1. A computer-implemented method for assessing data samples reported by vehicles traveling on roads, the data samples including information regarding the travel of the vehicles, the method comprising: receiving indications of multiple road segments of one or more roads; receiving information related to current traffic conditions of the multiple road segments, the received information including a plurality of data samples that each are reported from one of multiple vehicles and reflect a reported speed of the one vehicle at a reported geographic location and reflect a reported travel heading of the one vehicle; and for each of the multiple road segments, assessing traffic conditions for the road segment based on data samples identified to represent travel on the road segment by, identifying a group of multiple data samples from the plurality of data samples such that the data samples of the group have reported geographic locations that are within a predefined distance of one or more predefined geographic locations for the road segment and have reported travel headings that are within a predefined difference from one or more predefined headings for the road segment; automatically determining that one or more of the data samples of the group are unrepresentative of actual vehicle travel on the road segment based at least in part on the reported geographic locations of the determined data samples not corresponding to predefined portions of the road segment for which vehicle travel is of interest and based at least in part on the reported speeds of one or more vehicles that reported the determined data samples not corresponding to a range of speeds associated with the road segment, wherein the predetermined portions of one or more of the multiple road segments that are each part of a highway do not include any ramps on or off the highway and wherein the determined one or more data samples for each of the one or more road segments include at least one data sample having a reported geographic location that is determined to correspond to one the ramps, the automatic determining being performed by one or more configured computing systems; automatically excluding from the group the data samples determined to be unrepresentative of actual vehicle travel on the road segment, the automatic excluding being performed by the one or more configured computing systems; and after the excluding, automatically using the data samples remaining in the group to infer traffic conditions for all vehicles traveling on the road segment, so that inferred traffic conditions based on data samples are available for use in facilitating travel on the road segments.