Tunnels and Viaducts on the SS33 Motorway in Italy, by Kilometre Point

• 37entries listed
• 2.25 kmlongest bore
• 13.19 kmtotal length

The record table

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

How this table is compiled

The 36 entries are grouped on the page under 10 headings — exit val formazza (7), exit ornavasso (5), exit pieve vergonte (5), exit anzola (4) and exit varzo- viaduct campeglia 2 (77 m) on ramp (4) — a classification the table carries as section breaks rather than as a column of its own.

The route table lists 37 structures with a recorded length, giving both carriageways where the two bores differ. The table on this page runs to 36 rows and records Tunnel / Viaduct, Direction Simplon, Direction Gravellona Toce and Notes for each of them, which is the shape the original compiler chose rather than one imposed here.

The three longest entries alone account for 5.12 km of the 13.19 km on this page, which is 39 per cent of the total from 3 of 37 rows. The shorter half of the table totals 1.46 km against 11.72 km for the longer half, from the same number of rows.

Between the longest and the tenth-longest the drop is 1.88 km, which is the part of the table that changes when a single scheme opens. Where one of these 37 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 21 m and not a rounded figure. The longest entry is 107.0 times the shortest and 11.8 times the median, which is the quickest measure of how uneven the table is.

Reading the figures

The eighth longest is Diveria 2 at 0.56 km, which is about where this record stops being about record holders and starts being about ordinary infrastructure. The ten longest average 0.94 km against 0.14 km for everything below them, and that ratio is the clearest thing this table says about the distribution.

The note column places the route in Piemont, and the administrative area is recorded because a section is identified by it. Read down the direction simplon column, the 36 values run from 21 to 2 248 with a midpoint at 195; the spread rather than the maximum is what says how uneven this set is.

This page records the structures catalogued along the SS33 in Italy, in a tunnel almanac maintained at this address since the late 1990s. Laid end to end the entries on this page would run 13.19 km, which is a number with no engineering meaning but a useful sense of the scale of what is catalogued.

The next two longest are Gabbio at 1.6 km and Toce at 1.27 km. A tunnel list for Italy reads differently from a neighbouring country's: 0 of these 37 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.

The entries sum to roughly 13.19 km of bore, an average of about 0.36 km each, though that average describes no actual row. A new scheme in Italy would have to beat 2.25 km to change the head of this table, and that is the figure worth rechecking when one opens.