"There will be a mix of larger and smaller jobs making up the overall programme of works,"Gordon said.
"We have ensured that where possible the work is broken into bite-sized pieces suitable for smaller contractors. The meeting was well attended."
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Gordon said working in the rail corridor brought with it special safety requirements that were different from roads and other civil construction.
He said survey teams have already begun gathering detailed information to help design bridge replacements and plan essential tunnel maintenance.
The work is expected to finish by the end of November.
"Northland's railway lines are underused at the moment because of their condition. The [North Auckland Line] is around 100 years old, is mothballed north of Kauri and the whole line has been in a state of 'managed decline' until its future was determined," Gordon said.
The survey work was a major step in turning that around, he said.
KiwiRail chief executive Greg Miller and Regional Development Minister Shane Jones made the funding announcement last month.