Methods and systems for detecting a closure of a navigable element

1. A method of detecting the closure of a navigable element forming part of a network of navigable elements within a geographic area, wherein the network of navigable elements comprises a plurality of navigable elements connected by a plurality of nodes, the method comprising:

obtaining positional data relating to the movement of a plurality of navigation or driver assistance devices from the plurality of navigation or driver assistance devices along each one of a set of two or more alternative incoming navigable elements at a node of the network with respect to time;

using the positional data to determine a count of the navigation or driver assistance devices in a sequence of consecutive navigation or driver assistance devices that have selected a given one of the set of two or more alternative incoming navigable elements from among the incoming navigable elements of the set;

comparing the count to a predetermined threshold to determine whether another one of the set of two or more alternative incoming navigable elements at the node is closed, wherein the threshold is specific to the incoming navigable element in relation to which the count of navigation or driver assistance devices is determined; and

identifying the other one of the set of two or more alternative incoming navigable elements as being closed when the count exceeds the threshold.

2. The method of claim 1 , wherein the threshold is set to result in a determination of the existence of a closure only when the number of navigation or driver assistance devices in a determined count of a consecutive sequence of navigation or driver assistance devices selecting the given navigable element exceeds by a statistically significant amount a number expected in the absence of a closure affecting another one of the set of navigable elements.

3. The method of claim 1 , wherein the threshold is set by reference to a relative probability of the given one of the set of alternative navigable elements being selected from among the set of alternative navigable elements.

4. The method of claim 3 , wherein the relative probability is a historical relative probability, based, at least in part, upon positional data relating to the movement of a plurality of navigation or driver assistance devices along each one of the set of two or more alternative navigable elements at the node with respect to time.

5. The method of claim 1 , wherein the one or more navigable elements of the set of two or more alternative incoming navigable elements are each represented by one or more navigable segments in a geographical region covered by a digital map, the method further comprising:

defining a geographical area covered by the map containing the or each navigable segment representing the navigable element determined to be affected by a closure;

comparing a number of the navigation or driver assistance devices whose positions can be matched to a navigable segment of the digital map data throughout movement through the geographical area to a number of navigation or driver assistance devices whose positions cannot be matched to a navigable segment of the digital map within the geographical area throughout movement through the geographical area; and

using the results of the comparison to validate a determined closure.

6. The method of claim 5 , comprising at least one of:

determining that the determined closure is not valid when the ratio of the number of navigation or driver assistance devices whose positions cannot be matched to a segment of the digital map throughout travel through the geographic area to the number of navigation or driver assistance devices whose positions can be matched to a segment of the digital map throughout travel through the geographic region exceeds a predetermined threshold; and validating the closure when the ratio of the number of navigation or driver assistance devices whose positions cannot be matched to a segment of the digital map throughout travel through the geographic area to the number of navigation or driver assistance devices whose positions can be matched to a segment of the digital map throughout travel through the geographic region is below a predetermined threshold.

7. The method of claim 1 , further comprising associating data indicative of a determined closure with the navigable segment representing the navigable element affected in a digital map.

8. A non-transitory computer readable medium comprising computer readable instructions which, when executed by one or more processors of a computer, cause the computer to perform the method according to claim 1 .

9. A method of detecting the closure of a navigable element forming part of a network of navigable elements within a geographic area, wherein the network of navigable elements comprises a plurality of navigable elements connected by a plurality of nodes, the method comprising:

obtaining positional data relating to the movement of a plurality of navigation or driver assistance devices from the plurality of navigation or driver assistance devices along each one of a set of two or more alternative outgoing navigable elements at a node of the network with respect to time;

using the positional data to determine a count of the navigation or driver assistance devices in a sequence of consecutive navigation or driver assistance devices selecting a given one of the set of two or more alternative outgoing navigable elements from among the outgoing navigable elements of the set;

comparing the count to a predetermined threshold to determine whether another one of the set of two or more alternative outgoing navigable elements at the node is closed, wherein the threshold is specific to the outgoing navigable element in relation to which the count of navigation or driver assistance devices is determined: and

identifying the other one of the set of two or more alternative outgoing navigable elements as being closed when the count exceeds the threshold.

10. A non-transitory computer readable medium comprising computer readable instructions which, when executed by one or more processors of a computer, cause the computer to perform the method according to claim 9 .

11. The method of claim 9 , wherein the threshold is set by reference to a relative probability of the given one of the set of alternative navigable elements being selected from among the set of alternative navigable elements.

12. The method of claim 11 , wherein the relative probability is a historical relative probability, and is based, at least in part, upon historical positional data relating to the movement of a plurality of navigation or driver assistance devices obtained from the plurality of navigation or driver assistance devices along each one of the set of two or more alternative navigable elements at the node with respect to time.

13. The method of claim 9 , wherein the one or more navigable elements of the set of two or more alternative outgoing navigable elements are each represented by one or more navigable segments in a geographical region covered by a digital map, the method further comprising:

defining a geographical area covered by the map containing the or each navigable segment representing the navigable element determined to be affected by a closure;

comparing a number of navigation or driver assistance devices whose positions can be matched to a navigable segment of the digital map data throughout movement through the geographical area to a number of navigation or driver assistance devices whose positions cannot be matched to a navigable segment of the digital map within the geographical area throughout movement through the geographical area; and

using the results of the comparison to validate a determined closure.

14. The method of claim 13 , comprising at least one of:

determining that the determined closure is not valid when the ratio of the number of navigation or driver assistance devices whose positions cannot be matched to a segment of the digital map throughout travel through the geographic area to a number of navigation or driver assistance devices whose positions can be matched to a segment of the digital map throughout travel through the geographic region exceeds a predetermined threshold; and validating the closure when the ratio of the number of navigation or driver assistance devices whose positions cannot be matched to a segment of the digital map throughout travel through the geographic area to a number of navigation or driver assistance devices whose positions can be matched to a segment of the digital map throughout travel through the geographic region is below a predetermined threshold.

15. A system for detecting the closure of a navigable element forming part of a network of navigable elements within a geographic area, wherein the network of navigable elements comprises a plurality of navigable elements connected by a plurality of nodes, the system comprising one or more processors operable to:

obtain positional data relating to the movement of a plurality of navigation or driver assistance devices from the plurality of navigation or driver assistance devices along each one of a set of two or more alternative incoming navigable elements at a node of the network with respect to time;

use the positional data to determine a count of the navigation or driver assistance devices in a sequence of consecutive devices that have selected a given one of the set of two or more alternative incoming navigable elements from among the incoming navigable elements of the set;

compare the count to a predetermined threshold to determine whether another one of the set of two or more alternative incoming navigable elements at the node is closed, wherein the threshold is specific to the incoming navigable element in relation to which the count of navigation or driver assistance devices is determined: and

identify the other one of the set of two or more alternative incoming navigable elements as being closed when the count exceeds the threshold.

16. A system for detecting the closure of a navigable element forming part of a network of navigable elements within a geographic area, wherein the network of navigable elements comprises a plurality of navigable elements connected by a plurality of nodes, the system comprising one or more processors operable to:

obtain positional data relating to the movement of a plurality of navigation or driver assistance devices from the plurality of navigation or driver assistance devices along each one of a set of two or more alternative outgoing navigable elements at a node of the network with respect to time;

use the positional data to determine a count of navigation or driver assistance devices in a sequence of consecutive navigation or driver assistance devices selecting a given one of the set of two or more alternative outgoing navigable elements from among the outgoing navigable elements of the set;

compare the count to a predetermined threshold to determine whether another one of the set of two or more alternative outgoing navigable elements at the node is closed, wherein the threshold is specific to the outgoing navigable element in relation to which the count of devices is determined; and

identify the other one of the set of two or more alternative outgoing navigable elements as being closed when the count exceeds the threshold.