According to registry agency data, VDH holds a 90% stake in the tie-up.
The contract concerns the construction of Ihtiman traction substation, NRIC said in a notice.
The deal was signed of October 25, according to the notice.
The public procurement procedure for awarding the contract attracted two offers.
The project benefits from EU funding under Operational Programme Transport and Transport Infrastructure 2014-2020.
Earlier this month, NRIC signed a 26.3 million levs contract with VDH for the rehabilitation of railway infrastructure at the Zimnitsa and Straldzha train stations, which is also funded under Operational Programme Transport and Transport Infrastructure 2014-2020.
(1 euro = 1.95583 levs)