3) construction of an experimental design matrix, (4) testing of concrete mixtures, (5) analysis and empirical modeling to determine the Best Tested and Best Predicted Concretes, and (6) confirmation of predictions and selection of the Best Concrete. This Methodology is flexible and may be applied to a range of performance demands. It was developed to identify optimum contents of SCMs but is also able to select between sources of raw materials. A case study was conducted based on a hypothetical set of service conditions and using concrete raw materials from the Midwest. The performance predictions based on the case study experimental design were verified by confirmation testing. Finally, a computational tool (SEDOC) was developed to support the implementation of this Methodology.
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Supplementary Cementitious Materials to Enhance Durability of Concrete Bridge Decks
Author: Houston, William N | Size: 3.64 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2005 | pages: 95 | ISBN: -
Performance objectives for achieving durable bridge deck concrete and the properties of locally available concrete raw materials, particularly supplementary cementitious materials (SCMs) like fly ash, GGBFS and silica fume, vary by geographic region. Because of this variation, the optimum concrete mixture proportions for a given application must be determined by experiment. Since durability-related experimental programs investigating the performance of concrete mixtures are expensive and time-consuming, a methodology for designing and conducting an investigation using statistical experimental design concepts has been developed to efficiently identify the optimum concrete mixture proportions for a specific set of conditions. The approach implemented is based on fractional orthogonal experimental design, which supports modeling for a large number of factors (input variables) based on a minimum number of tests. The Methodology, presented in NCHRP Report 566: "Guidelines for Concrete Mixtures Containing Supplementary Cementitious Materials to Enhance Durability of Bridge Decks," consists of six steps: (1) definition of performance requirements, (2) selection of durable raw materials, (3) construction of an experimental design matrix, (4) testing of concrete mixtures, (5) analysis and empirical modeling to determine the Best Tested and Best Predicted Concretes, and (6) confirmation of predictions and selection of the Best Concrete. This Methodology is flexible and may be applied to a range of performance demands. It was developed to identify optimum contents of SCMs but is also able to select between sources of raw materials. A case study was conducted based on a hypothetical set of service conditions and using concrete raw materials from the Midwest. The performance predictions based on the case study experimental design were verified by confirmation testing. Finally, a computational tool (SEDOC) was developed to support the implementation of this Methodology.
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Environmental Effects in Pavement Mix and Structural Design Systems
Author: Houston, William N | Size: 2.26 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2005 | pages: 298 | ISBN: -
It is well documented that environmental effects play a significant role in characterizing the material properties, which in turn affect the pavement performance. Studies under the Strategic Highway Research Program (SHRP) were carried out to study the age hardening characteristics of asphalt binders and mixes. As a result of this study, laboratory procedures American Association of State Highway and Transportation Officials, provisional protocols (AASHTO PP1-98 and PP2-99) were developed to study the hardening potential of asphalt binders and mixes. The approaches followed in these procedures are of great value for the ongoing research on pavement aging; however, due to the limited resources and time constraints under the SHRP program, these provisional procedures have certain limitations associated with them. Research study, National Cooperative Highway Research Program (NCHRP) 9-23 was initiated to assess these limitations and if possible, enhance the predictive capabilities of these protocols. Binders and field cores were obtained from LTPP sections and other sites across the United States. Original, laboratory-aged, and field-aged binders were characterized. Based on the findings, an alternate procedure to the AASHTO PP1-98 protocol is suggested and presented. The alternate procedure includes field aging conditions and volumetric properties of the mix. The model developed was calibrated and validated using the data obtained from the field cores. Parametric analysis was performed on the final model to ascertain the practicality of the output. The assessment of the existing PP2-99 test protocol is also presented. Asphalt mix cores aged in the laboratory were tested for complex modulus. These modulus values were then compared to the modulus values of the field cores, the ages of which were known from the construction records. Due to the limited amount of data available, the PP2-99 protocol could not be improved.
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This document explores a methodology designed to predict the safety performance of various elements considered in the planning, design, and operation of nonlimited-access rural multilane highways. Chapter I provides an introduction, covering the background and the research objectives and scope of this project. Chapter II documents the literature review on existing statistical models, Accident Modification Factors (AMFs), and other predictive methodologies relevant to this study. Chapter III summarizes the results of a survey conducted in this study. Chapter IV describes the characteristics of the data collected in this project. Chapter V describes the model development and accident prediction methodology. Chapter VI summarizes the modeling results for estimating the safety performance of rural multilane highways. Chapter VII provides a summary of the work accomplished in this project and proposes recommendations for further work. The appendices document additional models from related research for consideration, Highway Safety Manual Chapter 9, the survey instrument, Cumulative Residuals (CURE plots), crash severity models, a methodology for estimating the variance of the product between baseline models and AMFs, and the Joint NCHRP 17-25/17-29 Expert Panel assessment.
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Multimodal Level of Service Analysis for Urban Streets: Users Guide
Author: Dowling, Richard G | Size: 1.82 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2008 | pages: 60 | ISBN: -
This document explores a set of procedures for predicting traveler perceptions of quality of service and performance measures for urban streets. Quality of service and performance are considered in terms of the needs of auto drivers, bus passengers, bicyclists, and pedestrians.
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A Guide to Emergency Quarantine and Isolation Controls of Roads in Rural Areas
Author: Graham, Jerry L | Size: 2.26 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2008 | pages: 113 | ISBN: -
This document contains an annotated bibliography that reviews several state emergency response plans associated with traffic control of rural roads in an agricultural emergency; a summary of the information gathered from interviews with state and local officials involved in agricultural emergency response; lessons learned from the case studies, the literature review, and phone interviews with state and local officials; a discussion of the development of the guide along with a taxonomy of the existing general procedures for handling an agricultural emergency; and a review of this guide by state and local officials, including the one-day workshops in four rural counties. The material contained in this document was used to help produce NCHRP Report 525, Volume 13: A Guide to Traffic Control of Rural Roads in an Agricultural Emergency, which explores recommended practices and procedures associated with traffic control on local and state roads during agricultural emergencies.
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Right of Way Methods and Tools to Control Project Cost Escalation
Author: Anderson, Stuart D Texas A&M University, College Station Molenaar, Keith R University of Colorado, Boulder Schexnayder, Clifford J Arizona State University, Tempe | Size: 2.40 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2008 | pages: 115 | ISBN: -
The ability of state highway agency management to control project cost escalation is dependent on strategic and structured project development processes. Right-of-way costs are among the most difficult to control and, therefore, necessitate disciplined estimating and management procedures. Yet in many agencies there exist “stove pipe” divisional structures that lead to failures in communicating important project information affecting scope, design, and cost. NCHRP Project 8-49 “Guidance on Cost Estimation and Management for Highway Projects During Planning, Programming, and Preconstruction,” and other estimating studies identified right-of-way cost estimating and management of right-of-way estimates and actual costs as critical to achieving estimate consistency and accuracy. The original NCHRP Project 8-49 addressed right-of-way cost estimating to a limited extent but the project’s scope did not allow for an in-depth treatment of this specialized area. This report describes the research process for additional NCHRP 8-49 work addressing right-of-way cost estimating and cost management. It provides an overview of the data gathering and analysis processes used to create a Procedures Guide specifically for right-of-way cost estimating.
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Transportation project management, for all modes of transportation, is under extreme budgetary, political, and community pressure to contain costs and improve efficiency in the delivery of projects “on time and on budget.” In order to meet these twin goals, transportation agencies must employ dynamic project management tools. The successful planning, design and implementation of transportation projects needs to meet various performance metrics depending on each stakeholder’s perspective. Thus, the general terms of “on time” and “on budget” can mean different things to the users and to their clients—whether public or private. (For example, a change order might be viewed by the designer as within the timeframe and an acceptable extension of costs; a client might view the same change order as outside both time and budget). It is essential that project management take these different perspectives into account. The purpose of this guidebook is to provide a toolbox that offers detailed project management subject areas and innovative practices that can be applied to achieve a higher level of project success. This guidebook has been developed to assist project managers who work for Department of Transportation (DOT) agencies or other public transportation agencies, whether they are DOT/agency employees or consultants working for the DOT/agency. Most DOT agencies have a project manual for each of the following phases of a project: planning, design, and construction. The guidebook has been developed to complement the agencies’ project manuals, not replace them. After researching numerous DOT websites and project manuals, the common milestones for the planning, design, and construction phases for transportation projects were compiled and made into a generic outline for each of the phases. The outline concentrates on those steps that are essential to a public agency project within the three phases of planning, design, and construction. The guidebook offers tools to better improve the agency’s process or to offer some suggestions to those that may be looking for a more innovative way to manage a project.
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