Road Tunnels in Japan — Complete List by Length

• 85entries listed
• 2.97 kmlongest bore
• 1956–2018openings span
• 163.3 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 8.85 km of the 163.3 km on this page, which is 5 per cent of the total from 3 of 85 rows. After the 1970s the next busiest decade here is the 1960s with 7 openings, so the building effort came in more than one wave.

Where one of these 85 lengths disagrees with an operator's own figure for Japan, the table keeps the published value and notes the difference instead of averaging the two. The 85 rows for Japan are ordered by length, not by date, so the 2018 opening sits well down the table without being any less current.

Dated entries run from 1956 to 2018, and the busiest decade is the 1970s with 13 recorded openings. The table on this page runs to 85 rows and records Tunnel, Length (m), Date of opening, Prefec. and Notes for each of them, which is the shape the original compiler chose rather than one imposed here.

A new scheme in Japan would have to beat 2.97 km to change the head of this table, and that is the figure worth rechecking when one opens. The longest entry is 3.0 times the shortest and 1.5 times the median, which is the quickest measure of how uneven the table is.

Dates for Japan refer to opening to traffic, not breakthrough, so the 1956 entry was under construction for some years before that. Laid end to end the entries on this page would run 163.3 km, which is a number with no engineering meaning but a useful sense of the scale of what is catalogued.

Reading the figures

The dated entries carry 22 distinct opening years across 62 years, and the median opening year is 1976. The material on this page is held in 45 captions rather than in running text, 364 words of it, each written against the image or row it belongs to by the compiler who put the page together.

Roughly 6 of the dated entries opened in this century, which is a rough measure of how much of the network is recent. The captions name 39 distinct places and structures — Expressway, Kyushu and Nagasaki among them — and those names are the index into the length tables where each is recorded with its own figure.

This page records the road tunnels catalogued for Japan in a tunnel almanac maintained at this address since the late 1990s. Only 36 of the 85 rows carry anything in the date of opening column, so that field describes a minority of this table and the rest of the rows are recorded without it.

Further down the table, Shin-Misaka is recorded at 2.78 km and Nitsusoku at 2.77 km. Read down the length (m) column, the 85 values run from 1 001 m to 2 970 m with a midpoint at 2 030 m; the spread rather than the maximum is what says how uneven this set is.

The entries sum to roughly 163.3 km of bore, an average of about 1.92 km each, though that average describes no actual row. Only 24 of the 85 rows carry anything in the prefec. column, so that field describes a minority of this table and the rest of the rows are recorded without it.