services

Overhead Line Design

Overhead line engineering is at the core of what Groundline does.

We plan optimal alignments for transmission lines across varied terrain, balancing engineering, land access, environmental, cultural, and constructability constraints. Our process draws on aerial imagery, LiDAR, site visits, and constructability assessments to define feasible corridors that reduce risk and ease future maintenance. 

What We Do

From new build “greenfield” routes to major upgrades of existing “brownfield” lines. Our overhead line design services span voltages from 11kV to 500kV. Our teams combine structural and electrical design expertise in-house, using PLS-CADD and the Power Line Systems suite to model complete systems, support construction readiness, and deliver optimised, constructible, standards-compliant solutions for network owners, developers, and independent connection providers worldwide.

Route Selection & Feasibility

  • Line route selection, optimum structure spotting, and constructability assessment — heavy vehicle access, construction lay-down areas, and machine setup sites.

  • Environmental constraints assessment — allowable easement widths, vegetation clearance, existing buildings and infrastructure, landowner and heritage constraints.

  • Ground-based and UAV line route surveys.

  • Front-End Engineering Design (FEED) for tenders and feasibility studies.
Electrical & Structural Design

  • Conductor and earth wire selection.

  • Electrical design — conductor spacings, earth wire shield angles, insulation coordination.

  • Insulation design and outage performance modelling.

  • Earthing design.

  • PLS-CADD modelling — line design optimisation, sag/tension analysis, conductor tensions, structure heights and foundations.

  • Conductor vibration and galloping design.
Line Upgrades & Augmentations

  • Increasing ground clearances.

  • Reconductoring and OPGW installations.

  • Line cut-ins and augmentations.

  • Wind and solar generation connections.
Construction Documentation

  • Line schedules.

  • Construction staking schedules.

  • Material lists.

  • Stringing schedules.

  • Damper placement charts.

value proposition

Overhead Line Design You Can Build, Operate, and Maintain

Our engineers have designed overhead lines in some of the most demanding operating environments in the world, from remote terrain and extreme weather conditions to densely populated urban corridors and sensitive heritage landscapes. That depth of experience means we don't just produce compliant designs; we produce designs that work in the real world, built for the people who have to construct and maintain them.

We integrate structural and electrical analysis from the outset, eliminating the interface risk that arises when these disciplines are managed separately. Our PLS-CADD models are built to be transferable, documented, version-controlled, and formatted for ongoing use by your asset management team  so you retain a live, maintainable design record long after project close-out.

The Result: Predictable, Reliable, Defensible Outcomes
  • Optimised Designs: Structure spotting, conductor selection, and foundation sizing resolved in a single integrated model, reducing cost and programme risk.

  • Constructability Built In: Designs that reflect real installation conditions, reducing RFIs, site queries, and construction delays.

  • Transmission-Grade Rigour: Standards discipline applied at every voltage level, regardless of project scale.

  • Transferable Deliverables: PLS-CADD models and documentation your team can use, update, and build on.

  • Fast-Track Capability: Proven ability to deliver complex overhead line projects under urgent programme constraints without compromising quality.

Our Experience

Overhead
Underground
Brownfield
Greenfield
NGED/WPD HS2 132kV EHV Cable & OHL Modernisation

Optioneering, Feasibility, Detailed Design & Contractor Design Design, CAD, Consulting & Geotechnical Investigations

Henderson Marsden

Overhead Line Design, Structure Design

Connecting Green Generation (Harapaki Wind Farm)

Overhead Line Design, Line Route Design, Electrical Design

USA PSE&G Reconfiguration

Managing the greenfield Cabling Design and the interface between the Utility and cable installation supplier.

SPEN 132kV Limekiln Wind Farm Connection - Wood Pole

Detailed Design & Construction Design construction CAp drawings inc temp works

USA PLS-CADD Overhead Cable Design

Drafting and PLS-CADD Services, Verifications and Peer reviews. Overhead Line Design

NGED 33kV Pickford Green Customer Grid Connection

Optioneering, Feasibility, Detailed Design & Geotechnical, design, CAD and SI

Our Work

Sunderland Diversion - 275kV-400kV – National Grid (UK)

Sunderland City Council's International Advanced Manufacturing Park required the diversion of the existing ZZA 275kV overhead line occupying the development site.

Three existing L2 towers needed removal and replacement with seven new L8c towers, with the conductor system upgraded to 2x500mm² AAAC Rubus and a Keziah-equivalent OPGW earthwire.

Read More

Let's Get to Work.

Discuss your needs with one of our experts.

Ben Liebing

Business Development Manager

Ross Quiney

Business Development Manager

Luke Brown

General Manager – Overhead Line Engineering