THE CONCRETE BRIDGE MAGAZINE

WINTER 2018

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.

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to be frustrating, particularly when attending large events with a specific start time. In addition, once parked in the four-level structure, pedestrians had to travel down to ground level, cross the north lot and a local street, enter the back of the building, and take an escalator up before finally reaching the building's Grand Hall. Union Station's m a n a g e m e n t w a n t e d t o i m p ro v e access from the parking structure to the building and make the pedestrian approach part of the overall visitor experience. Located at the west end of the Union Station building, the Carriage Pavilion and its roof structure were included in the 1999 renovation. This area was once used by horse-drawn carriages to drop off passengers at the Grand Hall. In more recent years, the Carriage Pavilion had been used by delivery trucks serving the post office within the building. As part of the expansion project, this area has once again become a passenger drop-off site, and it also allows vehicles to access the bridge and parking structure directly from the front of the building. The traffic crunch for major events has been alleviated with the additional entrance on the third level of the parking structure. Specific pedestrian needs have also been addressed with the new bridge s t r u c t u r e . T h e b a r r i e r- s e p a r a t e d pedestrian path is 10 ft wide to allow ample room for families with strollers visiting the attractions. Visitors can now park and walk into the Grand Hall at the same level, which has greatly improved the pedestrian experience. In addition, a 4-ft-wide overlook juts out from the path at the center of the bridge, to provide a location to stop and take in the 360-degree view of Kansas City. The span arrangement for the bridge was controlled by horizontal clearance to the local access road and was also set to frame the existing arches at the base of the Carriage Pavilion, resulting in spans of approximately 33, 33, 75, and 57 ft. Prestressed concrete box girders were selected for the superstructure system. These were preferred over steel girders or concrete I-girders because of their clean, low profile and because a "heavy" structure was desired to complement the aesthetic of the massive Union Station building. Also, because this bridge is located in an urban environment, Union Station's management required a "pigeon-proof" structure with no ledges, crevices, or other nesting spots that would attract birds. Traditional cast-in-place concrete diaphragms at the pier caps to fully enclose the ends of the precast concrete box girders were the cost-effective and clean-lined solution. Fabrication and Installation of Precast Concrete Components The 27-in.-deep, 48-in.-wide box girders were fabricated at a local precast plant. Eleven girders ranging in length from 31 ft 0 in. to 74 ft 1 in. were required for the project. The bridge design engineers worked closely with the precaster to simplify and economize the box girder design, such as duplicating strand UNION STATION KANSAS CITY INC., OWNER BRIDGE DESCRIPTION: Pedestrian and vehicular bridge with unusual geometry constructed using spread prestressed concrete box girders with precast deck panels and railings. The length of the four-span bridge is approximately 207 ft, the distance between the historic building and parking garage. STRUCTURAL COMPONENTS: Prestressed concrete box girders with 3-in.-thick precast, prestressed concrete deck panel forms, 15 precast concrete rail panels (193 linear ft total), 11 prestressed box beams (556 linear ft total), 43 prestressed panels (2300 ft 2 total), and precast concrete decorative pedestrian railing BRIDGE CONSTRUCTION COST: $1.2 million Cross section of bridge. Erection of a box girder in a tight space. ASPIRE Winter 2018 | 31

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