Ms Salthouse was driving a wheelchair accessible motorcycle on Commonwealth Avenue Bridge about 2.40pm on July 20 when it was involved in an incident with another car.

Police believe several pedestrians and joggers stopped to help Ms Salthouse at the scene but left without speaking to police, and have urged them to contact Crime Stoppers.

ACT police Superintendent Corey Heldon said last week, a male driver who was behind the wheel of a ute at the time of the collision was assisting police in their investigations.

"It appears the person in the vehicle hit the rear of the wheelchair-accessible motorbike and caused the collision which resulted in her death," Superintendent Heldon said.

Ms Salthouse was treated at the scene by paramedics but later died in hospital.

ACT Policing officer-in-charge of road policing Detective Inspector Marcus Boorman, said information from witnesses could assist in progressing the investigation.

"Whenever someone dies on the roads, police need to ascertain how and why it happened," he said.

"I would like to stress that the people who rendered assistance in this instance are not being sought for any reason other than that they may be able to help us work out the full circumstances surrounding this tragic incident.

"I understand these people may not wish to talk about it, but they may have seen something that police have not yet been made aware of. I urge them to come forward."

Ms Salthouse was prominent in the Canberra community as a passionate advocate for women with disabilities and was the 2020 ACT Senior Australian of the Year.

She has been remembered for her leadership and life of service and commitment to others.

Anyone who may have assisted or who has additional information, and who has not already spoken to police should contact Crime Stoppers on 1800 333 000, or via the Crime Stoppers ACT website and quote reference 6579817.

Information can be provided anonymously.