Gantry drawing, example of one of the 14 overhead structures to be installed on SH1 and the new Christchurch Northern Corridor motorway.

From this weekend, the Christchurch Northern Corridor team will be installing gantries on SH1 around and near the Waimakariri Bridge, north of Christchurch. This will involve lane and full road closures at night through to October, says the NZ Transport Agency.

A gantry is a steel overhead support structure that will hold traffic signs.

“To install the gantries safely, we need to reduce traffic lanes or close both lanes in one direction for several nights. For one full night, we will need to close all motorway lanes in both directions,” says Colin MacKay, NZTA portfolio delivery manager. 

There will be well signposted detours in place during any overnight closures.

The lane closures or diversions will be in place from 10pm till 5am the next day, over 18 nights (see timetable below). With lane reductions, lane closures and traffic diverted, traffic movements will be slower than usual, so please expect delays, says MacKay.

On SH1 there will be seven gantries: two on the north side of the Waimakariri Bridge and five on the south. The new Christchurch Northern Corridor motorway will also have seven gantries in key locations. Several of the gantries will hold the new T2/carpool lane signs on the Christchurch Northern Corridor. 

“We first install poles on both sides of SH1 and then position the gantry on top. To do this safely, both southbound lanes going towards Christchurch will be closed at night on Sunday 6 September, Monday 7 September and Tuesday 8 September. Southbound traffic will be diverted via the old Main North Road Bridge over the Waimakariri River,” says MacKay.

Chaneys off-ramp

Chaneys off-ramp will be closed overnight Tuesday, 8 September.

One night with traffic diverted both directions

For one night, Wednesday 30 September, when the largest gantry is being installed, all motorway traffic, in both directions, will be diverted.

MacKay says the work is weather dependent and the NZTA hopes to have it completed in time for the motorway opening just before Christmas.

SH1 night time traffic impact overview