The German rail company operates approximately 63.800 km of rail tracks, 67.000 track switches, 17.300 railroad crossings, 790 tunnels and 26.900 bridges. Maintenance and service work is carried out continuously, repair work is conducted, and new crossings such as bridges or tunnels are being built. Construction is often carried out during ongoing rail traffic operations. Maximum tolerated distances of rail track movements are small. ALLSAT Global Monitoring is the ideal solution to make sure thresholds are kept.
Numerous geodetic, geotechnical and meteorological sensors can be integrated into ALLSAT Global Monitoring, including GNSS receivers, total stations, inclination sensors, meteorological sensors, etc.
ALLSAT Global Monitoring is used in projects around the observation of potential movements of heavily used high-speed rail tracks.
In the course of the tunnel construction project Jenbach/Wiesing for renewal of the Inntal-Autobahn near Innsbruck / Austria, a Tunnel Boring Machine (TBM) is used on 3.5 km of transect. The tunnel runs in immediate vicinity of the River Inn, and undercuts the existing rail track. Soil stabilisation is required for large parts of the transect, because the TBM mostly drives through loose gravel. In order to support the rail track special drilling machines drive inclined boreholes into critical areas of the ground, into which in a second step liquid cement is injected (compensation grouting).
But injections may also result in deformations (namely: upheaval) of the heavily used high-speed track. Track movements must be limited to less than 1 cm. Close and continuous monitoring of movements is therefore required during compensation grouting. For automated monitoring over a period of three weeks the following combination of GeoMoS and auxiliary equipment is used:
- Leica total station TCA180
- Target prisms
- Alarm box
- Warning light
- Computer
The total station is installed on a stable, deeply founded steel monument close by the tracks. The sensor is controlled directly from the PC via GeoMoS. The PC is installed inside a construction container with power supply. Reference points for the independent stationing of the total station are mounted on stable points in the surroundings which have been used before in standard surveying tasks on the construction site.The system generates messages:
- if pre-set tolerances of track movement are exeeded, and
- if communication breakes down between the computer and total station.
The message is transferred to an alarm box to trigger the warning, flashing light. Thus GeoMoS warns workers on-site directly, should a critical of the tracks be registered. Implementation of remote messaging is possible with small alterations.
The system is installed for a period of three weeks. System installation takes about six hours, after which the system runs completely automatically. The installation replaces comprehensive manual measurements, which moreover could be carried out at discrete time intervals only. ALLSAT Global Monitoring, on the other hand, monitors the tracks continuously while reducing the staff’s workload. We estimate time saved to be about 80% as compared to manual measurements.
A comparable ALLSAT Global Monitoring project is implemented along a rail track in Lower Saxony / Germany. The system was installed in the spring of 2010. Heavy rainfall had caused instability of soil under a railroad dam. Monitoring is required during soils and dam stabilisation works, and for several months after their completion. Power supply at the somewhat remote location is organised with use of a fuel cell. Instead of the flashing light the remote messaging functionality of Leica GeoMoS is used in this project. Besides, ALLSAT software Gart-2000® Geomon is installed on a PC at the rail company’s primary control centre. The Geomon screen shows potential exeedances of thresholds in clearly laid out traffic light colours. An acoustic signal makes sure that the staff on duty in the control centre intervenes manually.
Gart-2000® Geomon delivers all information on staff in charge to be informed and, if required, emergency procedures to be followed – up to instantaneous closing of the track to all further traffic in case of jeopardy.
ALLSAT Global Monitoring means optimal system configuration for any monitoring application and implementation of respective projects by Allsat GmbH network+services.
