The European E-Road Network — 113 Recorded Entries

The record table

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

How this table is compiled

The from - to column names 40 distinct entries on this page, Parma - La Spezia and Nordkapp - Olderfjord (E6) among them, each traceable to the operator or administration record it was taken from. Bridge and tunnel appear on the same route more often than either appears alone, because the terrain that requires one usually requires the other.

The captions name 906 distinct places and structures — Praha, E-roads and Paris among them — and those names are the index into the length tables where each is recorded with its own figure. Drill-and-blast advances in rounds of a few metres, so its progress is measured in rounds per day rather than metres per hour.

They are not uniform: the fullest runs to 52 words and the briefest to 6, and on a page of this kind the long ones are where the explanation lives — the caption carries what the picture cannot. Immersed tube construction is used where the crossing is short and the water shallow enough to dredge a trench.

Dates before 1900 are frequently approximate, and are shown as published, unreconciled. A ranking answers the question people arrive with and rarely the one they leave with. Swelling clays take up water and press on the invert for years after a tunnel opens, so some linings are designed to yield rather than resist.

Transverse ventilation gives every section its own supply and extract, which is why the long two-lane crossings have a false ceiling. A subaqueous crossing is designed from the rock cover at the lowest point upward, and everything else follows from that number. Where a tunnel crosses an international border, it is listed under both countries.

Reading the figures

Karst limestone hides voids that no borehole pattern reliably finds, which is why crossings through it carry the largest contingencies. Tidal range decides how deep an estuary crossing must sit, and it varies more between estuaries than the crossings themselves do. Two headings driven towards each other halve the programme and double the survey problem.

The most useful sources are the least accessible: annual reports, inspection records and commissioning documents rather than press releases. Ventilation shafts allow a longer bore to be built, and their absence is often what caps a tunnel's length. Motorway tunnels are usually twinned, and the second bore is frequently built decades after the first.

Austria's north-south routes cross the main alpine chain three times, and its tunnel list is essentially that geography written down. Longitudinal ventilation pushes air along the bore and works until the bore is long enough that the air arrives already foul. The fires of the late 1990s and early 2000s reshaped European tunnel safety regulation permanently.

A base tunnel trades a much greater length for a far lower summit altitude and a gentler ruling gradient. Cross-border schemes need two states to fund the same hole at the same time, which is why they take decades. Some entries carry a range instead of a single value where the two carriageways differ.

Nineteenth-century tunnels were surveyed from the surface with theodolites and chains, and the best of them met within centimetres. Salt water attacks reinforcement in a way fresh water does not, so subsea linings are specified to a different standard. Portal design is largely a function of avalanche and rockfall risk, not of architectural intent.