Abstract: For pilots and drivers in ITS (intelligent transportation system), the high density of information in driving environments with advanced technology generates some requests for workload evaluation techniques. In this paper, four typical subjective mentalworkload evaluation techniques are reviewed. With the four methods, the evaluation calculations on the data of experiments in three different driving environments are made. The calculated results are compared by sensitivity analysis aswell as the subjective evaluation of participants, and the regression functions ofRNASA-TLX indexes forthe three different driving environments are set up.