600 metres of tunnel scanned safely in 40 minutes
PROJECT: Fast and safe kinematic reality capture in Elbe Tunnel, Germany
PRODUCT: Leica ProScan
OBJECTIVE: Documentation the three older tunnel tubes by kinematic 3D laser scanning to create current, accurate inventory documentation available to the Elbe Tunnel operator.
The three older tunnel tubes needed were captured by kinematic 3D laser scanning to create current, accurate inventory documentation for the Elbe Tunnel operator. Previously unachievable without considerable disruption, Leica ProScan enabled the rapid and accurate mapping of the underground environment within tight overnight access restrictions.
One of the most important components of northern Europe's infrastructure lies about 28 metres (92 feet) below the surface of the Elbe River: the Elbe Tunnel in Hamburg. As part of the A7 Autobahn, it connects the southern and northern portions of the Hanseatic city of Hamburg and the Scandinavian countries with Europe's metropolises. It is about 3.3 kilometres (1.9 miles) in length, with some 1,000 metres (3,280 feet) passing under the riverbed. At peak periods, up to 145,000 cars and trucks pass through the tunnel’s four tubes each day.
To ensure the future safety of this important traffic route, the three older tunnel tubes were renovated between 2009 and 2013 in accordance with the updated guidelines for facilities and operations of highway tunnels. The state geoinformation and survey office commissioned the Hamburg based company Dr. Hesse und Partner Ingenieure (dhp:i) with the documentation of every tunnel tube by kinematic 3D laser scanning. The objective was to make current, accurate inventory documentation available to the Elbe Tunnel operator (LSBG, state office for roads, bridges and waters).
The georeferenced information obtained will be needed for maintenance and repair support of Elbe Tunnel planning, design, construction and administration processes and as a basis for future Building Information Modelling (BIM), among other uses.
In addition to the tunnel geometry, all other objects and equipment in the tunnel also had to be recorded for this purpose within an accuracy of a few centimetres. This includes supply and safety installations, such as:
totalling more than 200 different 3D objects.
Selecting the appropriate procedure Because of the Elbe Tunnel's critical importance for traffic in and around Hamburg, the survey could only result in minimal blocking periods. It was, therefore, clear from the outset that the activities would have to take place in the low traffic period between 10 p.m. to 5 a.m., and only one tunnel tube could be blocked at a time.
The client's invitation to bid explicitly specified surveying by means of kinematic laser scanning. During the tendering procedure, several vehicle-based and mobile scanning systems from different bidders were evaluated. At the end of the selection process, the decision was made in favour of the ProScan T-Series system from p3d systems GmbH. In addition to other features, easy integration of the Leica ScanStation P15, high acquisition speeds and extremely accurate object recording were persuasive.
"The kinematic scanning system used by dhp:i not only guarantees us maximum precision but also a complete recording of the entire tunnel structure. We have the confidence of being able to rely on the data quality and, at the same time, minimise the blocking periods for this important tunnel," says Bernhard Cieslik, engineer and manager of municipal surveying at the state geoinformation and survey office responsible for the project.