Big Thompson River bridges facts for kids

Four special bridges over the Big Thompson River in Larimer County, Colorado have an interesting history. They were built a long time ago, in 1933 and 1937. These bridges were strong enough to survive a huge flood in 1976, known as the Big Thompson Canyon Flood.

At one point, all four bridges were listed on the National Register of Historic Places. This is a special list of places in the United States that are important to history. However, two of the bridges were later removed from this list because they changed too much.

The four bridges are:

• Big Thompson River Bridge I, located on US 34 near Estes Park, Colorado
• Big Thompson River Bridge II, also on US 34 near Estes Park
• Big Thompson River Bridge III, on US 34 near Loveland, Colorado
• Big Thompson River Bridge IV, also on US 34 near Loveland

All these bridges were designed as a special type called a "camelback pony truss bridge." This means they had a unique shape, like a camel's hump, and the main support structure was on the sides of the road, not above it. The Colorado Department of Highways designed them, and a company called Midwest Steel & Iron Works built the metal parts. Bridges III and IV were put together in 1933, and Bridges I and II were built four years later in 1937.

These bridges were considered important because they showed how transportation worked in the past. They also had a special design that was well-preserved for a while. Bridges I and II were taken off the National Register in 2010. This usually happens when a historic building or structure is torn down, or if it changes so much that it loses its original look and feel. Bridges III and IV have been changed a lot, and their original "camelback" shape is gone. But they are still on the National Register for now.

Bridge I: Near Estes Park

This bridge was built in 1937 near Estes Park, Colorado. It had special walkways for people to use on the outside edges. These walkways were "cantilevered," meaning they stuck out like a shelf. Bridge I was added to the National Register of Historic Places in 2002. However, it was removed from the list in 2010. 40°22′49″N 105°28′19″W / 40.38028°N 105.47194°W / 40.38028; -105.47194 (Big Thompson River Bridge I)

Bridge II: Also Near Estes Park

This bridge was built in 1937 and was very similar in design to Bridge I. It was also located near Estes Park, Colorado. Like Bridge I, it was listed on the National Register of Historic Places in 2002. It was also removed from the list in 2010. 40°23′22″N 105°27′49″W / 40.38944°N 105.46361°W / 40.38944; -105.46361 (Big Thompson River Bridge II)

Bridge III: Near Loveland

The Big Thompson River Bridge III was built in 1933 near Loveland, Colorado. It was a "camelback pony truss" bridge, designed by the Colorado Department of Highways. The metal parts were made by Midwest Steel & Iron Works. Lawrence Construction Company built the bridge.

The bridge was about 134 feet (41 meters) long, with its main section spanning 100 feet (30 meters). It had a steel frame and a concrete deck with asphalt on top. Around 1980, safety barriers called "flex-beam guardrails" were added to the bridge's entrances.

This bridge was considered important for its engineering design. It was one of the few remaining bridges of its kind in Colorado. Even though the original truss structure is now completely gone, the bridge remains on the National Register. A photo from 2012 shows that the old truss design has been replaced by a modern bridge. 40°24′54″N 105°11′42″W / 40.41500°N 105.19500°W / 40.41500; -105.19500 (Big Thompson River Bridge III)

Bridge IV: Also Near Loveland

The Big Thompson River Bridge IV was also a "camelback pony truss" bridge. It was built in 1933, just like Bridge III. This bridge is also located near Loveland, Colorado.

Today, a modern bridge stands at this spot. The original truss structure is completely gone, as shown in a 2012 photo. Even though its historic look is gone, this bridge also remains listed on the National Register of Historic Places. 40°25′7″N 105°10′47″W / 40.41861°N 105.17972°W / 40.41861; -105.17972 (Big Thompson River Bridge IV)

Images for kids

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  A 2012 photo of the modern replacement for Bridge III. The original truss structure is gone.

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  A 2012 photo of the modern bridge at the site of Bridge IV. The original truss structure is completely gone.