U.S. Department of Transportation
Federal Highway Administration
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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
This magazine is an archived publication and may contain dated technical, contact, and link information.
|Publication Number: FHWA-HRT-07-002 Date: Jan/Feb 2007|
Publication Number: FHWA-HRT-07-002
Issue No: Vol. 70 No. 4
Date: Jan/Feb 2007
Below are brief descriptions of products recently published online by the Federal Highway Administration's (FHWA) Office of Research, Development, and Technology. Some of the publications also may be available from the National Technical Information Service (NTIS). In some cases, limited copies are available from the Research and Technology (R&T) Product Distribution Center.
When ordering from NTIS, include the NTIS publication number (PB number) and the publication title. You also may visit the NTIS Web site at www.ntis.gov to order publications online. Call NTIS for current prices. For customers outside the United States, Canada, and Mexico, the cost is usually double the listed price. Address requests to:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Toll-free number: 800-553-NTIS (6847)
Address requests for items available from:
Federal Highway Administration
R&T Product Distribution Center, HRTM-03
For more information on research and technology publications from FHWA, visit the Turner-Fairbank Highway Research Center's (TFHRC) Web site at www.fhwa.dot.gov/research/tfhrc/, FHWA's Web site at www.fhwa.dot.gov, the National Transportation Library's Web site at http://ntl.bts.gov, or the OneDOT information network at http://dotlibrary.dot.gov.
Pedestrian Access to Roundabouts: Assessment of Motorists' Yielding to Visually Impaired Pedestrians and Potential Treatments to Improve Access
Publication No. FHWA-HRT-05-080
This report describes two related studies intended to address double-lane roundabout accessibility issues for visually impaired pedestrians. The first study was conducted on a closed course to evaluate a pavement treatment for alerting visually impaired pedestrians when vehicles have yielded to them. The second study examined drivers' yielding behavior at a two-lane roundabout and the effectiveness of the same roadway treatment in a real-world environment.
In the first study, there were two experimental conditions: a control condition and a treatment condition in which rumble strip-like devices were placed on the roadway surface. Seven people who have severe visual impairments participated. Participants stood at a crosswalk and used hand signals to indicate when they detected vehicles stopping or departing after a stop. Compared to the control condition, the "sound strips" treatment increased the probability of detecting stopped vehicles and decreased by more than 1 second the amount of time needed to make a detection. However, the treatment did not reduce the number of false detections that could result in the pedestrian crossing when moving vehicles are approaching the crosswalk.
The second study was an experiment at an operating roundabout. In that environment, the sound strips were not effective, probably because the majority of vehicles stopped in the circular roadway before crossing over the rumble strips. A "Yield to Pedestrians, State Law" sign that was placed in the roundabout exit between the two travel lanes resulted in more drivers yielding, from 11 percent of vehicles in the control condition to 16 percent in the experimental condition. Researchers concluded that the treatments explored in these studies do not appear promising for double-lane roundabouts, but should be explored further to see if they might work at single-lane crossings.
This document is available online at www.fhwa.dot.gov/publications/research/safety/pedbike/05080/.
Interim Recommendations for the Use of Lithium To Mitigate or Prevent Alkali-Silica Reaction (ASR)
Publication No. FHWA-HRT-06-073
Alkali-silica reaction (ASR) is a significant durability problem that has resulted in premature deterioration of various types of concrete structures in the United States and throughout the world. Although several viable methods exist to prevent ASR-induced damage in new concrete structures, very few methods mitigate further damage in structures already affected by ASR-induced expansion and cracking. Lithium compounds have been recognized for more than 50 years as effectively preventing expansion caused by ASR, and there has been renewed interest in recent years in using lithium compounds as either an admixture in new concrete or as a treatment of existing structures. This report is intended to provide practitioners with the necessary information and guidance to test, specify, and use lithium compounds in new concrete construction, as well as to use it in repair and service life extension applications. This report replaces the previous report, Guidelines for the Use of Lithium to Mitigate or Prevent ASR, and includes significant changes related to recommendations for testing and specifying lithium compounds.
This report provides a basic overview of ASR, including information on mechanisms, symptoms of ASR damage in field structures, mitigation approaches, test methods, and specifications. A comprehensive summary of lithium compounds is provided, including information on their production, availability, and use in laboratory concrete studies and field applications. Guidelines for using lithium compounds as an admixture in new concrete and for treating existing structures suffering from ASR-induced damage are presented, including information on how to assess the efficacy of lithium compounds in laboratory tests. Some basic information also is provided on the economics of using lithium both in new concrete and as a treatment for existing structures. A summary of conclusions is included and identifies several technical and practical issues that should be considered for future laboratory studies and field operations.
Job Site Evaluation of Corrosion-Resistant Alloys For Use as Reinforcement in Concrete
Publication No. FHWA-HRT-06-078
Premature deterioration of the Nation's concrete highway and bridge structures because of chloride (salt) exposure and resultant corrosion of reinforcing steel has evolved during the past four decades to become a formidable technological and economic problem. In response to this, epoxy-coated reinforcing steel (ECR) was adapted in the mid-1970s as a proactive measure to control this problem. Premature corrosion-induced cracking of marine bridge substructures in Florida indicated, however, that ECR is of little benefit for this type of exposure; and although performance of ECR in northern bridge decks has been generally good to date (30-plus years), the degree of corrosion resistance to be afforded in the long term to major structures with design lives of 75-100 years is uncertain. Corrosion-resistant reinforcements, including stainless steels, are an alternative for such applications and are a component of the FHWA Innovative Bridge Research and Construction (IBRC) Program. IBRC has addressed the incorporation of such reinforcements into approved State bridge construction projects. The present project evaluated a selected number of these in terms of the type of reinforcement used and difficulties and advantages that were encountered.
The various State projects demonstrated that, subject to availability, corrosion-resistant reinforcing steel can be incorporated into bridge construction with relative ease and placed with less difficulty than ECR. Thus, these reinforcements are a viable technical alternative to ECR. Realizing the full benefit of the IBRC program, however, will depend upon individual States acquiring performance data and maintaining records on these structures for decades into the future.
This document is available online at www.fhwa.dot.gov/publications/research/infrastructure/structures/06078/index.cfm.
Identifying Incompatible Combinations of Concrete Materials: Volume I—Final Report
Publication No. FHWA-HRT-06-079
Several test methods have been reviewed to assess their usefulness in detecting concrete material incompatibility early to help prevent problems with pavements in the field. A protocol has been developed to enable product manufacturers, concrete producers, contractors, and owners to monitor their materials and concrete systems. The protocol is phased to allow relatively simple field tests for providing early warnings of potential problems and then central laboratory tests for supporting and confirming the field work.
This is the first of two volumes. The other volume in this series is Identifying Incompatible Combinations of Concrete Materials: Volume II—Test Protocol (FHWA-HRT-06-080).
Identifying Incompatible Combinations of Concrete Materials: Volume II—Test Protocol
Publication No. FHWA-HRT-06-080
Unexpected interactions between otherwise acceptable ingredients in portland cement concrete are becoming increasingly common as cementitious systems become more complex and demands on the systems are more rigorous. Examples of incompatibilities are early stiffening or excessive retardation, potential for uncontrolled early-age cracking, and unstable or unacceptable air void systems. Several test methods have been reviewed to assess their usefulness in early detection of incompatibility, and thus to prevent pavement problems in the field. A protocol has been developed to enable product manufacturers, concrete producers, contractors, and owners to monitor materials and concrete systems. The protocol has two phases: relatively simple field tests to provide early warnings of potential problems and central laboratory tests to support and confirm the field work.
This is the second of two volumes. The other volume in this series is Identifying Incompatible Combinations of Concrete Materials: Volume I—Final Report (FHWA-HRT-06-079).
Protocol to Identify Incompatible Combinations Of Concrete Materials (TechBrief)
Publication No. FHWA-HRT-06-082
For this project, "incompatibility" of concrete materials is defined as interactions between acceptable materials that result in unexpected or unacceptable performance. The most common problems are associated with premature stiffening (rapid slump loss), erratic setting of concrete mixtures (flash set, false set, or delayed setting and strength gain), and increased risk of cracking and unacceptable air void systems. Proper consolidation, finishing, texturing, and curing also can be disrupted.
The aim of this project was to develop a protocol that enables users to assess whether a given combination of materials used to make concrete for pavements is likely to exhibit such incompatibility in a given environment.
The TechBrief is available online at www.fhwa.dot.gov/pavement/concrete/06082.
Intelligent Intersection Traffic Control Laboratory Fact Sheet
Publication No. FHWA-HRT-06-102
The Intelligent Intersection Traffic Control Laboratory (IITCL) is an outdoor facility that supports various research programs and research activities conducted by FHWA and other U.S. Department of Transportation (USDOT) agencies. This includes USDOT's two major intelligent transportation system programs: the Cooperative Intersection Collision Avoidance Systems initiative and the Vehicle Infrastructure Integration initiative. IITCL serves as a testing ground for intersection-related research projects and as a place to integrate and demonstrate advanced technologies. Since its inception, many successful demonstrations and research activities have been conducted there.
The fact sheet is available online at www.fhwa.dot.gov/publications/research/operations/its/06102/index.cfm.
Federal Outdoor Impact Laboratory Fact Sheet
Publication No. FHWA-HRT-06-107
The Federal Outdoor Impact Laboratory (FOIL) is a fully equipped outdoor crash testing laboratory and research facility used to support FHWA's Office of Safety Research and Development programs and other federally funded security initiatives. Researchers use the facility to extend their understanding of crashes by staging controlled, high-speed motor vehicle collisions. The facility typically is used to confirm the accuracy of computer-generated crash predictions. This ensures that tested roadside structures—structures that typically are located in close proximity to the Nation's roadways—function as intended when struck by a motor vehicle. Routine certification or compliance testing of roadside safety structures, including testing performed to ensure compliance with existing safety standards, is not conducted at FOIL.
The fact sheet is available online at www.fhwa.dot.gov/publications/research/safety/06107/index.cfm.