The monitoring of railway-bridge ‘A2 Vleuten – Amsterdam Rijnkanaal’ using GeoMoS in combination with the VDV Leica GeoMoS Interface

BouwRisk, The Netherlands (http://www.bouwrisk.nl/)

During this project, the Dutch company BouwRisk was responsible for the monitoring of the railway bridge Vleuten – Amsterdam Rijnkanaal during construction activities. The national motorwayA2 used to go underneath this bridge (see picture 1), but was relocated to a road tunnel nearby by the end of 2012, early 2013.

Due to the relocation of the road the bridge became unnecessary. However, it could not be removed, as it had to remain in use for rail traffic. It was decided that the best solution was to apply a so-called embankment underneath the bridge: i.e. filling the gaps between the pillars with sand, thus creating a bank (see picture 3 and 4).

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1: Before: A2 underneath the railway bridge.

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2: Railway bridge before construction of the bank.

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3: Work in progress: constructing the bank.

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4: Work in progress: constructing the bank.

During the construction activities it was very important to monitor the railway bridge for deformation, which could cause train to derail. For this reason, it was important for our client to have direct insight in the deformation data, so they could shut down the rail traffic in case of any (unexpected) deformation. With the help of Vista Data Vision (VDV), the VDV Leica GeoMoS Interface in particular, it was possible to visualise the data concerning the railway bridge in real time. Furthermore, working with VDV allowed three parties (the contractor, the railway manager and BouwRisk) to have access to the same data simultaneously, which resulted in easy and quick consultation of the data.

Working with GeoMoS in combination with the VDV Leica GeoMoS Interface was a great new experience for us as well as for our client.

THE PROCESS IN SHORT

At the location, the following equipment was installed: a Leica TotalStation, 36 Leica GMP104 measuring prisms (see picture 5) and geotechnical sensors for temperature and air pressure. Using a TotalStation in combination with geotechnical sensors makes it possible to understand the reasons of deformation and improve the prediction of failure.

Leica GeoMoS offers the possibility to automate the monitoring of the rails (i.e. performing a preconfigured measuring cycle and storing the obtained data in a database automatically).
The VDV Leica GeoMoS Interface reads the data from the database and stores it in VDV; the export process from the Leica GeoMoS database to VDV is also completely automated.

The Leica TotalStation and the 36 Leica GMP104 measuring prisms were configured to cooperate and obtain the data (see picture 6): the TotalStation measured each of the prisms once every hour, 24 hours a day, 7 days a week. Prior to every measuring cycle, Leica GeoMoS executes a so-called Free Station Adjustment to make sure the TotalStation is still in the right position. It does this by measuring 5 reference points before starting the measuring cycle containing the 36 prisms.

 

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5: Overview of TotalStation and prisms.

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6: Leica GMP104 measuring prism.

Once the data was obtained, it was stored in the GeoMoS database, which was installed on a laptop. This laptop also had the VDV Leica GeoMoS Interface installed and it was located in a locker underneath the railway (see picture 7 and 8). The VDV Leica GeoMoS Interface reads the data from the GeoMoS database and creates VDV compatible data files. Besides the laptop, the locker contained some other equipment (such as a modem) that facilitated the automatic transfer of these VDV compatible data files through an FTP connection.

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7: Datalogger with GeoMoS laptop and FTP facilities.

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8: TotalStation linked to GeoMoS laptop.

The data files, which were exported out of the GeoMoS database by the VDV Leica GeoMoS Interface, were automatically (and with a regular interval) transferred to our VDV server (located at our headquarters in Eindhoven) through an FTP connection. At the VDV server, Vista Data Vision’s ‘db.robot.c’ was installed and configured to automatically monitor new incoming data. Every time new data was found, the preconfigured graphs (made with ‘db.data.browser’) were automatically updated. The automatic transfer and processing of data saved us a lot of time every day and it is error-free; no errors can be made during the processing of the data since the graphs are preconfigured.

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9: An overview graph containing data of 6 prisms.

At the VDV server in Eindhoven we used VDV’s solutions to configure alarms. In case pre-defined limits are reached, alarm messages are sent by e-mail, so steps can be taken. Alarm messages are also sent if one of the prisms is not measuring for whatever reason. Using VDV, we also configured automatic week reports that gave an overview of the data and alarms of the last week. Finally, we created Real Time Displays. These are great to present an overview of the latest data sorted out per location (see picture 10 and 11).

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10: Real Time Display.

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11: Real Time Display (continued): the latest data of the 36 measuring prisms.

In short, Vista Data Vision solutions (especially the VDV Leica GeoMoS Interface), combined with excellent service and support, allowed BouwRisk to monitor the railway bridge entirely automatically. This was a great new experience for us: Vista Data Vision automates data generation and visualisation, is easy to use and saves a lot of (manual) work. We are convinced!