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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Recommended Practice for Stabilization of Subgrade Soils and Base Materials
Author: Little, Dallas N Texas Transportation Institute Nair, Syam Texas Transportation Institute | Size: 1.02 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2009 | pages: 67 | ISBN: -
Long-term performance of pavement structures is significantly impacted by the stability of the underlying soils. In situ subgrades often do not provide the support required to achieve acceptable performance under traffic loading and environmental demands. Although stabilization is an effective alternative for improving soil properties, the engineering properties derived from stabilization vary widely due to heterogeneity in soil composition, differences in micro and macro structure among soils, heterogeneity of geologic deposits, and differences in physical and chemical interactions between the soil and candidate stabilizers. These variations necessitate the consideration of site-specific treatment options which must be validated through testing of soil-stabilizer mixtures. This report addresses soil treatment with the traditional calcium-based stabilizers: Portland cement, lime, and fly ash. The report describes and compares the basic reactions that occur between these stabilizers and soil and the mechanisms that result in stabilization. The report presents a straightforward methodology to determine which stabilizers should be considered as candidates for stabilization for a specific soil, pavement, and environment. The report then presents a protocol for each stabilizer through which the selection of the stabilizer is validated based on mixture testing and mixture design. The mixture design process defines an acceptable amount of stabilizer for the soil in question based on consistency testing, strength testing, and in some cases (resilient) modulus testing. Within each additive validation and mixture design protocol, an assessment of the potential for deleterious soil-additive reactions is made.
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Recommended Practice for Stabilization of Sulfate-Rich Subgrade Soils
Author: Little, Dallas N Texas A&M University, College Station Nair, Syam Texas A&M University, College Station | Size: 1.08 MB | Format:PDF | Quality:Original preprint | Publisher: Transportation Research Board | Year: 2009 | pages: 66 | ISBN: -
Calcium-based stabilizers (CaO-based stabilizers) develop a high pH environment when mixed with water during construction. This high pH condition and the presence of lime (CaO) introduce an environment favorable to the formation of two expansive minerals, ettringite and possibly thaumasite, when sulfate-bearing salts are present in soil. The success of a lime stabilization project depends heavily on the accuracy of predictions regarding the potential of the native soils to form these disruptive minerals. This report describes the nature of these minerals and the mechanism of their formation in soils stabilized with lime, cement, or fly ash. The key issue for the engineer in deciding how to properly stabilize sulfate-bearing soils is to quickly and efficiently determine: (1) the sulfate content of the soils and (2) the threshold quantity of sulfates likely to cause damage. This report addresses both issues but focuses on the methods used to quantify sulfate content. Quick and effective field techniques and more precise laboratory tests are compared and evaluated. Recommendations are presented regarding the appropriate testing protocol to use. Specific recommendations for changes to the American Association of State Highway and Transportation Officials (AASHTO) test method T-290-95 (methods A and B) are made. The report also outlines techniques for effective risk assessment including reconnaissance, topographical assessment, pedological and geological assessment, climatic assessment, and soil sampling plans. The report also outlines construction tests that can reduce risks for various levels of sulfate determined using a method such as AASHTO T-290-95 (revised) or equivalent.
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This report documents and presents the results of a study of minimum reinforcement requirements for the design of concrete bridge structures. This study included a review of U.S. and international practice, test data and research findings related to minimum reinforcement requirements and flexural cracking of concrete structures. A total of 4 representative methods of specifying minimum reinforcement were evaluated and compared by performing design calculations on a wide range of concrete bridge members. The findings of this study suggest that in nearly all cases lightly reinforced concrete members can develop the nominal flexural strength and have significant strength and ductility reserves after cracking has occurred. Also, the modulus of rupture over estimates the flexural cracking stress of concrete bridge members. A rational approach to the specification of minimum reinforcement is proposed, where variables are appropriately factored and includes the maximum rather than nominal strength of the section as a true measure of ductile versus brittle response.
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Driveways are private roads that provide access (both ingress and egress) between a public way and abutting properties, and any facilities on those properties. The roadway engineers’ focus is often on a part of the driveway, the area where the driveway intersects the public highway or street. Since these connections form the link or interface between public streets and highways and the activities they serve, driveways are an integral part of the roadway transportation system. There has been relatively little comprehensive research on or national guidance for the geometric design of driveways in recent decades. The objective of this project was to develop recommendations for geometric design of driveways that will be useful to state departments of transportation, local governments, and consultants in preparing driveway design standards and practices. The project included an extensive review of related literature, a survey of transportation agencies, a listing of almost 100 factors that can affect the design of a driveway, a list of needed research topics, and research on issues related to driveway vertical alignment. The project produced two documents, the project report and a driveway design guide.
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This research provides a methodology for evaluation of durability related strength loss of bonded carbon fiber reinforced polymer (CFRP) systems applied to concrete beams. The report addresses test methods to establish a durability strength reduction factor, identification of corresponding field exposure conditions affecting durability, and suggestions for the application of the durability strength reduction factor for design of field applications. The durability strength reduction factor is a measure of the loss in strength over time due to environmental exposure. It is defined as the ratio of the flexural strength of a 4 in. x 4 in. x 14 in. concrete beam reinforced with CFRP exposed at 140°F and submerged in water or 100% relative humidity for 60 days to the flexural strength of a control specimen. The resulting durability strength reduction factor may be used to evaluate CFRP system performance. Two field environments are suggested: Wet and Air. In a Wet environment water accumulates at the bond surface. This is the default condition and corresponds to test results in submerged water at 140°F for 60 days. An Air environment allows drying between wetting episodes so water cannot accumulate on the bond surface. This condition corresponds to test results in 100% relative humidity at 140°F for 60 days.
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