Infrastructure records: the longest, deepest and highest structures

• 11entries listed

The record table

One line per class, each linking through to the full table with its sources and notes. Lengths are as published by the operator or the responsible administration; where a class has a definitional dispute, the note on that table says so.

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

How this table is compiled

Where a structure belongs to two classes, such as a sea crossing built partly as bridge and partly as immersed tunnel, it appears on both tables. The road, bridge and canal records are included because they are the networks tunnels belong to, and because the same measurement disputes recur across all of them.

Height is measured above mean sea level. Nothing here is estimated: where a value could not be corroborated from two independent sources, the row was left out rather than filled in. The unit matters as much as the number: a figure in feet and a figure in metres are routinely mixed up in secondary sources.

Disputed rows carry the dispute in the note column. Corrections have historically arrived by letter rather than by form, and that is still the way most errors in it have been found. Where a record is contested the table states both the figure and the reason for the dispute, instead of picking a winner silently.

Each class below has its own table, its own measurement convention and its own set of disputes, and none of them transfer. Renaming is common on long routes, so a designation in the table reflects the name in use at the time of recording. Ranking is by the figure named in the header, nothing else.

Altitude records sit apart again: height above sea level and length are unrelated, and the highest structures are rarely the longest. A record is a claim about a definition as much as a measurement. Geology and terrain decide cost and programme far more than distance does, on a road as much as in a bore.

Reading the figures

Superlatives attract dispute because they are the figures most often quoted without their qualifications attached. A superlative is only as good as its definition, and most disputes in this field are definitional rather than factual. Comparing one country's figure against a neighbour's is more informative than reading either alone, because designation practice differs sharply across borders.

The road and bridge tables were added because the same measurement questions recur there in a more visible form. That is not double counting: the two tables are measuring different things about the same object. The archive began as a private compilation and grew through correspondence with engineers and administrations in more than twenty countries.

Tunnels are the core of this archive and have the deepest coverage, with per-country inventories behind each world table. Cost figures are omitted throughout, because currency, inflation and differing project scope make them close to meaningless in comparison. The note column carries the qualifications, and on record tables the qualifications are usually the interesting part.

Reading the note column before the figure is usually the faster route to understanding what a record actually claims. A projected opening date is a forecast, and on schemes of this size forecasts have historically slipped by years. Figures are compiled from operator publications, national administrations and the engineering press, and checked against one another.

This is the index to an archive of infrastructure records kept at this address since the late 1990s. The tunnel tables are the oldest part of the archive and carry per-country inventories behind the world lists. Rows are ordered longest first, so the head of the table answers the question most readers arrive with.