Bøger af Federal Highway Administration

This report presents the summary and synthesis of the various components of the experimental study entitled "Effects of Gradation and Cohesion on Bridge Scour" conducted at Colorado State University between the dates 1991 through 1996. As a result of this effort, in excess of 250 new pier scour data was collected and a new equation was developed expressing pier scour in terms of the dimensionless excess velocity factor, flow depth, pier diameter and a correction factor for the coarse fractions present in mixtures was derived. The new method was tested with available data from previous research. This equation shows that gradation effects are not constant through the entire range of flow conditions but vary with flow intensity. Additionally, a new method to adjust FHWA's Colorado State University pier scour equation for initiation of motion and sediment size was developed. Abutment scour experiments resulted in over 384 new points and 2 new abutment scour equations. The first equation was derived from a 0.1 mm uniform sand mixture and defines an envelope relationship. The second equation applies to mixtures with coarse fractions. A coarse size fraction compensation factor Wg is presented to account for the presence of varying amounts of coarse material in sediment mixtures under different dimensionless flow intensities. These new equations represented the experimental data accurately but have not been tested with field data. Effects of cohesion on pier and abutment scour were studied systematically, and in excess of 200 new data points were collected covering a range of flow and cohesive parameter values. Relationships were developed to explain the variability of bridge scour in cohesive materials for various cohesive material properties.

The changing climate poses serious challenges to the transportation community, given the community's need to watch over transportation systems and infrastructure designed to last decades or longer. Transportation functions tied to construction, operations, maintenance, and planning should be grounded in an understanding of the environment expected to support transportation facilities. Decisions therefore need to be informed by an understanding of potential future changes in climate. The understanding of climate change science and the ability to model future change continues to advance, resulting in more precise estimates of future changes in climate. However, the practitioner can be overwhelmed by the sheer volume of information, including the ensemble of models employed, the variety of emissions scenarios used to drive the modeling results, the spatial resolution of the projected climate effects, and other parameters. The purpose of this report is to provide the transportation community (including highway engineers, planners, NEPA practitioners) with digestible, transparent, regional information on projected climate change effects that are most relevant to the U.S. highway system. This information is designed to inform assessments of the risks and vulnerabilities facing the current transportation system, and can inform planning and project development activities. The information in this report can help decision makers begin to address the challenges posed by climate change. It fills an important gap by providing the transportation community with information on climate change and the range of future changes in a usable format. It provides the most up-to-date information available, and is the place to start when seeking to understand how climate change may affect transportation systems and infrastructure. At the same time, this report does not answer every question on future climate change effects; research continues to progress on improving techniques for projecting and assessing climate effects and understanding extreme weather events. In the coming years, model simulations of the effect of changes in greenhouse gas concentrations on the climate will improve, and downscaling techniques that provide finer-scale climate projections will continue to evolve.

Durability of Culverts and Special Coatings is intended to provide up-to-date storm drain and culvert material selection methods and techniques to assist the highway engineer in designing culverts. While the program was to consider a variety of materials, the predominant focus was on Aluminized Type 2 corrugated steel pipe (CSP) and its performance versus galvanized CSP. This report is divided into two main sections-field investigation and literature review. The field investigation presents the results of a field evaluation of 32 pipes and their performance relative to that reported in FHWA-FLP-91-006, Durability of Special Coatings for Corrugated Steel Pipe. The present report also includes a review of previous research areas to evaluate conclusions and the utility of existing culvert life prediction methods. The literature review presents a discussion of the various factors affecting culvert durability and its prediction.

Hydraulic Design Series Number 5 (HDS 5) originally merged culvert design information contained in Hydraulic Engineering Circulars (HEC) 5, 10, and 13 with other related hydrologic, storage routing and special culvert design information. This third edition is the first major rewrite of HDS 5 since 1985, updating all previous information and adding new information on software solutions, aquatic organism passage, culvert assessment, and culvert repair and rehabilitation. The result is a comprehensive culvert design publication. This publication contains the equations and methodology used in developing the design charts (nomographs) and software programs, information on hydraulic resistance of culverts, the commonly used design charts, and Design Guidelines (DG) illustrating various culvert design calculation procedures.

Bridge piers and highway embankments leading to a bridge often obstruct the flow of floodwaters, causing an increase in velocity and the development of vortices. The increased velocity and vortices often cause scour near the bridge foundations. The damage to and failure of bridges caused by scour are problems of national concern. This report describes the results of the second USGS national field-data collection and analysis study on scour at bridges, funded by FHWA. The database originally developed during the first national study has been enhanced and many scour measurements added, including measurements of abutment and contraction scour. Sufficient local pier scour data are now available to permit a detailed analysis of local pier scour. Scour depths computed from published pier scour equations are compared to the field measurements. Many commonly cited dimensionless variables believed to control the depth of scour are evaluated and compared with equations developed from laboratory data. The effect of the size and gradation of the bed material on the depth of scour is investigated, and a correction factor for the HEC-18 pier scour equation is proposed. Available data are insufficient to permit a detailed investigation of contraction and abutment scour; however, some basic comparisons and qualitative observations are presented on the basis of a review of the literature. The results of scour analyses for two contracted bridges are compared with real-time field data.

Bottomless (or three-sided) culverts use the natural channel bed and are environmentally attractive alternatives to traditional closed culverts. Moreover, they are considered by many highway agencies to be economical alternatives for replacing short bridges. They are typically placed on spread footings, and the issue of scour and the depth of footing must be addressed. The scour problem is analogous to abutment and contraction scour in a bridge opening and can be treated in much the same manner. Since abutment scour estimates at bridge openings are often quite large, a scour protection task was included to determine the sizes of rock riprap that might be required to reduce scour in the most critical zones. A major consideration in estimating scour and riprap sizes is the flow distribution at the entrance of the culvert, especially when there is side flow that is being contracted to pass through the opening. Although the analysis was aimed at simple one-dimensional (1D) approximations for this flow distribution, some 2D numerical simulations of the laboratory experiments were conducted to demonstrate how this could be used if they are available to a designer. As numerical models become user-friendly and computers become more powerful, 2D and even 3D numerical results are likely to become readily available to designers.

The Federal Highway Administration document "Highways in the River Environment - Hydraulic and Environmental Design Considerations" was first published in 1975, was revised in 1990, and is now issued as Hydraulic Design Series 6, "River Engineering for Highway Encroachments." This document has proven to be a singularly authoritative document for the design of highway associated hydraulic structures in moveable boundary waterways. This revised document incorporates many technical advances that have been made in this discipline since 1990. In addition, Hydraulic Engineering Circulars (HEC) 18, 20, and 23, have been published since 1990. This document and the HECs provide detailed guidance on stream instability, scour, and appropriate countermeasures. In HDS-6, hydraulic problems at stream crossings are described in detail and the hydraulic principles of rigid and moveable boundary channels are discussed. In the United States, the average annual damage related to hydraulic problems at highway facilities on the Federal-aid system is $40 million. Damages by streams can be reduced significantly by considering channel stability. The types of river changes to be carefully considered relate to: (1) lateral bank erosion; (2) degradation and aggradation of the streambed that continues over a period of years, and (3) natural short-term fluctuations of streambed elevation that are usually associated with the passage of floods. The major topics are: sediment transport, natural and human induced causes of waterway response, stream stabilization (bed and banks), hydraulic modeling and computer applications, and countermeasures. Case histories of typical human and natural impacts on waterways are analyzed.

Bottomless culverts are three-sided structures that use the natural channel for the bottom. These structures could be used to convey flows from one side of a highway to the other. As such, they are an environmentally attractive alternative to box, pipe, and pipe arch culvert designs. Bottomless culverts range in size from less than a meter (1.5 feet) to more than 10 meters (35 feet) in width. The failure of such a structure could have severe consequences similar to the failure of a bridge. On the other hand, since the cost of the foundation and scour countermeasures represents a significant portion of the cost of this type of structure, overdesign of these elements can add significantly to the cost of the project. Several dozen physical modeling configurations of bottomless culverts were tested, and the resulting scour at the entrance along the foundation and outlet was measured. Predictive equations for estimating scour depth were developed and compared to MDSHA methodology. These equations will provide guidance for the design of footing depths for bottomless culverts. The study was conducted in two phases. The first phase focused on measuring maximum scour depths at the culvert entrance and developing an analysis procedure using methods found in the literature to approximate prescour hydraulic parameters that drive the analysis. No fixed-bed experiments were conducted in the first phase to measure actual prescour hydraulic parameters. No submerged entrance experiments were conducted in the first phase. The second phase expanded the investigation to include scour measurements at the outlet, submerged entrance scour measurements, and detailed velocity and depth measurements with a prescour fixed bed at locations where maximum scour occurred. Additional tests were conducted to evaluate the use of various measures to reduce scour including wingwalls, pile dissipators, riprap, and cross vanes.

This document discusses the physical processes of the hydrologic cycle that are important to highway engineers. These processes include the approaches, methods and assumptions applied in design and analysis of highway drainage structures. Hydrologic methods of primary interest are frequency analysis for analyzing rainfall and ungaged data; empirical methods for peak discharge estimation; and hydrograph analysis and synthesis. The document describes the concept and several approaches for determining time of concentration. The peak discharge methods discussed include log Pearson type III, regression equations, the SCS graphical method (curve number method), and rational method. The technical discussion of each peak flow approach also includes urban development applications. The document presents common storage and channel routing techniques related to highway drainage hydrologic analyses. The document describes methods used in the planning and design of stormwater management facilities. Special topics in hydrology include discussions of arid lands hydrology, wetlands hydrology, snowmelt hydrology, and hydrologic modeling, including geographic information system approaches and applications. This edition includes new sections on wetlands hydrology and snowmelt hydrology, an expanded section on arid lands hydrology, corrections of minor errors, and inclusion of dual units.

This Geotechnical Technical Guidance Manual (TGM) provides technical guidance for geotechnical work performed by the Federal Lands Highway (FLH). It provides guidance for understanding and applying policies, standards and criteria in recognition of the need to manage financial and public safety risk and accomplish the missions of FHWA, FLH and partner agencies. Specific topics include geotechnical reconnaissance, site and subsurface investigation, analysis and design, reporting, PS&E involvement, construction support, performance monitoring, emergency response and consultant roles. The guidance in this TGM supports the policies, standards and standard practices presented in Chapter 6 of the Project Development and Design Manual (PDDM). Additionally, the TGM provides guidance for activities where standards and standard practices do not exist and it provides access to and guidance for the use of new technologies. Chapter 6 of the PDDM is the source for general direction on "what" should be performed, whereas guidance herein provides recommendations and options for "how" to perform these tasks. Like the PDDM, the TGM is intended to be used primarily as a web-based electronic reference document. Not all guidance is presented directly in the manual. When published sources present guidance that satisfies the requirements of FLH, or does so with only minor modification required, the TGM provides citations and links to those sources. If necessary, commentary on the application of these sources is provided here. This is done to keep the TGM small and more manageable, and also to allow easy and timely incorporation of new guidance as it is developed and published by FLH, FHWA and others. Technical guidance references cited and linked in this manual are classified as either "Primary", or "Secondary". Primary sources either present preferred guidance on how to accomplish a task or, when equal guidance is available through many sources, the Primary source is most widely available. "Secondary" sources are additional documents that are often relied on for FLH work; they present guidance to augment the Primary source. The PDDM presents work requirements through the official statement of policy and standards so it is an essential companion manual to the TGM. The TGM does not stand alone; policies and standards are repeated here only as necessary to offer guidance on their application. If discrepancy in the statement of policy or standards exists, the PDDM has precedence. Division-level documents also exist within FLH to provide guidance on unique technical practices or procedures at FLH Divisions; where these exist they should be followed for work within that Division. Also, although the organization of each of the Divisions is similar, there are differences. For this reason, the project delivery process and how the Geotechnical Discipline works within that process is described largely at the Division level.

Highway hydraulic structures perform the vital function of conveying, diverting, or removing surface water from the highway right-of-way. They should be designed to be commensurate with risk, construction cost, importance of the road, economy of maintenance, and legal requirements. One type of drainage facility will rarely provide the most satisfactory drainage for all sections of a highway. Therefore, the designer should know and understand how different drainage facilities can be integrated to provide complete drainage control. Drainage design covers many disciplines, of which two are hydrology and hydraulics. The determination of the quantity and frequency of runoff, surface and groundwater is a hydrologic problem. The design of structures with the proper capacity to divert water from the roadway, remove water from the roadway, and pass collected water under the roadway is a hydraulic problem. This publication will briefly discuss hydrologic techniques with an emphasis on methods suitable to small drainage areas, since many components of highway drainage (e.g., storm drains, roadside ditches, etc.) service primarily small drainage areas. Fundamental hydraulic concepts are also briefly discussed, followed by open-channel flow principles and design applications of open-channel flow in highway drainage. Then, a parallel discussion of closed-conduit concepts and applications in highway drainage will be presented. The concluding sections include an introduction to energy dissipation, construction, maintenance, and economic issues.

Historically, culverts have been designed for hydraulic efficiency without consideration of fish passage or, more generally, aquatic organism passage. Over time, it has become apparent that culverts frequently become impediments to healthy aquatic ecosystems because they can prevent the movement of fish and other aquatic organisms upstream and downstream through the culvert. Therefore, aquatic organism passage through culverts has become an important design element component for road/stream crossings. Common physical characteristics that may create barriers include high water velocity, shallow water depth, large outlet drop heights, turbulence within the culvert, and accumulation of debris. Sediment deposition and erosion at the culvert may also create a barrier to passage. Culvert length, slope, and roughness may create conditions that impede passage as well. Further complicating design is that passage needs differ by species, life stage, and season. To address this complex task, the Federal Highway Administration (FHWA) developed a stream simulation approach for designing culverts. Stream simulation is based on the concept that if conditions inside a culvert are similar to those conditions in the stream upstream and downstream of the culvert, then aquatic organism passage will be provided without consideration of the specific physical requirements of one or more species. However, stream simulation is not appropriate for all situations. For example, an existing culvert that is blocking passage may not be a good candidate for replacement using stream simulation because of the size of the embankment or insufficient budget for a replacement. Applications of stream simulation may also be limited for new culvert installations. Site constraints or budget limits could dictate a smaller culvert installation than would be recommended by stream simulation. In these cases, it may be desirable to design a culvert crossing considering the specific passage needs of a specific species of fish. Doing so requires an understanding of the migration seasonality, life stage swimming capabilities, and stream flow rates expected during passage. Ideally, this information is developed by a multidisciplinary team of aquatic biologists, hydrologists, and engineers. From this information, the maximum velocity and minimum depth requirements for the target fish are derived. Considering only average velocity in a culvert masks that there are zones within the flow field where velocities both higher and lower than the average exist. The objective of this research is to assist in the design of culverts for fish passage by 1) identifying zones of lower velocity that are conducive to fish passage and 2) developing practical design methods quantifying these lower velocity zones.

This publication identifies and provides design guidelines for bridge scour and stream instability countermeasures that have been implemented by various State departments of transportation (DOTs) in the United States. Countermeasure experience, selection, and design guidance are consolidated from other FHWA publications in this document to support a comprehensive analysis of scour and stream instability problems and provide a range of solutions to those problems. Selected innovative countermeasure concepts and guidance derived from practice outside the United States are introduced. Management strategies and guidance for developing a Plan of Action for scour critical bridges are outlined, and guidance is provided for scour monitoring using portable and fixed instrumentation. The results of recently completed National Cooperative Highway Research Program (NCHRP) projects are incorporated in the design guidance, including: countermeasures to protect bridge piers and abutments from scour; riprap design criteria, specifications, and quality control; and environmentally sensitive channel and bank protection measures. This additional material required expanding HEC-23 to two volumes. Volume 1 now contains a complete chapter on riprap design, specifications, and quality control as well as an expanded chapter on biotechnical countermeasures. The guidance on scour monitoring instrumentation has been updated and now includes additional installation case studies. Volume 2 contains 19 detailed design guidelines grouped into six categories, including countermeasures for: (1) stream instability (2) streambank and roadway embankment protection, (3) bridge pier protection, (4) abutment protection, (5) filter design, and (6) special applications.

Storm drains generally collect storm runoff from streets, parking lots, and other structures and convey this water to a desired outfall. Access holes (or manholes), which allow staff to inspect, maintain, or repair a segment of the drainage, are usually spaced about 92 to 183 meters (m) (300 to 600 feet (ft)) apart along a given pipe and at every junction between multiple pipes. An access hole, which has at least one inlet pipe and one outlet pipe intersecting it, is usually constructed from a vertically oriented concrete pipe or box that is large enough for a person to enter by removing the cast iron lid and using a ladder. In addition to allowing access, access hole junctions also allow pipes to easily change one or more variables: direction, slope, diameter, and elevation. Estimating the energy loss associated with these access hole junctions is a critical step in designing a drainage network that can handle the incoming flow from various storm events. A preliminary method for determining such losses, based on early results from that study, was published in the Federal Highway Administration's (FHWA) Urban Drainage Design Manual (Hydraulic Engineering Circular No. 22 (HEC 22)). This report summarizes the additional experiments and the data collected and used to evaluate the new junction loss methodology.

The purpose of this document is to provide information useful to States as they plan, design, operate, and manage HOV facilities. It is intended to be non-binding and should be construed as a rule of general applicability. This document provides examples for States to follow in evaluating proposed significant changes to the operation of an HOV lane, to include conversion of an HOV lane to a High Occupancy Toll (HOT) lane. The FHWA supports HOV lanes as a cost-effective and environmentally friendly option to help move people along congested urban and suburban routes. As such, FHWA regulations at 23 C.F.R. 810.102 specifically provide that HOV lanes are eligible for Federal-aid participation. In locations where existing or anticipated excess HOV lane capacity is available, conversion to a HOT lane facility is encouraged as a way to increase throughput and to provide additional travel options for drivers. As part of an overall approach to respond to increased travel demand and address traffic congestion, HOV and HOT lanes can be a practical alternative to adding more general-purpose travel lanes. The FHWA encourages the implementation of HOV or HOT lanes as an important part of an area-wide approach to help metropolitan areas address their requirements for improved mobility, safety, and productivity, while also being sensitive to environmental and quality of life issues.

This Guide, "Flexibility in Highway Design," is about designing highways that incorporate community values and are safe, efficient, effective mechanisms for the movement of people and goods. It is written for highway engineers and project managers who want to learn more about the flexibility available to them when designing roads and illustrates successful approaches used in other highway projects. It can also be used by citizens who want to gain a better understanding of the highway design process. Congress, in the Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991 and the National Highway System Designation (NHS) Act of 1995, maintained a strong national commitment to safety and mobility. Congress also made a commitment to preserving and protecting the environmental and cultural values affected by transportation facilities. The challenge to the highway design community is to find design solutions, as well as operational options, that result in full consideration of these sometimes conflicting objectives. To help meet that challenge, this Guide has been prepared for the purpose of provoking innovative thinking for fully considering the scenic, historic, aesthetic, and other cultural values, along with the safety and mobility needs, of our highway transportation system.

These Standard Specifications for the Construction of Roads and Bridges on Federal Highway Projects are issued primarily for constructing roads and bridges on Federal Highway projects under the direct administration of the Federal Highway Administration. These specifications are cited as "FP-03" indicating "Federal Project" Standard Specifications issued in 2003. When designated in a contract, the FP-03 becomes part of the contract and binding upon all parties to the contract. All construction contracts of the Federal Highway Administration are also governed by the following regulations: Federal Acquisition Regulation (FAR), Title 48, Code of Federal Regulations, Chapter 1; and Transportation Acquisition Regulation (TAR), Title 48, Code of Federal Regulations, Chapter 12. The FAR and TAR regulations are not included in the FP-03. A complete copy of the FAR is available from the Superintendent of Documents, Congressional Sales Office, U.S. Government Printing Office, Washington, DC 20402. The International System of Units (SI) is used in the FP-03 as required by Public Law 100-418 (1988 Omnibus Trade and Competitiveness Act) and Executive Order 12770 (Metric Usage in Federal Government Programs).

In September 2004, the Federal Highway Administration (FHWA) published updates to the work zone regulations at 23 CFR 630 Subpart J. The updated rule is referred to as the Work Zone Safety and Mobility Rule (Rule) and applies to all State and local governments that received Federal-aid highway funding. Transportation agencies are required to comply with the provisions of the Rule by October 12, 2007. The changes made to the regulations broaden the former rule to better address the work zone issues of today and the future. Growing congestion on many roads, and an increasing need to perform rehabilitation and reconstruction work on existing roads already carrying traffic, are some of the issues that have lead to additional, more complex challenges to maintaining work zone safety and mobility. To help address these issues, the Rule provides a decision-making framework that facilitates comprehensive consideration of the broader safety and mobility impacts of work zones across project development stages, and the adoption of additional strategies that help manage these impacts during project implementation. The Rule requires agencies to develop an agency-level work zone safety and mobility policy to support systematic consideration and management of work zone impacts across all stages of project development. Based on the policy, agencies will develop standard processes and procedures to support implementation of the policy. The third primary element of the Rule calls for the development of project-level procedures to address the work zone impacts of individual projects. To help transportation agencies understand and implement the provisions of the Rule, FHWA has been developing four guidance documents. This Guide is the main Rule Implementation Guide and provides a general overview of the Rule and overarching guidance for implementing the provisions of the Rule. This document includes guidelines and sample approaches, examples from transportation agencies using practices that relate to the Rule, and sources for more information. While this Guide covers aspects of the Rule, it also contains information that can be useful to agencies in all of their efforts to improve safety and mobility in and around work zones, and thereby support effective operations and management of our transportation system.

Have you ever wondered how decisions are made about the transportation projects that affect your life? How do government officials decide where to put a bus stop, road, or bridge? How are these and other transportation projects planned? And how can you make sure your opinions are heard and considered by residents, planners, designers, and elected officials? The Federal Highway Administration and Federal Transit Administration created this guide to answer these and other transportation project-related questions. We hope this guide will help you understand how transportation decisions are made at the local, State, and national levels; and that you will take advantage of the opportunities provided to contribute your ideas. We believe that the better the public understand the transportation decisionmaking process, the more certain it is that the transportation system will be safe and efficient, and that the planning process will be responsive to public needs and concerns about their communities and the natural environment.

This Guide is designed to help transportation agencies develop and/or update their own procedures for assessing and managing the work zone impacts of their road projects throughout the different program delivery stages. Understanding work zone impacts is critical to developing effective work zone transportation management plans (TMPs) that provide for safety, mobility, and quality in maintaining, rehabilitating, and rebuilding the nation's highways. The primary intended audience for this Guide is transportation agency staff, including technical staff (planners, designers, construction/traffic engineers, highway/safety engineers, etc.); management and executive-level staff responsible for setting policy and program direction; field staff responsible for building projects and managing work zones; and staff responsible for assessing performance in these areas. This document also provides support to agencies in their efforts to implement the recently updated work zone regulations. In September 2004, the FHWA published updates to the work zone regulations at 23 CFR 630 Subpart J. The updated rule is referred to as the Work Zone Safety and Mobility Rule (Rule) and applies to all State and local governments that receive Federal-aid highway funding. Transportation agencies are required to comply with the provisions of the Rule by October 12, 2007. The changes made to the regulations broaden the former Rule to better address the work zone issues of today and the future. The Rule provides a decision-making framework that facilitates comprehensive consideration of the broader safety and mobility impacts of work zones across project development stages, and the adoption of additional strategies that help manage these impacts during project implementation. The Rule requires agencies to develop an agency-level work zone safety and mobility policy to support systematic consideration and management of work zone impacts across all stages of project development. Based on the policy, agencies will develop processes and procedures to support implementation of the policy. These include procedures that address work zone impacts assessment, work zone data, work zone training, and process reviews. The Rule also calls for the development of project-level procedures to help agencies assess and manage the work zone impacts of individual projects. While the Rule does not require a specific work zone impacts assessment process/procedure, it recommends that agencies develop and implement systematic procedures to assess work zone impacts in project development, and to manage safety and mobility during project implementation. This document is the last of four guidance documents developed on the Rule, and provides a general approach for conducting work zone impacts assessment and management, as well as many examples of the approaches currently being used by transportation agencies.

Trade growth between the United States and China has increased U.S. interest in how the Chinese transportation system handles exports. The Federal Highway Administration, American Association of State Highway and Transportation Officials, and National Cooperative Highway Research Program sponsored a scanning study to identify how China provides intermodal access to its ports and uses investment strategies to foster freight mobility and intermodal connectivity. The scan team learned that China's national, provincial, and metropolitan transportation policy is closely coordinated with the country's economic policy and social harmony goals. The transportation system is expanding rapidly to meet global intermodal freight demands and promote expansion into underdeveloped regions of the country. Team recommendations for U.S. implementation include reviving a national transportation infrastructure focus to maintain U.S. competitiveness in the global market, conducting a study on how China uses performance measures to manage transportation policy, and synthesizing the results of this and earlier scans on intermodal freight and connectivity around the world.

This guide is intended to assist residents, parents, community association members, and others in getting involved in making communities safer for pedestrians and bicyclists. The guide includes facts, ideas, and resources to help residents learn about traffic problems that affect pedestrians and bicyclists and to find ways to help address these problems and promote safety among all road users. The guide includes information on identifying problems, taking action to address pedestrian and bicycle concerns, finding solutions to improve safety, and resources to get additional information.

Everyone knows how frustrating it is to be caught in a long traffic backup due to road construction. In addition, work zones present safety challenges to both travelers and road workers. Using Intelligent Transportation Systems in work zones, however, can help ease the frustration and prevent crashes. Everyone knows how frustrating it is to be caught in a long traffic backup due to road construction. In addition, work zones present safety challenges to both travelers and road workers. Using Intelligent Transportation Systems in work zones, however, can help ease the frustration and prevent crashes. This cross-cutting study examines the real-world experiences of using ITS in work zones in four locations across the U.S. In addition, this study profiles new ITS work zone products that are under development or just now coming to market and new analytical tools that can be used to assist in work zone planning. The purpose of this document is to raise awareness among maintenance and construction engineers and managers of the applications and benefits of ITS in work zones. ITS technology can be applied in work zones for: Traffic monitoring and management; Providing traveler information; Incident management; Enhancing safety of both the road user and worker; Increasing capacity; Enforcement; Tracking and evaluation of contract incentives/disincentives (performance-based contracting); Work zone planning.

Transportation agencies have long been tasked with helping to support community goals of mobility, accessibility, and economic vitality. Recently, there has been a rising interest in having sustainability and livability goals help guide transportation system investments, with considerable focus on the interrelationship between transportation infrastructure, housing, and land use planning. In addition to planning and designing transportation infrastructure, State, regional, and local governments play a key role in operating transportation systems from maintaining local traffic signals and crosswalks to operating regional transit services and Statewide traveler information programs. However, the role that transportation systems management and operations (M&O) plays in supporting livability and sustainability has not been well defined. As a result, transportation planners, operators, and stakeholders are not fully aware of the role that M&O may play in achieving livability and sustainability goals and how M&O strategies can support these goals in a cost-effective and timely manner. This primer describes the role of transportation systems management and operations (M&O) in advancing livability and sustainability. The document highlights the connections between M&O and livability and sustainability objectives and the importance of a balanced, comprehensive approach to M&O in order to support those objectives. The document describes nine key elements for managing and operating transportation systems in ways that support livability and sustainability. The document also provides a vision of how the regional transportation system could look in the future if M&O strategies were comprehensively implemented to advance livability and sustainability goals. Case examples throughout and a section on implementation will help practitioners to get started on implementing M&O to support livability and sustainability in their communities. The primer is directed at transportation planners and transportation system operators at the State, regional, and local levels. It is also meant to support the broader audience of stakeholders involved in all aspects of transportation and community decisionmaking, from elected officials and interested citizens to practitioners in related fields such as land use planning, community development, housing, the environment, and public health.

The information contained herein reflects the new and revised sign designs that have been adopted in the 2009 Edition of the Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD). This Supplement serves as an interim update until a new edition of the Standard Highway Signs and Markings publication is released at a future date. The sign designs contained in this Supplement will be incorporated into the new edition of Standard Highway Signs and Markings. The new edition, currently in progress, will contain expanded sign design guidelines, the Standard Alphabets, and updated information for standard arrow designs, pavement markings, and symbolic traffic control signal indications.

The use of self-propelled modular transporters (SPMTs) for bridge moves was the top implementation recommendation of the 2004 Prefabricated Bridge Elements and Systems International Scan sponsored by the Federal Highway Administration (FHWA), the American Association of State Highway and Transportation Officials (AASHTO), and the Transportation Research Board's National Cooperative Highway Research Program. Prefabrication of bridges offsite under more controlled conditions followed by rapid installation onsite can achieve quality installations in significantly less time than the months or years typically required for conventional bridge construction. The use of SPMTs in combination with prefabrication should be considered for all bridge replacement projects in locations with high traffic volumes. The purpose of the scan was to learn how other countries use prefabricated bridge components to minimize traffic disruption, improve work zone safety, reduce environmental impact, improve constructability, enhance quality, and lower life-cycle costs. The scan team learned that European countries frequently use SPMTs to lift and drive bridges to their final location in just minutes. SPMTs are computer-controlled platform vehicles that can move bridge systems weighing up to several thousand tons with precision to within a fraction of an inch. The prefabrication of bridges offsite under controlled conditions followed by rapid installation onsite can achieve quality installations with traffic impacts of minutes to a few hours compared to the months typically required for conventional onsite bridge construction. The significantly reduced onsite construction time when using SPMTs to move prefabricated bridge superstructures, for example, is due to the collapse of the sequential processes of conventional onsite bridge construction to just one step: moving the prefabricated superstructure from the staging area to its final position. This technology should be considered for all bridge replacement projects where reduced onsite construction time is a priority. The manual provides details from project conception to completion for using SPMTs to remove or install a bridge. It describes equipment, lists benefits and costs, and identifies criteria to determine when this technology is appropriate. It also addresses planning-related issues such as traffic considerations and site requirements. Design issues discussed include temporary shoring and prefabrication requirements, allowable temporary stresses and deflections during the move, and possible design efficiencies because of offsite prefabrication. Contracting issues covered include staging area requirements and contracting strategies for reduced onsite construction time. Using this manual in combination with the FHWA decisionmaking framework and analysis of delayrelated user costs should provide the guidance that bridge owners and other bridge professionals need to understand the technology, determine whether using SPMTs will benefit a specific bridge project, and develop contract documents that incorporate the technology.

This Guide is designed to help transportation agencies develop and implement transportation management plans (TMPs). A TMP lays out a set of coordinated transportation management strategies and describes how they will be used to manage the work zone impacts of a road project. The scope, content, and level of detail of a TMP may vary based on an agency's work zone policy and the anticipated work zone impacts of the project. The intended audience for this Guide is the persons responsible for developing TMPs. Depending on the agency's processes and procedures, this may be agency personnel and/ or contractors. Persons responsible for TMP-related policy/procedure development and revision, implementation, review, approval, and assessment will also benefit from this Guide. This document also provides support to agencies in their efforts to implement the recently updated work zone regulations. In September 2004, the Federal Highway Administration (FHWA) published updates to the work zone regulations at 23 CFR 630 Subpart J. The updated rule is referred to as the Work Zone Safety and Mobility Rule (Rule) and applies to all State and local governments that receive Federal-aid highway funding. Transportation agencies are required to comply with the provisions of the Rule by October 12, 2007. The changes made to the regulations broaden the former rule to better address the work zone issues of today and the future. Growing congestion on many roads, and an increasing need to perform rehabilitation and reconstruction work on existing roads already carrying traffic, are some of the issues that have lead to additional, more complex challenges to maintaining work zone safety and mobility. To help address these issues, the Rule provides a decision-making framework that facilitates comprehensive consideration of the broader safety and mobility impacts of work zones across project development stages, and the adoption of additional strategies that help manage these impacts during project implementation. The Rule requires agencies to develop an agency-level work zone safety and mobility policy to support systematic consideration and management of work zone impacts across all stages of project development. Based on the policy, agencies will develop processes and procedures to support implementation of the policy. The third primary element of the Rule calls for the development of project-level procedures to address the work zone impacts of individual projects. This includes requirements for identifying significant projects and developing and implementing TMPs for all Federal-aid highway projects. This document is the third of four guidance documents on the Rule and contains guidance, as well as many examples of how transportation agencies have developed and implemented TMPs or similar plans.

Intelligent Transportation Systems, or ITS, is the application of electronics, communications, and/or information processing to improve the efficiency and/or safety of surface transportation systems. ITS can improve transportation safety, mobility, and societal productivity through the integration of advanced communications technologies into the transportation infrastructure and in vehicles. ITS encompasses a broad range of wireless and wire line communications-based information and electronics technologies. This report documents several case studies of how agencies used work zone intelligent transportation systems (ITS) to mitigate safety and mobility issues in work zones. The report illustrates how to apply a systems engineering-based decision-making process to designing, selecting, and implementing a system to address work zone needs. The report presents the steps followed by the agency/contractor in this decision-making framework for five specific projects. The work zone ITS deployments documented provide examples of selecting and deploying commercial off-the-shelf (COTS) systems; a tailored design and integration of ITS for a specific work zone purpose; and using and supplementing permanent ITS deployments for work zone management purposes. Tips are provided for how to effectively apply ITS to other work zones.

This document represents the "State of the Practice" with respect to all aspects of accelerated bridge construction (ABC). The intent of this manual is to fill in the gaps left by publication of the previous manuals. The manual covers ABC techniques, project planning and scoping, implementing ABC in a Transportation Agency, prefabricated elements, long-term performance of prefabricated elements, construction and design. The manual can be used by transportation agencies to establish a successful accelerated bridge construction program.

Have you ever wondered how decisions are made about transportation projects that affect your life? How do government officials decide where to put a bus stop, road, or bridge? How are these and other transportation projects planned? And how can you make sure your opinions are heard and considered by the planners, road designers, elected officials, and other citizens? The Federal Highway Administration (FHWA) and Federal Transit Administration (FTA) wrote this guide to give you the answers to these and other transportation-related questions. We hope this guide will help you understand how transportation decisions are made at the local, state, and national levels. We believe that the better citizens understand the transportation decisionmaking process, the more certain it is we will have a transportation system that is safe, efficient, and responsive to public needs and concerns about their communities and the natural environment.