Jheni Osman: Bridges
Einstein’s special theory of relativity helped to design the world’s tallest bridge. The bridge is taller than the Eiffel Tower and can carry 35,000 tonnes. All bridges have to cope with two main forces, tension and compression.
Engineers also had to consider the problem of accuracy when working on such a large scale. They used GPS to check the positioning of cables. GPS receivers calculate their position by timing how long signals take to travel to satellites.
For accuracy to within a few minutes, the atomic clocks on the satellites must be extremely precise, to within about ten nanoseconds. However, the atomic clocks on satellites are slightly slower than those on Earth, and this has to be taken into account when making measurements.