"This pedestrian signalised mid-block crossing was always in the project scope, but was going to be let through a separate contract."
He said the rates in the stage one contract were such that it was cheaper on council to extend the scope to include this.
Devine said, when roading staff sought the first increase, councillors requested that this crossing was delivered earlier in the programme.
"Therefore most of this cost is not an increase overall, merely that we are delivering it through this contract."
The crossing accounts for $242,420 of the latest increase, while $137,415 is for additional work resulting from new design standards and safety standards imposed by KiwiRail.
The remaining $15,000 is contingency.
He said KiwiRail, like the council in a resource consent situation, decides the standards the council must build to.
"Unfortunately for us those standards changed part-way through our project. KiwiRail, in conjunction with NZ Transport Agency, had just completed a brand new set of standards, the first in decades and we agreed it was reasonable to modify our crossings to meet the new standards, rather than have to as a new project after it was commissioned."
Devine said the cost of the stage one contract would not rise again, stage two was tracking well, and the council did not expect any variations.
He said a project control group made up of representatives from KiwiRail, NZTA, the council and the contractor meet fortnightly to discuss issues which could affect cost, timelines, quality and reputation.
"Through this group we have found many opportunities to tweak the design to achieve either greater outcomes or reduced costs, such as using left over timber from stage one boardwalk for retaining walls in stage two."
"With these regular meetings with KiwiRail, we are able to work with them to ensure a no surprises environment, as much as practically possible, which has meant very few variations to stage two which were easily covered through contingencies allowed for within the contract."
He said both cost increases were covered by budgets already allocated within the Long Term Plan.