ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.
Issue link: http://www.aspiremagazinebyengineers.com/i/297024
Eugene, Ore., is one of the leading regional areas for non-motorized commuting. A bicycle- and pedestrian- friendly transportation system is a way of life in this medium-sized university town located at the south end of the W illamette Valley. Not surprisingly, the residents of Eugene consider natural space very important and seek environmentally friendly solutions to problems. As a result, the city of Eugene boasts an extensive path network. The city, bisected by the Willamette River and a four-lane highway, has promoted bicycle and pedestrian commuting by building paths near the river, connected by a series of bridges at strategic points. In north Eugene, Delta Highway runs roughly parallel to the east bank of the river. Historically, bicycle and pedestrian traffic for this 2-mile-long stretch was restricted to crossing the highway at two busy interchanges. The Delta Ponds Pedestrian Bridge, c o n s t r u c t e d i n 2 0 1 0 , p r o v i d e s a k e y c o n n e c t i o n b e t w e e n t h e neighborhoods east of Delta Highway and the popular riverbank path system to the west of the highway. The bridge skirts the south edge of the Delta Ponds city park and natural area, a backwater pond system hydraulically connected to the Willamette River. The sweeping structure not only provides a much-needed safe crossing of the highway for bicycle and pedestrian traffic that is compliant with the Americans with Disabilities Act (ADA), it also offers a very popular and pleasant vantage point for viewing the surrounding ponds. Structural Form The primary feature crossed by the Delta Ponds Pedestrian Bridge is Delta Highway. The bridge also crosses a slough immediately west of the highway and skirts one of the larger ponds in the Delta Ponds system. Keeping a light footprint on the ground dictated a bridge with a total length of 760 ft and out-to-out width of 18 ft 11 in. The width inside handrails is 14 ft. Because it crosses the highway, the bridge occupies a visually prominent position in the landscape. Trees in the area are seldom taller than 50 ft, and buildings are no taller than two stories, so a properly proportioned structure would blend into this surrounding rather than overpower it. Spans had to be short, allowing slim columns and a shallow deck. profile DELTA PONDS PEDESTRIAN BRIDGE / EuGENE, OREGON BRIDGE DESIGN ENGINEER: ObEC Consulting Engineers, Eugene, Ore. CoNSuLTING ENGINEER: Jiri Strasky, Greenbrae, Calif. PRIME CoNTRACToR: Mowat Construction, Clackamas, Ore. PRECASTER: Knife River Prestress, Harrisburg, Ore., a PCI-certified producer CoNCRETE SuPPLIER: Eugene Sand and Gravel, Eugene, Ore. PoST-TENSIoNING CoNTRACToR: DYWIDAG-Systems International uSA, Long beach, Calif. by Andrew Howe, OBEC Consulting Engineers Delta Ponds Pedestrian Bridge Extending a Sustainable Transportation Network The Delta Ponds Pedestrian Bridge provides a safe crossing over a busy highway. All photos and drawings: OBEC Consulting Engineers. 20 | ASPIRE , Spring 2012 Book_Spr12.indb 20 4/3/12 9:18 AM