Mayor Chris Beutler today said the Antelope Valley trails in Union Plaza are closed from "N" to "Q" streets because of problems with cracking concrete surface material on the bottoms of the four bridges above the trails. The trails were closed Tuesday after a piece measuring about 18 inches across and several inches thick fell off the bottom of the "O" Street bridge.
"This is totally unacceptable," said Mayor Beutler. "Because these bridges are part of Antelope Valley, a signature project for our City, we understand the public will take an interest in this and will be concerned. That concern is justifiable and is shared by my administration. These are new bridges over a public park, and public safety is our top priority. The trails in the park will remain closed until we can be assured that the issue is resolved and it is safe for pedestrians and bicyclists to use the trail."
The bridges on "N", "O", "P" and "Q" streets are safe for vehicle and pedestrian traffic. The bridges opened to traffic between July 2007 and October 2009.
Public Works and Utilities staff first noticed the cracking on the "Q" street bridge. At that time, they also noticed other areas where the surface layer had broken off, and the supporting steel was exposed. When the concrete was originally stained on that bridge, the exposed steel also was stained, so it appears that this cracking occurred during construction, and the contractors had not patched the concrete before the stain was applied. Staff said those areas may have been damaged by a backhoe when crews excavated under the bridge, which was previously built by another contractor.
Engineers from Parsons Brinckerhoff have tested for hollow areas in the concrete on all four bridges and found areas on the bridges'edges near the steel conduit used for electrical wiring for the bridge lights. There was some indication that water may have gotten into parts of the conduit, and the cracking could have been caused by the water freezing and expanding in that conduit. All the cracking has occurred on the edges where the lighting conduits were installed.
"In the short term, we are focusing on two issues — one is finding the cause," Beutler said. "The second is providing a temporary solution so the trails can be reopened. Once we determine a cause, we will be able to determine who is accountable and how we make permanent repairs."