An innovation using Google Earth to display digital terrain model data for the display of ground monitoring has been developed by the Costain Skanska joint venture project team constructing Crossrail’s Paddington Station.

Normally movement data is displayed and analysed in a tabular spreadsheet which is taken forward to display various trend–line graphs used to build up a picture of the geotechnical and building movement related to construction activities over time. By developing a method of importing data straight from the field and subsequent database extraction and transformation into Google Earth, the project team has been able to create a digital terrain model to formulate a colour banded display which shows movement results.

Sean Brown, Engineering Surveyor for Costain Skanska JV, said:

“With over 1600 geodetic prisms and over 800 permanent level points (PLP’s) to monitor at various frequency requirements (currently the Automated Total Station systems runs every 6 hours), we can save considerable time in analysis by using the display model to review the site as a whole.  This also helps our daily review meeting with Crossrail as we can very quickly identify any behaviour that we may need to investigate further, as well as being a clear visual display aid.”

The model looks just like any other Google Earth map but with the extra functionality of being able to display a bespoke kml file which is colour banded into displacement zones in relation to the zone of influence defined contour intervals. This shows the displacement of all monitoring sensors in relation to a colour legend.

In addition to this the model displays all individual sensors and will highlight any points that display trigger breaches which are colour banded into green, amber and red alert colours. The model can also be used to compare the actual movement against predictions and identifying seasonal ground movement and effects.