The Genesee & Wyoming Australia (GWA) railroad company will not provide coal haulage services to the controversial Adani mine in Queensland, while a second carrier is facing internal pressure to reject it as well.

"GWA has previously been approached to service the Adani Carmichael project and we have decided not to participate," the company said in response to an inquiry by the ABC.  

This is only one of the limits on Adani's options on moving coal from the open-pit mine in the Galilee Basin to port some 400 kilometers away.  One of the only two railways to stick with the Adani project, Aurizon, may not be of any help.  UniSuper, which is one of Aurizon's five largest shareholders, is calling on the company to refuse to provide any rail service beyond its current arrangements.  

"It is our opinion that Adani does not represent a viable commercial proposition," goes the letter from UniSuper to Aurizon, obtained by the ABC.  "We confirm that our Chief Investment Officer has been engaged with Aurizon at the highest levels to convey the concerns of our membership base and seek confirmation that any engagement by Aurizon with Adani is restricted to meeting minimum legal requirements."

Meanwhile, Adani has also settled the claim from engineering firm AECOM Australia, which said Adani owned more than $20 million for work on the original rail plan.