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IoT for Railway Bridge Monitoring

The IoTBridge project aims to develop a technical platform to monitor bridges. The platform combines different types of sensors embedded into wireless sensor networks which exchange information utilising cloud technologies. Data on the use of bridges and status of various parts will be analysed to optimise inspection intervals and maintenance to reduce the costs for upkeep and ensure safety. The project targets railway bridges as use case, but the developed platform is suitable to support various types of infrastructure.

The project is implemented by three Swedish partners, KTH, SICS, CNet, and the Swiss firm DecentLab. The project is funded by the EU research program Eurostars.

To demonstrate the project results the newly developed monitoring system is tested on a pilot site in Årstabron, Stockholm (Sweden).

bridges1 bridges2 Bridge_3

Owner: The Swedish Transport Administration (Trafikverket)

Construction date: 2003-2005

Length: ~ 833 m

Type: Prestressed concrete

Traffic: Railway (two unballasted tracks)

Why this bridge was chosen and what is interesting to measure …

For the IoTBridge tests, the New Årsta Railway Bridge in Stockholm was chosen. The bridge is an optimised and very complex pre-stressed concrete structure. In total the bridge is approximately 833 meters long and consists of eleven spans with main spans of 78 meters. Elevation and site plan of the bridge are visualized in Figure 1, which also shows the position of the instrumented section.

bridge_schematic

Figure 1. Elevation and plan view of the New Årsta Bridge. Between the northern and southern abutment, NL and SL, respectively, the 10 piers are designated P1 to P10. The two wireless nodes are installed at the point marked as point of interest (POI) in the middle of span P8-P9.

The bridge carries two unballasted railway tracks, as illustrated in Figure 2, and a walkway along each side of the bridge – a pedestrian and cycle path on the western side and a service road on the eastern side.

bridge-graphic model

Figure 2. An artist’s impression of the New Årsta Railway Bridge and the track fastening device.

The two meter thick transversal beams (without manholes) at each pier make the bridge very complicated to inspect under operation. Therefore a structural health monitoring system, such as the one developed in the IoTBridge project, would provide valuable information on the actual condition of the bridge in real-time, reducing the number of traditional inspections and thus reducing the management cost as well as traffic disturbances. With the developed IoTBridge monitoring system it will also be possible to monitor passing trains (number, direction, speeds and loads), enabling the development of more realistic traffic simulation models and site specific loads to improve assessment of existing bridges on the line.

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