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Cedar Rapids, Iowa 52401
Time Machine: A pontoon rail bridge
The world’s first, and longest, one crossed the Mississippi at Marquette
In the early 1800s, navigating across the Mississippi River between Marquette, Iowa, and Prairie du Chien, Wis., meant a trip on a raft or a boat.
John Lawler, vice president of the McGregor and Sioux City Railway Co., created a barge ferry to take railcars across both channels of the river at that spot, charging a fee for each car.
Rails were run down to the river where four or five freight cars would be loaded on a barge. The barges ferried the rail cars across the river where they were reattached and continued on their journey. When winter came, temporary bridges were built across the ice. In spring, the bridges were removed.
After doing that for a couple of years, Lawler figured there had to be a better way.
In 1873, one of Lawler’s employees, Mike Spoettle, came up with the idea of lashing barges together, putting rail tracks on top, and creating a railroad bridge that spanned the river channel.
The result was the first — and largest — pontoon railroad bridge in the world that could be opened in one minute and closed in three.
The bridge was 8,000 feet long, so more than a mile. A regular railroad bridge was built with pilings in the shallow part of the river on each side. Then the barges — or pontoons — would fill the gap, forming an unbroken track.
The pontoons each had a boiler and steam engine that powered the huge chain that swung the pontoons into place and then reopened them to allow river traffic to proceed.
The cost was far less than building a rail bridge to span the river.
River pilots liked it
Engineers across the country soon began checking out the novel floating bridge, and pontoon bridges were built the following year in Clinton, Dubuque and Sioux City.
The pilots who plied the river on their boats favored the pontoon bridges.
“It is as safe, at least, as a stationary bridge,” the Sioux City Journal reported, “and pilots on the Mississippi say they do not have one-twentieth the apprehension in approaching it that they do in nearing the enormous stone piers of ordinary bridges. It consists of two parts. It is partly fixed and partly movable.”
Lawler patented the idea and operated the bridge as a private enterprise, charging the railroads $1 for each rail car that crossed. After making a fortune in tolls, Lawler sold the bridge to the railroad.
When Lawler died in 1891, his invention was known throughout the U.S. and Europe. Only a few years before his death, Russian engineers began to investigate using pontoon bridges in that country.
Updating the bridge
The pontoon barge for the east channel of the Mississippi was replaced in August 1914. The new span was 210 feet long, 58 feet wide and 7 feet, 8 inches high. It was made of 3,058 tons of lumber, 175 tons of iron and 68 tons of creosote.
The west section, leading to Marquette, was replaced a few years later.
James Doyle of Marquette was responsible for keeping the floating rail track in the main channel in working order. He kept the tracks level by removing or replacing blocks to adjust the height of the bridge.
“When the pontoon was put in the main channel here, Lawler gave me the job of tending it,” Doyle said. “He was beside me the first day when the first train went over. I’ll never forget that day.”
Doyle had 50 years on the job in 1924, when the pontoons were again replaced. He tried to retire in 1933, but was back at it the next year.
in 1930, steam engines dredged the riverbed when the river level fell so low the Marquette pontoon rested on the river bottom. The next year, the barge had to be lifted onto a framework to replace its bottom. A temporary bridge took its place until repairs were made.
Final years
In 1941, the pontoon bridges’ kerosene lanterns were replaced with electric lights. But the signal used by boats to alert the rail bridge to swing open stayed the same — one long whistle, one short whistle, followed by a long blast.
In 1955, electricity replaced the steam boilers and engines that moved the pontoons.
Six years later, in 1961, rail traffic had declined to the point the bridge was dismantled and the pieces towed to La Crosse, Wis.
Somewhat ironically, a National Guard pontoon bridge was proposed in 1981 when the 7-year-old Highway 18 bridge over the Mississippi between Marquette and Prairie du Chien was closed because of structural defects. Instead, an 18-passenger ferry took passengers from Marquette to the mid-river island, where they were shuttled by van into Prairie du Chien.
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