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Team: SAR Traffic Monitoring

Recording traffic data

This team is concerned with the subject of traffic data recording using SAR. Current work focuses on satellite-supported applications and on adapting the operational TerraSAR-X SAR processor (TMSP), which was further developed to yield the TerraSAR-X Traffic Processor (TTP). This processor generates images of a traffic situation just a few minutes after receiving the required data and forwards them to users. Figure 1 shows a small part of a TS-X radar image of western Paris, onto which the vehicles detected from space have been superimposed and color coded for velocity.

Fig. 1: Traffic on the A12 and A13 motorways west of Paris

This technology is used to supplement and confirm the results of traditional traffic data recording systems. Thus TerraSAR-X images can be used to detect errors in existing information systems.

The envisioned goal is to provide high-quality information such as the current estimated travel time on particular road segments. Because this approach can be used globally, it is predestined for use in connection with natural disasters such as forest fires and floods. In addition to the usual image masks for burned or flooded areas, a traffic situation image can also be generated to reveal what streets are still accessible and available for relief transports and evacuations. The methodology was successfully demonstrated during a flood in Honduras and forest fires in Australia. (See link at left for an example of traffic monitoring from space)

The processor can also be adapted to detect moving ships and determine their velocity. Figure 2 shows an example in which so-called Along-Track Interferometry (ATI) was employed to determine the velocity of ships on the lower Elbe River where it flows into the North Sea near Cuxhaven. The procedure will greatly benefit from the availability of data from the TanDEM-X mission, with its significantly more sensitive measurement instruments.

Fig 2: Ships on the Elbe River, whose velocity could be determined from the interferometric phase (color coded)

With the help of SAR Along-Track Interferometry the velocity of ocean and river currents can also be determined. One application involves providing support in finding suitable locations for tidal energy power plants.