Kanmon Bridge

Listen first. Before you look up, listen to the water. Down below, the Kanmon Strait is moving. On many days the current runs fast enough that you can see it pulling, forming small whirls and ridges on the surface. Above you, a long white bridge hangs from two cables and crosses from one main island of Japan to another. The steady hum you hear is traffic on the deck, far overhead. Down here, the sound of the sea is louder.

This is the Kanmon Bridge. It joins Shimonoseki, at the western tip of Honshu, to the Moji district of Kitakyushu, on the island of Kyushu. The name comes from two place names. "Kan" comes from Akamagaseki, an old name for Shimonoseki. "Mon" comes from Moji. So the bridge carries both cities in its name. When it opened in 1973, it was one of the longest suspension bridges in Asia. The distance between its two towers is roughly 712 metres.

A suspension bridge is simple in principle. Two tall towers hold up two main cables, and those cables hold up the road through a row of vertical hangers. Look at the curve of the main cables. They dip low in the middle of the strait and rise to the tops of the towers. That curve is the whole idea of the structure. The weight of every truck and car above you travels up the hangers, into the cables, over the towers, and down into anchors buried in the ground on each shore.

Why build a bridge here at all? The strait is narrow, and that is the first surprise for many visitors. Kyushu looks close enough to swim to. It is not. The current changes direction several times a day with the tides. Ships of every size squeeze through this channel between the Sea of Japan and the Seto Inland Sea, the calm body of water between Honshu, Shikoku and Kyushu. A bridge had to be high enough for that traffic to pass underneath.

Watch the water for a few minutes. Container ships, tankers, ferries and small fishing boats move through in a steady line. Some ride the current. Others push hard against it. Large ships often need to time their passage with the tide. For people who live in Shimonoseki, this parade of hulls is ordinary daily scenery. For a first-time visitor, it can be the most memorable part of standing here.

The bridge is not the only crossing. This is the second surprise. Beneath your feet, under the seabed, run tunnels. Trains pass through railway tunnels built in the twentieth century. There is also a road tunnel, and inside it, a separate pedestrian walkway. You can take a lift down from the Shimonoseki side, walk under the strait, and come up on Kyushu. Halfway along, a line on the floor marks the border between Yamaguchi Prefecture and Fukuoka Prefecture. Many people stand with one foot on each side for a photograph.

The bridge itself carries the expressway, so it is for vehicles. Walking across the deck is not part of the visit. Instead, most people experience the bridge from below and from the shore. The park at the Shimonoseki end, often called Mimosusogawa Park, sits almost under the deck. From here you look straight up at the steel, and straight across at Kyushu.

This stretch of water is also one of the most important places in Japanese history. In 1185, the final sea battle of the Genpei War was fought here, at Dan-no-ura. The war was a struggle between two warrior clans, the Taira and the Minamoto. The Taira were defeated in these waters. According to the classic war tale of the period, the young emperor Antoku, still a child, was carried into the sea and drowned. The battle helped open the way to rule by samurai governments for centuries afterwards.

Local legend keeps that battle alive in a strange way. Fishermen here have long spoken of the Heike crab, a small crab whose shell has ridges that look like an angry human face. Heike is another name for the Taira clan. Locals say the faces are the spirits of the fallen warriors. It is a folk tale, not history, but it shows how deeply the battle sits in local memory. Nearby, Akama Shrine, with its bright vermilion gate, is dedicated to the drowned child emperor.

The strait saw conflict again in the nineteenth century. In the 1860s, the Choshu domain, which controlled this area, fired on foreign ships passing through the channel. Western naval forces answered with bombardments and landings. In the park you can see a row of replica cannons pointing out across the water toward the ships. They are a reminder of a short, violent period when this narrow channel stood at the edge of Japan's opening to the outside world.

Now look again at the bridge, with all of that history below it. When it opened in the 1970s, it changed travel between Honshu and Kyushu. Drivers no longer depended on ferries or the tunnel alone. Today the deck forms part of the main expressway route linking the two islands. Goods, families and holiday traffic flow across it every hour of the day and night. The structure is practical first. Its graceful shape comes from engineering, not decoration.

If you can, stay until dusk. The bridge is lit after dark, and the lights trace the line of the cables across the strait. Lights on the Kyushu shore come on too, and ship lights slide slowly beneath the deck. For a wider view, many visitors go up Mount Hinoyama, the hill behind the park. From the top, the whole strait opens up, with the bridge in the middle and both cities spread along the water.

Before you leave, stand still one more time and look across. The far shore is a different island, a different prefecture, and in the past it was a different world for travellers. Feel the wind coming up the channel. Listen to the water under the deck and the faint rumble of traffic above. As you walk away, notice how often the bridge appears between buildings and trees. In Shimonoseki, it is never far from view.