The longest tunnel in each country: road and railway side by side

• 47entries listed

The record table

One row per country, giving its longest road tunnel and its longest railway tunnel with the opening year, and linking to that country's full inventory. Structures not yet open to traffic are excluded.

How this archive measures: lengths, bores, dates and ordering

How this table is compiled

A record of this kind moves whenever one scheme opens, and a page that is not re-checked drifts out of date silently. Geology and settlement pattern shape a national list far more than transport policy does. Published lengths for the same structure often differ by a few metres between sources, depending on whether the cut-and-cover approach is counted.

Where a country has been redrawn administratively since an entry was recorded, the region code reflects the classification then in use. Corrections have historically arrived by letter rather than by form, and that is still how most errors in it have been found. Comparing a national list against a neighbour's is more informative than reading either alone.

Switzerland heads this table, with St. Gotthard 16.94 km as its longest recorded structure. This is the cross-country view the per-country pages cannot give: one row per country, road and rail side by side. The same journey time can be bought with one long bore in one country and a dozen short ones in another.

Switzerland heads the rail column, and will keep it until the Turin to Lyon base tunnel opens. That absence is usually real rather than a gap in the data: many countries have no railway tunnels at all. Nothing on this page is estimated: a value that could not be corroborated is left blank rather than filled in.

Twin-tube crossings frequently carry two slightly different lengths, because the two carriageways rarely follow the same line through the rock. Toll arrangements and traffic figures are excluded throughout, because both change far faster than the structures do. Cross-border tunnels are recorded under both countries, so the Channel Tunnel appears for France and for the United Kingdom alike.

Reading the figures

Opening dates refer to the admission of traffic rather than to breakthrough, which normally falls a year or two earlier. Figures are compiled from operator publications, national administrations and the engineering press, and checked against one another. Country inventories in this archive are deeper than the summary row suggests, often running to a hundred entries or more.

The table covers 47 countries, each linking through to an inventory that usually runs far deeper than one row. Norway heads the road column by a wide margin and has done since the Laerdal tunnel opened in 2000. Gradient limits are the main reason a country's longest railway tunnel usually exceeds its longest road tunnel.

Subaqueous tunnels are governed by rock cover above the bore rather than by the depth of water above that. Where a country's best-known project is still under construction, its entry here is the longest structure actually carrying traffic. Ventilation shafts allow a longer bore to be driven, and their absence is often what caps a national record.

A country's entry links to its full inventory. Two sources were required for every figure. Every figure is traceable to a named source. Opening year means the year traffic was admitted. This archive has held per-country tunnel inventories since the late 1990s, and this page is the aggregation across them.