The Japanese designers and engineers tested their designs by building complex models. These were tested in wind tunnels which helped them refine the design so that the bridge could cope with severe weather and typhoon conditions. The photograph opposite shows 40 metre long model, set up for a variety of scientific tests.

After vigorous testing had taken place, construction of the real bridge could begin.

The two towers stand on two large circular foundations. The moulds for the two foundations were built in dry dock weighing 15 000 tonnes and 60 metres in height. In March 1989 a major stage of construction was reached with the moulds for the foundations to the towers being towed out to their positions in the sea by numerous tugs. When in position the moulds were flooded with two hundred and fifty million litres of water, taking eight hours to complete. By the time the moulds were full, they were resting on the sea bed.

Each of the two foundations were filled with 265 000 cubic metres of concrete. However, ordinary concrete does not mix with water and so the Japanese had to develop special concrete which was capable of mixing with sea water.

In 1989 work on the two towers began. Each is nearly as high as the Eiffel Tower and is designed to have a two hundred year lifespan. The towers are 283 metres in height and if the foundations are included, this adds a further 60 metres.
Each tower is made up of 90 sections and they were built with absolute precision as the design allowed only a 25mm offset at the top. In order to achieve this level of accuracy each of the blocks were ‘surface ground’ to a precise finish. 700 000 bolts were used to fix each of the towers together.
Each tower is designed to flex / move in storm force conditions. They and even have a special mechanism that counteracts and dampens movement.

QUESTIONS:

1. Why do you think it is important to make models of complex structures before their full scale construction?

2. What is special about the towers of the Akashi-Kaikyo Suspension Bridge?

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