Projects

Dunnagan Road Bridge over
East Chickamauga Creek

Whitfield County, Georgia

Dunnagan Road is a rural two-lane roadway with light traffic volume. The existing Dunnagan Road Bridge over East Chickamauga Creek is 32’ wide measured between copings and a 30’ clear width including 2-10’ lanes with 5’ shoulders. The existing bridge is a two span bridge with 37’ spans and was originally constructed in 1922 as a single lane concrete arch bridge. The bridge was eventually widened to the south in 1979 to facilitate two lanes of traffic. The widened portion has similar foundations to the original structure but the superstructure consists of W18 x 60 rolled steel beams and a concrete deck. The existing bridge was designed to support H-15 loading but due to excessive deterioration of the bridge deck under the asphalt overlay, the bridge has been posted for an inventory capacity of H-10.

The new bridge will be a three-span structure with 30-foot end spans with a 60-foot center span comprised of AASHTO Beams for the superstructure and drilled shafts for the substructure. It will be designed in accordance with AASHTO LRFD using HL-93 loading. The proposed typical section will be 35’-3” measured from coping to coping and 32’-0” between gutter lines in accordance with the GDOT Bridge and Structures Design Policy Manual. The new design will take into account seismic loading for seismic zone 2.

As a result of the bridge replacement the proposed profile elevation increased almost 3-feet at the bridge. The approach roadway design was performed so that cost and environmental impacts were minimized the horizontal alignment shifted south approximately 10-feet so that the bridge could be constructed on a tangent. Super elevation was used to minimize the curve radii in an effort to reduce the amount of impact to the adjacent wetlands and stream. As a result, TVA and the USACOE did not require permits for the construction of this project.

Dunnigan Road Bridge
before redesign