Communication Product Updates
Below are brief descriptions of reports recently published by the Federal Highway Administration's (FHWA) Office of Research, Development, and Technology. All of the publications are available from the National Technical Information Service (NTIS). In some cases, limited copies of the publication are available from the Research and Technology (R&T) Report Center.
When ordering from NTIS, include the NTIS PB number (or publication number) and the publication title. You may also 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
Telephone: (703) 605-6000
Toll-free number: (800) 553-NTIS (6847)
Expanded Sales Desk Hours: 8 a.m. to 8 p.m. EST, Mon.-Fri.
Requests for items available from the R&T Report Center should be addressed to:
Federal Highway Administration
R&T Product Distribution Center, HRTM-03
For more information on research and technology publications coming 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://isweb.tasc.dot.gov/library/library.htm.
Corrosion Inhibitors in Concrete: Interim Report Publication No. FHWA-RD-02-002
The overall objective of this work-in-progress is to assess the effectiveness of corrosion inhibitors for steel in concrete. Three commercially available inhibitors, DCI-S (calcium nitrite-based) and FerroGard 901 and Rheocrete 222+ (both on organic compounds), were selected for detailed examination. To determine the amount of inhibitor remaining in concrete, an accurate method to analyze for calcium nitrite was developed, and analyses for the other two inhibitors are being explored. The ability of calcium nitrite to stay in place was examined by laboratory experiments of inhibitor diffusion in concrete and by examination of available concrete samples exposed for long times to the outdoor environ- ment. Results indicated a nitrite ion diffusivity comparable to that of chloride ions in concrete. Tentative tests with FerroGard 901 suggest similar behavior. Examina- tion of long-term outdoor specimens indicated that a high level of corrosion protection was achieved when the mass of nitrite ion per volume of concrete equaled or exceeded that of chloride ions.
Researchers with the Florida DOT installed concrete pillars at Crescent Beach, FL, to evaluate various corrosion inhibitors in a marine environment.
Service Life Prediction Based on Sorptivity for Highway Concrete Exposed to Sulfate Attack and Freeze-Thaw Conditions Publication No. FHWA-RD-01-162
This report documents a study that investigated permeability as an indicator of the general durability of hydrau- lic cement concrete. Since many concrete deterioration mechanisms depend on the ingress of moisture and other materials into the concrete, it was theorized that permeability might be a good indicator of durability potential. During the project, it was determined that sorptivity is the most relevant transport characteristic of the concrete. A test method for sorptivity was therefore developed, which has two different setups, to better reproduce the exposure condition being simulated.
A user-friendly software, CONCLIFE, was then developed for estimating the service life of concrete pave- ments and bridge decks exposed to sulfate attack and freeze-thaw deterioration. CONCLIFE uses three concrete models and user-specified data on concrete properties and external environmental conditions to estimate the time at which the concrete surface spalls beyond a user- specified limit. Ingress of sulfate ions and water are the primary means of degradation considered by the software. CONCLIFE uses the results of the laboratory test described above, currently in the American Society for Testing and Materials standardization process, for measur- ing concrete sorptivity. The software produces graphs of concrete sorptivity, annual precipitation, and estimated rates of concrete spalling based on the input. Details of the experimental program conducted in support of the software development and the underlying technical bases for the computer models employed in CONCLIFE also are included.
Corrosion Cost and Preventive Strategies in the United States Publication No. FHWA-RD-01-156
This report describes the annual total cost of metallic corrosion in the United States and preventive strategies for optimum corrosion management. The total direct cost of corrosion is estimated at $276 billion a year, which is 3.1 percent of the 1998 U.S. gross domestic product (GDP). This cost was determined by analyzing 26 industrial sectors in which corrosion is known to exist and extrapolating the results for a nationwide estimate. The sectors were divided among five major categories: infrastructure, utilities, transportation, production and manufacturing, and government. The indirect cost of corrosion is conservatively estimated to be equal to the direct cost (i.e., total direct cost plus indirect cost is 6 percent of the GDP). Evidence of the large indirect corrosion costs are lost time, and thus lost productivity because of outages, delays, failures, and litigation. It was found that the sectors of drinking water and sewer systems ($36 billion), motor vehicles ($23.4 billion), and defense ($20 billion) have the largest direct corrosion impact. Within the total cost of corrosion, a total of $121 billion per year is spent on corrosion control methods and services.
The current study showed that technological changes have provided many new ways to prevent corrosion, and there has been improved use of available corrosion management techniques. However, better corrosion management can be achieved using preventive strategies in nontechnical and technical areas. These preventive strategies include: (1) increasing awareness of large corrosion costs and potential savings; (2) chang- ing the misconception that nothing can be done about corrosion; (3) changing policies, regulations, standards, and management practices to increase corrosion cost- savings through sound corrosion management; (4) improving education and training of staff in recogni- tion of corrosion control; (5) advancing design prac- tices for better corrosion management; (6) advancing life prediction and performance assessment methods; and (7) advancing corrosion technology through research, development, and implementation.
Safety Effects of Marked Vs. Unmarked Crosswalks at Uncontrolled Locations: Executive Summary and Recommended Guidelines Publication No. FHWA-RD-01-075
Pedestrians are legitimate users of the transportation system, and they should be able to use this system safely. Pedestrian needs in crossing streets should be identified, and appropriate solutions should be se- lected to improve pedestrian safety and access. Deciding where to mark crosswalks is only one consideration in meeting that objective.
The study involved an analysis of 5 years of pedes- trian crashes at 1,000 marked crosswalks and 1,000 matched unmarked comparison sites. All sites in this study had no traffic signal or stop sign on the approaches. Detailed data were collected on traffic volume, pedestrian exposure, number of lanes, median type, speed limit, and other site variables. Poisson and negative binomial regressive models were used.
The study results revealed that on two-lane roads, the presence of a marked crosswalk alone at an uncontrolled location was associated with no difference in pedestrian crash rate, compared to an unmarked crosswalk. Further, on multi-lane roads with traffic volumes greater than 12,000 vehicles per day, having a marked crosswalk alone (without other substantial improvements) was associated with a higher pedestrian crash rate (after controlling for other site factors) compared to an unmarked crosswalk. Raised medians provided significantly lower pedestrian crash rates on multi-lane roads, compared to roads with no raised median. Older pedestrians had crashes that were high relative to their crossing exposure.
More substantial improvements were recommended to provide for safer pedestrian crossings on certain roads, such as adding traffic signals with pedestrian signals when warranted, providing raised medians, speed-reducing measures, and others.
The NTIS order number for this report is PB2002- 104240.