Building bridges: U.S. 50 bridge reconstruction in Hamilton county continues

There are more than 25,000 bridges of all types and sizes in Kansas. KDOT is responsible for approximately 5,000 of these bridges. Each is important to the state's transportation system, allowing drivers to cross valleys, waterways, railroad tracks and other highways, as well as local roads and streets. 

Like bridges, bridge replacements come in a variety. Some replacements take months, while others take years depending on the type, size and location of the bridge. Some replacements require a complete shut-down of the bridge and detour during reconstruction.  Others may use a shoo-fly or temporary bridge very close to the original bridge to move traffic during reconstruction. Some bridges are completed by reducing the number of traffic lanes on a bridge, from two lanes to one lane or four lanes to two lanes, so that traffic continues on one half of the bridge at a reduced rate while the other half of the bridge is reconstructed. While this has its pros and cons as well, this configuration allows traffic to continue without a detour or the additional time and expense of a shoo-fly bridge.

This last option of reducing traffic on the bridge while it is rebuilt is new and is currently being used by Bridges Inc. of Newton to replace the U.S. 50 bridge approximately one mile west of the K-27 junction in Hamilton County.  Here is how one part of a bridge replacement works.

Step 1: Crews remove the south side of the bridge deck while traffic continues on the north side of the bridge.

Step 2: Bridge piers and supports are removed on the south half of the bridge so crews can rebuild the south half of the bridge.

Step 3: Piles and concrete piers provide the support for the bridge.  Piles or H-beams are driven approximately 17-feet into the ground (on this project) until they reach bedrock.  Crews then assemble the pier’s form around the H-beams.  This form is filled with concrete to form the pier. The first concrete pier shown above has been poured and the H-beams are visible at the top of the form. The second pier form has been built and is ready to be poured. 

Next, Crew members stand atop the pier form preparing to pour concrete for the pier using a drop bucket.

Step 4: Crews have poured the concrete for the pier and have begun to place beams as part of the falsework that will become the bridge’s deck.  Falsework is a temporary structure that, along with forms, will hold the liquid concrete that becomes the bridge’s deck until the concrete is set, cured and strong enough to support itself.

Above:  A Bridges Inc. crew member wraps the freshly poured pier in a “blanket” to protect it from the below-freezing temperatures expected overnight.