A method for a traffic volume publication system to publish traffic volumes in a road traffic network includes: receiving traffic information including information on a plurality of road segments and original traffic volume data for the road segments at a first timestamp and calculating a first window size for each road segment for the first timestamp; predicting a second window size for a third timestamp subsequent to the first timestamp, either based on the first window size calculated at the first timestamp or based on the first window size and a window size calculated in advance at a second timestamp prior to the first timestamp; determining a privacy budget allocated to the first timestamp based on the first window size and the second window size; and returning noisy traffic volume data which is obtained by inserting noise into the original traffic volume data, based on the determined privacy budget.