赵州桥
Zhaozhou Bridge, the world's oldest open-spandrel arch
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如果你去河北赵县，当地人一定会带你去看一座石头桥。它看起来并不大，也不特别漂亮，可是它已经在河上站了一千四百多年。它就是赵州桥。
赵州桥建在隋朝，大约是公元595年到605年之间。设计这座桥的是一位普通的工匠，名字叫李春。关于他，历史上几乎没有留下什么记载，我们只知道他的名字，是因为唐朝人写的一篇文章里提到了他。
这座桥全长五十多米，中间只有一个大拱，跨度有三十七米多。在一千四百年前，用石头造这么长的一个拱，是一件非常了不起的事。
不过，赵州桥最聪明的地方，不在中间的大拱，而在大拱两头的“肩膀”上。仔细看，你会发现那里还开着四个小拱，左边两个，右边两个。这种设计叫“敞肩拱”。
为什么要在这里多留四个小洞呢？李春至少想到了两个好处。第一，桥变轻了。用的石头少了很多，桥自己的重量也就小了很多，不容易压坏。第二，不怕洪水。夏天河水上涨的时候，水可以从这些小拱里流过去，不会把整座桥推倒。唐朝人在文章里就专门称赞过这四个小拱，说它们能减少洪水的力量。
这个办法到底有多先进？在欧洲，类似的石拱桥要到很多个世纪以后才出现。今天，赵州桥被认为是世界上现存最古老的敞肩石拱桥。1991年，它被美国的一个工程组织评为“国际历史土木工程里程碑”。
一千多年来，赵州桥经历了多次洪水、战争和地震。1966年，离这里不远的邢台发生了大地震，赵州桥竟然没有倒下。
当然，老百姓更喜欢讲自己的故事。民间传说这座桥是鲁班一夜之间造好的。还有一首古老的民歌里唱，神仙张果老骑着毛驴过桥，想试试它到底结不结实，结果在桥上留下了驴蹄印。据说，鲁班赶紧跳进河里，用手托住了桥。
今天，汽车早就不从赵州桥上过了，它成了一座只让人走的桥。下次你走过一座有小拱的桥，不妨想一想：这个主意，李春一千四百年前就想到了。
Key words
| Word | Pinyin | Meaning |
|---|---|---|
| 当地 | dāngdì | local; in the locality |
| 石头 | shítou | stone; rock |
| 建 | jiàn | to build; to construct |
| 设计 | shèjì | design; plan; to design; to plan |
| 记载 | jìzǎi | to record; to write down; record; account |
| 造 | zào | to make; to build; to create |
| 洞 | dòng | hole; cave |
| 重量 | zhòngliàng | weight |
| 上涨 | shàngzhǎng | to rise; to go up (prices, water) |
| 称赞 | chēngzàn | to praise; to commend |
| 力量 | lìliang | strength; power; force |
| 先进 | xiānjìn | advanced; progressive; advanced individual or unit |
English (for the teacher)
If you go to Zhao County in Hebei, the locals will certainly take you to see a stone bridge. It isn’t big, and it isn’t especially beautiful, but it has stood over the river for more than 1,400 years. It is the Zhaozhou Bridge.
The bridge was built in the Sui dynasty, roughly between 595 and 605 AD. It was designed by an ordinary craftsman named Li Chun. History has left almost no record of him; we only know his name because a Tang dynasty writer mentioned him.
The bridge is over fifty metres long, with a single great arch in the middle spanning more than thirty-seven metres. Building a stone arch that long 1,400 years ago was a remarkable achievement.
But the cleverest part of the bridge isn’t the great arch in the middle; it’s on the arch’s “shoulders” at either end. Look closely and you’ll see four small arches opened up there, two on the left and two on the right. This design is called an “open-spandrel arch”.
Why leave four extra holes here? Li Chun thought of at least two benefits. First, the bridge became lighter. It used much less stone, so its own weight was much smaller and it was less likely to crush itself. Second, it wasn’t afraid of floods. When the river rose in summer, the water could flow through these small arches instead of pushing the whole bridge over. The Tang writer specially praised these four small arches, saying they could weaken the force of floods.
Just how advanced was this idea? In Europe, similar stone arch bridges didn’t appear until many centuries later. Today the Zhaozhou Bridge is regarded as the oldest surviving open-spandrel stone arch bridge in the world. In 1991 an American engineering society named it an “International Historic Civil Engineering Landmark”.
Over more than a thousand years, the bridge has been through many floods, wars and earthquakes. In 1966 a major earthquake struck Xingtai, not far away, and amazingly the bridge didn’t fall.
Of course, ordinary people prefer their own stories. Folk legend says Lu Ban built the bridge in a single night. An old folk song says the immortal Zhang Guolao rode his donkey across to test how sturdy it really was, and left the donkey’s hoof prints on it. It is said that Lu Ban jumped into the river and held the bridge up with his hands.
Cars stopped crossing the Zhaozhou Bridge long ago; it is now a bridge only for people on foot. Next time you cross a bridge with little arches, you might stop and think: Li Chun had this idea 1,400 years ago.