Bursic 2:00
Group R11
AMERICA’S AGING BRIDGES
Andrew Resek (ajr114@pitt.edu)
INTRODUCTION: AMERICA’S BRIDGES
ARE CRUMBLING
I believe that America’s deteriorating system of bridges
is a subject of great importance. This topic is very important
to me because of where I live. I drive over many bridges
every day. Many of them are structurally deficient and that
worries me. Bridges are a vital part of our national network
of roads and highways. This nation’s bridges have been
neglected for too long and now we are facing the
consequences. Over the past few years more attention has
been brought to America’s failing infrastructure. Currently
our national infrastructure is in a very poor condition. In
2011 at the World Economic Forum, the United States was
listed as the 24th in the world with respect to its
infrastructure. That number is down from 5 th in 2002. [1].
Thousands of bridges across the nation have been deemed
unsafe due to structural deficiency. There are numerous
factors that have led to our national network of bridges to
deteriorate to what they are today. These factors include
cuts in state and federal budgets towards road maintenance,
an increasing number of vehicles on the road, and poor
bridge design and maintenance. Civil engineers are in a
unique position. We have the opportunity to change our
current situation. We need to devise a way to repair the
bridges that can be fixed and engineer a new way to build
bridges that will last for hundreds of years.
FIGURE 1, MAP OF STRUCTURALLY DEFICIENT
BRIDGES IN PITTSBURGH AREA
The red icons indicate structurally deficient bridges. [3].
CUTS IN THE BUDGET
There are several major factors that have contributed to
the deterioration of our bridge network. One major factor is
the lack of money that state and federal budgets designate
for bridges and roads. India spends approximately 5% of its
gross domestic product (GDP) on its infrastructure. China
spends about 9% of its GDP on infrastructure. Meanwhile
the United States only spends about 2.5% of its GDP on
infrastructure. [2]. Currently the federal budget is spending
$5.2 billion annually on bridges. Analysts predict that the
United States needs to spend approximately $19 billion
annually over the next 50 years in order to improve our
network of bridges. [6].
THE CAUSES OF THE PROBLEM
THE FACTS
Every four years the American Society of Civil
Engineers (ASCE) releases a report card rating America’s
infrastru0cture. The last report card to be released was in
2009. The overall average of the report card was a D, and
bridges received a C. [2]. A C may not seem like a bad
grade, C is average, but when you take into account that
there are over 603,245 state and federal bridges in the United
States that means there is a large number of bridges that
below average. Currently 12% or 71,179 of our nation’s
bridge are structurally deficient. [3]. The term structurally
deficient means a bridge is in relatively poor condition, or
has insufficient load carrying capacity for modern design
loadings. [2]. Currently in the Pittsburgh area there are
hundreds of structurally deficient bridges. [4].
University of Pittsburgh,
Swanson School of Engineering
OLD AND OUTDATED
Age is a major contributor to the state of the bridges.
The average age for all bridges in the United States is 43
years old. Many of our nation’s bridges were built after
World War II during the baby boom era of the 1940’s and
1950’s. They were designed to only last for 50 years and
that time is fast approaching. [6]. Demands for roads and
bridges increased for two reasons.
First, individual
transportation in the form of the automobile became
affordable and accessible to many people thanks to advances
in assembly line technology developed during World War II,
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Andrew Resek
which lowered the cost of automobiles. The second reason
is more people left rural areas to move to metropolitan areas.
As time went on attention from these new roads and bridges
were diverted to roads and bridges built before this post war
boom. Today many of these 1940-1950 era bridges are
simply falling apart. Their designs we made to handle traffic
patterns of the era. The materials they were constructed with
were only rated to last for so long. Also these bridges were
only rated to handle a certain maximum capacity weight.
Some of these aging bridges did not receive proper
maintenance when needed. Often they were only fixed with
short term solutions that would only expand the life of the
bridge for a few years. It was like putting a Band-Aid on
something that needed stitches. [7], [pp. 45, 46]. An
example is the Beechwood Boulevard Bridge that goes over
Rt. 376. That bridge is in need of major repair but instead
they wrapped it in netting and put up a rock shield to prevent
cars below from getting hit by debris that falls from the
bridge.
FUGURE 3, GROWTH CHART OF VEHICLES IN U.S
The graph shows that there was a rapid growth of car
production the mid 1940’s all the way up to the 1990’s [5].
HOW TO FIX THE BRIDGES
FUNDING THE FIX
Fixing our network of bridges is vital to every aspect of
American life. In order to maintain bridges at their current
levels for the next fifty years will take $650 billion [7], [pp.
101]. President Barack Obama’s administration is currently
using stimulus style infrastructure spending plans. This
method creates jobs that are dedicated to fixing our bridges
and infrastructure. [1]. One proposed idea on how to
generate the revenue needed to pay for these construction
projects is to increase state fuel taxes. If the state fuel tax
were to be increased by one cent, it would generate $1.9
billion in revenue. If the tax were to be increased by two
cents it would generate $3.8 billion, by three cents $5.7
billion and so on. This new revenue would go towards
improving and maintaining our infrastructure. Our nation
government needs to take serious action to find the revenue
and resources in order to fix our infrastructure and bridges
before it is too late. [7], [pp. 103].
FIGURE 2, GRAPH OF BRIDGE DETERIORATION
This graph shows the rate at which bridges deteriorate with
and without proper maintenance. [7], [pp. 78].
SELFHEALING CONCRETE
Bridges have long been built out of concrete, stone,
wood, iron, and steel. Each of these mediums has their own
strengths as well as their weaknesses. Wood is cheap,
readily available, and easy to work with, but it rots and is
weak compared other mediums listed above. Steel and iron
have high tensile strength which is good for bridges but
corrodes when exposed to air, salt, and water. Stone and
concrete have high compressive strength but they become
brittle over time. A majority of our bridges are built using a
mixture of concrete reinforced with steel rebar. These two
mediums make up for what the other lacks. The steel
provides the tensile strength that the concrete lacks and the
concrete protects the steel from the elements and gives the
bridge great compressive strength. In a perfect world these
bridges would never need maintenance. The reason bridges
TO MUCH TRAFFIC
The design of the 1940’s and 1950’s era bridges were
meant for the traffic patterns and traffic density of that era
and a decade or two into the future. With each decade that
passed traffic patterns and traffic density changed. Each
year more automobiles were put on the roads putting more
strain on the bridges across America. The bridges received
more abuse with each year that passed. Also during this
time, money for road and bridge maintenance began to
decline in order to pay for other parts of state and federal
budgets.
Bridges were neglected while daily traffic
continued to increase. As a result of neglect, the rate at
which the bridges deteriorated increased and today we are
facing the issue of how to fix and replace them.
University of Pittsburgh,
Swanson School of Engineering
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Andrew Resek
need maintenance is because when heavy traffic loads drive
over them they create cracks in the concrete. These cracks
allow water and salt to make contact with the steel causing
corrosion. This is a major problem. One new technology
may solve this problem. Victor Li a professor at the
University of Michigan has created a new type of concrete
that may be the solution to America’s aging bridge problem.
Li created a new type of concrete that is flexible and is selfhealing. This new type of concrete is infused with a material
created by Li in the 1990’s called cementitious composite.
When the concrete receives a stress load it flexes and bends
without fracturing. [8]. If a crack were to form, the concrete
heals itself much like the human body heals a paper cut.
Li’s concrete costs about three times more than normal
concrete, but the bridge will have a lower lifecycle cost than
a bridge made out of normal concrete. Lifecycle cost is the
amount of money a bridge will require in order to be
properly maintained throughout the course of its life. Li is
also currently working on a concrete that will notify you
when it is damaged. [8]. I believe that this new type of
concrete is the answer to our bridge problem. By retrofitting
old bridges and building new bridges with this
groundbreaking material, bridges would be more resilient to
stress from vehicles and the elements. Also these bridges
would need less maintenance.
number of our bridges have been deemed unsafe or
structurally deficient. This problem has resulted from poor
bridge design and maintenance. For example, one of the
United States greatest bridge disasters was the collapse of
the I-35W Highway Bridge back in 2007. The I-35W was
an eight-lane, 1,900ft long bridge that spanned the
Mississippi River. On August 1, 2007, a 1,000ft section of
the bridge collapsed, plummeting 108ft into the Mississippi
River. As a result from the collapse, 13 people died and 145
people were injured. An investigation was launched by the
National Transportation Safety Board to determine the cause
of the accident. The investigation found that the I-35W
Bridge lacked sufficient quality control from the bridge
design firm as well as a lack of how to accurately assess the
condition of key bridge components. [10]. The ASCE states
in its fundamental canon that “Engineers shall act in such a
manner as to uphold and enhance the honor, integrity, and
dignity of the engineering profession and shall act with zerotolerance for bribery, fraud, and corruption.” [11]. This is an
extremely important ethic in my opinion. Engineers who
violate this ethic do not deserve to be engineers. They are
responsible for people’s lives. When engineers fail people
die. This ethic has been violated and is one reason the I35W collapsed and why many of our bridges are falling
apart. It is morally wrong to neglect the condition of
America’s bridge system. Bridges are a quintessential part
of the national infrastructure. Everyday millions of lives are
at risk because they are traveling on bridges are could fail
without any warning. We must take action to ensure that
future bridges are designed with safety and longevity in
mind. Fixing our bridge system is morally right and will help
return America to its former glory. It will create thousands
of jobs as well as strengthen our infrastructure. Bridge
safety is a very important topic. The code of ethics for
engineers makes a path for future engineers to follow. This
path will lead to the improvement of bridge design that will
make our bridges safe again.
FI
GURE 2, STRESS TEST ON A SAMPLE OF LI’S
FLEXIBLE CONCRETE
This sample is a precursor to the self-healing concrete but
has the same flexible characteristics as the self-healing
concrete. [8].
WHAT I LEARNED
Researching this assignment was very beneficial for my
education. I had some knowledge of this topic before
conducting my research, but this assignment required me to
look much further into the topic. It showed me the daunting
challenge that civil engineers are faced with. They must
determine how to repair our network of bridges as well as
design better ones. I learned that there is a lot of work to do
but there is action being taken as well as revolutionary
technology in development. This assignment also gave me a
knowledge of the ethics of engineering. This topic could be
a valuable research project for the Swanson school of
Engineering by studying the flaws of old bridges and how to
better design new ones. These ethic are extremely important
to know because these are the rules that we as engineers
must follow in the work place as well as in college. This
ETHICS AND EDUCATION
MORAL RESPONSIBILITY WITH OUR BRIDGES
I believe that civil engineers hold a great moral
responsibility when it comes to the safety of our country’s
bridges. The National Society of Professional Engineers
(NSPE) lists in its fundamental canon that engineers, “Hold
paramount the safety, health, and welfare of the public.” [9].
Bridge safety is a major concern in America today. A large
University of Pittsburgh,
Swanson School of Engineering
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Andrew Resek
assignment required us to use PITTCat to find sources. I
was able to obtain an understanding of how the library
website works and how to access information through it.
This skill is very beneficial because I will use it for
numerous future assignments and projects. This assignment
has helped me narrow my choices of which field of
engineering I want to major in.
[10] National Transportation Safety Board. (2008).
“Accident Highway Report.” National Transportation Safety
Board.
(Online
Article).
http://www.ntsb.gov/investigations/summary/HAR0803.htm
[11] “Code of Ethics.” American Society for Civil Engineers.
(Online
Article).
http://www.asce.org/Leadership-andManagement/Ethics/Code-of-Ethics/
CONCLUSION
ACKNOWLEDGMENTS
American infrastructure is not what it was 20 years ago.
Our roads and bridges are deteriorating every day. Every
day that we don’t take action is another day for tragedy to
strike. There have already been two major bridge collapses
that have resulted in several dead and hundreds injured. Our
infrastructure is the back bone of our nation. It impacts every
aspect of our lives, if we were to lose our roads and bridges
our nation would shut down. This is why we must fix our
bridges and improve our national infrastructure.
I like to thank my environmental science teacher for high
school, Mr. Steve Gotwols. Mr. Gotwols got me interested
in the situation of our national infrastructure. He taught us a
lot about what is and not being done about it. Much of the
information in this paper I learned from him.
REFERENCES
[1] J. Keyser. (2012). “WHY IT MATTERS: Creaky
Bridges, Potholed Roads, Tricky Politics.” Star Tribune
National. (Online Article).
[2] R. Schlesinger. (2010). “America’s Crumbling Roads
and
Bridges.”
CBSNews.
(Online
Article).
http://www.cbsnews.com/8301-18563_162-6833955.html
[3] U.S. Department of Transportation, Federal Highway
Administration. (2011). “Deficient Bridges by State and
Highway
System.”
http://www.fhwa.dot.gov/bridge/nbi/defbr09.cfm
[4] The Fix We’re in For: The State of Our Bridges. [Map].
(2012).
Retrieved
October
8,
2012,
from:
http://t4america.org/resources/bridges/#?latlng=40.2737002,
-76.88441790000001
[5] [Car
Chart].
October
8,
2012,
from:
http://www.zerohedge.com/category/tags/corporate-america
http://www.startribune.com/politics/national/173140761.htm
l?refer=y
[6] J. Patterson. (2011). “America’s Failing Infrastructure: A
Scary
Picture.”
Kiplinger.
(Online
Article).
http://www.kiplinger.com/businessresource/forecast/archive/
americas-failing-infrastructure.html
[7] B. B. LePatner. (2011). Too Big to Fall: America’s
Failing Infrastructure and the Way Forward. Lebanon, NH:
University Press of New England. (Print Book). Pp. 45, 46,
78, 100, 101, 103
[8] A. V. Broek. (2009). “Self-Healing Concrete.”
www.forbes.com.
(Online
Article).
http://www.forbes.com/forbes/2009/1102/revolutionariesengineer-victor-li-self-healing-concrete.html
[9] “NSPE Code of Ethics for Engineers.” NSPE. (2007).
(Online
Article).
http://www.nspe.org/Ethics/CodeofEthics/index.html
University of Pittsburgh,
Swanson School of Engineering
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