Mississippi River’s Bridges
At 2,320 miles long, the Mississippi River is the fourth longest river in the world, originating in Minnesota and flowing south to the strategically important town of New Orleans. Throughout the vital waterway’s travels, dozens of bridges span it, carrying people and goods across the significant waterway.
The bridges that span the Mississippi River vary, ranging from cable-stayed bridge structures to continuous truss bridges. As a result of the large amount of bridge crossings, the Mississippi River is one of the most heavily traveled inland waterways in the United States, with both commercial and recreational traffic.
According to the U.S. Army Corps of Engineers, there are 59 bridges that span the Mississippi River. Of these, 48 are highway bridges, nine are railroad bridges, and two are footbridges. The oldest bridge is the High Bridge, which was built in 1876 and spans the Kentucky-Tennessee section of the Mississippi River. The most recently built bridge is the Greenville Bridge, completed in 2010, which crosses the Mississippi at the Mississippi-Arkansas state line.
The most famous bridge that spans the Mississippi River is perhaps the St. Louis Gateway Arch, located in downtown St. Louis, Missouri. The 630-foot tall stainless steel sculpture is an iconic sight, and the view from the observation deck at the top is breathtaking.
Crossing the Mississippi River comes with its own unique set of challenges. According to bridge expert Rich Kafura, the Mississippi’s vast width, the frequent flooding and the corrosive marshlands account for the River’s unique and complex engineering needs. Technology-wise, construction of the bridges is mostly conventional, but they must be designed and constructed with maximum flexibility and strength to account for the environmental changes.
In addition, the bridges must be built to account for seasonal swings in river traffic as well as accommodating commercial, recreational, and fishing boats, all of which can be several stories tall. The construction of bridges that meet all of these demands is no small feat.
Impact of Bridges on Economy
From an economic standpoint, the bridges that span the Mississippi River are incredibly valuable. By cutting the time, money and frustration associated with navigating the lengthy 2,320 mile voyage of the Mississippi, the bridges have greatly accelerated the movement of goods and people between the states that border the River.
The benefit of the bridge crossings on commerce is obvious. Each bridge is a time-saver that can dramatically reduce the cost of producing and moving goods—especially if the goods are traveling from one side of the River to the other. For example, according to the Financial Times, the four lane Interstate 35 bridge, completed in 1988, decreased the time for a four-hour drive on the Great River Road to just a few minutes. This has led to an increase in economic activity in the affected states.
Bridge engineering is a complex art, requiring an in-depth knowledge of the river dynamics and other environmental factors. It is through the skill of the engineers and their appreciation of the Mississippi River’s unique characteristics that make the dozens of existing bridges a reality.
The contributions of the existing bridges to the economic development of the area are obvious. The bridge crossings now offer an efficient, safe and cost-effective commerce link between states, drastically reducing the time and money needed to move goods and people between the banks of the River. According to the U.S. Army Corps of Engineers, the bridges on the Mississippi are providing an estimated $490 million in annual transportation benefits.
Environmental Benefits
In addition to the economic benefits, the bridges also bring environmental benefits. Given the length of the River, without the bridges, there would be a much greater reliance on motorized shipping as the primary means of crossing the Mississippi, leading to more air and water pollution. But with the greater availability of bridge crossings, crossing the River doesn’t require using boats and other forms of motorized transportation.
The bridges have also come with positive social impacts. Tourists and locals alike now have the opportunity to cross the Mississippi quickly and efficiently, meaning people in both states have easier access to the natural beauty and attractions of the region. This has created a boost in tourism, which has also helped local economies.
Drawbacks of Bridges
Despite the many advantages that bridges have brought to the region, there has been criticism in some quarters about the bridges’ impact on the environment. Some experts have noted the effects of bridge construction on the shorelines and wildlife habitats. Additionally, a few bridges have suffered particularly severe damage from floods, adding to the environmentalists’ criticism.
Additionally, the cost of building bridges has been cited as a major factor in the environmental impact of bridge crossings. The 2007 I-35 bridge collapse in Minneapolis is one example of the potentially huge cost of bridge failures. It took three years and more than $250 million to repair and replace the shattered bridge.
Nevertheless, as the economic and environmental benefits of bridge crossings continue to be realized, more bridges are likely to be built in the future, including ones not just across the Mississippi River, but across other major rivers as well.
Mississippi River Bridge Projects
Projects for bridge crossings across the Mississippi are constantly in the works. One such project, the Harahan Bridge, is an upcoming bridge project in Memphis, Tennessee. Currently, the bridge will feature bike and pedestrian lanes, but the plans are to convert one of the automobile lanes to a rail line as well. This project will provide an important link in the historic and strategic Ohio River River Loop.
The Illinois Department of Transportation is currently planning the I-74 Bridge Replacement in the Quad Cities area, a major project scheduled to be completed in 2020.
In addition to these projects, the Louisiana Department of Transportation and Development is currently working on a major bridge project in New Orleans, the Huey P. Long bridge expansion, scheduled for completion in 2019. In all, the project is anticipated to cost over $1 billion and is likely to be one of the largest bridge projects ever undertaken in the United States.
The BNSF Railway is also planning multiple projects across the Mississippi River, including a proposed bridge in Martin, Minnesota, and another in St. Paul, Minnesota. The Minnesota-based railroads are looking to upgrade their infrastructure, and the Mississippi is a major focus for the company.
Mississippi River Traffic
Due to the large number of bridges that span the Mississippi, the River sees considerable traffic. Both commercial boats and recreational boats can be seen travelling the River, with activity picking up in the summer months. Navigational aids such as buoys and signs have been installed to help guide boats down the River.
Vessels navigating the Mississippi River usually carry a variety of cargo, ranging from grains to coal, petroleum and other products. This cargo is then offloaded at the ports located along the River. Major ports on the Mississippi include the ports of New Orleans, Baton Rouge, Memphis, St. Louis, and Vicksburg.
The many bridges also bring foot traffic to the area as people cross the River on foot. In some areas, people cross the River in boats and ferries, as the waterway is wide and unnavigable in some places. Additionally, the River boasts a number of recreational activities, such as watersports and fishing.
Safety Concerns
Frequent flooding is one of the unique challenges that bridges spanning the River must face. The Army Corp of Engineers notes that the majority of bridges on the Mississippi are operated at less than full capacity during flooding, although some bridges have permanent heights above typical flood stages. In some cases, the bridges have even required temporary closure due to dangerous flooding.
It is for this reason that bridge operators must be especially aware of the flooding potential that exists on the Mississippi, and bridge operators must be prepared to close the bridges quickly if necessary. To help mitigate the safety risks associated with flooding, navigation systems and weather alert systems have been implemented on the bridges.
The sheer size of the Mississippi River combined with its many bridges make it an especially important piece of infrastructure. The bridges have led to increased commerce, tourism, and recreation in the area, while also bringing environmental and safety benefits. As bridges continue to be built, the role of the Mississippi River as an enabler of commerce and recreation will continue to be felt for years to come.
