Assumptions about the Queenstown Lakes District Council's responsibilities to pay for road works associated with the proposed Dart Passage Tunnel will be discussed by its infrastructure services committee meeting in Wanaka on Tuesday.
Council asset management engineer Andrew Edgar said in his report on the council's submission to the proposed $150 million, 11.3km tunnel linking the Routeburn and Hollyford roads, it was unclear what consents the developer would require from the council.
However, it was possible the process would not allow the council to require Milford Dart Ltd to contribute to addressing issues the council would face if the tunnel was constructed.
Mr Edgar said the portal and access roads were proposed to be constructed on Department of Conservation land and the unsealed Routeburn Road was "relatively narrow, although adequate for the current road volumes".
"The last 2km of this road is within the Mt Aspiring National Park. Although there is a road extending into the park, the road itself does not follow the legal alignment.
"Despite this, the Department of Conservation in its report on the concession application attributes the maintenance and operation of this section of road to the 'local authority'.
"Council does not have plans to upgrade this road."
The road would be likely to need widening in places and greater maintenance because of the increase in larger vehicles, with dust also likely to become an issue in the summer.
The Rees River Bridge may need to be widened if more than 80 buses a day used the road and tunnel.
"Increases in usage should be expected since the tunnel will be a commercial venture and the operators will be aiming to increase usage to gain a greater return."
The Glenorchy Rd, east of Bob's Cove, may also need to be widened which would require "a lot of work", he said.
"Although the road is funded 100% [by the New Zealand Transport Agency as a 'special purpose road'] and the widening of the road is likely to help address the rock instability issues occurring at this location, the cost of doing the work could potentially outweigh any benefits gained from the development of the tunnel.
"Although the majority of the road between Queenstown and the proposed tunnel gains 100% funding from the NZTA for maintenance, operations and capital works, the NZTA may not fund work that is principally to address issues created by a single commercial operator.
"As there is no plan to upgrade this route with works that would address the issues described ... the council cannot be expected to make these upgrades when no budgets have been identified and set aside.
"Not upgrading the roads is likely to limit the predicted number of buses actually using the route and hinder the movements of current road users."
Mr Edgar said his report only covered the transport-related issues likely to arise if the tunnel was constructed and operated as proposed.
Last month 100 people attended a meeting in Glenorchy, culminating in a unanimous vote to oppose Milford Dart Ltd's plans, perceived by community members as a threat to Glenorchy's role as a long-stay tourist destination.
