  We study streamwise turbulence intensity definitions using smooth- and
rough-wall pipe flow measurements made in the Princeton Superpipe. Scaling of
turbulence intensity with the bulk (and friction) Reynolds number is provided
for the definitions. The turbulence intensity scales with the friction factor
for both smooth- and rough-wall pipe flow. Turbulence intensity definitions
providing the best description of the measurements are identified. A procedure
to calculate the turbulence intensity based on the bulk Reynolds number (and
the sand-grain roughness for rough-wall pipe flow) is outlined.
