Tech Talk with Shane Gilmour


Shane Gilmour, Senior Land Surveyor at McGarrell Reilly, talks with about the surveying technologies and instruments that are changing the roles of the surveyor and site engineer.

Can you tell us about your career as a surveyor?

After completing a land surveying course at the University of East London, in 1980, my first job was on a large scale off-river water storage dam in Southern Zimbabwe. It involved the construction of a main earth wall of a height of 26m and 450m in length, two saddle dam walls of a height of 12m and each 750m in length together with a 3km pipeline and pump house. Since then I have always been involved in surveying in one way or another throughout my working life.

What major changes have you witnessed in instrumentation?

Instrumentation over the last decade has changed considerably from sighting through optical telescopes and using programmable calculators, with the surveyor/engineer having a good understanding of trigonometric functions and Pythagoras’ Theorem, to today’s satellite systems, robotic stations and CAD field software.

The past decade has seen a huge reduction in the use of large A1 size paper detailed drawings which you had to carry around with you in the wind and rain, to now using your mobile phone/tablet to access any detail you want to know. CAD has allowed files to move quickly from engineers to the mobile workforce in the field.

The surveyor/engineer always had to have an assistant to hold the prisms/staff/poles and tapes called a ‘chainman’. These days you can work on your own and at greater speed, thus reducing costs and being more productive. Human errors have also been reduced with the introduction of the modern systems.

New instruments are increasing accuracies and speeding up the time spent in the field. Global Navigation Satellite Systems (GNSS) have made life a great deal simpler, allowing you to locate your exact position anywhere and at any time with the RTK (real time kinematic) receiver.

The hybrid systems which combine GNSS positioning with the Robotic Total Station allow you to move from one system to another achieving accuracies of 5mm. McGarrell Reilly sites use Topcon’s DS Series auto-tracking/Robotic Total Stations, combined with the Hiper SR RTK receiver.

The European Galileo satellite navigational system will increase the satellite coverage overhead and thus further increase accuracies. The end result of all this can be seen by the rapid pace of development around Dublin city.

How are these changes influencing your work at present and how do they change the surveyor’s role?

On the housing development I am currently on, I have been able to set out over 60 houses in a little over 3 weeks. I had never achieved that before. The new setting-out systems have made it easy, for young engineers/surveyors coming through into the workplace. Their numerical skills and mental arithmetic ability appear weak. However, they are generally good on the software side and pick up the systems quickly.

The old faithful ‘dumpy’ level still has its uses and its accuracy is guaranteed. New self-levelling graded lasers and the pipe laser have made the life of ground workers far easier to maintain accurate levels and gradients.

What other new technologies are improving accuracy on site?

Drones are already starting to play an important role and are currently used in the calculation of volumes of stockpiles on many sites. Scanners can scan buildings and are practically useful in restoration work on listed buildings. Road scanners are also able to detect depressions or changes in surface heights with their locations while driving along.

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