"No one else has to die," she said.
As well as guardrails, Foster said the road would ideally also have a lower speed limit, speed bumps and barriers that could lock drivers out on weekends.
She said she would like to see defensive driver training courses made mandatory by the government, to reduce the number of "naive" young people the road.
The petition had been signed by people from all over New Zealand, not just Ashburton - the girls' hometown - and it would be "life changing" if authorities listened, Foster said.
"It would mean that lives were saved and that both Tayla and Sunmara didn't die in vain."
Christchurch City Council did not say whether it would consider changes to Summit Road, but noted that it was due to make $2.6 million worth of safety improvements to the adjacent main road on the Port Hills, Dyers Pass Road, by the end of winter next year.
Those safety improvements include a guard-rails, motorcycle underrun-rails, a wider sealed section on road shoulders and additional space for cyclists.
The Transport Agency has been contacted for comment.
- RNZ
