The traffic proximity indicator is based on AADT count divided by distance in meters from the Census block centroid. The proximity score is based on the traffic within a search radius of 500 meters (or further if none is found in that radius). This distance was selected to be large enough to capture the great majority of road segments (with traffic data) that could have a significant impact on the local residents, balanced against the need to limit the scope due to computational constraints. The closest traffic is given more weight, and the distant traffic is given less weight, through inverse distance weighting. For example, traffic 500 meters away is given only one tenth as much weight as traffic 50 meters away.