A computerized method is disclosed of creating map data from position data derived from the positions of at least one vehicle over a period of time, the map data including a plurality of navigable segments representing segments of a navigable route in the area covered by the map and the map data also including intersections between navigable segments representing intersections in the navigable route. In at least one embodiment, the method includes using a processing circuitry to perform the following: i. processing the position data; ii. calculating from the processing of the position data a transit time or set of transit times for at least some of the intersections in the map data; and iii generating further map data, which for at least some of the intersections therein, contains the calculated transit time or set of transit times associated with the intersection for which the calculation was made.