Big Chickies No. 2 Bridge Auction Road (T-875) over Big Chiques Creek Replacement

Lancaster, Pa.

Since the 1920 erection of this historic concrete tied arch bridge, degradation had set in and slowly lowered the maximum allowable load to a low of 5 tons. In 2005, Rettew Engineering was hired to design a replacement structure. Maintaining the aesthetic and the contextual sensitivity of the original bridge was of the utmost importance in the new design. In addition to this was the necessity to meet new loading, flooding, sight, and safety constraints. The most difficult of these additional requirements was the need to increase the width of the new bridge to two lanes and withstand the increases in deck torque and flexure with the arches. The engineers choose precast concrete as the means for meeting these challenges because of its blending of art, engineering, and function. Utilizing the full advantages provided by precast concrete, in one night the contractor placed the arches, braced the arches against deadmen, supported the deck formwork from the bottom chord of the arches, and released the temporary erection post-tensioning. Additionally, precast concrete eliminated the need to place any formwork or scaffolding in the creek below, saving time and money and limiting environmental impact. With the help of precast concrete, the new bridge easily withstands the new loads while maintaining the original’s structure strong aesthetic appeal.

Precaster: Newcrete Products, Roaring Spring, Pa.
Website: www.newcrete.com

Engineer of record: RETTEW Engineering, Lancaster
Website: www.rettew.com

Deck area: 2200 ft²
Bridge length: 72 ft
Bridge longest span: 72 ft
Bridge width: 34 ft 4 in.
Precast concrete components:

2 precast concrete arches with the following dimensions:
Bottom chord = 20 in. x 31.5 in. x 72 ft 0 in.
Arched top chord = 20 in. x 24 in. x 72 ft 0 in.
Webs = 12 in. x 13 in. x varies
Total truss height = 11 ft 7.5 in.