Alternative routes

A system for generating routes through a navigable network, the navigable network being represented by an electronic map comprising a plurality of segments representing navigable elements of the navigable network, the segments being connected by nodes, the system comprising:

• a processor;
• and
• a memory;
• the processor configured to:
• define a sub-network of the navigable network comprising a network of intersecting routes through the navigable network between an origin and a destination of a first origin-destination pair, the sub-network being represented by a subset of segments of the electronic map, and wherein nodes at which there are two or more outgoing segments of the subset of segments are indicative of decision points of the sub-network;
• generate a main route between an origin and a destination of a second origin-destination pair;
• and
• identify a first decision point of the sub-network to be encountered along the main route, and generating an alternative route between the decision point and the destination of the second origin-destination pair using a routing process in which at least a first segment of the portion of the main route outgoing from the node representative of the first decision point is blocked and in which the subset of segments representative of the sub-network are favoured.

A non-transitory computer readable medium comprising instructions which, when executed by one or more processors of a system, cause the system to perform a method for generating routes through a navigable network, the navigable network being represented by an electronic map comprising a plurality of segments representing navigable elements of the navigable network, the segments being connected by nodes, the method comprising:

• defining a sub-network of the navigable network comprising a network of intersecting routes through the navigable network between an origin and a destination of a first origin-destination pair, the sub-network being represented by a subset of segments of the electronic map, and wherein nodes at which there are two or more outgoing segments of the subset of segments are indicative of decision points of the sub-network;
• generating a main route between an origin and a destination of a second origin-destination pair;
• and
• identifying a first decision point of the sub-network to be encountered along the main route, and generating an alternative route between the decision point and the destination of the second origin-destination pair using a route generation process in which at least a first segment of the portion of the main route outgoing from the node representative of the first decision point is blocked and in which the subset of segments representative of the sub-network are favoured.