Inveraray to Port Ann overhead line and substations project heads for the finish line

With all new-build towers now topped out and the offline overhead wiring complete, the Inveraray to Port Ann project team continues to make excellent progress and are on track to fully complete the commissioning of the new protection and control schemes and fully energise the new build line next month.

The existing Inveraray-Crossaig overhead electricity transmission power line was installed back in the 1950s and, after a long service life, is reaching the end of its operational life. The new replacement line is being built in two phases, is one of the most significant electricity network projects in the region in decades, reinforcing the transmission network to ensure a safe and secure supply of electricity is maintained for the communities it serves and transmitting renewable generation to areas of demand. 

With over 750,000 manhours spent to date by a workforce of over 250 at the peak of construction, SSEN Transmission’s delivery partner Balfour Beatty has now completed 100km of new and upgraded access tracks, 74 piled foundation sites and 55 conventional foundation sites to enable the erection of 129 new overhead line towers along the 40km route.

Despite making excellent progress, the project has had to overcome several challenges along the way, including the remote location and high elevation that left it susceptible to some very challenging extremes of weather, including lots of rain, heavy snow and even a risk of wildfires. However, it was the global pandemic which brought the biggest challenge, pausing the project in March 2020.

Classified by Government as an essential project, the project team worked together to review the way work was carried out, how they travelled, and accommodate the workforce within the local communities. Work was able to recommence following a full review of operating procedures and methods and social distancing measures were adhered to across the project site.   

In recent weeks the team have been focused on the safe delivery of the remaining activities which must all be completed under circuit outages, including the completion of primary plant modifications at Port Ann GSP and protection and control commissioning at five substation sites along the route.

Project Manager, David Fraser said: "When you reach major milestones, such as the topping out of the final tower and completing the offline overhead wiring, it helps to bring extra focus to reflect and fully appreciate the efforts of the project team, that are key to making the project a success. Reaching this milestone is a testament to the positive efforts of everyone working on the project, from the team on-site every day, to those supporting the project remotely."

“Projects of this scale are always a challenge, not only the remote location and the often-unforgiving Scottish weather but working throughout a pandemic that has brought unprecedented challenges and changes to the way we work. By working closely with Balfour Beatty and our supply chain we have been able to adapt and continue to deliver on time, cost and quality "

Looking ahead to next month, David said: "With all 129 towers now complete and only two short spans left to wire under outage we are now targeting successful completion of substation commissioning and delivery of the challenging protection scheme, to ensure we are ready for full energisation in July whilst also continuing to optimise the delivery of the remaining dismantling and reinstatement activity. So, it is important that we maintain the same enthusiasm and focus at this key stage of the project."

Meanwhile on phase two of the Inveraray to Crossaig project, enabling works, including tree felling are now underway to facilitate construction of the access tracks required to facilitate the construction of the new tower foundations.

Once complete, the project, will initially operate at 132kV with the capacity to be upgraded to 275kV in the future, forming a key part of SSEN Transmission’s Argyll 275kV strategy, which will see the network in the region reinforced to enable the connection of up to 600 MW new renewable generation, playing a key role in the transition to net-zero emissions.