Six precast concrete panels, each measuring 11 feet tall, 53 feet long, and weighing 42,000 pounds, put the finishing touches on a new bridge built across the Milwaukee River by Lunda Construction Co.
Although the job was bid using the panels, this approach reduced what would have certainly been weeks of hand work to achieve the same look by making the façade by mounting individual stones.
The new bridge, owned by Milwaukee County and the Wisconsin Department of Transportation (WisDOT), replaced a decades-old bridge that had occupied the same site.
The bridge carries the scenic Milwaukee River Parkway and Oak Creek Bike Path over the Milwaukee River.
Lunda Construction Co., Black River Falls, WI, won the $1.45-million job via the normal WisDOT bid lettingsystem.
Sigma Development, Inc., Milwaukee, was the state's representative providing on-site consultation andinspection.
According to Lunda's project manager, Laremy Sacia, the project called for demolition of the existing bridge, and construction of a longer and slightly wider bridge that retained the historic look of the original Lannon stone structure.
Lunda began work in February of this year, and completed the project in time for Labor Day weekend.
The project specifications called for the use of precast concrete façade panels to re-create the Lannon Stone look, so the new bridge would retain the aesthetic appeal of its predecessor and match a nearby bridge.
Lunda began its work by demolishing the existing 54-foot-wide, 72-foot-long bridge. The demolition included not only the superstructure, but also the abutments. All of the demolition waste was trucked away for recycling and reuse in other projects.
As Lunda demolished the original bridge, it gave samples of the stones to Karlson Forming Specialists, Amery, WI, for use in making the casting and stamping forms needed to re-create the stone look on the new structure.
Karlson used the stones to make the 4-foot by 8-foot rubber forms that Lunda later used to stamp the stone look into the piers and that Crest Precast Inc, La Crescent, MN, used to form the six 11- by 53-foot arched façade panels that finish the sides of the structure.
After the old bridge had been demolished, Lunda excavated the banks at each end of the site and added stabilizing riprap so the area could accommodate more flow during times when the river runs high, such as the spring thaw.
As a result, the new three-span, cast-in-place, slab-deck bridge will measure 159 feet long instead of the original72 feet.
In addition, the new bridge was built 60 feet wide, instead of 54 feet, to accommodate a bi-directional bicycle lane.
Work on the two in-river support piers started with construction of a three-sided sheet-pile cofferdam to contain sediment. Lunda excavated into the river bottom and cast the two piers of standard concrete. The formliner was attached to Lunda's pier forms, so when they stripped the forms, the concrete had the look of the original bridge.
That work was followed by the abutments and cast-in-place deck, which were constructed using conventional forms. In all, the bridge structure required 1,230 cubic yards of cast-in-place concrete.
When Lunda had completed forming and pouring the bridge structure, the formliner it had used to construct the sides of the superstructure was sent to Crest Precast in La Crescent, MN, just across the Mississippi River from La Crosse, WI.
There, Crest's craftsmen combined the formliner that Lunda had used along with others supplied by Karlson so the precast arch would match the original bridge's stone facade.
The panels were reinforced with epoxy-coated steel and post-tensioned to 24,800 psi with six tensioning cables each.
Each of the six façade panels was transported from the casting plant to the job site on its own flatbed trailer truck, then up-righted and lowered into place along the bridge side using a lattice-boom crawler crane.
Each arched panel was constructed to match the arch of its corresponding section of bridge. Each panel sits on beam seats and is secured to the bridge structure by steel plates and rods.
A crew from Hi-Boom Erectors, Black River Falls, WI, helped Lunda's crew with the installation.
All six panels were installed in a total of two days.
After the panels were installed, Lunda completed the parapet walls by pouring a stone-look cap that covered both the top of the parapet and the top of the façade panel.
Payne and Dolan, Inc., Waukesha, WI, finished the job by paving 2 inches of polymer-modified asphalt atop the concrete bridge deck. The polymer-modified asphalt protects the concrete deck from water and salt, without requiring use of an underlying membrane.
Says Sacia, “This entire project went smoothly from start to finish, thanks to experienced crews and excellent coordination between all the companies involved.”