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/319569
Interstate 5 is a major transportation corridor that is parallel to the Pacific Ocean coastline and links California, Oregon, and Washington. Motorist traveling north from California cross the Siskiyou Summit in Oregon and descend into the Rogue River Valley and the cities of Ashland, Medford, and Grants Pass. Interstate 5 also parallels Bear Creek from Ashland to just north of Medford where the creek flows into the Rogue River. Medford is the southern gateway to the famous Crater Lake National Park. The South Medford Interchange (SMI) links I-5 and East Barnett Road and is only one of two freeway interchanges in Medford. The existing interchange did not meet current design standards and was severely congested during peak traffic periods. Projections of future traffic demands showed worsening congestion with levels of service far below reasonable driver expectations. T h e O r e g o n D e p a r t m e n t o f Transportation (ODOT) elected to c o n s t r u c t a n e w S o u t h M e d f o rd Interchange about 0.4 miles south of East Barnett Road. It eliminated I-5 access at East Barnett Road. Instead, Highland Drive, which runs north-south, would be extended south from East Barnett Road, curve west to I-5, and meet with the eastward extension of Garfield Street. The new interchange would then be at the Garfield Street and Highland Drive intersection with I-5. The South Medford Interchange improves the safe and efficient movement of goods, people, and services to the rapidly growing community. Design challenges T h e B e a r C r e e k G r e e n w a y a n d pedestrian-bicycle pathway are located just east of the interchange and then pass under I-5 just south of the project. The proximity of Bear Creek limited ramp access to the new interchange. Therefore, all traffic movements on and off I-5 had to be held close to I-5. ODOT selected a single-point urban interchange (SPUI) to minimize the right of way required and impacts to the existing neighborhoods, businesses, and sensitive environmental area. The SPUI improves the primary function of the interchange including safe and efficient travel, accommodating planned land use and growth, improving multimodal connectivity, and improving interchange o p e r a t i o n s . O D O T h a s p r e v i o u s experience with this type of interchange. It constructed a SPUI at the intersection of Market Street and I-5 in Salem, Ore., in the late 1990s. That SPUI was under I-5. The SMI SPUI, however, needed to be constructed above the I-5 alignment. A n o t h e r u n i q u e c h a l l e n g e f o r the designers was the need for a mechanically stabilized earth (MSE) island on the east edge of the interchange. This island incorporates four abutments: the main bridge over I-5, on and off ramps for I-5 northbound, and the Highland Drive Bridge spanning Bear Creek to the east. The island was sized and located to allow each of the four bridges to remain independent and provide a stable base to obtain maximum vertical bridge clearance with the smallest footprint. The existing bridges carrying I-5 over Bear Creek were replaced. The longest bridge over Bear Creek with a 172-ft-long span, replaced an existing bridge over Bear Creek on East Barnett Road. Other structures were required to span local creeks on the project. A total of 11 profile SOUTH MEDFORD INTERCHANGE BRIDGES / MEDFoRD, oREGoN BrIDge engIneer: H.W. lochner Inc., Salem, ore. generAL contrActor: Wildish construction co., Eugene, ore. precAster: Knife River corporation—Northwest, Harrisburg, ore., a PcI-certified producer by Keith Kaufman, Knife River Corporation—Northwest and Daniel J. McIntier, formerly with H.W. Lochner Inc. Interchange THE I-5 SouTH mEdford eleven bridges were required for the project This is a view looking south where Highland Drive crosses I-5 at the South Medford Interchange. Four bridges over Bear Creek are shown south of the overpass. All photos: Wildish Construction Co. 36 | ASPIRE , Fall 2010 ASP10-1704.indb 36 9/17/10 2:06 PM