This list ranks the world’s five longest operational mainline railway tunnels by a simple, consistent metric: the linear route length measured in kilometres along the railway alignment between portal points. The ranking includes only in‑service railway tunnels (no metro/subway, road tunnels or tunnels still under construction) and reports official project or operator figures where small authoritative differences exist.
Rail tunnels are feats of civil engineering that reshape travel across mountains and seas, shortening journeys and enabling higher‑capacity, year‑round rail links. Measuring them consistently—by the route length between portals for a single bore—lets us compare very different projects on an even footing, from alpine base tunnels to long undersea crossings.
Quick Comparison
| Rank | Item | Location | Ranking Value | Date/Year |
|---|---|---|---|---|
| 1 | Gotthard Base Tunnel | Swiss Alps (Erstfeld — Bodio) | 57.104 km | Opened 1 June 2016 (regular service from 11 Dec 2016) |
| 2 | Seikan Tunnel | Honshu–Hokkaido, Japan (Tsugaru Strait) | 53.85 km | Opened 1988 |
| 3 | Channel Tunnel | Folkestone (UK) — Coquelles (France) | 50.45 km | Opened 1994 |
| 4 | Yulhyeon Tunnel | Gyeonggi Province, South Korea (Suseo–Pyeongtaek corridor) | 50.3 km | Construction completed June 2015 (operations from 2016) |
| 5 | Lötschberg Base Tunnel | Bernese Alps, Switzerland (Frutigen–Raron/Brig) | 34.6 km | Opened 2007 |
#5 — Lötschberg Base Tunnel
Location: Bernese Alps, Switzerland (Frutigen–Raron/Brig axis)
Ranking value: 34.6 km
Relevant year: opened 2007
The Lötschberg Base Tunnel is a central element of Switzerland’s New Rail Link through the Alps (NRLA). Measured between its portals along the railway alignment, the tunnel’s single longest equipped bore is 34.6 km. It ranks fifth on this list because several other in‑service rail tunnels worldwide are substantially longer by the chosen portal‑to‑portal metric. An important operational note—one bore of the Lötschberg complex is the only one that is fully equipped for regular traffic, a factor that affects capacity and how the tunnel is used within the Swiss rail network.
#4 — Yulhyeon Tunnel
Location: Gyeonggi Province, South Korea (part of the Suseo–Pyeongtaek / Suseo high‑speed corridor)
Ranking value: 50.3 km
Relevant year: construction completed June 2015 (operations began 2016)
The Yulhyeon Tunnel, reported by Korean project authorities as 50.3 km, forms the majority of the Suseo–Pyeongtaek high‑speed route. Completed in June 2015, it was widely reported at the time as South Korea’s longest rail tunnel. Some technical tables elsewhere mix tunnel route length with adjacent line sections and give different figures; for this ranking we use the official project/operator figure for the tunnel itself, which places Yulhyeon narrowly behind the Channel Tunnel on route length between portals.
#3 — Channel Tunnel
Location: Folkestone, Kent (UK) — Coquelles, Pas‑de‑Calais (France)
Ranking value: 50.45 km
Relevant year: opened 1994
Commonly known as the Channel Tunnel or “Chunnel,” this fixed link between the UK and France measures 50.45 km along the rail alignment and remains one of the world’s longest rail tunnels. It is notable not only for its overall length but for having the longest undersea rail tunnel section—around 37.9 km under the seabed—making the crossing a singular engineering achievement. Measured by our portal‑to‑portal rule, the Channel Tunnel sits between Seikan and Yulhyeon in this Top 5.
#2 — Seikan Tunnel
Location: Honshu–Hokkaido (undersea section across the Tsugaru Strait), Japan
Ranking value: 53.85 km
Relevant year: opened 1988
Japan’s Seikan Tunnel spans 53.85 km between portals and was opened in 1988. It contains an undersea section of roughly 23.3 km across the Tsugaru Strait and held the record as the world’s longest railway tunnel until the Gotthard Base Tunnel entered service. Its exceptional length and undersea construction reflect the national imperative to link Honshu and Hokkaido by rail across challenging maritime terrain.
#1 — Gotthard Base Tunnel
Location: Swiss Alps (Erstfeld, Canton Uri — Bodio, Canton Ticino), Switzerland
Ranking value: 57.104 km
Relevant year: officially opened 1 June 2016 (regular service from 11 Dec 2016)
The Gotthard Base Tunnel is the world’s longest operational railway tunnel by the single‑tube portal‑to‑portal metric. The project comprises two single‑track tubes; the longest single tube—the east tube—is reported at 57.104 km and is the figure used for this ranking. The tunnel’s opening in 2016 marked a new global benchmark in length for mainline rail tunnels and is a centerpiece of Swiss alpine rail infrastructure.
How We Ranked Them
We ranked operational mainline railway tunnels by linear route length measured in kilometres along the railway alignment between portal points (do not sum parallel tubes). Scope: in‑service mainline railway tunnels worldwide. Exclusions: urban metro/subway tunnels, road tunnels and any tunnel not yet in service. The reporting period for the values is current as of 21 September 2026; where authorities reported small differing measures we used the official project or operator figure for the single longest tube or the published route length between portals and noted disagreements where relevant.
Important clarifications: for tunnels with two or more parallel tubes we used the longest single‑tube route length rather than summing bores (for example, the Gotthard Base Tunnel’s east tube is reported at 57.104 km). Some projects publish differing numbers depending on whether approach sections are included; in those cases the project/operator tunnel figure between portals was used. Borderline candidates that would be longer if completed—most notably the Brenner Base Tunnel—were excluded because they were not fully in service as of the reporting date.
Frequently Asked Questions
Why don’t you sum parallel tubes to get a longer length?
We report the linear route length between portals for a single bore to keep comparisons consistent across tunnels. Summing parallel tubes would count the same route more than once and would not reflect the single continuous distance a train travels between portals.
Does “tunnel length” include approach sections or only the bore between portals?
The ranking uses the route length measured along the railway alignment between portal points—that is, the continuous length of the tunnel bore as reported by project or operator sources. Some publications mix in approach or ancillary sections; in such cases we used the official tunnel figure between portals.
Why is the Brenner Base Tunnel not on this list?
The Brenner Base Tunnel is a major project that would be among the longest when completed, but it was excluded because the scope covers only operational (in‑service) tunnels as of 21 September 2026. Tunnels not yet in service do not qualify for this ranking.
What if different authorities report slightly different lengths for the same tunnel?
Small discrepancies exist in official reporting (for example, tube‑by‑tube chainage differences). Where they occur we used the official project or operator figure for the single longest tube or the published portal‑to‑portal route length, and we noted relevant disagreements in our verification notes.
Sources
- Gotthard project data (57.104 km east tube) — project documentation reporting Gotthard Base Tunnel tube lengths.
- Japan Railway Construction, Transport and Technology Agency — Seikan Tunnel summary — official Seikan Tunnel length (53.85 km) and undersea section details.
- Institution of Civil Engineers — Channel Tunnel technical summary — authoritative reference for Channel Tunnel length (50.45 km) and undersea section.
- Chunnel.co.uk — Channel Tunnel overview — project and engineering overview supporting the Channel Tunnel figure.
- Korean rail project summary (KORASS) — Yulhyeon Tunnel — official project figure reporting 50.3 km for the Yulhyeon Tunnel.
- Korea.net — coverage of Yulhyeon Tunnel completion — government press coverage noting completion and service start dates.
- BLS network statement — Lötschberg Base Tunnel length — infrastructure statement reporting the Lötschberg Base Tunnel length as 34.6 km.
- Swiss Federal Office for Transport (NRLA flyer) — context on Switzerland’s New Rail Link through the Alps including Lötschberg.
- JRTT — Seikan Tunnel project pamphlet — additional Seikan Tunnel engineering and project information.
- Swiss Federal government — NRLA overview — broader documentation on Swiss alpine base tunnels and reporting conventions.
- AP News — reporting on major European rail projects — context noting the Brenner Base Tunnel as an excluded, not‑yet‑in‑service candidate.
Last Updated
September 2026
Discover more from Magazine of AI
Subscribe to get the latest posts sent to your email.