The elderly woman involved in an accident in Kings Langley has been taken to St Mary’s Hospital in London.
The East of England Ambulance Service took the woman with "potentially serious head injuries" to St Mary’s, near Paddington for emergency treatment.
Emma Chadwick, 26, who went out to help the injured woman said: "I went out and gave her a blanket and they put it under her head.
"She was moaning, she was trying to roll over, but the other people there would not let her. She was semi-conscious.
"I would not say I cared for her, I just gave her a blanket.
"I walked up to her, asked if she was alright and they put the blanket under her head. I asked if she wanted any water."
Hertfordshire Constabulary were called to the High Street at 12.44pm following reports that a pedestrian and motorcyclist had been injured.
Terry Fidler, another eye-witness added: "I heard the crash and came out and saw the lady lying on her back. She was unconscious and a district nurse was passing by. She came across and made the woman comfortable."
The man who was riding the motorcycle was taken to Watford General Hospital with minor injuries.