2012 is an exciting year for construction in London; the new Olympic Park has brought massive regeneration to the East of the city, and there has already been widespread development of the transport systems both above and below ground.
Something any returning visitor to London will notice immediately is the rapid change in the city’s skyline over the last decade. There are currently 12 buildings more than 100 metres in height in development, and six of the city’s current tallest buildings were completed in the last decade. Perhaps the most noticeable of these is the Shard London Bridge: a striking multi-use development sitting just south of the River Thames, next to London Bridge Railway Station.
When completed later this month, the Shard will extend 306m (1,017 feet) into the sky and will be the tallest building in the European Union. The development, towering 70 floors above London, will be split into offices, restaurants, a hotel and residential apartments. The Shard has a public viewing platform between levels 69 and 72, and is expected to attract at least a million visitors within its first year of operation.
Renzo Piano, the architect for the Shard, considers the slender, spire-like tower a positive addition to the London skyline. The sophisticated use of glazing with expressive facades of angled panes is intended to reflect light and the changing patterns of the sky so that the form of the building will change according to the weather and seasons.
In the summer of 2009, Leica Geosystems was approached by Byrne Bros, one of the UK’s – and the world’s – leading formwork construction companies, to develop a real-time, slip-form rig positioning system that would be used to construct the central concrete core of the Shard. Slip-form construction is perhaps one of the safest, most efficient and economical methods of building vertical structures, which can enable formwork construction to rise at rates of up to 8 meters per 24 hours. Accurate controlling of the rising slip-form rig is essential for this process and traditional methods of doing this are time consuming and labour intensive. They require traverse computations from observations taken with total stations and optical plummets to compute grid coordinates and check the core is being constructed as designed.
“When it comes to structural monitoring, there is no room for risk. At Byrne Bros we pride ourselves in ensuring the delivery of best in class structures with the upmost of safety and care. It is integral for us to be able to work with a technology that is adaptable to the project and delivers without fail. That’s why we chose Leica Geosystems and that’s why we were able to deliver
one of the largest engineering projects with absolute precision.”
Donald Houston, Byrne Bros
After some consultations between Byrne Bros and our technical team, we developed a solution combining TPS and GNSS sensors, inclinometers, SmartNet RTK corrections and GeoMoS software to allow accurate and instant measurement of the vertical and horizontal position of the slip form rig. The information from the multiple measurement systems was relayed back to a central bespoke interface where the results were presented in an easy-to-understand graphical display. These results were cross-checked against wind speeds, allowing any decisions to be made with complete confidence. The rig manager was then able make adjustments to the rig position via the use of hydraulic pumps.
Working with Satellite Positioning in an urban environment like London can often prove challenging. For example, existing buildings and infrastructure can obscure the satellite signals, which can impair position quality and in some cases even prevent positions from being achieved. To account for this, prisms were co-located with the Leica Geosystems antenna to allow both Total Station and satellite measurements to be gathered simultaneously. The measurements made using the Total Stations served as a backup and to check the accuracy of the satellite positioning results.
This new and innovative approach for controlling the position of a slip-form rig has proved highly successful on the Shard project. The fact that the results obtained could be verified and correlated to those obtained via traditional methods was extremely important in building confidence in the system. After this success, other tall buildings in London being constructed using slip-form methodology have already adopted this system and Byrne Bros plan to use this system again on future projects.
Facilitating the European Union’s tallest building through expert precision – that’s shaping change.