In relation to the development of the interfacial area transport equation, local measurements of the void fraction, interfacial area concentration, interfacial velocity, and Sauter mean diameter using the double sensor probe method as well as the liquid velocity and turbulence intensity using hotfilm anemometry, were performed extensively for vertical upward bubbly air-water flows in a round tube with an inner diameter of 25.4 mm at three axial locations of L/D=12.0, 65.0 and 125, and fifteen radial locations from r/R=0 to 6.95. The liquid flow rate and the void fraction ranged from 0.292 m/s to 3.49 m/s and from 3% to 27%, respectively. The data set obtained in this study will eventually be used for the development of reliable constitutive relations which reflect the true transfer mechanisms in bubbly flow systems.