1. A computer program product for estimating travel demand with mobility data, the computer program product comprising: a non-transitory computer readable storage medium having computer usable program code embodied therewith, the computer usable program code comprising a computer usable program code configured to: determine a plurality of modes of travel with mobility data for a plurality of users; generate travel information for each of the plurality of modes of travel with the mobility data, wherein the computer usable program code configured to generate travel information with the mobility data for each of the plurality of modes of travel comprises computer usable program code to update an origin-destination matrix for each of the plurality of modes of travel, wherein the origin-destination matrix indicates a number of users that travel between each pair of the origins and the destinations for the mode of travel; adjust the travel information for a first of the plurality of modes of travel based, at least in part, on a travel-related event that corresponds to the first mode of travel to generate an adjusted travel information for the first mode of travel; and compute an estimated overall travel demand with a combination of the adjusted travel information for the first travel mode and the travel information of a second travel mode of the plurality of modes of travel, wherein the combination of the adjusted travel information comprises a combination of the origin-destination matrix for the first travel mode and the origin-destination matrix for the second travel mode.