The Royal Commission inquiring into the Pike mine disaster has heard the Pike River coal company had applied to construct a second exit tunnel, two years before the explosion in which 29 men died.
The Department of Conservation told the hearing in Greymouth on Friday the company had been planning the tunnel for more than five years.
DoC's West Coast mines liaison person, Craig Jones, said under its access agreement with the department, the company had to file an annual work plan for approval.
He said in every year from 2005, the company had outlined a plan for a second tunnel, but it wasn't until its 2008-09 plan that it sought approval for a mine roadway allowing access into the Pike Stream Valley.
Mr Jones said progress was slow on many of the company's plans.
Every time it failed to meet a schedule, it would apply for a variation to it, and there were 144 of these from 2005 to the time of the explosion.
A spokesperson for the Pike River families says it was more devastating news to discover a second exit at the mine had been in the planning for five years.
The families' spokesperson Bernie Monk says at least the Royal Commission is uncovering more about the tragedy.
He says the Commissioners are to be congratulated for the way the hearing has been conducted this week.
On Thursday, a former chief inspector of coal mines said he told the Pike River company it was madness to have only one access into the mine because of its gas risk.