Life really does have its ups and downs. Some parts of Europe and America, for
example, can rise and fall by as much as 10 cm every day. Now, scientists at the
University of Newcastle upon Tyne in England are using satellite technology to
produce the first national map of “bounce” to help civil engineers make ends meet
when they build bridges, dams and tunnels.

Britain is the first country in the world to
begin such a project which, when completed, could make surveying ten times more
accurate and allow big savings on large construction projects. The “bounce” is caused
by the tides. As the weight of water increases on the continental shelf around Britain”s
coastline, the whole country sinks a little into the earth”s crust, rebounding as the tide
recedes. The problem for engineers is that the land does not sink evenly, resulting in
local distortions which cause inaccuracies when satellite surveying techniques are
used in construction projects. Dr Peter Clarke, of the Department of Geomatics at the
University of Newcastle, is leading a research team which is using orbiting U.S.
satellites to monitor the positions, with an accuracy of a millimetre or two, of more
than 30 Global Positioning System (GPS) receivers located all over Britain. It should
then be possible to estimate the “bounce factor” in any part of Britain at any time of day.

Although “bounce” has previously been measured in certain locations by similar
techiques in the USA and some other countries, none has produced an accurate and
comprehensive national map. The project, which should be completed by Autumn
2004, has received £64,000 in funding from the Natural Environment Research
Council and also involves the Proudman Oceanographic Laboratory and Ordnance
Survey, with help from the National GPS Archive at Nottingham University. Dr Clarke
said: “The phenomenon has been known about for some time but it has only become
necessary to measure these movements because of the increasing use of precise
satellite surveying by civil engineers.

“For example, a great deal of time and money was spent during the construction of the
Channel Tunnel to ensure that the two halves met in the middle at the right height. A
few centimetres difference would have proved very costly to put right.

“The same principal applies to other large construction projects such as railways,
dams and bridges.

“Our measurements will be used to adjust the data obtained by surveying to produce
results which are perhaps ten times more accurate – to within millimetres rather than
centimetres. This could significantly reduce the cost of large construction projects.”



For further information contact Dr Peter Clarke on 0191 222 6351/6445. This press
release is issued by the University Press Office, 0191 222 7850. E-mail