The 23-year-old victim, Sian Green, was struck in a Rockefeller Center plaza Tuesday.
Union plumber David Justino fashioned a tourniquet with his work belt for one of Green's legs. He used a dog leash for the other injured leg.
Mehmet Oz, who was walking in the area, rushed over when he heard the accident. He credits Justino for saving the woman's life.
Police Commissioner Raymond Kelly said Wednesday the woman's family is en route from Leicester, England. She remains sedated.
Police say the cab driver was issued a summons for being an unauthorized driver. The accident is under investigation; he could face other charges.