The problem was first noticed towards the end of the 19th Century, when train speeds became high enough to encounter it.
This travel time results in an average train speed of 43 km/h.
This improved rail design permitted higher train speeds and more reliable operation.
The bridge has been designed for a train speed of 160 km per hour.
Once fully completed the average train speed should be around 160 km/h.
Although no plans exist at present for 125mph train speeds, a more general extension of 110mph services is likely to start in 1990.
It features much milder grades and is designed for faster train speeds.
Average train speeds had doubled from 1919 to 1959, but unions resisted efforts to modify their existing 100- to 150-mile work days.
From end to end, it takes around 16 minutes, with an average train speed of 32 km/h.
The devices are required only where train speeds can reach 80 miles per hour or more.
