A traffic monitoring system comprises a traffic estimating module that estimates an average traffic level on the road during prior ones of first periodic periods. A traffic monitoring module estimates a current traffic level on the road during a first portion of a current one of the first periodic periods based on vector and location information received from at least one of cellular phones and vehicles during the first portion. A traffic predicting module predicts traffic levels on the road during a remaining portion of the current one of the first periodic periods based on the average traffic level and the estimated current traffic level during the first portion.