|Drill auger sections and debris on the London |
Underground track (photograph courtesy of Network Rail)
"This was a serious incident that could have ended very differently had it not been for the vigilance and prompt reporting and actions of our drivers. We carry two million people a year on the Northern City Line" First Capital Connect managing director Neal Lawson, as reported by the BBC.The construction site was 13 metres above the tunnel and because the location of the tunnel wasn't shown on any map available to the site developer or the local planning authority, Network Rail was not consulted during the planning application stage. As a result, no one knew the tunnel and the drills were going to collide.
It also turns out that when the Rail Accident Investigation Branch examined the incident, over half the piles intended for the site would have crashed their way through the tunnel, had they been constructed.
You can read more about it in the RAIB Rail Accident Report.
This kind of scenario, where an asset (e.g. railway tunnel) is damaged or affected by something else (e.g. a drill), is known as a strike.
How on earth can a 'strike' happen with today's advanced detailed mapping technology?This situation could have been avoided entirely had the data about the ground beneath the construction site been coordinated and available to the right people at the right time. Sadly, this incident is just one of many.
At the moment, subsurface information is quite tricky to get at unless you know what you are doing. Data quality can be variable - entirely absent or poor. Meanwhile political and organisational boundaries make it difficult to get a wider picture of the subsurface conditions. Ultimately, there is no central digital map showing what is present, exactly where it is and what issues you need to be aware of.
An incomplete view of subsurface data can have costly and far-reaching outcomes. As well as damage to the underground assets themselves, other consequences include environmental costs and economic costs associated with the millions of hours of road disruption, huge repair and replacement costs, project re-designs and overruns. The Department of Transport estimates that street works account for an estimated cost of £4.3bn annually. Meanwhile the Treasury estimated in 2013 that greater cross-infrastructure collaboration can save the economy an estimated £3bn.
Introducing Project IcebergProject Iceberg aims to address the serious issue of the lack of information about the ground beneath our cities and the un-coordinated way in which the subsurface space is managed. This is an exploratory project undertaken by the British Geological Survey, Future Cities Catapult and the Ordnance Survey.
What are we likely to find in the ground beneath a city?The short answer is ... a lot. It's a complex, highly variable environment that has been through multiple phases of development. Not only are the natural ground conditions varied and often highly disturbed, but the ground contains a large number of built structures and utilities. There are gas mains, sewers, water supply pipes, drains, oil pipelines, old mine workings, tunnels, power cables, telecom cables, boreholes, landfills, basements... and the list goes on. These are owned or managed by different entities, making the job of uniting data quite an undertaking. As well as assets, there's geological information that needs to be taken into account for the design of foundations, slopes, retaining walls, tunnels, roads, rail and more.
Take a look at this:
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