As early as 1986, the former EOS, which later became Alpiq, announced its intention to build a UHV line linking Romanel to Chippis in three sections including Chamoson-Chippis. In January 1997, a public enquiry into a first project was undertaken by the Federal Inspectorate for Heavy Current Installations (ESTI). This project, having prompted numerous complaints as well as negative initial assessments from certain federal and cantonal authorities, was suspended and then restarted with the agreement of ESTI at the stage of a detailed project without the need for a preliminary study.
In June of 2002, Alpiq presented a new project and submitted an approval request for technical plans to ESTI, followed by a second request in 2006 to cover changes requested during the approval process, which specify the construction of a 380-kV line between Chamoson and Chippis and, amongst other things, combining the lines of the Force Motrices Valaisannes (FMV) and SBB on the same tower support. On 11 June 2007, ESTI forwarded the file to the Swiss Federal Office of Energy (SFOE) for the next steps of the authorization process.
In June of 2010, the SFOE approved the plans submitted by Alpiq in 2002 along with the changes that were later requested, and authorized Alpiq to build the section between Chamoson and Chippis in the form of an overhead line. Many appeals were then filed with the Federal Administrative Court (FAC), and then with the Federal Tribunal, which confirmed the urgency of the line, of the overhead line corridor, and the request of the FAC to study the possibility of further reducing nuisance noise from the 380 kV line.
On 19 January 2015, the SFOE granted permission to build the line. The Swiss Federal Administrative Court rejected the appeal in December 2016. With its ruling on 1st September 2017, the Federal Court has provided ultimate confirmation of the Swiss Federal Office of Energy's planning approval decision made on 19 January 2015. The construction work on the overhead line between Chamoson and Chippis in the canton of Wallis began. The line was put into service on 30 September 2022.
The commissioning of the new line does not mean the end of the project. The construction permit for the line requires Swissgrid to dismantle 322 pylons and 90 km of existing overhead lines on the Rhône plain. Priority will be given to the dismantling of the old 220 kV Chamoson – Chippis line, which crosses a number of residential areas. Dismantling work will begin in 2023 and is expected to be completed by 2027.