Mayor Chris Beutler today announced that design and construction issues contributed to the July 21st collapse of a pedestrian bridge in Wilderness Park. The Mayor also announced that a new inspection program for pedestrian bridges in the City is now in place.
"This unfortunate incident prompted us to take a closer look at all our pedestrian bridges and how we monitor their safety," Beutler said. "We made this a priority. The new program will assure residents and visitors that they can safely use these bridges."
About 20 youths and counselors from the Wilderness Nature Camp were on the bridge when it dipped 12 to 15 feet in the middle, but only minor injuries were reported. Initial engineering investigations by Speece Lewis Engineers, Inc. indicate that the structure was not properly designed for the load limit stipulated in the design code.
While the youth and counselors were on the bridge, the walkway hand rail buckled and moved sideways several inches. The movement of the hand rail resulted in a loss of structural support, which caused a transfer of additional weight through the support cables into the support towers at each end of the bridge. The support towers were attached to wooden abutments, and Speece Lewis determined they were inadequately designed and constructed. The increased load on the support towers caused the wooden abutments to fail. Once the support towers were free to move, they rotated toward the creek under the weight of the collapsing walkway.
The bridge is about a half mile north of Saltillo Road and was built in 2003. The City took ownership of the bridge only after construction was complete and it was approved by the design engineer.
The Parks and Recreation Department plans to remove the bridge in the next few weeks. The replacement of the bridge is under consideration.
Immediately after the collapse, Mayor Beutler directed the City Public Works and Utilities Department to visually inspect the remaining 11 trail bridges in Wilderness Park. Most of those bridges are over smaller tributaries. The collapsed bridge and one in the middle of the park were blocked off. On July 23rd, a 65-foot bridge over a tributary between Densmore Park and Salt Creek was closed due to bank erosion. The three bridges remain closed.
Lincoln Parks and Recreation has compiled a list of all pedestrian bridges along trails and walkways and on public golf courses. Of the 98 bridges, nine are over streets or highways and are inspected every other year by the City Public Works and Utilities Department and the Nebraska Department of Roads.
The City will conduct a visual inspection of the remaining 89 bridges by quadrants on a four-year cycle. The 68 bridges that are more than 20 feet in length will be inspected by certified bridge inspectors on a six-year cycle.
Inspections will be conducted in the late fall and winter when crews can best see the bridges and surrounding area. The first round of inspections will begin this year.
The cost of the program is being determined. Funds will be included in the Parks and Recreation operating budget for the 2010-2011 fiscal year. In future years, the funding source will be Parks and Recreation maintenance funds which come from cell tower fees. An additional amount will be added every year to remedy any issues found during the inspections.