It originally asked for answers to be supplied by February 1, but has agreed to extend that deadline for a couple of weeks.
The issues include lighting, stormwater management, social and economic effects, impacts on the roading network and cultural assessments.
A KiwiRail spokesman said there were no surprises in the request.
“For a project of this scale it is common for there to be additional questions from the council.”
They said the two parties had been working constructively together on the process.
“KiwiRail is working through these questions with our project team and expects to respond to the council in mid-February.”