Palmer Engineering’s Bridge Design Wins Award
KY (April 20, 2006) – Raccoon Creek Bridge in Pike
County, KY, designed by Palmer Engineering, recently received
the 2006 Grand Conceptor Award by the American Council of
Engineering Companies (ACEC). This award is the highest
honor given at a State level. The bridge design was entered in
the national level competition in Washington, D.C. and was
recognized as a finalist.
The bridge, actually a pair of twin bridges over the Raccoon Creek
Valley, is part of the new alignment of US 119. The steep terrain,
curving roadway, and crowded valley made for a true test of engineering
innovation and will provide the residents of Pike County a tremendously
improved route to Charleston, WV.
The new corridor will replace the existing winding, steep, two-lane
version of US 119 with a safe, modern, four-lane, limited-access
expressway. Access to schools, fire stations, police services
and hospitals will be improved. Additionally, the economic development
of the region will be significantly enhanced. Manufacturing and
shipping businesses that rely on trucking will be attracted by
the efficient road system.
The bridge, which is owned by the Kentucky Transportation Cabinet
(KYTC) Pikeville District, was built by Bush and Burchett, Inc.,
a subcontractor to Bizzack Inc.,
the beginning of design, the Raccoon Creek Bridge posed
numerous design and construction challenges. The valley
floor, 200 feet below the bridge, was already home to Raccoon
Creek, a railroad, a coal tipple, various small roads, and
private residences. These physical elements left little
room for the piers necessary to support the bridge, making
it necessary for the designers to stretch the span lengths
of the bridge. The longest of the three spans crossing this
1275-foot valley is nearly 400 feet.
The geometry of the roadway also presented considerable
challenges. Traditionally, bridges of this size would utilize
I-shaped steel girders. But such girders, combined with the tightly-curved
road would have caused excessive rotation of the bridge deck.
This design would have led to driver discomfort and deck cracking.
The designers at Palmer Engineering and the Transportation Cabinet
decided to try a design previously unused in Kentucky: Steel box
girders. These girders will provide far greater resistance to
this rotation than I-girders.
steel girders 200 feet above a valley floor with limited
room for cranes also presented problems. To facilitate construction
at such heights, temporary supports at the top of the piers
were suggested by the designers. These “angel wings”
proved to be a very effective and economic aid in the construction
of the girders.
The complexity of this project demanded the collaboration of all
involved parties throughout the process. While the obstacles initially
appeared almost overwhelming, engineering innovation, teamwork,
and determination resulted in a solution that will serve the people
of Pike County, KY for generations to come.