May/June 2002
Recent
Publications
Compiled
by Zac Ellis of FHWA's Office of Research and Technology Services
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:
R&T Report Center, HRTS-03
Federal Highway Administration
9701 Philadelphia Court, Unit Q
Lanham, MD 20706
Telephone: (301) 577-0906
Fax: (301) 577-1421
For more information on research and technology publications coming
from FHWA, visit the Turner-Fairbank Highway Research Center's (TFHRC)
Web site at www.tfhrc.gov, 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.
![Photo of researcher evaluating concrete pillars on beach](images/recpub01.jpg) |
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.
![Photo of bridge corrosion](images/recpub02.jpg) |
Corrosion
of bridge members, as seen here, is a serious problem in the
United States.
|
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.
Corrosion
of bridge members, as seen here, is a serious problem in the United
States.
Other
Articles in this issue:
Arizona
Tackles Work Zone Delays
A
Hallmark of Context-Sensitive Design
Safer
Roads Thanks to ITS
Do
Better Roads Mean More Jobs?
Exciting
Opportunity for ITS Work
See
It Before It's Built
Roadway
Lighting Revisited
The
Man Who Loved Roads
Benefitting
from LTPP—A State's Perspective