The existing single-circuit Colfax-Highland 69kV line #1 needs to be upgraded between Highland and Logan’s Ferry substations. This upgrade is one of the projects outlined in Duquesne’s Transmission Enhancement Plan (DTEP). It is the most economic way to implement Duquesne’s plan to improve reliability for its customers in this area.

The 345kV line is required to complete construction of a 345kV “backbone”, a main cross-system transmission connection, that will join the generation located in the western area of Duquesne’s system to the generation and load located in the northeastern area of its system.

This single-circuit 345kV line is required for the following reasons:

• Implement Duquesne’s overall strategy to eliminate 69kV as a transmission supply voltage.
• Eliminate single-contingency overloads of the Colfax-Highland 69kV lines.
• Provide an alternative supply to the northeastern area of Duquesne’s system to prevent transmission overloads and deterioration of area voltage.
• Provide the second independent 345kV source to serve the metropolitan Pittsburgh load. The two 345kV sources will be Collier and Logan's Ferry substations.
• Provide long term support for future load growth by allowing access to generation in the western area of Duquesne’s system via the 345kV transmission.
• Maintain reliable operations and improve contingency capabilities in the northeastern area of Duquesne’s system.
• Increase reliability to the Highland area, including Penn Hills and Plum boroughs.