Case Study 14: SZ Route FEED study

SCOPE OHL Pre Tender FEED study - uprating
START / COMPLETION June 2020 – November 2020


The SZ Route is a 93 span 132kV Overhead Line made of PL16 Type Towers. It was due for reconductoring and modernisation in 2021. The route was made up of 132kV Lynx Phase and Earthwire and there was a desire to restring this line with Single Upas and 96 Fibre OPGW.

This route also had a planned customer loop in, loop out arrangement at tower 57 of the route which Groundline delivered the feasibility and detailed design for.

As the planned loop in, loop out works had a connection data of August 2021, WPD made the decision to tender both of these works at the same time to minimise the outage requirements on this line, and also enable Groundline to design the loop in, loop out point of connection based upon the replacement UPAS conductor.

In addition to the design, Groundline where required to LiDAR the route, undertake a walkover review for construction purposes, measuring accesses and identifying hazards, along with a non intrusive test and reporting of the foundations using TDR.


Groundline where instructed by a contractor to undertake the full construction design FEED study and loop in loop out design.

The 2 key deliverables associated to this project was to provide a feasible arrangement with 2 new towers to a provided sub station design, and a full FEED Study Modernisation Report which would be put into tender documentation for WPD go to market with. The FEED study allowed WPD to fix the cost of the bids from construction partners to remove any provisional sums due to unknown foundation upgrades, strengthening or clearance mitigation requirements.

The scope included the requirement to work closely with WPD Substation Design, to focus on both elements of the project. The operations the Groundline team had to perform in order to deliver the scope included:

• PLS-TOWER and PLS-CADD Modelling
• Structural Analysis, Strengthening and Design
• Scaffold Positions
• Temporary Works Identification
• Landowner Negotiation
• Clearance Reporting and Mitigation
• Geotechnical Analysis
• Foundation Design
• Insulator Drawings
• Wire Clearance Diagrams
• Profiles
• Non Intrusive Foundation Condition Assessments
• Walking hazard assessment
• Access walking and trackway measurements
• Vegetation clearance review
• Boreholes
• Reporting


Groundline offered a full turn key, site, survey and design package. WPD where provided information which allowed them to create a tender, free from the requirement for provisional sums.

In addition to the survey and design captured by Groundline in house. Groundline spent weeks on site walking the access routes and identfying hazards, vegetation clearance requirements, and testing of the foundations.

This information all fed into the FEED study which allowed WPD to create a tender free from the requirement of provisional sums. With the information Groundline provided, all requirements for upgraded steel, upgraded foundations, semi tension sets or over tensioning where costed for by the contractors pre tender, in the most competitive environment.

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