Deenergizing transmission facilities to accommodate construction tasks requires careful planning, often affecting the line design. In the age of rebuilding transmission, outages are shorter and more difficult to obtain. Implementing design components that do not require outages serves to reduce reliance on outage schedules and provide flexibility in the construction schedule, which may result in overall cost savings.
To reduce the reliance of foundation construction on the outage schedule, American Electric Power Co. Inc. (AEP) and DiGioia Gray & Associates LLC (DGA) co-developed a method to increase the construction productivity of drilled shaft concrete foundations during live line conditions. This method mechanically splices full-depth anchor bolt cages — so multiple, but shorter, sections may be set safely beneath energized lines. This unique foundation construction approach has enabled foundation contractors to install drilled shaft foundations successfully with limited overhead clearance to energized conductors and better meet project schedules.
For more information, read the cover story in the April print issue of T&D World magazine or check out the following photo gallery.
Note: Adam G. Bowland, a senior engineer in the transmission engineering group for DiGioia Gray & Associates LLC, also contributed to this story and gallery.