Tunnels and Viaducts on the A4-A31-A27 Motorway, by Kilometre Point

• 8entries listed
• 6.5 kmlongest bore
• 10.07 kmtotal length

The record table

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

How this table is compiled

This page records the structures catalogued along the A4-A31-A27 in Italy, in a tunnel almanac maintained at this address since the late 1990s. Only 15 of the 29 rows carry anything in the p. km. column, so that field describes a minority of this table and the rest of the rows are recorded without it.

1 of the 8 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 10.07 km, which is a number with no engineering meaning but a useful sense of the scale of what is catalogued.

The three longest entries alone account for 8.4 km of the 10.07 km on this page, which is 83 per cent of the total from 3 of 8 rows. The route crosses 2 provinces, recorded in the note column by their vehicle-registration codes (TV, VI), which is how the operator identifies a section.

Also recorded here are Schiavonesca at 0.45 km and Fosse at 0.35 km. A tunnel list for Italy reads differently from a neighbouring country's: 1 of these 8 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.

Between the longest and the tenth-longest the drop is 6.44 km, which is the part of the table that changes when a single scheme opens. Where one of these 8 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.

Reading the figures

Lengths for Italy are recorded in metres which is how the operators publish them and why the shortest entry here reads as 65 m and not a rounded figure. The longest entry is 100.0 times the shortest and 13.7 times the median, which is the quickest measure of how uneven the table is.

The eighth longest is FS Montebelluna at 0.07 km, which is about where this record stops being about record holders and starts being about ordinary infrastructure. 4 of them are under 500 metres, which on a route of this kind usually means a cut-and-cover section or a short spur and not a driven bore.

The entries sum to roughly 10.07 km of bore, an average of about 1.26 km each, though that average describes no actual row. A new scheme in Italy would have to beat 6.5 km to change the head of this table, and that is the figure worth rechecking when one opens.

6 entries fall below a kilometre, short enough that portals and approaches usually decided their cost more than the bore itself. Riese at 1 km and FS Montebelluna- Treviso at 0.9 km follow it, and lengths are given per carriageway because the two bores of a dual route are rarely cut to the same length.

The table on this page runs to 29 rows and records Tunnel / Viaduct, Length (m) Direction A27, Length (m) Direction A4, P. Km. and Notes for each of them, which is the shape the original compiler chose rather than one imposed here. Italian motorway inventories list tunnels and viaducts together in running order along the A4-A31-A27.