"There is a dramatic increase in the demand for Gautrain services. The Gautrain is experiencing continuous growth, as could be expected of a system at the beginning of its commercial life cycle," he told reporters in Johannesburg.
The average number of passengers on a week-day had risen from 26 000 in April last year to 42 000 at the end of March this year, said Vadi.
Passenger growth stood at 2.1 percent a month.
Gautrain also operated 125 buses as feeder transport to the train stations and for general passenger services.
There were at least 26 bus routes, and trips had also increased, Vadi said.
"The average daily bus trips have doubled from 9000 per day in 2012 to 18000 a day in March 2013."
Gautrain CEO Jack van der Merwe said there were plans to link other modes of transport, such as the Bus Rapid Transport system and minibus taxis, as feeders to the Gautrain buses.
"I may say that I would like to see the number of our buses growing to at least 160 in 10 year's time, but having at least a 100 taxis operating as well with the buses would be favourable."
A taxi-owned company was already providing a shuttle service from Marlboro station in Sandton, he said.
This news comes as the nation wide bus strike enters it third week, including the suspension of the Western Cape's MyCiTi buses.
Fin24 reports unions and employers are "optimistic" that a solution to the bus drivers' strike might be reached before the end of the week.
"I am optimistic that there will be a solution at least by tomorrow [Friday]," said SA Transport and Allied Workers' Union general secretary Zenzo Mahlangu.