President-elect Andrés Manuel López Obrador posted on his official website details of the proposed passenger rail line.
A postponement would result in more delays for investments in the north-south rail network.
The agency will release the study in a seminar on September 18.
Almost half will be in infrastructure, according to the bank.
Beto Richa was arrested on allegations he benefited Odebrecht in the bidding for a highway PPP.