When the Los Angeles Bureau of Street Services needed to pour a 4000-foot bike path connecting an existing path in Burbank, Calif., to the North Hollywood arts district, it abandoned traditional wood forms in favor of reusable metal forms and a truss screed that simplified finishing.
Because wood forms can be used only a limited number of times and are difficult to clean, the city decided to try Base Line heavy-duty forms from Milwaukee-based Metal Forms Corp. The 10-gauge steel forms incorporate box-type stake pockets with wedges, eliminating nailing and allowing quick vertical positioning without the need to pull nails. They also feature full-height end connections that easily attach the 10-foot form sections and provide full-depth alignment with a sturdy, reinforced joint.
The 16-foot-wide path was placed on a 98%-compacted, 4-inch-thick crushed aggregate base. The city purchased 4 inch forms, but for this project they needed a 6-inch thickness, so workers set them on blocks to support the screed and provide the added height. Typically, the crew set the forms one day and poured the next.
“A crew of 12 worked best, with five people in front of the screed placing the concrete and pulling the wire mesh up; two people running the screed; and five more behind the screed running the bull float, cutting the edges and joints, and doing the final finishing and brooming,” says street services supervisor Dennis Martin Jr. The crew used Metal Forms' Speed Screed Cruiser vibrating truss screed to strike off, consolidate, and finish the concrete.
A construction joint was placed every 10 feet and an expansion joint every 200 feet. A sawcut joint was used to divide the path into bicycle and pedestrian lanes. For further definition, the finish was broomed longitudinally for the pedestrian portion and transversely for bicycles. Crew member Roy Ponce developed a longitudinal broom to finish along the path's length without walking on the fresh concrete. Sections were colored to form decorative end caps at each end of the path as well as at two intersections.