Floating serenely high above the valley of the Tarn, the Viaduct of Millau represents not only a truly remarkable feat of modern engineering but is also supremely beautiful and elegant in design, entirely worthy of its popular sobriquet, “the Pont du Gard of the 21st century”. The world’s longest cable-stayed bridge, the Viaduct rises to a lofty 343 metres atop the tallest of its seven masts. Its 2.5km sweep across the valley between the Causse Rouge and the Causse du Larzac takes a mere seven giant steps; it rests on slender streamlined concrete piers, or pylons, each with its own unique geometrical shape in cross-section, tapering from 200sqm at its base to a mere 30sqm at the top where it supports the road deck, after splitting over its top 90m into a graceful fork. The tallest pier, P2, rises a staggering 245 metres above the Tarn valley. Above the two-lane dual carriageway the graceful 87m masts continue the upward sweep, their filigree network of steel cabling giving the appearance of a regatta of sailing vessels in graceful procession.
Conceived by French engineer Michel Virlogeux and designed by British architect Sir Norman Foster, the Viaduct was constructed over a three-year period, at a cost of €400 million by the French Eiffage Group. It represents the last link in the A75 autoroute between Clermont-Ferrand and Béziers, one of the major north-south routes linking Paris and the north with the Mediterranean coast and Spain, and was intended as a solution to the chronically diabolical traffic black hole around Millau. The first plans for a crossing in this area were made in 1987, and the high crossing over the Tarn chosen in 1991. After over a decade of planning and conception, the first “stone” was laid on 14 December 2001 by Mr J C Gayssot, the French Minister for Transport and Infrastructure. A year of groundwork and foundations followed, and in February 2003 the first section of the road deck was launched from the southern end. The majestic concrete piers were completed in November, and on 28 May 2004, the deck sections from north and south were joined, 270m above the Tarn, an event captured in several excellent documentaries, and one which rivals the Laying of the Golden Spike in American rail history as a moment of celebratory culmination. After several months of tensioning the cables and testing, the Millau Viaduct was officially inaugurated on 14 December, 2004, by Jacques Chirac, President of the French Republic, and two days later was opened to traffic.
The launching of the road deck from either end of the bridge was itself a wonder of engineering. The deck is essentially a relatively lightweight steel cage, whose central “spine” was prefabricated at Eiffel’s plants and transported to the edge of the site, where the construction of each 171m long section was completed. This procedure saved time and ensured worker safety, as 96% of the work was carried out at ground level and not up in the dizzy heights above the Tarn. Temporary metal framework pilings, themselves the tallest ever built, were raised midway between each pair of piers, which stand 342 metres apart, and using a system of mighty hydraulic wedges and rams, the sections of road were slid out over the abyss, from pier to temporary piling to pier, at an average rate of 600mm per 4 minutes, or 2.5mm per second. Two-thirds of the expanse - 1743 metres - was rolled out from the southern end, and 717 metres crawled its way inward from the north. Once the ends were welded together, and the metal stays tensioned, the metal pilings were dismantled and the road was ready for paving.
The Viaduct is monitored 24/7 and maintained by the highest-tech methods, with an extensive staff of attendants, receptionists, supervisors, patrolmen, technicians, and administrative personnel. There are variable message boards, a 3 metre wide hard shoulder, windshields, high-resistance safety rails, and emergency call phones and fire terminals at regular intervals. It is closed to pedestrians, so all daredevil BASE jumpers need to evade security and jog quite a ways before hurling themselves (and their parachute or parasail, hopefully) over the edge. The state-of-the-art toll plaza can accommodate eight lanes of traffic in either direction, and nestles under a picturesque leaf-shaped canopy; there is a carpark with a scenic outlook adjacent.
There are of course many other spots from which to admire the Viaduct and the Tarn Valley, notably from the belvedere at Luzençon, the village of Peyre along the river, hilltop Soulobres on the northern side, and famously from the Belfrey terrace in the heart of Millau. At the Cazalous rest area 5 km from Millau along the D992 towards Albi, there is a Viaduct Espace Info, which is open daily from 10 to 7 in summer, with free admission. It features films, explanatory panels, and a model illustrating various stages in the construction. The “Jardin des Explorateurs” (admission €5.50/€3) run by the Companie Eiffage, offers a one-hour guided tour (available in English) of a 6000sqm exhibition of the Viaduct, including a life-size recreation of the base of P2, and a demonstration of how the conveyors were used to lift and place the sections of the road deck. There is a belvedere with panoramic views of the Viaduct, and of course a gift shop.
For a more dramatic view of the Viaduct, try a helicopter ride from nearby Rodez airport. For prices and reservations, contact Bruno Rault, +33 609 30 52 51, firstname.lastname@example.org Or if you’re really feeling daring, you can book a flight with Gilbert Siino and his 2-seater microlight airplane, for an eagle’s-eye view of the Viaduct. Contact: email@example.com , tel. +33 685 74 81 74, www.millau-ulm.com Or more sedately, drift down the Tarn (and under the Viaduct) with the Bateliers du Viaduc: reservations required: +33 565 60 17 91, firstname.lastname@example.org www.bateliersduviaduc.com
There are a number of websites devoted to the Viaduct and its construction, with plenty of fascinating information. Visit www.leviaducdemillau.com , and look for repeats of the aforementioned documentaries: Extreme Engineering (The Discovery Channel, first aired 15 November 2004) and Megastructures, first broadcast on the National Geographic Channel 20 December 2005.
© OT Millau