Tunnels and Viaducts on the A43 Motorway in France, by Kilometre Point

• 9entries listed
• 12.9 kmlongest bore
• 24.93 kmtotal length

The record table

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

How this table is compiled

1 of the 9 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 24.93 km, which is a number with no engineering meaning but a useful sense of the scale of what is catalogued.

Where one of these 9 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. The longest entry is 43.0 times the shortest and 10.8 times the median, which is the quickest measure of how uneven the table is.

Lengths for France are recorded in metres which is how the operators publish them and why the shortest entry here reads as 300 m and not a rounded figure. A bridge and a tunnel across the same water are rarely close in cost, and the choice is usually settled by shipping rather than by engineering.

The table below lists 9 entries with a recorded length, each giving a name, a length in metres and, where documented, the year of opening. The three longest entries alone account for 19.7 km of the 24.93 km on this page, which is 79 per cent of the total from 3 of 9 rows.

Also recorded here are Des Hurtieres at 1.16 km and D' Aiguebelle at 0.9 km. Read down the length (m) direction fréjus column, the 7 values run from 300 m to 3 092 m with a midpoint at 924 m; the spread rather than the maximum is what says how uneven this set is.

Reading the figures

The entries sum to roughly 24.93 km of bore, an average of about 2.77 km each, though that average describes no actual row. A new scheme in France would have to beat 12.9 km to change the head of this table, and that is the figure worth rechecking when one opens.

2 of the 9 entries fall within a quarter of the median length, which is how tightly this particular list clusters around its typical structure. The eighth longest is St. Etienne de Cuines at 0.3 km, which is about where this record stops being about record holders and starts being about ordinary infrastructure.

Read down the length (m) direction lyon column, the 8 values run from 300 m to 12 895 m with a midpoint at 1 352 m; the spread rather than the maximum is what says how uneven this set is. Tunnel building in France is shaped by geology and settlement pattern as much as by transport policy.

The tunnel column names 9 distinct entries on this page, Fréjus and Orelle among them, each traceable to the operator or administration record it was taken from. Cut-and-cover is faster and cheaper where the depth allows it, and it is the reason some urban entries have no portal in the ordinary sense.

A tunnel list for France reads differently from a neighbouring country's: 3 of these 9 structures pass three kilometres, and the same journey time is bought with one long bore in one country and a dozen short ones in another. Reconstruction after a fire changes the ventilation and the escape arrangement, and often the recorded length as well.