I was there, in the crowd, with moist eyes and a warm feeling in my heart, on August 8 of 2004, when a series of runners carried the Olympic Torch across the Harilaos Trikoupis Bridge, near Patra. It was a moving moment because the day represented two spectacular national events, two achievements, each with its nuances and symbolic markers: The opening of the Olympic Games in Greece, for the first time since they were held in 1896, and the opening of the Rion-Antirion Bridge, its most common name.
My home in Greece is only 4 kilometers away, where I would ride my bicycle for exercise daily. So, here was a world-class structure being constructed practically at my doorstep, and naturally, I took a keen interest in it.
The bridge was designed and built by the French, with lots of Greek, British, Italian, and Spanish workers, technicians, and engineers. Its design and construction took seven years. Its superlatives are many. It’s a genuinely grand bridge to see, spanning 2252 meters (7,390 feet,) almost the same total length as the Golden Gate Bridge. Its cable-stayed deck has the longest single supported length in the world, and the depth of its foundations is also a record. With my background as a Bridge Engineer, every summer I would show up at the construction site from California, and out of professional courtesy, and delighted with my interest in their project, they would give me a personal, exhaustive tour of the progress. Here’s a thumbnail of the work as it happened:
Although the above-water parts are what we finally see, for us Engineers, it’s what’s invisible that is the most challenging: The foundations! They had to be built on soft mud at an unprecedented 60 meters below the Mediterranean. So the mud was “stiffened” with a forest of steel tubes, and added lots of gravel on top. (The gravel was to let the bridge “slide around” in case of an earthquake!)
These footings (Greek: Πέλμα) were of indeed “Olympic” size – each 90 meters (300 feet) in diameter! Each weighed almost precisely as much as the Battleship USS New Jersey, at 48,500 tons. They were built in drydock, and they were floated and towed to their proper site. It typically took four tugs, some of the most powerful in the world, and several hours, to ever so slowly move these massive footings to their pre-determined locations, and then slowly sunk, with modern GPS accuracy.
Schematic (to scale) of the foundation, with a tug and the stabilizing tubes on a barge
Construction of one footing at its drydock
Once the piers were finished, four tower-legs extended to the sky, to support the towers for the cables, that were in turn to support the “deck” itself (the part that cars ride on.) I used the construction crane/elevator partway up the pier, but the rest of the climb was hand-over-hand, with vertical hand/footholds on the concrete walls. But the view from the top, 160 meters (525 feet) above the blue Mediterranean, was breathtaking – and landed me an award-winning photograph!
View of construction from on top of a pier
I met many Greek engineers working on the bridge. Most were young, eager, and happy to work on such an important project; however, they had their complaints, mainly that, according to them, the French were not divulging their technical “secrets” to them. But they knew that time was on their side – when the job was done, there would be ample opportunities to learn during the long years of maintenance service.
The deck itself was constructed from a series of segments, and each brought out by barge, lifted with a giant floating crane to fit and join the previous one. At the pier’s top, I watched as the experienced crew fed the steel cables down their enclosing tubes to the deck, to be anchored and tensioned. The top was a cramped area, but I knew to stay out of their way, and they tolerated me.
From each pier emanated the cable pairs, creating their distinctive fan arrangement. This type of bridge is known as a Cable-Stayed type, as opposed to, say, the Golden Gate Bridge, which is known as a Suspension type, where the deck hangs by vertical cables from its two massive cables. (I’ve had the luck to also stand, some years back, at one of the pier tops of the Golden Gate Bridge, 227 meters, or 745 feet, above the sea.)
We Bridge Engineers tend to be pessimists: We look for the worst possible conditions – strongest earthquakes, heaviest loads, highest winds, etc. that may attack our structures, to make allowances for them. We also search for what we call “modes of failure,” that is, the various ways in which a structure can fail, and always worry about “did we think of all of them?” Lessons learned from the past are still incorporated in everything new we build. Gefyra has aerodynamic wings on the sides of the deck, and special spirals on the cable tubes to minimize wind problems that can make them shake like fishing rods.
The second most challenging engineering feat – after the foundations mentioned earlier – was how to deal with tectonics. According to Geologists, Peloponnisos and mainland Greece are moving apart at a rate of 1 meter every 100 years. Gefyra, designed to last 120 years, has allowed for an unprecedented 5 meters! (just in case Mother Nature gets annoyed with us & goes beyond average.) The expansion of the strait of Rion-Antirion does not happen smoothly – it occurs in a series of nasty earthquakes. Overall, the bridge is designed to withstand earthquakes on the order of 7+ Richter.
Aerial photo of Rion-Antirion: The Mainland (Antirion, Nafpaktos on the left) is separating from Peloponnese (Rion, right)
Ferry boats passing by the almost-completed bridge
One fun event stands out in my memory: I think I was the only person not associated with the project, that walked the full length of Gefyra before it was completed, and there was still a gap! How can that be? Well, when the last segment was yet to be placed, there was a construction scaffold below to receive it. This scaffold spanned across the gap, so by climbing down to it, crossing on the scaffold, and then up the other side. Until then, one had to use the ferries – or swim.