Tunnels and Viaducts on the A12 Motorway in Italy, by Kilometre Point

• 185entries listed
• 9.62 kmlongest bore
• 83.18 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 14.14 km of the 83.18 km on this page, which is 17 per cent of the total from 3 of 185 rows. The shorter half of the table totals 11.45 km against 71.73 km for the longer half, from the same number of rows.

The route table lists 185 structures with a recorded length, giving both carriageways where the two bores differ. The table on this page runs to 223 rows and records Tunnel / Viaduct, Direction Genova, Direction Cecina, Notes and km for each of them, which is the shape the original compiler chose rather than one imposed here.

168 entries fall below a kilometre, short enough that portals and approaches usually decided their cost more than the bore itself. Read down the direction genova column, the 171 values run from 20 to 35 377 with a midpoint at 240; the spread rather than the maximum is what says how uneven this set is.

Between the longest and the tenth-longest the drop is 8.16 km, which is the part of the table that changes when a single scheme opens. Where one of these 185 lengths disagrees with an operator's own figure for Italy, the table keeps the published value and notes the difference instead of averaging the two.

This page records the structures catalogued along the A12 in Italy, in a tunnel almanac maintained at this address since the late 1990s. The captions name 13 distinct places and structures — Connection, Pietro and Palazzi among them — and those names are the index into the length tables where each is recorded with its own figure.

Reading the figures

The next two longest are Poggio Iberna at 2.52 km and Monte Castelletto at 1.91 km. The material on this page is held in 5 captions rather than in running text, 39 words of it, each written against the image or row it belongs to by the compiler who put the page together.

Lengths for Italy are recorded in metres which is how the operators publish them and why the shortest entry here reads as 20 m and not a rounded figure. The longest entry is 480.9 times the shortest and 39.7 times the median, which is the quickest measure of how uneven the table is.

A new scheme in Italy would have to beat 9.62 km to change the head of this table, and that is the figure worth rechecking when one opens. The note column records 24 exits, 12 motorway connections, 4 toll barriers and 5 service areas along the route, in running order rather than by size.

The eighth longest is M. Sperone at 1.67 km, which is about where this record stops being about record holders and starts being about ordinary infrastructure. The ten longest average 2.59 km against 0.33 km for everything below them, and that ratio is the clearest thing this table says about the distribution.

Poggio Iberna at 2.52 km and Monte Castelletto at 2.01 km follow it, and lengths are given per carriageway because the two bores of a dual route are rarely cut to the same length. Ventilation shafts allow a longer bore to be built, and their absence is often what caps a tunnel's length.