Ashburton’s bottleneck on State Highway 1 is set to be a construction zone for five weeks which “will cause congestion and delays in the area during daytime”.

NZ Transport Agency Waka Kotahi has confirmed night works are due to start on March 30 and go through until around May 9.

“Although the work’s biggest impacts will be experienced overnight after 8pm, this work will slow down traffic during the daytimes also,” NZTA said in a statement announcing the work.

NZTA’s Mid Canterbury maintenance contract manager Chris Chambers said contractors will be renewing the asphalt on SH1 West Street from the SH77 intersection at Moore Street to the Ashburton River Bridge in three stages.

“Crews will be working on SH1 from 8pm each night through to 6am each morning.

“Detours will be available for all traffic but there will be delays at times.”

He said there will be a changing range of traffic management across the five weeks.

“It will range from Stop/Go, to highway closures and local road detours, each night between 8pm and 6am.”

SH1 reopen each day at 6am, under temporary speed limits with reduced lane widths.

“We acknowledge that even though we are completing the most impactful work at night, the work site will cause congestion and delays in the area during daytime.

“We only have a few short weeks left before autumn temperatures make this kind of project unviable, so crews will be doing their best to complete it as fast as they can.”

Chambers advises allowing an extra 30 minutes if you are travelling through Ashburton after 8pm – and if possible, avoid travelling during the typical morning and afternoon peaks.

There will be no work undertaken over Easter Weekend (April 18-21).

While the road is closed, KiwiRail plans to take the opportunity to complete maintenance work on the SH1 level rail crossing prior to the resurfacing, which will reduce disruptions around further works being required in the immediate future.

The road works will start on March 30 but before then, the Ashburton District Council will be replacing a 110-year-old watermain within SH1, between Kermode Street and SH77.

That means drivers can expect some disruption and delay with construction works in the area from March 10 while the renewal works are completed ahead, and in preparation for, the highway surfacing rehabilitation works.

NZTA estimates that around 6,000 tons of asphalt will be placed in three layers - two structural layers and a top/wearing course.

Overall, the area will measure 10,000 square metres, 250mm thick and highways re-surfaced like this “have a design life of around 25 years before they need future full reconstruction”.

The three stages:

- Three-and-a-half weeks of night closures of SH1 West St from the SH77 / Moore St intersection to South Street. Detour via Walnut Ave, Chalmers Ave and South St.

- Two nights of closures at the SH1 and SH77/Moore St intersection.SH77 detoured via Oak Grove and Walnut Ave.SH1 detoured via Walnut Ave, Chalmers Ave and South St.

- One week of night-time Stop/Go on SH1 from South St to the Ashburton River Bridge.