The collapse of the I-35W bridge in Minneapolis didn't change our infrastructure needs but it made the public aware of the immediate need for maintenance.
Credit: Minnesota Department of Transportation
On August 1, 2007 the I-35W bridge over the Mississippi River in Minneapolis collapsed, killing several people and leaving us with more questions than answers. The news media quickly reported that recent bridge inspections by engineers rated it to be “structurally deficient.” In the days following the collapse, the public became aware that this structurally deficient rating of the bridge wasn't considered to be all that unusual because a startling 26% of other bridges around the country have the same rating. One immediate response was that other state governors ordered new inspections for their bridges to address public safety concerns. The collapse served to make the public aware of our deteriorating infrastructure, resulting in pressure on government at all levels to allocate funds for repair.
At the same time, the rupture of an old steam pipe under a New York City street caused the death and injury of pedestrians, and a report about the inadequate condition of the New Orleans' levees further emphasized the need. However, politics and public safety are at odds over the funding required to fully address the needed repairs. The price tag to upgrade our infrastructure and make it safe is considerable—much more than the war in Iraq is costing. The only way to raise this kind of money is to increase taxes and politicians won't do that until after the next election. So what is likely to happen and what is the role that concrete will play?
The American Society of Civil Engineers (ASCE), Reston, Va., defines our infrastructure to include aviation, bridges, dams, drinking water, energy systems, hazardous waste, navigable waterways, parks and recreation, rail, roads, schools, security, solid waste, transit, and wastewater management. In its 2005 report card, it advocates spending $1.6 trillion over the next five years to upgrade our infrastructure to acceptable levels.
Here is a rundown of infrastructure needs that most affect concrete.
The I-35W Bridge
The collapse of the I-35W Bridge became the tipping point that alerted the public to the sad state of our infrastructure. The replacement of the bridge will start immediately; the signal that it sent will take much longer to permeate. The Minnesota Department of Transportation (MnDOT) already has secured state and federal funding to rebuild the bridge. Four groups did the design/build package. The winner is the contracting joint venture of Flatiron, Longmont, Colo., and Manson Construction, Seattle. Figg Engineering, Talahassee, Fla., is the design/engineering member of the team.
Credit: Joe Nasvik
In order to keep up with maintenance, the U.S. should spend $94 billion each year for repairs and upgrades to
Kevin Gutknecht, media contact for MnDOT, says that construction is expected to start on Oct. 15, with completion scheduled for Dec. 24, 2008. MnDOT allowed alternate proposals for structural steel or structurally reinforced concrete; the one proposal for structural concrete got the job. Features include high-performance concrete for increased durability, multiple levels of structural redundancy, low-maintenance costs, and a state-of-the-art sensor and monitoring system built into the structure. MnDOT brought together a panel representing different interests to evaluate the “best value bid process” applications. The selection criteria included cost, length of construction,
Maintaining our nation's bridges
The Federal Highway Authority (FHWA) national bridges survey. lists 596,842 bridges in the U.S. Of this total, 73,764 are listed as “structurally deficient” and 80,226 are listed as “functionally obsolete.” This means that 26% (or 153,990 bridges) are in need of either repair or replacement. The states that lead the nation in this need are Texas, Pennsylvania, and Missouri. When funding isn't available for repairs, many bridges are closed to traffic until repairs can be made. The ASCE estimates it will cost $9.4 billion each year for the next 20 years to perform the needed maintenance.
The Portland Cement Association's (PCA), Skokie, Ill., bridge department currently is studying the information about bridge maintenance. David Bilow, director of engineering structures, says there are significantly more steel bridges needing maintenance than concrete ones. “Based on the Federal Highway Authority (FHWA) national bridges survey, concrete bridges last longer and are more durable, and have fewer structural deficiencies—true no matter how you look at the data,” he says.
Roads and highways
The ASCE report card grade for our nation's roadways is a “D” and the association recommends spending $94 billion each year to repair and upgrade the system. Like bridges, there is also a huge backlog of structurally deficient roadways. In addition to this, the American Association of State Highway & Transportation Officials' (AASHTO) “Invest in Our Future” program has a goal to increase our interstate highway capacity by 80% and fix the 100 worst freight bottlenecks in the nation by 2015. Funds for this work come from the Highway Trust Fund (HTF), which by law can't do deficit funding. Congress can allocate spending in this fund but projects can't go forward until they also allocate money to the fund to cover the costs. Until there are new revenue sources there won't be significant movement on approved projects. Additional funding will probably come in the form of increased fuel taxes after the next election.
The I-70 Freeway was one of the first built in the country after the Interstate Highway bill was signed into law in 1956. It served for 50 years, much longer than originally intended, before being completely replaced. With better engineering and understanding of materials it will hopefully outlive the original.
Credit: Joe Nasvik
With the start of the interstate highway program in 1956, the nation embarked on the greatest public works project in the country's history. Over time 47,000 miles of interstate highways were constructed, boosting our productivity and increasing our gross national product tenfold. Leif Wathne, director of highways for the American Concrete Paving Association (ACPA), attributes the success of the interstate system partly to the fact that the majority of it was constructed with concrete. Those early pavements were long lasting with tremendous load carrying capacities and very low life cycle costs.
For example, the San Bernardino Freeway just east of Los Angeles was originally constructed in 1946 as part of Route 66 (now part of I-10). In 1965 it became the first highway in the country to be continuously diamond grinded to restore the surface. This was done again in 1984 and in 1997. Today, after 60 years of service, the pavement carries more than 200,000 vehicles each day.
In recent years the importance of longevity has become more of an issue because funding for highway infrastructure purposes has diminished. As tempting as short-term fixes are for front-end costs, long-term costs end up being more. Concrete is the better alternative.
The ASCE grade for our nation's airports is “D+”—only a little better than for roadways. The problem is that passengers boarding aircraft are expected to surpass 1 billion within the next 10 years. Funding is provided by the Aviation Trust Fund (ATF), which Congress enacts. They already have approved a spending package of $3.8 billion for 2008, more than was spent in 2007. It is likely that $15.8 billion will be spent over the next four years.
Having an adequate supply of drinking water is tied to wastewater management. The ASCE gives both drinking water and wastewater treatment a “D-”. One problem is that many existing facilities are aging and need to be replaced. It's estimated that $11 billion annually is needed to upgrade our system but nowhere near this amount currently is allocated. Congress recently authorized $23 billion for water resource projects that include drinking water, wastewater, and flood control but the legislation doesn't authorize funds for the projects so it remains to be seen how many approved projects actually will have money to proceed.
Each year billions of gallons of untreated wastewater are sent to our nation's waterways. Some of this is caused by storms that overflow treatment facilities. The Environmental Protection Agency (EPA) estimates that $390 billion must be spent over the next 20 years to replace treatment facilities, build new ones, and control runoff. But in 2006 only $730 million was spent—less than .2% of what is needed.
Waterways, flood control, dams
Many of the maintenance items for our infrastructure relate to the productivity of our businesses and industries. Barge traffic on our waterways can move 58 semiloads of material at one-tenth the cost. But the 257 locks on our 12,000 miles of waterways are aging and need attention. The ASCE says that 50% of them are functionally obsolete.
There are now more than 3500 unsafe nonfederally owned dams in the U.S. that could cause the loss of life if they failed. The ASCE says $10.1 billion is needed to fix those problems over the next 12 years.
The levees that protect New Orleans are in serious need of repair, a problem made clear to all after hurricane Katrina. Providing Congress supplies the funds, $3.5 billion is approved for upgrades to their levees, as well as other flood regions in Louisiana.
Credit: Joe Nasvik
On Sept. 24, the Senate passed a $23 billion bill authorizing water resource projects. This includes $3.5 billion for work on New Orleans levees and other flood regions in Louisiana. But again, a future spending bill will be needed to provide the funds for these projects.
As one of the categories of our infrastructure, schools are near the top of the list of necessary funding to build, replace, or perform rehab work. The ASCE gives our schools a “D” and estimates that as much as $268 billion is needed to repair and upgrade them. Funding for schools is more complicated, however, because local, state, and federal funds are involved. Contractors specializing in school construction could be busy as monies are appropriated.
Where to go from here
There are many more questions than answers at this point, most of which have to do with where funds will come from to pay for the work. We might wish to blame the current administration and congress for the problems we now face. But it's clear that past governments chose not to address infrastructure issues either. That's why the present need is so great. The I-35W bridge collapse has forced the issue, bringing up the following questions without ready answers.
- Can we afford to spend $1.6 trillion on our infrastructure?
- Can we spend less in other areas of government in order to spend more for infrastructure repairs?
- Where will the money come from to do this work? Nobody wants increased taxes.
- The ASCE report card breaks infrastructure needs into 15 different areas. How should available funds be distributed?
- What should the balance be between repairs and improvements? Can we only allocate funds for repair?
However this problem is addressed, public awareness could force action. As the most used commodity in the world, concrete will play a strong role in the upgrading of our infrastructure. Hopefully it will be more durable and sustainable, making our infrastructure robust for the next 100 years.