Uplifting Overpass Project

Hydraulics Lift I-85 Bridges
Like other types of construction, highway work requires a can-do attitude. From estimating to execution, Archer Western Contractors uses that approach, so when presented with work on a stretch of Interstate Highway requiring raising 15 bridges, the company proved to be up to the task.

The work is on approximately 14 miles of I-85 about two dozen miles south of Atlanta, and it involves lane additions as well as raising grades and bridges by a nominal 20 inches.
Fifteen bridges are being raised; six northbound and six southbound mainline bridges, and three crossing bridges.
A new roadway is being placed on top of the old one, with the old pavement becoming part of the subgrade of the new paved interstate. The impetus for all of this is a combination of a need for greater vertical clearance above multiple railroad crossings and a new GDOT 17 foot minimum clearance requirement for side-road crossings.

Practice Makes Perfect
At this writing, three of the crossing bridges near Newnan, GA have been raised, with excellent results. Start-to-finish time restrictions (road closing-to-reopening) were imposed on all three—seven days for the first two and 10 days for the third. All were completed timely, and the third was reopened a day early.

“The actual jacking process took approximately 10 hours for the first bridge and seven hours for each of the last two bridges,” says Josh Blythe, Archer Western Assistant Project manager. “We were able to learn from the first bridge and found ways to make the second two bridge jackings a lot more efficient.”

The 44 jacks are powered by eight 1½ hp, 10,000 psi pumps with 10 gallon reservoirs.
The pumps include user adjustable relief valves, allowing operators to easily set working pressures. To retract the load return cylinders, Enerpac equipped each pump with a venturi valve. When actuated the venturi valve creates a suction on the hydraulic lines which causes the load return cylinders to retract.

Blythe says actual lift heights range from 19–27 inches on the first three crossing bridges.

Cylinders are supplied by Enerpac electric pumps through manifold-valve sets.

The load return type jacks incorporate lock rings for safety (note threaded cylinder)

Mainline Bridges
The line drawing on the following page, top, illustrates the sequence of steps for the mainline bridges. First, the inner
lane of each of the three-lane northbound and southbound bridges is demolished. Then a new 2+2 lane bridge is
constructed between the existing bridges. Finally, traffic is diverted onto the new center bridge, and the existing bridges are raised to the new height. All three bridges are then connected with closure pours.
In order to simultaneously lift all resting points, each bridge lift employed up to 44 Enerpac single-acting, 100 ton, 8-inch stroke jacks 

Cylinders are supplied by Enerpac electric pumps through manifold-valve sets.
The load return type jacks incorporate lock rings for safety (note threaded cylinder).
“In each case, once the existing bridge is jacked up and shored, the existing caps are demolished and rebuilt to the
required new height,” explains Blythe. “The existing columns do not get demolished or extended; the new cap is taller to support the new bridge height.”
Archer Western’s first venture into bridge-raising has indeed been an uplifting experience.
Mike Nudd is a Territory Manager for Enerpac Integrated Solutions (www.enerpac.com).
—    Photos courtesy of Archer Western






The major steps in widening and raising mainline bridges.
1) Cross-hatched portion of the North and
Southbound bridges are removed, changing
from two lanes each to one and a shoulder lane.
2) A new two-lane bridge is constructed at the
new height.
3) Traffic is diverted to the new bridge while the
old sections are raised to the new height and
finished with closure pours.

I-85 Facts
Interstate 85 traverses 664 miles of the southeastern United States, passing through Alabama, Georgia, South Carolina, North Carolina, and Virginia.
Along the way, it intersects with seven other Interstate Highways: I-65, 75, 20, 26, 77, 40, and 95.