Transportation Intelligence

Volume 8 Number 3

June 2010

Pavements
Administration
Maintenance
Safety
Feedback

Administration
Economic Impact of Traffic Signals
To inform the debate on the cost and benefits of traffic signals GLA Economics commissioned Colin Buchanan (CB), in 2007, to undertake an initial exploratory study which used a model of a theoretical junction to investigate whether or not it is beneficial, in economic terms, to remove traffic signal control and revert in that instance to a major / minor road priority rule. The initial study concluded that the economic benefits and disbenefits of traffic signals are heavily dependent not only on the volumes of traffic but also traffic composition, vehicle occupancy, pedestrian volumes and time of day. For this study, further analysis was undertaken using actual traffic flows at signalised junctions in London during different times of the day. Junctions were evaluated using an assessment framework to assess the requirement for traffic signals and to define the considerations required to determine suitable alternative methods of control in place of existing traffic signals. (Greater London Authority report, November 2009, 56p.)

Construction
Materials Risk Analysis
This paper describes a materials risk analysis process and the conclusions from that risk analysis conducted at the Washington State Department of Transportation (WSDOT). Typical construction materials are examined for two critical risks: the risk of having a material fail to meet specification and the consequences of that material failing to meet specification. Subject matter experts (materials, construction, structures, maintenance, traffic, etc.) within the WSDOT rated these risks through a Delphi process. Results of the risk analysis classify materials into four appropriate categories for either more or less intensive examination by the state highway authority: highest risk materials undergo physical acceptance testing or are inspected during fabrication under a manufacturer’s quality system plan; moderate risk materials are accepted through the manufacturer’s certification of compliance (often combined with a quality systems plan or visual inspection); lower risk materials are accepted with a manufacturer’s certification or with a catalog cut; and the lowest risk materials are accepted through visual inspection in the field. Future materials risk analyses may be performed on periodic intervals (five to ten years suggested) to re-examine the risks and rankings by subject matter experts. (Washington State Department of Transportation Report WA-RD 745.1, February 2010, 18p.)

Environment
Assessing Mechanisms for Integrating Transportation-Related Greenhouse Gas Reduction Objectives into Transportation Decision Making
This report is the product of research to provide a factual basis for judging the merits of alternative methods that state departments of transportation (DOTs) and metropolitan planning organizations (MPOs) can use for managing GHG emissions from transportation. The project was undertaken to help policy makers to understand (a) how these alternative approaches to GHG emissions would affect states and metropolitan areas, (b) what approaches may be most effective for evaluating mobile-source GHG emission-management strategies, and (c) what particular tools are available to support implementation of these alternative approaches. (National Cooperative Highway Research Program (NCHRP) Web-Only Document 152, January 2010, 100p.)

Pavements

Preliminary Investigation of RAP and RAS in HMAC
A laboratory study was undertaken to investigate how various proportions of reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS) added to hot mixed asphalt concrete (HMAC) mixtures affect the Superpave performance grade of the blended binder. Only tear-off shingles (those obtained from re-roofing projects of residential structures) were included in the study. A secondary objective was to develop recommendations for changes to the mix design method and specifications for HMAC, incorporating RAS and RAP for use in special provisions for a pilot study. Specifications and special provisions of several agencies that allow tear-off RAS, and particularly those that allow tear-off RAS and RAP together, were reviewed to determine restrictions, criteria, test methods, mix design procedures, etc. applicable to inclusion of RAS and RAP in HMAC paving mixtures. Proposed modifications to ODOT specification SP745 were developed from this review. (Oregon Department of Transportation Report OR-RD-10-12, February 2010, 50p.)

Mechanistic-Empirical Asphalt Overlay Thickness Design and Analysis System
The placement of an asphalt overlay is the most common method used by the Texas Department of Transportation (TxDOT) to rehabilitate existing asphalt and concrete pavements. The type of overlay and its required thickness are important decisions that TxDOT engineers make on a daily basis. To perform well, an asphalt overlay must have a balance of both good rut and crack resistance. Furthermore, overlay performance is highly influenced by many factors, such as existing pavement conditions, traffic loading, and environmental conditions. It has also recently become common practice to use two different materials in an overlay, the first being a crack resistant level up course and the second being a wearing surface. The properties of both overlay types have a big impact on performance. The main objective of the Research Project 0-5123 was to develop a comprehensive mechanistic-empirical (M-E) asphalt overlay design system to assist TxDOT engineers to make these design decisions. (Texas Transportation Institute report 0-5123-3, October 2009, 154p.)

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Structures

Bridge Scour Monitoring Technologies: Development of Evaluation and Selection Protocols for Application on River Bridges in Minnesota
Bridge failure or loss of structural integrity can result from scour of riverbed sediment near bridge abutments or piers during high-flow events in rivers. The team worked with Mn/DOT engineers to identify variables of scour critical bridges that affect the application of scour monitoring technology. The research team will used this information to develop a Scour Monitoring Decision Framework (SMDF) that will aid Mn/DOT in selecting the best technologies for specific sites. The final component of the project will involve testing the SMDF on five bridges in a case-study type demonstration; work plans for two of the sites were developed for demonstration of deployed instrumentation. (Minnesota Department of Transprtation report MN/RC 2010-14, March 2010, 193p.)

Evaluation of Select Methods of Corrosion Prevention, Corrosion Control, and Repair in Reinforced Concrete Bridges
The objective of this study was to evaluate the effectiveness of selected techniques for corrosion prevention, control, and repair of reinforced concrete bridges. Thirty laboratory specimens were subjected to six months of accelerated corrosion testing that consisted of cyclic wet/dry cycles and an applied regulated voltage. The use of galvanic thermal sprayed zinc, galvanic embedded anodes, sealers, coatings, and epoxy repair mortar was evaluated. The long-term effectiveness of some admixtures and sealers was evaluated on nine different bridge decks across Wisconsin through an extensive analysis of chloride ingress. (Wisconsin Department of Transportation Report WHRP 09-04, October 2009, 370p.)

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Administration

The Use of Operations Objectives and Performance Measures in Private and Public Organizations White Paper
This paper examines lessons and insights from private companies and public organizations that may apply to agencies in the United States working to advance transportation planning for operations using a strategic approach. The use of specific objectives and performance measures to manage operational performance is common practice among self-sustaining private and public organizations that are responsible for generating sufficient revenue to meet costs and, in some cases, produce profit. Based on the information gathered, several useful practices were identified for consideration in transportation planning for operations including developing of a balanced set of objectives and performance measures and assigning weights to objectives based on their impact on customer satisfaction. (US Federal Highway Administration report FHWA-HOP-10-029, February 2010, 20p.)

Linking Transportation Performance and Accountability
The Federal Highway Administration, American Association of State Highway and Transportation Officials, and National Cooperative Highway Research Program sponsored a scanning study of how transportation agencies in other countries apply performance management programs. The scan team found that the nations it studied articulate a limited number of national transportation policy goals, negotiate intergovernmental agreements on how state, regional, and local agencies will achieve the goals, and evaluate performance by tracking the measures and reporting them in clear language appropriate to the audience. The team developed an implementation plan that includes outreach efforts to disseminate scan findings and put international best practices into use in the United States and research efforts to translate some aspects of the best practices into useful American context. (US Federal Highway Administration International Technology Scanning Program report FHWA-PL-10-011, April 2010, 95p.)

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Maintenance

Performance Evaluation of Various Rehabilitation and Preservation Treatments
The effectiveness of pavement preservation activities has not been well documented or publicized throughout the United States. Intuitively for pavement professionals the philosophy makes perfect sense, however, hard facts supporting this stance are still elusive except for anecdotal examples. The objective of this study was to conduct a synthesis to highlight the degree to which pavement preservation treatments (including minor rehabilitation treatments) extend the service life of pavements with or without adding strength. This study was carried out by conducting a study of six target states that were known to perform, collectively, the totality of all treatments under consideration. The results of this study are summarized in a series of tables documenting the data provided by the states. A summary of each treatment's performance is also contained in this report. A series of observations, conclusions, and recommendations are also included. (US Federal Highway Administration report, January 6, 2010, 97p.)

Work Zone Design and Operation Enhancements
Oregon Department of Transportation contractors are required to implement Traffic Control Plans (TCPs) to protect and direct traffic through work zones. The design and implementation of TCPs have shown variation from project-to-project across the State. The impact of this lack of consistency is magnified as a result of an increase in the number of work zones, higher traffic volumes, more work being conducted at night to minimize traffic interruptions, a greater number of parties (consultants) involved, and the pressure to complete projects faster. The primary purpose of this research study was to enable improved safety performance through work zones on state roadways. To fulfill this goal, the research aimed to identify ways to modify TCPs to improve their quality and consistency and develop suggested guidelines to follow to design, review, implement, and inspect TCPs. Implementation of the research results is expected to improve consistency of TCPs and decrease the number of work zone fatalities and injuries. Auxiliary benefits resulting from improvements in traffic flow through work zones and the elimination of work zone crashes will include greater mobility, smoother operations, and increased efficiency across the State’s roadway network. (Oregon Department of Transportation Report FHWA-OR-RD-10-16, February 2010, 197p.)

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Safety

Transportation Planner's Safety Desk Reference
The updated Transportation Planner’s Safety Desk Reference includes strategies derived from the National Cooperative Highway Research Program’s (NCHRP) Report 500 Guidance for Implementation of the American Association of State Highway and Transportation Officials (AASHTO) Strategic Highway Safety Plan. All 22 emphasis areas are now covered, including five new ones (young drivers, bicycle collisions, speeding, head-on collisions on freeways, and motorcycles). Additional sections on collecting and analyzing highway safety data and developing emphasis area plans have also been added. This document discusses the planner’s role in transportation safety and the incorporation of safety into the transportation planning process. Each emphasis area section includes: overview of the problem; data defining the problem; descriptions of safety strategies that are most relevant to planners; crash modification factors that can be used to determine the reduction in crashes anticipated from specific safety improvements; and additional resources and best practices, where available. (US Federal Highway Administration report FHWA-HEP-10-001, February 2010, 133p.)

Evaluating Safety and Operation of High-Speed Intersections
This Final Report reviews a research effort to evaluate the safety and operations of high-speed intersections in the State of Oregon. In particular, this research effort focuses on four-leg, signalized intersections with speed limits of 45 mph or greater where the intersections are not in the immediate vicinity of other signalized intersections. This report includes a literature review of high-speed intersection safety treatment strategies, a description of the research methodology used in this project, and a summary of final results. The final results include crash conditions at these high-speed intersections, a format for evaluating safety at these and similar intersections, a hierarchy of safety treatment options, and a demonstration of the use of these tools through example analyses of eight Oregon intersections. (Oregon Department of Transportation Final Report SPR 660, March 2010, 146p.)

Analyzing the Effects of LED Traffic Signals on Urban Intersection Safety
The use of light emitting diodes (LEDs) in traffic signals has become widespread over the past decade. Could improved safety be another, less obvious benefit? The objective of this study was to evaluate the safety benefits of LED traffic signals. The development and use of LEDs was discussed to identify additional impacts to safety that may not be fully recognized. (ITE Journal, April 2010, pp. 22-27.) (To obtain this article, please contact the TIS.)

Safety Evaluation of Improved Curve Delineation
The Federal Highway Administration (FHWA) organized a pooled fund study of 26 States to evaluate low-cost safety strategies as part of its strategic highway safety effort. One of the strategies chosen to be evaluated for this study was improving curve delineation. Geometric, traffic, and crash data were obtained at 89 treated curves in Connecticut and 139 treated curves in Washington to determine the safety effectiveness of improved curve delineation. Treatments varied by site and included new chevrons, horizontal arrows, and advance warning signs as well as the improvement of existing signs using fluorescent yellow sheeting. All sites were on two-lane rural roads. An economic analysis revealed that improving curve delineation with signing improvements is a very cost-effective treatment with the benefit-cost ratio exceeding 8:1. (US Federal Highway Administration report FHWA-HRT-09-045, September 2009, 56p.)

Effects of In-Vehicle and Infrastructure-Based Collision Warnings at Signalized Intersections
The potential effectiveness of warnings to drivers of the imminent threat of a collision with a red light violator was evaluated in an experiment that used a driving simulator. Three warnings were tested: (1) an infrastructure-based warning that immediately turned the traffic signal red and activated red wig-wag lights, (2) an in-vehicle warning that consisted of a brake pulse, voice annunciation, and activation of a red dashboard light, and (3) simultaneous activation of both of these warnings. In addition to testing three warnings with different groups of drivers, drivers in each group were exposed to one of three traffic conditions: (1) driving with no other vehicles ahead or behind, (2) following closely to another vehicle, or (3) being closely followed by another vehicle. (US Federal Highway Administration report FHWA-HRT-09-049, December 2009, 46p.)

Traffic Safety Data: State Data System Quality Varies and Limited Resources and Coordination Can Inhibit Further Progress
Traffic crashes kill or injure millions of people each year. High-quality traffic safety data is vital to allocate resources and target programs as the Department of Transportation’s (DOT) National Highway Traffic Safety Administration (NHTSA) and states work to improve traffic safety through data-driven approaches. To qualify for federal funding, states must submit plans which include fatality and crash data analyses to identify areas for improvement. This requested report provides information on (1) the extent to which state traffic safety data systems meet NHTSA performance measures for assessing the quality of data systems, and (2) progress states have made in improving traffic safety data systems, and related challenges. To conduct this work, GAO analyzed state traffic records assessments, visited eight states, and interviewed federal officials and other traffic safety experts. (US Government Accountability Office report GAO-10-454, April 2010, 58p.)

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Design

Access Management in the Vicinity of Intersections
This technical summary is designed as a reference for State and local transportation officials, Federal Highway Administration (FHWA) Division Safety Engineers, and other professionals involved in the design, selection, and implementation of access management near traditional intersections (e.g., signalized, unsignalized and stop-controlled intersections). Its purpose is to provide an overview of safety considerations in the design, implementation, and management of driveways near traditional intersections in urban, suburban, and rural environments where design considerations can vary as a function of land uses, travel speeds, volumes of traffic by mode (e.g., car, pedestrian, or bicycle), and many other variables. The technical summary does not include any discussion on roundabout intersections. (US Federal Highway Administration Technical Summary FHWA-SA-10-002, February 2010, 20p.)

Roundabouts
This technical summary is designed as a reference for State and local transportation officials, Federal Highway Administration (FHWA) Division Safety Engineers, and other professionals involved in the design, selection, and implementation of roundabouts. Its purpose is to provide an overview of safety considerations in the design, implementation, and operation of roundabout intersections in urban, suburban, and rural environments where design considerations can vary as a function of land uses, travel speeds, volumes of traffic by mode (e.g., car, pedestrian, or bicycle), and many other variables. This technical summary explores the characteristics of modern roundabouts while reinforcing the need to apply a principles-based approach to design. It provides readers with an overview of the key considerations for planning, analysis, and design of single-lane and multilane roundabouts. (US Federal Highway Administration Technical Summary FHWA-SA-10-006, February 2010, 32p.)

Mini-Roundabouts
This technical summary is designed as a reference for State and local transportation officials, Federal Highway Administration (FHWA) Division Safety Engineers, and other professionals who may be involved in the design, selection, and implementation of mini-roundabout intersections. Because experience with mini-roundabouts is limited in the United States, the information presented here draws primarily upon guidance and experience from other countries with reference to American guidance as appropriate. This technical summary explores the unique characteristics of mini-roundabouts while reinforcing the need to apply the principles-based approach common to all roundabout design. It provides readers with an overview of the key considerations for planning, analysis, and design of single-lane mini-roundabouts. US Federal Highway Administration Technical Summary FHWA-SA-10-007, February 2010, 20p.)

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Urban

Restructuring the Commercial Strip: A Practical Guide for Planning the Revitalization of Deteriorating Strip Corridors
Arterial strip corridors are less than a century old in the United States, but they are now omnipresent in every populated region from small towns to big cities. The once-focal transportation and development roles they initially played in our communities have changed dramatically with the completion of the interstate highway system and the resulting transformations in Americans’ work, home, and leisure choices. The retail industry has evolved with these changes to create development formats that no longer demand long corridors of commercial properties. Because of this market change, corridors have seen marked disinvestment, which has become a structural problem that is not simply a result of boom and bust cycles. Strip corridors contribute to sprawling development patterns that increasingly are defined by traffic congestion. Finally, most corridors leave much to be desired as physical places that inspire community care and pride. (US Environmental Protection Agency Report, 2010, 64p.)

Advancing Metropolitan Planning for Operations: An Objectives-Driven, Performance-Based Approach - A Guidebook
This guidebook presents an approach for integrating management and operations (M&O) strategies into the metropolitan transportation planning process that is designed to maximize the performance of the existing and planned transportation system. This approach is recommended as a means to meet Federal transportation planning requirements for promoting efficient system management and operations and implementing a congestion management process (CMP). The approach is driven by operations objectives for the regional transportation system and performance measures for achieving those objectives. The MTP resulting from this approach contains specific, measurable operations objectives, performance measures, and M&O strategies that directly influence the projects selected for the transportation improvement program (TIP). (US Federal Highway Administration report FHWA-HOP-10-026, February 2010, 81p.)

Smart Growth: A Guide to Developing and Implementing Greenhouse Gas Reduction Programs
Smart growth development, based on 10 key principles, benefits the economy, the community, the environment, and public health. This guide provides information on how local governments have planned, designed, and implemented approaches that encourage smart growth in their communities. It is designed to be used by city planners, local energy managers and sustainability directors, local elected officials, regional planning agencies, metropolitan planning organizations, and citizen groups. Readers of the guide should come away with an understanding of smart growth principles and how they can be applied in practice, foundations and strategies for smart growth development, expected costs, and potential funding opportunities. (US Environmental Protection Agency report, March 2010, 55p.)

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