Tunnels and Viaducts on the D15 Motorway in Italy, by Kilometre Point

• 9entries listed
• 1.04 kmlongest bore
• 4.08 kmtotal length

The record table

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

How this table is compiled

Between the longest and the tenth-longest the drop is 0.96 km, which is the part of the table that changes when a single scheme opens. Where one of these 9 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.

Lengths for Italy are recorded in metres which is how the operators publish them and why the shortest entry here reads as 75 m and not a rounded figure. The longest entry is 13.8 times the shortest and 2.9 times the median, which is the quickest measure of how uneven the table is.

A new scheme in Italy would have to beat 1.04 km to change the head of this table, and that is the figure worth rechecking when one opens. The eighth longest is Bozano at 0.08 km, which is about where this record stops being about record holders and starts being about ordinary infrastructure.

This page records the structures catalogued along the D15 in Italy, in a tunnel almanac maintained at this address since the late 1990s. The three longest entries alone account for 2.51 km of the 4.08 km on this page, which is 62 per cent of the total from 3 of 9 rows.

The next two longest are Fresonara at 0.79 km and Prati at 0.37 km. A tunnel list for Italy reads differently from a neighbouring country's: 0 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.

Reading the figures

The longest stands 0.14 km clear of the next longest, which is the margin to watch when a new scheme is announced. Laid end to end the entries on this page would run 4.08 km, which is a number with no engineering meaning but a useful sense of the scale of what is catalogued.

8 entries fall below a kilometre, short enough that portals and approaches usually decided their cost more than the bore itself. Read down the 75 column, the 7 values run from 146 to 1 037 with a midpoint at 362; the spread rather than the maximum is what says how uneven this set is.

4 entries sit above the median and 5 at or below it, so the table is top-heavy and not clustered at one end. Read down the 75 column, the 7 values run from 111 to 1 037 with a midpoint at 362; the spread rather than the maximum is what says how uneven this set is.

The table on this page runs to 8 rows and records Bozano, 75, 75 and Reg. Liguria – Prov. SP for each of them, which is the shape the original compiler chose rather than one imposed here. The kilometre point is recorded for each structure on the D15, which is how the operator identifies it.

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 bozano column names 8 distinct entries on this page, Magra and Fornola among them, each traceable to the operator or administration record it was taken from.