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.

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.

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.