Structural

While employed at KCI Technologies in Raleigh, North Carolina, Mr. Parnell worked on the design of Ramp C over Mallard Creek, in the Charlotte area, a seven-span prestressed concrete bridge on a heavily skewed alignment. Heavy skew complicates a prestressed girder bridge at every stage: bent caps and end bents run at an angle to the girders, girder lengths and bearing layouts vary across each span, deck reinforcement and expansion joints must follow the skew, and load distribution to the girders departs from the simple case assumed for square bridges. The design carried those effects through the superstructure and substructure detailing.

At Hobbs, Upchurch & Associates, Mr. Parnell served as design engineer on the roadway and bridge work for the Piedmont Triad Regional Water Authority’s Randleman Lake project. Randleman Lake is a reservoir on the Deep River in Randolph and Guilford Counties, created by the Randleman Lake Dam to supply drinking water to the greater Greensboro area. Impounding the reservoir raised the water surface over existing roads and stream crossings, requiring five roadway realignments and the re-elevation and rebuilding of five bridges. He designed the realigned roadways and the replacement bridges, setting new grades and structure elevations above the reservoir pool and carrying the crossings on new alignments where the original routes were to be inundated.

Two further bridge assignments were on military installations in North Carolina. The greenway project at Marine Corps Base Camp Lejeune, described under Transportation, included four waterway crossings carried on simple bridge structures for pedestrian use. At Pope Air Force Base, a wetland crossing was designed as part of a munitions-depot development, carrying the access route across jurisdictional wetland with a structure sized to the crossing and detailed to limit disturbance to the wetland beneath it.