New research by the Greens Democracy4Sale Project reveals that the motorway lobby has donated more than $13 million to the Liberal, National and Labor parties over 15 years.
CMIC, also known as Leightons, was the second biggest donor of the companies analysed handing over more than $3.3 million to the major parties.
Leightons is part of a consortium of companies that have won more than $8 billion worth of contracts from the NSW Government across the first two stages of the WestConnex project.
Greens democracy spokesperson Senator Lee Rhiannon said, "Hefty donations over 15 years coincides with a period in which federal and state governments approved billions of tollways and major road projects built by big companies.
"We do not know if deals are done behind closed doors, but there is the public perception that companies expect something in return for their donations.
"We do know that MPs, both Coalition and Labor, are favouring private companies to build roads at the expense of public transport.
"The analysis of donor returns show that Abigroup, Macquarie, Transurban, Transfield Services, Lend Lease and Leightons, with its subsidiaries Thiess and John Holland, accounted for 78 per cent of the total political donations made by the motorway lobby.
"Thousands of dollars in political donations were flowing from the motorway lobby to Labor and the Coalition during the 2012/2013 financial year. At this time the then Federal Transport Minister Anthony Albanese granted $25 million to advance the Westconnex Project," said Senator Rhiannon.
Greens candidate for Grayndler, Jim Casey said, "The failure of both major parties to back political donation reform adds to public concerns about the corrupting influence of political donations.
"The Greens are calling for far reaching reforms to ban political donations from for profit companies, for caps on election expenditure, a ban on foreign donations and greater transparency," concluded Casey.