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/306849
The bridge's seven girder lines form four continuous spans that cross Monument Creek and a rail yard with a 148-ft main span. The flared alignment was used to accommodate the variable deck widths. Officials in the City of Colorado Springs, Colo., wanted to create a bridge that would relieve congestion and provide the major access to the downtown area, as well as project an image that allowed the structure to serve as a welcoming image for the city. To achieve these goals, designers created a bridge with a spliced, post-tensioned, precast concrete superstructure that features innovative prestressing layouts and variable cross- sections to accommodate a unique erection scheme. The approach allowed the project to be completed in only 10 months, including the demolition of the existing bridge that was necessary before construction could begin. The bridge's seven girder lines form four continuous spans that cross Monument Creek and a rail yard. The girders vary in spacing from 13.2 ft to 22.8 ft to fit the deck width, requiring the girders to be kinked at closure joints. The bridge's design matches the lanes from a new I-25 overpass and provides three continuous lanes of traffic into downtown, plus two lanes that cross I-25 into west Colorado Springs, two left-turn lanes to give freeway access, a n d s i d e w a l k s a n d b i c y c l e l a n e s in both directions. The bridge deck's profile transitions from the at-grade roadway in the downtown area to a combined crossing over the rail lines and Monument Creek. It then blends into the I-25 ramps and overpass. City officials wanted to improve user safety by providing a more gradual vertical curve to increase the sight distance on the bridge. This severely limited the vertical depth of the structure to ensure adequate clearance over the rail yard. In addition, the railroad wanted to limit foundations and construction access in the rail yard. A main span of 148 ft 3 in. was agreed upon to provide enough clearance for all current and future active tracks. Only one pier was placed in the yard, isolating an obsolete storage track. Access was limited to construction equipment, and no temporary supports for the girders were allowed in the yard. profile BIJOU STREET BRIDGE / COLORADO SPRINGS, COLORADO ENGINEER: Summit Engineering Group Inc., Littleton, Colo. PRIME CONTRACTOR: Rockrimmon Constructors Inc., Englewood, Colo. PRECASTER: Encon Bridge Co. LLC, Denver, Colo., a PCI-certified producer AWARDS: Best Bridge With Spans Between 75 and 150 Feet, 2008 Precast/Prestressed Concrete Institute Design Awards Unique precast concrete superstructure features variable cross sections to help finish complex structure in 8 months Innovation Speeds Construction Bijou Street Bridge over MonuMent Creek by Gregg A. Reese, Summit Engineering Group Inc. Designers of the Bijou Street Bridge in Colorado Springs, Colo., created a spliced, post-tensioned, precast concrete superstructure that features innovative prestressing layouts and variable cross-sections to accommodate the unique geometric requirements and erection scheme. 18 | ASPIRE , Summer 2009 P R O J E C T ASPIRE_Summer09.indb 18 6/5/09 1:51:02 PM