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We can lose a section if a radar fails but we might not lose coverage because another radar covers the section in question. So this means we can always have overlapping tracking coverage but we can't have the concept of overlapping with traffic stats gathering when using nearest because its always 1 section to 1 radar. In the image below, the radar with a black boundary has failed, but the range of the radar either side of it will have overlapping tracking coverage, but there will not be tracking stats within the black boundary:
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All in Range
In this mode the radar will gather traffic stats from all sections within range of the radar. This means where radar have overlapping coverage then we will gather duplicate statistics for sections covered by more than one radar.
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Your allocation images can be used to explain how section - radar allocation works
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Here is the map showing a carriageway with a healthy carriageway coverage status for a section.
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If a radar develops a fault or goes offline then the coverage and allocation statuses can change. The following can have an impact…reduce opacity of map…In addition, the carriageway where the radar is unhealthy, is highlighted in red dashed lines as above.
In the examples below we are going to focus on three radar, each with a contour area - Radar 205 with a contour area which covers sections of the carriageway from 30 to 34:
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Radar 206 with a contour area which covers sections of the carriageway from 25 to 30:
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Radar 207 with a contour area which covers sections of the carriageway from 23 to 25:
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At this point the radar health is healthy for all of them:
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The Carriageway Statistics confirm this with 100% Coverage for the whole Carriageway and for Section 26, and a healthy Coverage and Statistics Status:
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However, if radar 206 fails then we would expect to lose Coverage for sections 26 to 29, and because the system has a Sensor Allocation Mode of Nearest we would not expect that statistics for the sections 26 to 30 which have been allocated to Radar 206 to be available.
The system clearly shows that the sections of carriageway allotted to Radar 206 are compromised by the display of dashed amber and red lines:
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We would still expect that there would be coverage for section 30, as Radar 205 has a contour area which covers this, and why that section is highlighted in amber dashed lines rather than red:
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The coverage status change is reflected in the ICD-001 Carriageway Statistics Report.
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