How Greece Is Building a €2B Highway That Needs 266 Walls to Stay Above the Sea

Greece is spending €2 billion on a new highway across northern Crete — the Northern Road Axis, or BOAK — on a coast where the mountains come down to the sea and there is almost nowhere to put a road. The proof is one number in the project file: 266 retaining structures — retaining walls and piled walls — along roughly 155 kilometres of route. That averages one every 580 metres. This is a road that is almost never simply sitting on the ground. WHY THERE IS ONLY ONE ROAD Crete is about 260 kilometres end to end, with a mountain spine down its length, some peaks over 2,000 metres. Its six main towns — Kissamos, Chania, Rethymno, Heraklion, Agios Nikolaos and Sitia — all sit on one strip of the north coast, joined by one road: Greek National Road 90, under construction from 1968. Two lanes, one each way, a platform about 12 metres wide, and for most of its length nothing between the opposing streams of traffic. There is no parallel route inland, because the interior is mountains — so a lorry across both lanes cuts the island in half until it is cleared. It was never widened because there is nothing to widen into: rock on one side, sea on the other. WHAT €2 BILLION BUYS The concession, held by GEK TERNA on the project Greeks call BOAK or VOAK, covers Chania to Heraklion — 157 kilometres — plus an option adding about 30 kilometres west to Kissamos, for a 187-kilometre corridor. Construction cost, in the contractor's own words, stands at €2 billion, over a 35-year concession whose first five years are design and construction. It buys 26 single-bore tunnels, built in pairs so each direction gets its own tube — about 34 kilometres of tube, which converts to roughly 17 kilometres of route inside the mountain, about 11 per cent of the whole thing. Then 10.8 kilometres of new bridge deck, 23 of those bridges over 100 metres long, and across the corridor 89 bridges and 43 grade-separated junctions. The finished cross-section is 21.5 metres at a design speed of 100 km/h. The new road is therefore a different alignment, not a widening. THE NUMBER THAT DESCRIBES THIS COAST The project file for the Chania–Heraklion section lists those 266 retaining structures alongside 136 culverts, 58 grade separations, and a tunnel count made a different way again: 21 bored tunnels and 18 cut-and-cover ones. Each wall is there because otherwise the slope above would come down onto the carriageway, or the ground beneath it would slide away toward the sea. TWO TUNNELS WORTH NAMING The longest is Gerani, west of Rethymno, through Mount Nippoi: twin bores of unequal length, about 3,630 metres on the left and 3,150 on the right — normal, because the geology decides where each portal can safely sit. The second is Aptera, east of Souda Bay, described by the designers as the largest on the route; it runs beneath a protected archaeological site and was cleared in 2021 only because the cover above the tunnel crown was thick enough. GROUND THAT MOVES, WEATHER THAT FLOODS On 27 September 2021 a magnitude 6.0 earthquake struck beneath the centre of the island at a depth of only 6 to 9 kilometres, and the nearest station recorded peak ground acceleration of about 0.62 g horizontally — and 0.82 g vertically, the figure that governs bridge bearings and tunnel linings. Western Crete is also rising, at roughly 2.5 to 2.7 millimetres a year. And in February 2019 a station at Askifou recorded 596 millimetres of rain in two days and 1,202 in the month, a European monthly record for an inhabited place. That is what the drainage behind all 266 walls is for. BUILT WITHOUT CLOSING IT With no alternative route, the stretches where the new alignment upgrades the existing corridor rather than bypassing it have to be built while traffic keeps running — the method used on the Corinth–Patras motorway on the mainland. Under the contract, construction runs five years from the start of the concession, with major works beginning in early 2026. Chania to Heraklion then falls from a little over two hours to about 70 minutes. The receipt still stands at Vrachasi: 285 metres of tunnel cut in 1971, the first road tunnel ever built on the Greek national road network, on this same corridor. Fifty-five years later, the road it belongs to is still not finished. CHAPTERS 00:00 The tunnel Greece cut in 1971 00:48 One island, six towns, one road 02:43 Why it was never widened 04:40 What €2 billion buys 06:58 266 walls — one every 580 metres 08:39 Gerani and Aptera 10:27 Ground that shakes, weather that floods 12:32 Building it without closing it 14:04 What changes #Crete #Greece #Megaprojects #BOAK #CivilEngineering #TunnelEngineering #RoadConstruction #Chania DISCLAIMER _______________ This is not engineering advice. Everything here is for informational and entertainment purposes only. Contact an engineer licensed to practice in your area if you need professional advice or services. All non-licensed clips used for fair use commentary, criticism, and educational purposes.