Discover the Longest Bridge in Michigan — a 5-Mile-Long Monster
Michigan is home to one of the longest suspension bridges in the United States: the massive Mackinac Bridge. Also fondly referred to as the “Big Mac” and the “Mighty Mac,” this architectural wonder is designed to withstand the forces of nature that batter it with relentless fervor. Spanning five miles of open water, the Mackinac Bridge is the longest bridge in Michigan and connects the state’s Upper and Lower Peninsulas. Let’s take a closer look at this incredible architectural wonder!
Where Is the Mackinac Bridge?
Stretching above the Straits of Mackinac is the Mackinac Bridge.©Craig Sterken/Shutterstock.com
The Mackinac Bridge on Interstate 75 in Northern Michigan stretches above the Straits of Mackinac. It connects the Upper Peninsula and the Lower Peninsula of the state. At the south end of the bridge is Mackinaw City, with St. Ignace at the bridge’s northern end.
Construction of the Mackinac Bridge
Although the Mackinac Bridge officially opened up to the public on November 1,1957, the vision for it began many decades earlier. In the 1880s Mackinac Island was becoming a popular tourist destination, with the newly designated Mackinac National Park (now Mackinac Island State Park) and the Grand Hotel on Mackinac Island. However, to reach the park and hotel, visitors had to travel by boat, which was difficult in the winter. So, in 1888, the Grand Hotel’s board of directors gathered to discuss the need for a bridge to transport guests over the straits.
The Michigan legislature also discussed the idea of building a suspension bridge to connect the state’s Upper and Lower Peninsulas. Rather than build a bridge, however, the Legislature created a ferry service for crossing the Straits in 1923. But within just five years the ferry service had so much traffic it was barely able to function!
So, the Legislature returned once again to the idea of building a bridge above the Straits of Mackinac. Plans projected that such an endeavor would cost around $30 million (the equivalent of $377 million in 2021). Even though both the U.S. Army Corps of Engineers and President Roosevelt endorsed it, obtaining funding for such a large project was a challenge.
Designing the Mackinac Bridge
Two lanes of the bridge are an open-grid design, allowing airflow.©Kenneth Keifer/Shutterstock.com
It was not until the 1950s that Michigan could secure funds for the construction of the bridge, which would now cost $93 million (the equivalent of $779 million in 2021). The Mackinac Bridge needed to be flexible and have the ability to constantly move with changes in wind, temperature, and weight.
David B. Steinman took on the role of designing Michigan’s new bridge. He took into account the mistakes of the Tacoma Narrows Bridge, which collapsed in 1940 due to strong winds. In his theoretical analysis of suspension-bridge stability issues, Steinman suggested that future bridges would need deep stiffening trusses and open-grid roadways to make them steady against high winds.
The Mackinac Bridge is built with a stiffening truss to reduce wind resistance and a road deck shaped like an airfoil to provide lift in crosswinds. The center two lanes are open grid so air can flow upwards and balance out the lift, making it safe when winds reach up to 150 miles per hour.
Under high wind, the deck at the center span might move as much as 35 feet east or west. But the bridge doesn’t swing like a playground swing — it just slowly moves in one direction, based on the force and direction of the wind. Once the wind stops, the weight of the cars driving across the bridge help to bring it back to its original spot in the middle.
The Mackinac Bridge officially opened to the public on November 1, 1957. It took just over three years to complete, and tragically, five men died during its construction. Although myths and legends abound, their bodies are not embedded in the concrete of the bridge. There is, however, a memorial dedicated to them near the northern end of the bridge.
How Long Is the Mackinac Bridge?
The Mackinac Bridge is the 27th longest main-span suspension bridge in the world.©KyleHohler/Shutterstock.com
Measuring a suspension bridge is a bit complicated. Traditionally, we measure them based on their main span length, or the distance between the two towers. The main span of the Mackinac Bridge is 3,799 feet. That makes it the 27th longest main-span suspension bridge in the world.
Another common measurement is the suspended length, or the length of the bridge deck supported by only the cables. The Mackinac Bridge’s suspended length is an astounding five miles long! That makes it the longest suspension bridge in the western hemisphere by suspended length.
The bridge is 54 feet wide. Only motorized vehicles are allowed on it, with the exception of the Mackinac Annual Bridge Walk. The Annual Bridge Walk is a tradition going back to 1958, held each year on Labor Day. This is the only day of the year that you may walk the entire length of the five-mile-long Mackinac Bridge!
Wildlife Under the Mackinac Bridge
The waters under Mackinac Bridge are home to a diverse array of wildlife.©ehrlif/Shutterstock.com
Michigan’s Mackinac Bridge is suspended over the waters of the Straits of Mackinac, a 70-mile body of water that connects Lake Michigan and Lake Huron. The Straits of Mackinac are rich in biodiversity. Hundreds of islands pepper this area, with far-reaching shorelines that stretch for miles. The landscapes in and around the Straits of Mackinac include lush boreal forests and deciduous woodlands teeming with life.
The wetlands and reefs in this area also act as a haven for sportfish. Lake whitefish are common, and the DeTour Reef and Spectacle Reef are home to populations of lake trout who lay their eggs in the rocky areas here. The Straits of Mackinac are also crucial for the annual migration of waterfowl, songbirds, and raptors. During the late fall and early winter, an impressive flock of over 7,000 redhead ducks can be spotted here! In addition, the Mackinac Straits Raptor Watch holds the record for the highest number of hawks sighted in a single day anywhere in the world — an astonishing 5,300 red-tailed hawks have been seen here in just one day!
In addition to the wildlife beneath the Mackinac Bridge, there are also 13 shipwrecks in this area. Spanning an impressive 148 square miles, the Straits of Mackinac Shipwreck Preserve encompasses Wilderness State Park to Cheboygan, stretching up to the northern edge of Mackinac Island. This vast area is divided into two parts by the Mackinac Bridge. Within the preserve, there are 13 shipwrecks that were brought down by ice, fog, and narrow shipping lanes. Experienced divers can visit these shipwrecks and other underwater formations in this area.The post Discover the Longest Bridge in Michigan — a 5-Mile-Long Monster appeared first on AZ Animals.
