The Wally Road Scenic Byway is a winding vehicle route through rural Loudonville, Ohio, a village located between Columbus and Cleveland. A project to replace an old steel bridge along the byway over the Mohican River was recently finished. What’s unique about the project is that the nondescript trestle-style structure was replaced by an eye-catching, old-fashioned, covered wooden bridge – with a modern twist.
The new bridge retains the charm of an old-style covered bridge but is actually made of a combination of wood and steel. The 100-year bridge’s style and composition and the resulting construction effort were no small undertaking, but now complete, it is befitting the scenic surroundings — the Mohican River, over which the bridge traverses, is Central Ohio's best recreation area, with more than 1.5 million visitors every year.
ALL Erection & Crane Rental, flagship yard of the ALL Family of Companies, provided heavy lift equipment for a series of lifts, primarily involving the large trusses used to construct the new bridge.
The bridge’s structural support is provided by Pratt trusses, assembled on site by Kokosing Construction, the project’s general contractor. Pratt trusses are triangle-shaped, with diagonal supports that slope toward the center of the bridge (they were introduced in 1844 as an effective way to cover long spans of 250 feet or more; this bridge is 300 feet).
The most recent lift work required only a single crane after an initial run of dual picks. For the single-crane picks, ALL used a 770-ton Liebherr LTM 1650-8.1 all terrain crane with 171 feet of main boom in the T5Y configuration, meaning Y guying was added to boost lift capacity. On one action-packed workday, the 1650, set up on a flat bank of the river below, lifted two Pratt trusses, set a half-dozen 50-foot floor beams, and several roof trusses.
Liebherr’s VarioBallast® was key to setting so many large pieces so efficiently. It allows the ballast radius to be infinitely adjusted using a hydraulic slewing mechanism. “The operator can constantly transfer and adjust the counterweights depending on the weights of each piece and the radius required for each pick,” said Rick Cope, project superintendent for Kokosing. “Seeing what these large specialty cranes are capable of is impressive.”
The Pratt trusses weigh 168,000 pounds and measure 160 feet long. For lifting, three spreader bars were hooked to the crane, and nine men handled tag lines attached to the ends of the truss. Once set in place, the trusses were temporarily braced before setting the next.
The 1650 was assembled the day before the work, and all lifts were completed within 10 hours.
Earlier in the year, ALL brought in two Liebherr ATs to set the first two trusses in a complex series of maneuvers. A 550-ton Liebherr LTM 1450-8.1 joined the Liebherr LTM 1650-8.1 to bring these trusses from the ground to their final resting places on the bridge abutments.
The bridge opened to vehicle traffic over the Labor Day weekend.