Crest Precast Inc., La Crescent, MN, welcomed visitors to Minnesota by placing the Minnesota Monument signs.
Working with Joel Ecker of Global Specialty Contractors, Burnsville, MN, the work consisted of the fabrication of 12 entrance signs and two exit signs with skirting delivered to all major highway entrance locations. Erection sites included Dresbach, St. Croix, Taylor Falls, Albert Lea, Bigelow, Beaver Creek, Moorhead, East Grand Forks, Grand Portage, International Falls, and two sites in Duluth.
The precast concrete signs presented several challenges in fabrication and erection. The conceptual design was first arrived at through a contest from the University of Minnesota Landscape Architecture Department and Minnesota Department of Transportation (MnDOT). Amy Bauer of Roseville submitted the design for the signs and landscaping.
Manufacturing followed after an intense 10 weeks of final design in surface texture and color. Ten different samples were cast to verify the exact texture as perceived by the MnDOT Principal Landscape Architect Jim Reierson and Project Engineer Paul Juckel.
Form liners were cast specifically for the project by Buck Scott of Scott Form Liners, Denver, CO. The liners depict the various surfaces of the state with northeast Minnesota.
Concrete testing was intensive as state and independent testing were required to insure the architectural monuments met state requirements of 5,000 psi, and 6.5 percent air content to achieve the expected usage of 50 years. Tom Strieff and Karl Anderson from the Rochester MnDOT Materials Lab monitored testing and curing. Braun Intertec verified all testing.
The size and weight of the sign are impressive at 46 centimeters (18 in.) thick by 4.9 meters (16 ft. 3 in.) wide by 8.9 meters (29 ft. 4 in.) high and 46 centimeters (18 in.) thick.
The size of the sections challenged Crest Precast on several fronts: the first, to engineer a lifting and handling system for the 29,700-kilogram (66,000 lb.) elements that would allow stripping and handling of this architectural element; second, to safely ship and erect the sections.
The over-width measurement of more than 4.8 meters (16 ft.) dictated night movements thru Metro Twin Cities with police escorts. LLL Transport of Lakeville, MN, moved the signs using a 45-metric-ton (50 ton) triple-axle trailer, while Crest provided escorts to the sites. The state of Minnesota was crossed north to south and east to west as some sites were 450 miles from the La Crescent casting plant.
Crest Precast, with structural engineer John Wernert P.E. of Arnold and O’Sheridan Engineers, Madison, WI, designed a back brace spreader beam similar to a trailer frame to bolt directly to the back of the signs. This system eliminated patching lifting holes and simplified erection in the field.
Once the precast section was vertical, the bottom half of the spreader beam was removed allowing the sign to be placed into a C.I.P. foundation pocket 2.4 meters (8 ft.) deep.
The sections were reinforced with a double layer of No. 6 epoxy rebar 15.24 centimeters (6 in.) o.c. with stirrups for wind loads and handling.
Once on site, Global Specialty Contractors placed the elements with a 108- to 158-metric-ton (120 to 175 ton) crane into the foundation, grouted in the base section, placed precast (pre-stained) skirting and installed the red aluminum “Minnesota” letters.
Crest Precast Inc. received the National Precast Concrete Association 1999 First Place Award for the building and site amenities and the Landscape Architecture Award for its involvement in fabrication and finish design.
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