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, in English NRLA) programme. It runs 57.1 km / 35.5 mi between the Erstfeld portal in canton Uri (rail level 460 m / 1,509 ft) and the Bodio portal in canton Ticino (312 m / 1,024 ft); AlpTransit's final project data (June 2016) give the east tube as 57.104 km / 35.48 mi and the west tube as 57.017 km / 35.43 mi. The Federal Office of Transport says it overtook Japan's Seikan tunnel as the world's longest railway tunnel. With up to 2,450 m / 8,038 ft of rock cover (AlpTransit's final data; the Federal Office of Transport and the Gottardo 2016 opening booklet still state 2,300 m / 7,546 ft) it is also, in the words of that booklet, the deepest-lying railway tunnel in the world.

The structure consists of two single-track tubes linked by 178 cross-passages 325 m / 1,066 ft apart, with emergency stops below Sedrun and Faido. The tubes, cross-passages, shafts and access adits together total 152 km / 94.4 mi. The Gottardo 2016 opening booklet gives a timetable speed of 100 km/h / 62 mph for freight and up to 200 km/h / 124 mph for passenger trains, with maximum speeds of 160 km/h / 99 mph and 250 km/h / 155 mph, and a passenger train takes just under 20 minutes to pass through.

The client, AlpTransit Gotthard AG, was an SBB subsidiary founded in 1998; it was merged into SBB at the end of April 2023 and deleted from the commercial register in May 2023. Construction was split into five sections built by the consortia ARGE AGN (Strabag-led), ARGE Transco-Sedrun and ARGE TAT, and the CHF 1.69 billion railway-systems contract went to the Transtec Gotthard consortium. Two longer or comparable tunnels are not yet open: TELT lists the Mont-Cenis base tunnel of the Lyon-Turin line at 57.5 km / 35.7 mi and still under construction, and the Brenner Base Tunnel has a 55 km / 34.2 mi main tunnel, or 64 km / 39.8 mi counting the Innsbruck bypass, with opening postponed to 2034 (Salzburg24, 20 October 2026).

The Gottardo 2016 opening booklet gives an effective total cost of CHF 12.2 billion (approx. USD 15.0 billion at the 4 November 2026 rate) including inflation, VAT and construction interest, against CHF 9.7 billion at 1998 prices. It lists a capacity of up to 260 freight and 65 passenger trains per day. According to the Swiss foreign ministry, the previous mountain line was limited to 180 freight trains per day, and the base-tunnel route is around 30 km / 19 mi shorter.

Switzerland's voters backed shifting transalpine freight from road to rail in several votes, among them the Alpine protection article approved on 20 February 1994; swissinfo notes that the law provides for no more than 650,000 trucks a year crossing the Alps two years after the Gotthard Base Tunnel opens. The NRLA decree itself passed on 27 September 1992 with 63.6% of the vote. The 1882 Gotthard line climbs to a summit tunnel at 1,151 m / 3,776 ft with gradients of up to about 27 per mille; the base tunnel's summit lies at 549 m / 1,801 ft and its maximum gradients are 4.055 per mille on the north ramp and 6.76 per mille on the south ramp (AlpTransit's final project data, June 2016). The Swiss foreign ministry notes that, thanks to the low gradient, trains no longer need an additional locomotive on this route and heavier, longer freight trains can run. The target has not yet been met: the Federal Council reported 960,000 transalpine truck trips in 2024, against the 650,000 target, and a rail share of 70.3% at the end of 2024, which the Federal Office of Transport's March 2026 report puts at 68.6% for 2025.

The TBM sections were excavated at diameters of 8.83 to 9.58 m / 29.0 to 31.4 ft (AlpTransit's final project data (June 2016)). 178 cross-passages connect the tubes at a standard spacing of 325 m / 1,066 ft. The track is slab track of the Low Vibration Track (LVT) type, standard gauge (1,435 mm / 4 ft 8.5 in), electrified at 15 kV 16.7 Hz AC, and train protection is ETCS Level 2; Rhomberg Sersa renewed 7 km of slab track after the 2023 derailment. The Gottardo 2016 opening booklet gives a timetable speed of 100 km/h / 62 mph for freight and up to 200 km/h / 124 mph for passenger trains, and maximum speeds of 160 km/h / 99 mph for freight and 250 km/h / 155 mph for passenger trains. The summit lies at 549 m / 1,801 ft, 89 m above the north portal and 237 m above the south portal, with maximum gradients of 4.055 per mille (north) and 6.76 per mille (south). The Sedrun intermediate attack has two shafts 850 m and 820 m / 2,789 and 2,690 ft deep. The excavation produced 28.2 million tonnes / 31.1 million short tons of spoil: 9.3 million tonnes (33%) of quality A for concrete aggregate, 18.7 million tonnes of quality B for fill and reclamation, and 0.2 million tonnes of quality C. The maximum rock temperature is approximately 46 C / 115 F and the maximum working temperature 28 C / 82 F.

The Gottardo 2016 opening booklet lists a capacity of up to 260 freight and 65 passenger trains per day through the tunnel. According to the Swiss foreign ministry, the previous mountain line was capped at 180 freight trains per day, the new route is around 30 km / 19 mi shorter, and the Confederation has invested about CHF 22.8 billion (EUR 21.5 billion) in the whole NRLA, almost 3.5% of GDP. The same booklet expected Zurich-Lugano journeys to be about 45 minutes shorter once the axis was complete (2020), and SRF reported in September 2024 that Zurich to Ticino again takes a good 1 h 50 min. AlpTransit's final project data count about 2,600 people working on the project. In November 2025 the Federal Council said that the potential of the Gotthard, Lötschberg and Ceneri base tunnels was not yet fully used five years after the last one opened.

By design the tunnel supports Switzerland's road-to-rail policy, but the shift is incomplete: the Federal Council reported 960,000 transalpine truck trips in 2024 and, in March 2026, roughly the same in 2025, with the rail share of Alpine freight at 68.6% in 2025, down from 70.3% in 2024. Spoil was a visible part of the project. According to SRF, the six artificial islands in southern Lake Uri, used for bathing and nature protection, were built from tunnel spoil (about 2.4 million tonnes since 2005, plus about 1 million tonnes from the Flüelen bypass) to stop erosion of the Reuss delta, and more than 200 bird species have been seen in the delta. A brochure on the tunnel's spoil use names the Neptune nature-reserve islets and the Lorelei bathing islands, and adds that surplus spoil from Sedrun was used to create the Lag Claus Surrein swimming lake. Of the 28.2 million tonnes excavated, AlpTransit's final project data list 9.3 million tonnes (33%) as suitable for concrete aggregate.

The NRLA was politically contested. Voters approved it on 27 September 1992 with 63.6% yes, but Uri (40.9% yes) and both Appenzell cantons rejected it; Swissvotes records that environmental groups called it oversized and a cause of additional environmental burdens, while motoring associations criticised the cost and the use of fuel-duty revenue. The federal financing of large rail projects (FinÖV) passed on 29 November 1998 with 63.5% yes. On cost, the Gottardo 2016 opening booklet gives CHF 9.7 billion at 1998 prices but an effective CHF 12.2 billion including inflation, VAT and construction interest; bahnonline.ch reports final costs for the Gotthard and Ceneri tunnels together of CHF 12.105 billion, more than CHF 1 billion below the CHF 13.157 billion (1998 prices) approved in 2008. SRF reports that nine tunnel builders lost their lives.

On 10 August 2023 a freight train derailed inside the west tube. The Swiss Transportation Safety Investigation Board's interim report of 28 September 2023 found that fatigue cracks broke the wheel disc of the 11th wagon and that fragments fell from the wheel from about 10 km into the tunnel; its final report of 2 June 2025 again pointed to a wheel cracked by fatigue and, according to swissinfo and bluewin, to a systemic problem. SBB said in November 2023 that more than 7 km / 4.3 mi of track had to be renewed and estimated the damage at CHF 100-130 million; freight meanwhile ran through the undamaged east tube from 23 August 2023, at roughly two-thirds of normal volume (Railtarget). Full service resumed on 2 September 2024. SBB put the total cost of the interruption at about CHF 150 million; SRF reports that SBB is insured but still bears the cost because liability claims are unresolved, and Ticino Turismo estimated tourism losses of at least CHF 10 million.

The Ticino public prosecutor's office has opened proceedings, and nothing has been decided. According to a May 2026 report by watson, citing SRF, an expert opinion finds that SBB overlooked warning signs and that the scale of the damage could have been reduced; SBB firmly rejects this and points out that the investigation board found no failure of SBB systems or of operations management. Derailment detectors on the approaches to the tunnel entered service overnight on 10-11 May 2026 and a temporary 160 km/h limit was lifted; SBB is asking for a review of liability rules, since today the railway undertaking is liable, not the wagon keeper (SBB news, 12 May 2026).