Northland storm: Some roads still closed after slips and flooding cause major damage

Several slips, including this, blocked SH1 through the Mangamukas after Friday night's deluge. The road through the Mangamukas will be closed, possibly for several days, while the slips are cleared.

Friday night's torrential storm caused major damage to Northland's roads, with state highways and local roads left blocked, slipped or flooded, with some expected to be closed - or have access restricted - for several days.

The storm dumped more than 200mm on Whangārei over the evening and night, including 156mm in four hours, with the rest of the region getting intense rainfall amounts.

This led to flooding and slips blocking roads across the region, with mammoth efforts to clear them, but some roads may still be closed or partly blocked today.

Far North District Council estimates there is at least $2 million of repairs needed on its roading network, and that figure is expected to be higher for Whangārei's local roads while the cost of repairing Kaipara's local roads is also yet to be worked out.

A campervan sends up spray as it crosses the Otiria Stream bridge at the bottom of Turntable Hill on SH1, Moerewa, after the road was closed cue to extensive flooding on Friday. Photo / Peter de Graaf

There is also expected to be several millions of dollars worth of damage to Northland's state highway network after slips, slumps and flooding.

Waka Kotahi NZ Transport Agency Northland system manager, Jacqui Hori-Hoult said the region's state highway network, with the exception of SH1 through the Mangamuka Gorge, was open as of late yesterday.

"Motorists are advised to check the Waka Kotahi NZ Transport Agency travel information website for latest updates because the situation could rapidly change with rivers already high and the ground saturated after days of exceptionally heavy rain. Plan your journey before setting off, take your time and allow extra time," Hori-Hoult said.

A motorist checks out the depth of a washout on Oromahoe Rd before opting to try a different route. Photo / Peter de Graaf

"Drive to the conditions, keep your speed down and watch out for unexpected road hazards like potholes where flood waters have receded. More rain could lead to renewed surface flooding in low-lying areas and slips. Heavy rain can also reduce visibility."
In the Far North, there are at least eight significant slips, both across and under the road, through the Mangamuka Gorge. SH1 was closed from Makene Rd to Victoria Valley Rd late yesterday.

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Somewhere under the floodwaters is Otiria Rd, west of Moerewa. Photo / Peter de Graaf

The biggest slip is just north of the summit and fully blocking the road, with about 5000 cubic metres of earth and fallen trees to be cleared. There are two slips either side of the summit slip and one is still moving following the recent heavy rain.

The road is likely to remain closed for several days while the slips and state of the road are assessed. The detour route is SH10 which will add 20-30 minutes to most journeys.

She said on SH10, motorists can expect to see repair work on the tomo site north of Kaeo at the start of the week and there is a longer term temporary speed limit at works near Taipa.

South of Whangārei on SH1, through the Loop Road roundabout construction site, road crews were yesterday using rolling blocks at five-minute intervals to minimise disruption to traffic while they carry out urgent pothole repairs. The southbound lane was most affected.

SH1 at Mangamuka Bridge was impassable on Saturday due to this slip.

With schools returning today, motorists are reminded to allow extra time for their journeys as there may still be issues on some roads.

In Whangārei many roads were left impassable during the storm and aftermath.

Flooding or slips blocked roads including Millbrook Rd; Helmsdale Rd; Waipū Caves Rd; Mangapai Caves Rd; Ormandy Rd; Whangārei Heads Rd; Matapouri Rd at Sandy Bay; Pataua North Rd; Old Parua Bay Rd was closed due to dangerous trees; Whananaki South Rd; Whananaki/Bland Bay/Russell Rd.

Whangārei District Council said the storm on Friday night led to widespread damage which included flooding, slips, scouring, dropouts and uprooted trees. This damage was widespread across the district and hit the Whangarei urban area particularly hard.

Shoemaker Rd, Waipū, remains closed today, and will need additional restoration work.

Immediate actions ensured roads were kept open and safe to traverse, apart from those that were completely submerged due to flooding.

The roading contractors teams started clearing roads at daybreak on Saturday and worked through yesterday to clear the damage. The priority was to clear slips to enable both lanes to be opened on the city and rural arterial roads, and at least one lane on other rural roads.

Flooding across Whangārei Heads Rd at Waikaraka. Photo / Rachel Ward

However, some sites will require additional restoration works to ensure the longevity of the repair and road formation. This work will be carried out over the next three months and in some cases the sealing will be carried out later in the warmer/drier months.