WHEN the Berlin Wall fell, Europe began repairing its sundered east-west transport networks. A revived Paris-Moscow train heralded the new era. Berlin’s cathedral-like main station, opened in 2006, became the continent’s new hub. But old north-south bottlenecks are back in the spotlight. Of the nine “Core Network Corridors” currently earmarked for EU investment, six are more vertical than horizontal. The centrepiece of this strategy is the “Scandinavian-Mediterranean corridor” from Sweden and Finland, through Denmark, Germany, Austria and Italy to Malta in the south. This programme—jointly funded by the EU and member states—includes railway electrification, port modernisation and the two largest engineering projects on the continent.

The greatest progress has been at the route’s northern end. The Oresund link, a 16km road-and-rail, bridge-and-tunnel link from Malmo to Copenhagen that opened in 2000, has knitted the two cities into one region. The next step is to link them to Hamburg with a tunnel bearing two train tracks and a four-lane highway under the Fehmarn Strait (“Fehmarnbelt” in German), explains Lars Friis Cornett, deputy director of the forthcoming Fehmarnbelt project, soon to be the biggest construction site on the continent. This would create a new regional economy dubbed “STRING”.

Why is it necessary? With their tightly interlinked shipping lanes and industrial supply chains, Copenhagen and Hamburg are already one economy in many senses. But getting between them is a hassle. The land route—taken by hundreds of lorries a day—is a six-hour drive. There is a sea link, but this too is tortuous. After the short run from Copenhagen to the southern Danish coast, the train slows as it enters the port of Rodby. On special rails it enters a ferry alongside the cars and trucks. Passengers disembark and hurry to the on-board shop (alcohol and cigarettes can be sold only in German waters, which account for just 17 minutes of the trip). After an hour the ferry docks at Puttgarden and passengers return to the train, which pulls out onto German tracks and speeds on to Hamburg. The whole journey between the two cities takes four hours, 33 minutes.

The Fehmarnbelt project was agreed on by German and Danish governments in 2007, and endorsed by Danish planning authorities in 2015. Now it just remains for German planners to give it the green light by 2020, when construction is to start. Despite protests, the planners are confident that they will have clearance by next year. Funded by the Danish government, which will recoup its money from toll charges, construction will involve sinking large sections of tunnel units into the seabed; the “Lego principle”, Mr Cornett calls it. When completed in 2028, this will be the longest immersed tunnel in the world. With associated road and rail improvements it will cut the Hamburg-Copenhagen train ride to two hours, 40 minutes. Builders expect road traffic across the strait in 2030 to be more than double what it was in 2011. From Hamburg the immediate journey south is smooth on Germany’s autobahns and high-speed train tracks. The southward rail fork via Berlin was accelerated by a recent upgrade of lines through Saxony and northern Bavaria. On December 8th Angela Merkel joined other dignitaries for a train ride of less than four hours from the German capital to Munich, down from more than six hours. Then, though, the journey slows drastically. From Innsbruck in Austria the train creeps up to the Brenner Pass, through which 40% of all trans-Alpine traffic travels along a narrow, steep shelf that winds along the side of a valley. The train goes so slowly that passengers can observe Alpine flowers peeping through the snow. Not until two hours after leaving Innsbruck, at Fortezza in Italy, does it speed up downhill, snow giving way to vineyards and the plains of the Po valley. The roads are no better: 1m lorries a year travel through the pass and long tailbacks are common. Hence the impending Brenner Base Tunnel, 40% funded by the EU and the rest by the Austrian and Italian governments, which at 64km from Innsbruck to Fortezza will be the longest in the world when it opens in 2026. It could transform intra-European trade by increasing the daily number of trains through the pass from 240 per day to 591, mostly carrying goods.

From Fortezza the speed picks up thanks to the Italian rail network. Since 2009 sleek Frecciarossa and Frecciargento (red and silver arrow) trains have cut Milan-Naples travel times from eight hours to just over four. But from Naples the investment stops. There is a slow, twice-a-day service to Sicily with a ferry from Salerno, and one a day from Villa San Giovanni. The contrast with Europe’s north is stark: the Strait of Messina is half as wide as the Oresund crossing, but a bridge to Sicily has been a glint in politicians’ eyes for decades. The island remains too poor for it to be economical to build such a link and run high-speed trains to Palermo, its capital.

That is a reminder to European politicians, who are fretting about the revival of the east-west divide. That rift is about politics, a product of historical happenstance. It is soluble. But the continent’s north-south rift is in many ways deeper: it involves intransigent barriers like high mountains and foaming seas, as well as deep cultural and economic differences. In its own way, the Malmo-Palermo express would be as great a political achievement as its Paris-Moscow counterpart.