Der Alte Elbtunnel, the Old Elbe Tunnel in Hamburg, Built 1907 to 1911

The record table

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

How this table is compiled

Der Alte Elbtunnel, D is recorded in this archive at 0.45 km, opened in 1907, on the list it belongs to rather than only on this page. 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.

The captions name 5 distinct places and structures — Elbe, Free and Hanseatic among them — and those names are the index into the length tables where each is recorded with its own figure. A national administration publishes what it maintains, so a crossing that changes owner can vanish from one list and appear in another.

Geology decides cost and programme far more than distance does; a short bore through squeezing ground can take longer than a long one through sound rock. The cheapest kilometre of a route is the one already built, which is why upgrades follow old alignments even when a new one would be shorter.

Overburden decides whether a bore is driven or built in a trench, and the switch usually happens within a few hundred metres of a portal. A short bore in a city can cost more than a long one in a mountain, because the expensive part is what sits above it.

This page records the structures catalogued for Germany in a tunnel almanac maintained at this address since the late 1990s. Tunnel building in Germany is shaped by geology and settlement pattern as much as by transport policy. Immersed tube construction is used where the crossing is short and the water shallow enough to dredge a trench.

Reading the figures

Tidal range decides how deep an estuary crossing must sit, and it varies more between estuaries than the crossings themselves do. Names follow the operator's spelling, including local diacritics, not an anglicised form. Fixed links change settlement patterns, so the traffic a crossing carries after ten years is not the traffic it was justified on.

Motorway tunnels are usually twinned, and the second bore is frequently built decades after the first. Metro tunnels are shallow, closely spaced and built under streets, which makes them a different engineering problem from an alpine crossing. Japan's rail network drove long-bore practice decades before its roads did, and its list reflects that order.

A subaqueous crossing is designed from the rock cover at the lowest point upward, and everything else follows from that number. Route numbering changes over time, so a road reference in the table reflects the designation at the time of recording. Traffic figures are deliberately excluded, since they date far faster than the structures themselves.

A suspension bridge carries its deck from cables in tension; a cable-stayed one carries it directly from the towers, and the two suit different spans. Drill-and-blast advances in rounds of a few metres, so its progress is measured in rounds per day rather than metres per hour. Older entries were compiled from printed sources and correspondence, not from online publication.

Catenary needs headroom that a road tunnel does not, so an electrified bore is taller for the same traffic. Two headings driven towards each other halve the programme and double the survey problem. Alpine countries dominate the rail column and coastal ones the subsea column, and neither is an accident of compilation.