This data is part of the strategic transport modelling undertaken for Urban Transport Crowding and Congestion, a supplementary report of the Australian Infrastructure Audit 2019. This project looks at historical data from 2016, and with that data it analyses the trends to predict what congestion will be like in 2031.
This is a companion discussion topic for the original entry at https://opendata.transport.nsw.gov.au/dataset/urban-transport-congestion-maps