Gotthard Base Tunnel

The Gotthard Base Tunnel (Gotthard-Basistunnel in German, galleria di base del San Gottardo in Italian) is the centrepiece of Switzerland's Neue Eisenbahn-Alpentransversale (NEAT) programme. Running 57.09 km / 35.47 mi between portals at Erstfeld (460 m / 1,509 ft) in canton Uri and Bodio (312 m / 1,024 ft) in canton Ticino, it is by length the world's longest railway tunnel and by overburden — up to 2,300 m / 7,546 ft of rock beneath Piz Vatgira — the deepest traffic tunnel ever built.

The structure consists of two parallel single-track tubes connected by cross-passages every 325 m / 1,066 ft, plus two underground multifunction stations at Sedrun and Faido that handle ventilation, track crossovers and emergency evacuation. Total excavation across main tubes, cross-passages, access adits and shafts reached 152 km / 94.4 mi. Maximum design speed is 250 km/h / 155 mph, with passenger services authorised at 200 km/h / 124 mph and freight at 160 km/h / 99 mph.

Client AlpTransit Gotthard AG, a wholly owned SBB subsidiary established in 1998, awarded five geographic construction sections to consortia including ARGE AGN (Strabag-led), Transco-Sedrun (Bilfinger/Implenia/Frutiger/Pizzarotti), and ARGE TAT (Hochtief/Implenia/Impregilo). The CHF 1.69 billion railway-systems contract went to Transtec Gotthard in April 2008. After completion, AlpTransit Gotthard AG was wound up and merged into SBB Infrastructure in April 2023.

Current costs reached CHF 12.2 billion (approx. USD 15.6 billion at the 13 May 2026 reference rate of 1 CHF = 1.28 USD), against a 1998 base-year estimate of CHF 6.323 billion. The tunnel was financed almost entirely from the federal FinöV fund, fed by the heavy-goods vehicle charge, a 0.1% VAT contribution and the mineral oil tax. It carries up to 260 freight and 65 passenger trains per day, cuts the Basel/Zurich-Milan passenger journey by roughly one hour, and is a critical link in the Rhine-Alpine TEN-T corridor between Rotterdam and Genoa.

Switzerland's 1980 referendum-driven Alpine Initiative committed the federation to shifting transalpine freight from road to rail. The 1882 Gotthard mountain railway, with its 26 per mille gradient and 1,151 m / 3,776 ft summit at the old Gotthard Tunnel, capped freight train weight at roughly 1,400 t / 1,543 short tons and required banking locomotives. A flat base-tunnel route — peak gradient 12.5 per mille, summit altitude lowered to 549 m / 1,801 ft — was designed to allow standard 2,000 t / 2,205 short ton freight trains hauled by a single locomotive, doubling line capacity, removing an estimated 1 million heavy trucks per year from Alpine motorways and cutting Basel/Zurich-Milan passenger times by about one hour to support cross-border integration with Italian high-speed lines and the EU Rhine-Alpine TEN-T corridor.

Each of the two single-track tubes has an internal diameter of about 8.83-9.58 m / 29.0-31.4 ft. Standard-gauge (1,435 mm / 4 ft 8.5 in) ballastless slab track is electrified at 15 kV 16.7 Hz AC. Maximum design speed is 250 km/h / 155 mph; authorised passenger speed is 200 km/h / 124 mph, freight 160 km/h / 99 mph. Cross-passages connect the tubes every 325 m / 1,066 ft. The Sedrun multifunction station sits roughly 800 m / 2,625 ft below the surface, accessed by two vertical shafts of 8 m / 26.2 ft diameter; the Faido multifunction station includes a 1.7 km / 1.06 mi underground emergency stop. Four Herrenknecht Gripper TBMs of 9.58 m / 31.4 ft diameter excavated the Erstfeld, Amsteg, Faido and Bodio sections; the squeezing Tavetsch intermediate massif beneath Sedrun was driven by drill-and-blast. Some 28.2 million tonnes / 31.1 million short tons of rock were removed, of which roughly one-third was processed on site into concrete aggregate and the rest reused to create new wetland islands in Lake Uri and a new bathing lake at Sedrun. Maximum in-situ rock temperatures reach about 46 C / 115 F, requiring large-capacity tunnel ventilation and cooling systems sized at 18 MW.

The Gotthard Base Tunnel raised the Rhine-Alpine corridor's freight capacity from roughly 180 to up to 260 trains per day and lifted maximum train weight from 1,400 t / 1,543 short tons (on the old mountain line) to 2,000 t / 2,205 short tons hauled by a single locomotive, reducing per-tonne transalpine freight cost. SBB reports the Basel/Zurich-Milan passenger journey is now around 3 h 17 min, roughly one hour faster than via the historic Gotthardbahn. The Federal Office of Transport considers the tunnel a cornerstone of the modal-shift goal set by Article 84 of the Federal Constitution, which targets a ceiling of 650,000 transalpine truck transits per year. The 17-year construction programme sustained an average of 2,400 jobs on site at peak (2008-2010). Cumulative current-price expenditure reached CHF 12.2 billion / approx. USD 15.6 billion at the 2026-05-13 rate of 1 CHF = 1.28 USD.

By design the tunnel supports Switzerland's road-to-rail modal-shift policy, with the Federal Office of Transport estimating savings equivalent to several hundred thousand truck transits per year across the Alpine arc. The flat profile cuts traction-energy per gross-tonne by roughly 40% relative to the 1882 mountain route. Spoil management was a centrepiece of the project: of 28.2 million tonnes / 31.1 million short tons excavated, around one-third was processed into concrete aggregate on site, and surplus material was used to create the artificial islands of the Reuss delta Neptun nature reserve on Lake Uri and a new bathing lake near Sedrun. Construction effluent and groundwater drawdowns were monitored under federal hydrogeological permits; tunnel inflow water above 30 C is heat-recovered for district heating at Erstfeld and for a tropical greenhouse project at Frutigen on the parallel Lötschberg axis.

The NRLA project was politically contested from inception. Voters approved the Bundesbeschluss on 27 September 1992 by 63.6% (with all 26 cantons concurring), but the financing FinöV fund needed a second referendum on 29 November 1998 (approved 63.5%) after parliament re-baselined costs. The 1998 cost projection of CHF 6.323 billion ballooned to CHF 12.2 billion in current-price final accounting — roughly double — largely on geological surprises in the Tavetsch intermediate massif near Sedrun and on inflation, VAT and construction-loan interest. Nine workers died during construction. On 10 August 2023 a freight wagon derailed inside the tunnel after a wheel disc on the 11th wagon's first axle fractured, damaging more than 7 km / 4.3 mi of track and a tube-separating safety door. The west tube reopened to limited freight on 23 August 2023, but full service across both tubes only resumed on 2 September 2024 after CHF 150 million / USD 192 million of repairs. The Porta Alpina underground station proposed at Sedrun was shelved by the Federal Council in 2007 on cost-benefit grounds.