1. An apparatus for passively measuring vehicle speed, comprising: at least one video camera for acquiring a plurality of images of a roadway upon which at least one moving vehicle travels upon, each of said plurality of images comprising a plurality of pixels; a computer for processing pixel data associated with said plurality of pixels, said computer having code operable for processing said pixel data, wherein said processing said pixel data comprises: performing background subtraction using an adaptive background subtraction model on said pixel data to identify a plurality of foreground pixels and to extract a plurality of blobs from said plurality of foreground pixels; rectifying said plurality of blobs to form a plurality of rectified blobs using a homography matrix, said homography matrix obtained by comparing at least one known distance in said roadway with distances between said plurality of pixels and using a planar homography transform, identifying said moving vehicle from said plurality of rectified blobs, respective ones of said plurality of rectified blobs including vehicle data associated with said moving vehicle, and computing a speed of said moving vehicle from said vehicle data.