The accident happened at about 08:50 near the Plattekloof turnoff. Van Heerden, who is from Strand, died at the scene.
"A Toyota Hilux bakkie, which was driving in the direction of Bellville, broke down on the N1 after the Plattekloof turnoff. A Corsa bakkie stopped to help the man," said Captain Marie Louw of the Parow police station.
"The next moment a black Hyundai Atos drove into the stationary vehicles."
The driver of the Hilux bakkie was taken to hospital with light injuries. The driver of the Corsa bakkie was treated on the scene for shock.
Performed with jazz legends
Van Heerden, a trumpet and accordion player, was originally from Port Elizabeth.
He had been playing music since the age of 17 and had performed in the orchestras of jazz legends like Robbie Jansen, Winston Mankunku, Hilton Schilder and Mac McKenzie.
Van Heerden had performed in countries like Norway, Sweden and Hong Kong and had recorded several albums with Swedish producers. Last year, two of his albums were distributed internationally: Nefertiti, which he recorded with Magnus Johansson of Sweden and his solo album, In the Name of Bushtech.
Van Heerden was also involved with the Delta Optel Band, which he had formed with musicians from the wine farm Solms-Delta, between Paarl and Franschhoek.
Dr Mark Solms, owner of the farm and a globally known neuropsychologist described Van Heerden as a white Afrikaner boy who had to rise up after rejection after initially playing in a township jazz orchestra in Port Elizabeth.
"Alex decided that he would then study his own ethnic music and in the process became aware of the influence of ghoema, vastrap (a SA dance form), and other Coloured music on boeremusiek.
"This made him realise how artificial the separation between the brown and white Afrikaans communities was."
His father, Lex van Heerden, 56, said on Wednesday his son was a "bright star" who had been a fulltime musician since his schooldays.
Van Heerden's wife, Kate, was in Germany at the time of the accident and would arrive in South Africa on Thursday.