Road Tunnels in France — Complete List by Length

• 67entries listed
• 11.61 kmlongest bore
• 1882–2014openings span
• 124.42 kmtotal length

The record table

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

How this table is compiled

The three longest entries alone account for 30.32 km of the 124.42 km on this page, which is 24 per cent of the total from 3 of 44 rows. 22 entries sit above the median and 22 at or below it, so the table is evenly weighted and not clustered at one end.

Between the longest and the tenth-longest the drop is 8.31 km, which is the part of the table that changes when a single scheme opens. Where one of these 44 lengths disagrees with an operator's own figure for France, the table keeps the published value and notes the difference instead of averaging the two.

A new scheme in France would have to beat 11.61 km to change the head of this table, and that is the figure worth rechecking when one opens. The 44 rows for France are ordered by length, not by date, so the 2014 opening sits well down the table without being any less current.

The longest entry is 11.5 times the shortest and 6.2 times the median, which is the quickest measure of how uneven the table is. The ten longest average 6.04 km against 1.88 km for everything below them, and that ratio is the clearest thing this table says about the distribution.

Second and third place go to Duplex A86 at 10.1 km and Somport at 8.61 km. The table on this page runs to 68 rows and records State, Tunnel, Length (m), Date of opening and Dep. for each of them, which is the shape the original compiler chose rather than one imposed here.

Reading the figures

4 of the 44 measured entries exceed five kilometres, and those are the ones that carry a full ventilation and escape regime. Laid end to end the entries on this page would run 124.42 km, which is a number with no engineering meaning but a useful sense of the scale of what is catalogued.

Roughly 15 of the dated entries opened in this century, which is a rough measure of how much of the network is recent. Read down the dep. column, the 56 values run from 1 to 972 with a midpoint at 69; the spread rather than the maximum is what says how uneven this set is.

The longest entry is Mont Blanc / Monte Bianco, at 11.61 km, opened in 1965. 59 of the 68 rows carry an entry in the notes column — 87 per cent of the table — and that column is where the qualifications live: tube counts, closures, boundaries and the reason a figure reads the way it does.

Dated entries run from 1882 to 2014, and the busiest decade is the 1990s with 22 recorded openings. The material on this page is held in 36 captions rather than in running text, 374 words of it, each written against the image or row it belongs to by the compiler who put the page together.

The longest stands 1.51 km clear of the next longest, which is the margin to watch when a new scheme is announced. The captions name 30 distinct places and structures — France, Peripherique and Italy among them — and those names are the index into the length tables where each is recorded with its own figure.