NZ Transport Agency contractors have been working urgently throughout the day to assess the safety of key South Island state highway routes, clear slips and safely reopen roads as soon as conditions allow.

SH6 between Rai Valley and Renwick has now re-opened, after being closed earlier in the day due to surface flooding.

Transport Agency highways manager Neil Walker said given the scale and the complexity of the slips which have closed SH1 the immediate focus is on establishing reliable alternative routes to re-connect communities which have been cut off by damage from Monday's quake.

"We've re-opened the alternative inland state highway route from Picton to Christchurch, via Murchison and the Lewis Pass," he said.


"This will be the main state highway route from Christchurch to Picton for at least several weeks, given the size of the slips which have closed SH1.

"We're also working urgently with Kaikoura District Council to open the inland road (route 70) between Culverden and Kaikoura. Crews have been working from both ends since early this morning to clear slips and assess the road and structures for damage, including aerial bridge inspections being conducted by helicopter, and contractors will do everything possible to have this route safely open by the weekend."

State Highway 1, Picton to Blenheim/Seddon is now open but Seddon to Cheviot remains closed. Cheviot to Christchurch is open.

With the closure of State Highway 1, Walker said the Lewis Pass route will be carrying higher volumes of traffic, and people are urged to allow extra time for their journey. They should allow an additional 90 minutes to two hours for the journey between Christchurch and Picton on the Lewis Pass route, with average journey times between Christchurch and Picton currently expected to take seven and a half hours.

An aerial view of slip impact on State Highway 1 near Kaikoura. Photo / Supplied
An aerial view of slip impact on State Highway 1 near Kaikoura. Photo / Supplied

Convenient fuel, café and toilet stops are along the route at Culverden, Springs Junction and Murchison.

State Highway 7A, giving access to Hanmer Springs from State Highway 7, reopened at 7am today after being closed overnight due to the risk of further rockfalls. The road is open for light vehicles only, and under escort by contractors.

The Transport Agency will be undertaking a detailed assessment of the scale and complexity of the large slips which are blocking SH1 on either side of Kaikoura, Walker said.

In assessing sites blocked by large slips, the safety of the public as well as Transport Agency staff and contractors is paramount, particularly with the continuing strong aftershocks and the risk of further slips and rockfalls, he said.

With continuing aftershocks contributing to the ongoing risk of further slips and rockfalls in several parts of the South Island, people are urged to drive with extra caution and comply with all temporary speed restrictions.