A computer-implemented method for using probe points collected by at least one probe source travelling along road segments of a road network, a probe point indicating the location of a probe source at a particular time, the method comprising: identifying an ambiguous probe region, (14,16) wherein an ambiguous probe region is a region of the road network within which it is difficult to reliably identify the road segment with which each probe point is associated, and wherein the ambiguous probe region is identified by one or more of (i) identifying a shift of a road centre by at least a predetermined amount, and (ii) identifying a change in the width of a probe distribution comprised of probe points having the same or similar headings, the change being more than a predefined amount or percentage over a predetermined length of road; separately identifying probe trajectory identifiers (IDs) of probe points along at least a portion of each of first and second road segments that lead away from the ambiguous probe region, wherein a probe trajectory ID uniquely identifies the probe points collected by a particular probe source during a particular time period, and wherein the probe trajectory IDs identified along at least a portion of the first and second road segments comprise first and second sets of probe trajectory IDs; for the ambiguous probe region, identifying probe trajectory IDs of the probe points along a third road segment that leads toward the ambiguous probe region, wherein the probe trajectory IDs along the third road segment comprise a third set of probe trajectory IDs; associating probe trajectory IDs from the third set with the first road segment in an instance in which the probe trajectory IDs are included in both the first and third sets; and associating probe trajectory IDs from the third set with the second road segment in an instance in which the probe trajectory IDs are included in both the second and third sets. identifying an ambiguous probe region, (14,16) wherein an ambiguous probe region is a region of the road network within which it is difficult to reliably identify the road segment with which each probe point is associated, and wherein the ambiguous probe region is identified by one or more of (i) identifying a shift of a road centre by at least a predetermined amount, and (ii) identifying a change in the width of a probe distribution comprised of probe points having the same or similar headings, the change being more than a predefined amount or percentage over a predetermined length of road; separately identifying probe trajectory identifiers (IDs) of probe points along at least a portion of each of first and second road segments that lead away from the ambiguous probe region, wherein a probe trajectory ID uniquely identifies the probe points collected by a particular probe source during a particular time period, and wherein the probe trajectory IDs identified along at least a portion of the first and second road segments comprise first and second sets of probe trajectory IDs; for the ambiguous probe region, identifying probe trajectory IDs of the probe points along a third road segment that leads toward the ambiguous probe region, wherein the probe trajectory IDs along the third road segment comprise a third set of probe trajectory IDs; associating probe trajectory IDs from the third set with the first road segment in an instance in which the probe trajectory IDs are included in both the first and third sets; and associating probe trajectory IDs from the third set with the second road segment in an instance in which the probe trajectory IDs are included in both the second and third sets.