No static billboard in the RA, RA1, RB, RB1, RC, RC1, RC2, RC3, PDD1, PDD2, NB, GB, GB1, NB, GB, GB1, CB, HB, LI and IP Districts shall be converted to a digital billboard, Converting a static billboard to a digital billboard may be allowed by special permit only in the TED District subject to a traffic impact analysis to be approved by the Massachusetts Department of Transportation.