The SFO claims the two former Broadspectrum employees took kickbacks in exchange for awarding deals to subcontractors between 2015 and 2018.
Judge Kevin Glubb has described the alleged offending as an "elaborate scheme".
One of the two ex-employees, former maintenance manager Aurelian Hossu, has pleaded guilty to four charges of acceptance of gifts by agent and is due to be sentenced next month, the Herald has earlier reported.
Court documents show Hossu was accused by SFO of jointly accepting more than $390,000 in bribes.
Name suppression remains for the other employee, who faces three charges of obtaining by deception and 12 charges of acceptance of gifts by agent, pending an appeal in the High Court.
The SFO's accusations against them include accepting for himself and others more than $1.26 million in bribes, court documents earlier obtained by the Herald read.
His deception charges relate to 205 allegedly false invoices submitted to Broadspectrum which saw three other companies obtain a total of $4.48m, including one firm collecting $3.77m in 2017.
Two subcontractors are also facing charges, Richard Motilal and another who has interim name suppression.
Motilal, a director of Engineering & Aviation Supplies, is accused of making two bribes totalling about $54,212 in 2018, court papers read.
In 2017, the head of roading contracting business Projenz Stephen Borlase was jailed in what was New Zealand's largest bribery prosecution.
An investigation by the SFO found Borlase bought-off Auckland Transport and Rodney District Council officials, including Murray Noone and Barrie George, in exchange for contracts worth tens of millions of dollars between 2005 and 2013.