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SURVEYING
DAVID SHIPMAN
through automation SAFER SURVEYING
R
educing the safety risks our workforces are exposed to is vital, and there have been
many initiatives to keep railway workers safe from harm.
Of course, the best way of doing this is by taking people away from the live railway altogether. This is great in theory, but how do we do this in practice? It requires us to use new ways to complete all those tasks currently undertaken by people out on the railway. In terms of surveying, this means we have to find new methods to: » Gather information about existing assets; » Review and assess that information; » Visualise new and modified assets; » Monitor the progress of construction.
What are our options? Existing aerial imagery plays a part, particularly in the early
planning stages. However, it can lack the accuracy required for detailed design and doesn’t capture the necessary drivers’ perspective for signal sighting and route learning, especially when video footage is required to support these activities. A further risk with using existing data is that footage may not be sufficiently recent, depending on when the area was last surveyed. The latest changes may not be captured - missing essential detail for renewals or enhancement projects and undermining the quality of the survey and the accuracy of the finished design. If this is discovered at a late stage of a project, the cost of rectification is far greater than the cost of getting it right before design has commenced. The Signalling Innovations Group (SIG), now part of the Network Services directorate within Network Rail, works hard to offer answers to the rail industry. Our range of tools PHOTO: WWW.ENABLEMYTEAM.COM
Rail Engineer | Issue 181 | Jan/Feb 2020
and services are designed to keep individuals away from the operational railway without compromising on detail. Train-borne data capture uses laser, infra-red and 4K video equipment attached to Network Rail’s inspection fleet. Commissioned early in the project lifecycle, it can provide an up-to-date record of the asset with an accuracy of just a few millimetres. This is precise enough to meet the demands of multiple disciplines, without exposing workers to the risks of undertaking traditional manual surveys on the live railway. Lowering the risk to the workforce is complemented by time and cost reductions. Using data from the onboard systems with SIG’s suite of advanced tools, asset and network features can be captured with geo-location, and exported as a threedimensional model using SIG’s System Data Exchange Format (SDEF), for use in other tools alongside the laser point cloud and video data. Overlaying video with laser data enables highly accurate measurements in three dimensions and, with data captured across the whole project area, there is no need to revisit sites to check or recapture information if the design needs change. New design, such as new signal structures and overhead gantries for signalling and power, can then be added as virtual-reality models, enabling planned changes to be visualised easily. For signalling renewals, this has revolutionised the signal sighting process; the traditional method of an expert committee attending each signal location is replaced with
