Permanent Raising of the US 41 Bridge over US 301

Описание: This project was the result of a need to provide increased vertical clearance at the US 41 bridge over US 301 which over the years has been hit multiple times by vehicles exceeding the existing clearance. Generally, FDOT has completely demolished old bridges and constructed new structures to accommodate such improvements. However, the Department considered the cost and time savings by implementing the jacking method used in this video.

The US 41 (SR55) over US 301 (SR43) Bridge needed to be adjusted 15 inches vertically. How was it done? By using the same process used when replacing existing bridge bearings - which requires minimal raising of the bridge, just a few inches. The bridge in this video was raised to a new permanent elevation.

Before construction, detours were set up, rerouting traffic for nearly three months. The approach road was closed during the new construction and jacking phase, using the off and on-ramps with law enforcement assistance for traffic maintenance.

The equipment utilized included heavy duty hydraulic jacking equipment - 100 ton jacks and jacking beams (2 feet by 10.5 feet) and (2 feet x 13.5feet) and the Enerpac Synchronous lifting system to digitally manage the operation. An operator entered the data for each jack on a control panel similar to the one shown.

The bridge was cut into manageable sections prior to lifting by saw-cutting one joint down the centerline, two at the bent lines and the existing piers, reducing the weight of the four span bridge into eight lighter pieces.

Pedestals were formed over the old ones using cold joints. Doweling into the existing pedestal, adding rebar for the concrete, forming the pedestal extension, and placing new concrete was a challenge alone besides lifting over 200,000 pounds of steel and concrete in the span itself. The concrete was placed into the forms with little clearance. Once the strength requirements were met and forms were removed, it was time to set the bridge on its higher pedestal.

The bridge was supported by locking collar jacks, steel pedestals and shims during jacking. Once it reached its final elevation it was supported by the newly constructed pedestals. New neoprene pads were placed under the concrete beams. The contractor also installed shear blocks to provide lateral stability at the piers.

The northbound bridge was raised first, using five beam lines at a time to raise the bridge to its target elevation. The bridge was jacked in nominal 1 to 3 inch increments. This process is slow and tedious, requiring constant load balance checks and elevation checks. Video has been sped up to show how the span is advanced. The jacking beams were raised using two 100 ton hydraulic jacks under each jacking beam. Individual jacks next to each of the five beams were used to raise the end bents.

The end spans at the end bents were jacked to the required increment before jacking the piers. The contractor installed five hydraulic jacks and pedestals/shim extensions with neoprene pads against the beams’ flanges and end diaphragms. This operation was followed by jacking the end span slightly over the required increment so shims could be added to the diaphragm support, locking the jack collars when increment was reached.

The piers were jacked one end of each span at a time. The end span was raised slightly over the required increment so that shims could be added to the diaphragm support and the jack collars were locked when the increment was reached. Pedestals and shims were installed under the jacking beam and the bridge was lowered to the new supports.

Once the northbound bridge reached the target elevation, the contractor raised the southbound bridge following the same procedure.

You can see the final elevation of the bridge, with the new clearance of 15 feet, 5 inches.

We hope you have enjoyed viewing this video. Through the use of innovation to address an old issue the FDOT Office of Construction has again shown why it is a leader nationwide and demonstrated its own Vision by being the best in providing safe and efficient facilities for the traveling public.