The process of testing the market for a high-speed train linking Durban and Johannesburg will start next month, said Transport Minister Sbu Ndebele.

The "concept framework" for a Johannesburg-Durban speed rail link should be completed by March next year, the transport department said on Wednesday.

The Gautrain moved into operation between Sandton and the OR Tambo International Airport on Wednesday when it was awarded its safety permit.