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-14-004 Date: May/June 2014|
Publication Number: FHWA-HRT-14-004
Issue No: Vol. 77 No. 6
Date: May/June 2014
Below are brief descriptions of communications products recently developed by the Federal Highway Administration’s (FHWA) Office of Research, Development, and Technology. All of the reports are or will soon be available from the National Technical Information Service (NTIS). In some cases, limited copies of the communications products are available from FHWA’s Research and Technology (R&T) Product Distribution Center (PDC).
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:
Requests for items available from the R&T Product Distribution Center should be addressed to:
R&T Product Distribution Center
Szanca Solutions/FHWA PDC
13710 Dunnings Highway
Claysburg, PA 16625
For more information on R&T communications products available from FHWA, visit FHWA’s Web site at www.fhwa.dot.gov, the FHWA Research Library at www.fhwa.dot.gov/research/library (or email email@example.com), or the National Transportation Library at ntl.bts.gov (or email firstname.lastname@example.org).
Publication No. FHWA-HRT-13-048
This report discusses a project to develop a method for determining driver expectations at interchanges and how these expectations affect driver behavior at interchanges of varying complexity. The report provides initial recommendations for navigation signage to aid drivers at complex interchange designs.
Interchange navigation presents a range of challenges different from those associated with driving on continuous roads. Often, drivers’ directional errors at interchanges are more difficult for them to correct because they may transfer to a grade-separated freeway, highway, or roadway with limited access points for return to the original roadway.
Clear navigation signage is needed to guide drivers and minimize errors. Currently, there is little consensus on a single best way to design signs for interchanges, and available data present an incomplete picture to guide relevant sign design.
This project involved multiple tasks to study driver expectations. Researchers began with a literature review of prior work on driver navigation problems and driver expectations at interchanges, followed by a series of focus groups to collect qualitative information about driver expectations. The researchers then completed a task analysis of various interchange navigation scenarios and an experimental study to collect data on driver performance given various signage alternatives at complex interchanges.
The focus groups indicated that most drivers have problems at complex, unfamiliar interchanges. When drivers do not receive the information they expect, they become stressed, especially if they are surprised or need to execute multiple lane changes in a short distance.
The task analysis indicated that multiple concurrent driving tasks may be common at complex interchanges and could lead to higher workloads for drivers. The empirical data collected showed that perceptual factors associated with the spatial layout of signs have a significant impact on driver interpretation of information. The problems that drivers experience, and their responses to those challenges, potentially have implications for safety and capacity at complex interchanges.
This report will be useful to traffic safety researchers and traffic engineers responsible for highway design and public safety. It is available to download at www.fhwa.dot.gov/publications/research/safety/13048/index.cfm. Printed copies are available from the PDC.
Publication No. FHWA-HRT-13-096
A geographic information system (GIS) is designed to capture, store, manipulate, analyze, manage, and present all types of geographical data visually. By optimizing datasets and bringing disparate information into a single, location-based data system, GIS technology can help identify safety countermeasures and bolster state-of-the-practice safety analyses. This report discusses a project conducted by FHWA’s Office of Safety Research and Development to assess GIS practices, needs, and obstacles and to determine opportunities for expanded use of GIS technology in traffic safety programs.
The project used a series of resources, including peer exchanges, a comprehensive literature review, and the input of a technical working group, to determine recommendations for improving the state of the practice in GIS use for highway safety analysis and decisionmaking at the State and local levels. The team developed a marketing, communications, and outreach plan that includes recommended actions for FHWA to further incorporate GIS into its safety programs.
Many States are only beginning to discover the full capabilities of a modern GIS to support advanced safety data analysis, and many anticipate enhancing GIS capacity and making use of more advanced techniques in the future. Some States are building their own tools, while others are adopting or adapting tools that are already available. The project team found that States would welcome help in this area, not just to aid in the determination of best practices, but also in identifying and promoting tools and advanced analytic techniques.
States cite both administrative and technical barriers to successful implementation of a GIS-based safety program. They need guidance, models, and direct assistance in working with local agencies that are likely to be the source of much of the new data that need to be collected in order to meet the requirements of the Moving Ahead for Progress in the 21st Century legislation. Findings and recommendations from this project offer insight into FHWA’s role in advancing the use of GIS-based safety data systems. Leveraging these advanced data systems will help provide State and local agencies with the tools needed to make informed and effective safety decisions.
This report includes recommendations for FHWA to help agencies overcome challenges related to tools, marketing, training, and research. It is available to download at www.fhwa.dot.gov/publications/research/safety/13096/index.cfm. Printed copies are available from the PDC.
Publication No. FHWA-HRT-13-100
This technical brief discusses a research project to develop a non-proprietary, cost-effective, ultra-high performance concrete (UHPC) with exceptional compressive strength, tensile strength, and durability properties. The long-term goals of the project are to facilitate the use of UHPC among U.S. suppliers and contractors, accelerate its application in construction, and promote a more resilient and sustainable future infrastructure in the United States.
Employing a progressive approach for UHPC development, researchers analyzed and optimized the performance of the paste, matrix, and fiber-reinforced concrete composite. They defined an efficiency factor to consider the performance in workability, compressive strength, and costs in order to select the most effective materials.
Researchers recommend four UHPCs that contain only fine aggregates and three UHPCs that include coarse aggregates. Compressive strength of all recommended UHPC mixes exceeded the minimum required compressive strength of 20 kips per square inch, ksi (138 megapascals, MPa).
Researchers note that future efforts to tailor the weight ratio of cement to silica fume and supplemental material in terms of performance versus cost would be beneficial. A reduction in the amount of the most expensive material and an increase in the amount of the least expensive material might lead to a further improvement in performance versus cost.
Adding fiber reinforcement of 1.5 percent by volume to the UHPC mix increases the costs by about $470 per cubic yard ($615 per cubic meter), so the report also proposes further research to identify cost-effective fiber reinforcement solutions.
As non-proprietary UHPCs are further developed, additional properties beyond those discussed in this study will need to be addressed. Further research should examine durability properties, such as chloride ion penetration and scaling resistance to deicing chemicals. Other tests, such as strength development, long-term creep behavior, shrinkage behavior, abrasion resistance, and bond behavior between reinforcement bars and composites should be completed to aid the consideration of non-proprietary UHPC in the U.S. highway bridge sector.
This document is available to download at www.fhwa.dot.gov/publications/research/infrastructure/structures/bridge/13100/index.cfm. Printed copies are available from the PDC.
Publication No. FHWA-HRT-13-102
Development of high-performance steel (HPS) began in the 1990s as a result of cooperation between FHWA, the U.S. Navy, and the American Iron and Steel Institute. Researchers created three new weathering grades of HPS with minimum yield strengths of 50, 70, and 100 ksi (345, 383, and 690 MPa), respectively. These are referred to as HPS50W, HPS70W, and HPS100W. At the time, one of the early problems was identifying cost-effective welding consumables that would work for these higher strength materials, in particular for the HPS100W grade. An alternative to relying on the strength of the weld consumable is the optimization of the butt-welded joint by changing its geometric proportions. This TechBrief explores the optimization of the HPS100W butt-welded joints.
Researchers found that butt welds of HPS70W plates could be optimized and thus perform satisfactorily. This performance can be accomplished provided the width-to-thickness ratio is 7, the weld-to-plate yield ratio is 0.91 or greater, and the weld-to-plate tensile ratio is 0.87 or greater.
However, the 1.5-inch (3.8-centimeter)-thick HPS100W plates could not be optimized unless the weld metal yield and tensile strengths were 0.95 times that of the plate and the width-to-thickness ratio was 7 or greater. None of the 1-inch (2.5-centimeter)-thick HPS100W specimens could be optimized. Researchers could not definitively identify whether this was a thickness dependence or because the weld-to-plate strength ratios were not 0.95 or greater, but note that it is likely an effect of the plate being so thin. For this reason, careful consideration should be given when trying to optimize welds of plates less than 1.5 inches (3.8 centimeters) thick.
This document is available to download at www.fhwa.dot.gov/publications/research/infrastructure/structures/bridge/13102/index.cfm. Printed copies are available from the PDC.