69kV Overhead to Underground Conversion

Realtime engineered the relocation of a 69kV transmission line for a large highway expansion project. All utility facilities in the area were to be relocated underground.

Project Scope:

  • Work with existing old paper P&P line information and P-DOT survey information to install (2) riser structures and (2) splice vaults for approximately (1) mile of 69kV underground
  • Size cable and conduits appropriately to thermal conditions
  • Design (2) non-standard guyed “I-beam” riser structures
  • Design (2) non-standard splice vaults
  • Develop pulling tensions through installed conduits
  • Work closely with cable manufacturer for proper installation and grounding
  • Develop all construction specifications for equipment and installation


This relocation project involved already highly congested utility and transportation facilities. The design area was squeezed on a prohibitively narrow strip of land between a large waterway, highway, and railroad. Adverse space constraints included maintaining access requirements for semi, truck, and railroad traffic, in and out of a very busy manufacturing district area.

Design requirements included accommodating for multi-ton loads of coal and material, to be driven on soil, directly adjacent to the transmission line poles, foundations, and vaults. Due to adjacent waterways, soil borings and geotechnical requirements were significantly more challenging.

As a result of the complexities of the highway expansion project, systems coordination efforts between contractors necessitated stringent communications amongst all stakeholders. The combination of designing in a physically congested, high traffic area, while meeting aggressive timeframes and budget constraints, allowed Realtime the opportunity to provide valuable design solutions to the Client.