Last month my daughter Elizabeth and my grand-daughter Rachael had the opportunity to spend a few weeks in Japan. Elizabeth was there as sponsor for nine Pitt students on a Study Abroad project. One of the highlights of their trip was a visit to the Akashi-Kaikyo Bridge, near Kobe. Completed in 1998, this bridge provides a vehicular link between Honshu, Japan’s main island, and the southern island of Shikoku, via an intermediate island, Awagi. Currently it is used by about 30,000 vehicles per day. When it was built, it was the longest suspension bridge in the world. Last year the “1915 Canakkale Bridge” over the Dardenelles Strait in Turkey was opened and took over that title, with a main span 105 feet longer than Akashi-Kaikyo.
Despite surrendering its title, the Akashi-Kaikyo Bridge retains its place as one of the world’s most impressive structures. In 1995, well into its construction, the Kobe region was subjected to Japan’s second most severe earthquake, surpassed only by the 1923 Kanto event. This seismic event killed 6,400 people, mostly in the city of Kobe. It also moved the piers for the bridge almost forty inches farther apart, necessitating major changes to its design. I recall the event distinctly because Elizabeth was nearby at the time, studying at the University of Nagoya.
Akashi-Kaikyo has a total length of 12,808 feet with a main span between towers of 6,530 feet. For comparison, it is forty two percent longer than our beloved Golden Gate Bridge, and ten times as long as Pittsburgh’s signature Tenth Street suspension bridge. Its towers are 975 feet high and are equipped with tuned mass dampers to prevent sympathetic harmonic vibration during high winds. Its deck is supported by a pair of deep trusses, stiff enough to protect it against harmonic resonance of the type that destroyed the Tacoma Narrows Bridge (aka “Galloping Gertie”) due to high winds. Clearance above sea level is 215 feet, sufficient to permit passage of the largest container vessels currently contemplated.
Each year I try to include a bridge among the sketches I produce for the calendar I distribute to my close friends and family. This year’s attempt was a pen-and-ink pontilistic view of Akashi-Kaikyo. I wanted to mimic the style of the classic Japanese wood-block artists – Hokusai and Hiroshige. The closest thing I could find was a contemporary wood-block print of the bridge, at sunset. As is usually the case, the result of my sketching is barely acceptable.
Akashi-Kaikyo certainly is a world class structure, one that I wish I had had the chance to see before I became ancient and feeble. Rachael, however, is proving to be an adequate surrogate for me. After returning home from Japan, she promptly left for a six weeks study abroad experience in Avignon, France. This automatically required her to visit the remnants of the famous bridge over the Rhone River memorialized in the French song, “Sur le Pont, d’Avignon”. Originally built in 1234 AD, it was nearly three thousand feet long, a series of twenty-three stone arches. All that remains today are four arches and the song. It was built by an uneducated shepherd, Benezet, probably on the site of an earlier Roman bridge.
Even more impressive, she and her colleagues went canoeing one weekend at the Pont du Gard. About fifteen miles west of Avignon, it originally carried the Nimes aqueduct over the Gardon River. Nimes was a Roman city in the colony of Nemausus; the aqueduct was over thirty miles long. The Pont du Gard, constructed in the first century AD, is a remarkable structure about 1,200 feet long, in three tiers of stone arches. The bottom tier alone would be a memorable structure – six stone arches, seventy-two feet high, each spanning about seventy-six feet. It supports the second tier, another series of arches sixty-six feet high. On top of it is the third tier, a series of smaller arches twenty-three feet high, each spanning nineteen feet. The combination is spectacular, and twenty centuries old!
Not to be outdone, the Asian branch of the Oyler Family Bridge Explorers team recently visited Quanzhou, an historic port city in Fujian Province in southeastern China. While there, John, Victoria, and Lai An checked out two ancient bridges – Luoyang and Anping. Luoyang was constructed in 1058 AD during the Northern Song Dynasty. It is about 4,000 feet long, with forty-seven spans each about eighty-four feet long, crossing the estuary of the Luoyang River. Its forty-six piers are “boat-shaped” to protect them against the ebb and flow of the tide as well as the current in the river. Stone girders support the deck between the piers. Like the Pont du Gard, Luoyang has been designated a World Culture Heritage Site.
Also in Quanzhou, the Anping Bridge is another World Culture Heritage Site. Built in 1151 AD, during the Southern Song Dynasty, it originally spanned the tidal estuary of the Shijing River. Today the Shijing has been “silted up” to the extent that the estuary is a collection of ponds, wetlands, and open channels. Anping was famous for being China’s longest bridge. It originally was over 7,200 feet long and consisted of 362 individual spans. It, too, has boat-shaped stone piers supporting stone girders spanning about twenty feet. Both Anping and Luoyang were designed primarily for pedestrian traffic.
John claims that, when he was young, our family trips were frequently interrupted because our car was programmed to slow down and stop every time we passed a significant bridge, a road-side cut with rock outcroppings, or an historic landmark. That is an exaggeration, but it would have been a good idea. I am pleased that our children have inherited my curiosity about such things.