South Australian Transport Services Minister Chloe Fox announced on Wednesday that the state has imposed about $218,000 fines on three Adelaide bus contractors because their buses are always late.

The penalties were slapped on Southlink, Torrens Transit and Transfield because of the three transport firms' delayed bus services for the first quarter of 2012. The fine is equivalent to 2 per cent of their total contract.

Among the three bus companies, the worst is Transfield which was slapped with $121,345 penalty, followed by Southlink ($50,455) and Torrens Transit ($46,043).

Buses of Transfield north-to-south routes was on time only 51.6 per cent and 79.8 per cent for its Southlink routes to the Hills. Transfield attributed the hefty fine to the large number of buses on its fleet.

The bus companies also blamed the gridlock for their delayed trips, which Ms Fox accepted as a contributing factor but pointed out that it does not adequately explain the significant failure of some services to achieve on-time running performance standards.

"I do not expect the bus contractors to be happy with these penalties... nor do I expect the penalties to ease the legitimate frustrations of commuters," Ms Fox was quoted by News.com.au.

To help these laggard bus contractors meet their contract obligations, South Australians Transport Department head Rod Hook said timetables are being reviewed for the eight-year contracts.

"We have to have a relationship with these contractors where we work together to deliver the outcomes that we want so we can't go in and break contracts," Mr Hook told ABC.