First probe data for a first probe type and second probe data for a second probe type are received and stored. A relationship between the first probe type and the second probe type is determined based on at least a portion of the first probe data and at least a portion of the second probe data. The relationship is categorized based on a property of the travel conditions under which the at least a portion of the first probe data and the at least a portion of the second probe data were collected. First real-time probe data for the first probe type is received. The first real-time probe data is converted into second real-time probe data based on the relationship.