Since 1928, a line on 178 pylons has stretched between Bickigen, near Wynigen BE, and Mettlen, near Eschenbach LU. The line was built at 132 kV and upgraded to 220 kV in 1951, and its 53 km cross the Emmental and the Lucerne hinterland. Swissgrid’s project page calls it “the oldest line in the Swiss transmission grid”. It has run every morning for 98 years, and nobody on the Mittelland had to think about it. That is the highest compliment infrastructure gets.

Replacing it starts with respect for the object. Swissgrid surveyed all 178 pylons, foundations, insulators and conductors included. The plan has two steps: a repair planned for February to October 2026 to extend operation by 15–20 years, then a new 220-kV line at the same voltage. Project leader Jullier gave the lifecycle reason in 2025: “Höchstspannungsleitungen haben eine Lebensdauer zwischen 80 und 100 Jahren.” The repair buys the years that federal permitting needs. The line crews and surveyors who read 178 foundations one by one are the quiet authors of the plan.

A corridor, not yet a line

On 19 October, Swissgrid presented the preferred corridor, recommended by a support group led by the Federal Office of Energy (BFE). It is 400–2,400 m wide and runs Bickigen → south of Huttwil → Willisau → south of Neuenkirch → north of Rothenburg → Mettlen, bundled from Rothenburg with the 380-kV Innertkirchen–Mettlen line. Neuenkirch and Rothenburg gain the most, because the old alignment leaves their settled areas. About 130 people came to the info evening in Wynigen on 2 November, neo1 reported, where Jullier put it plainly: “Was aber ändert, ist die Leitungsführung, also wo die Leitung durchgeht.”

←TODAY: a 1928 line, a planned stopgap repair, and a federal corridor up to 2.4 km wide open for comment until 8 January 2027.
→3012: the grid is read as a century-scale building, renewed bay by bay while it stays energised.
Fulcrum: the old line comes down only once the new one runs, so the spare path is kept until its successor carries the load.

Why it stays in the air

Every consultation brings the same question: why not bury it? Swissgrid’s Kabelstudie, written up by Jan Schenk on the Swissgrid blog in April 2025, answers with physics rather than preference: “Der Neubau von Erdkabeln ist im Schweizer Übertragungsnetz nur noch in sehr beschränktem Ausmass möglich.” A long buried AC cable behaves electrically unlike an air-insulated conductor, and the grid has to be compensated for it. Switzerland has 42 km of transmission cable built and 250 km more approved; largely undergrounding the grid would add about CHF 1.4 bn in compensation costs, according to the study. RTE International validated the work, and ETH confirmed it for the BFE.

The trade-off is plain. A cable takes the mast out of the view but adds equipment, cost and repair time to the whole system; an overhead line keeps the system simple and puts the pylon in the landscape. Stricter limits on electric and magnetic fields also mean the new masts will be “ein bisschen höher”, Jullier said.

The consultation runs from 30 November 2026 to 8 January 2027, and the Federal Council decides in mid-2027. Planning approval follows in 2029–2030, construction in 2031–2034 and dismantling of the old line in 2035 — all assuming no court proceedings. As PAZ’s Two Clocks piece set out, Swiss grid projects often take 15 years or more from plan to wire. neo1 headlined its report: “Das Projekt ist ein Marathon, kein Sprint.”

On the building site, the corridor is a band across parcels, Zonenpläne and Gestaltungspläne from the Bernese stretch to Rothenburg, and it stays a band until the Plangenehmigung fixes the pylons. A Bebauungsstudie drawn today may meet a mast footprint in 2031.

Atelier: An office with active parcels between Wynigen and Eschenbach cannot treat this as background noise. The corridor is a planning fact now, even though the exact pylons are not. The Monday move: assign one person to import the published corridor map into the office’s Archicad or Rhino site template as a locked layer, and flag every live project that falls inside the 2.4 km band.

Hack: See why field limits push masts upward by computing how a conductor’s magnetic field falls off with height. Take the simplest model, a single straight conductor with B = μ₀I / 2πr, and an illustrative current, not the line’s rating. Real three-phase bundles partly cancel each other, so the binding figures come from Swissgrid’s own calculation under the NISV.

import math
mu0, I = 4e-7 * math.pi, 1000   # I in A, illustrative only
for h in (20, 30, 40):            # conductor height above ground, m
    print(h, "m:", round(mu0 * I / (2 * math.pi * h) * 1e6, 2), "µT")

Doubling the height halves the field at ground level. That one line of physics explains the taller masts.

Download the corridor map, overlay it on your site model, and file any comment before 8 January 2027.