Updated 11am: Heavy fog that blanketed part of Auckland this morning is wreaking havoc at Auckland Airport, with over 60 regional flights now grounded.

About 35 domestic flights have been cancelled and 27 domestic flights delayed due to the fog so far.

Domestic flights to Wellington, Christchurch, Dunedin and Queenstown are so far not affected by the fog.

One passenger waiting for a flight to Whanganui said there were some "grim-looking expressions".

 

"Many are resigned to accepting the delays will be longer than they'd hoped.

"Frustrated passengers are on phones, trying to rearrange plans for the day and explain it isn't yet known when they will be able to travel."

Buses have been brought in for some passengers, including to Tauranga, Taupō and Kerikeri.

A bus driver taking passengers to Tauranga at 9am said he had been busy since 5am taking rail passengers into Auckland city.

"I had a call from the international airport wanting me to help with 200 passengers there and I had to say 'sorry, no can do'."

Megan Powell and son Pax Kay, 5, had their 8.30am flight to Rotorua cancelled and rebooked on an 11am flight.

"We started out from Perth last night at 7.45," she said. "So the delay does make it a long trip."

Powell said the disruption was understandable, as everyone couldn't help but notice the fog.

"We'll just walk around a bit. Pax can play with his dinosaurs. It's not too bad at all, really."

Powell was returning home to visit her parents in Rotorua.

Shaun Burton's flight to Blenheim was originally scheduled to leave at 7.55am, then it was delayed to 10am. Now it has been cancelled.

Passengers are advised to check in with their airlines about delays and cancellations.

In domestic departures and arrivals Air New Zealand and Virgin flights (operated by Air NZ) early this morning to and from Whangārei, Tauranga, New Plymouth, Taupō, Napier, Blenheim and Nelson have been affected.

Fog was affecting several airports in the upper North Island this morning, including in Hamilton, Whenuapai, Rotorua and Kerikeri.

Ann-Marie Edmonds said planes were "going nowhere" in Rotorua this morning.

So far three flights from there had been delayed - to Auckland, Wellington and Christchurch, and two cancelled, Air NZ flight NZ 8150 to Auckland and NZ 8149 arriving from Auckland.

Fog also affects motorists

Motorists are facing delays with heavy fog blanketing parts of Auckland this morning.

State Highway 1 traffic is delayed just south of Wellsford after a logging truck rolled.

A Fire and Emergency spokesman said they received reports of the crash near Davies Rd and Port Albert Rd around 8.15am.

"The driver is not seriously injured, however the road is currently blocked and diversions are being put in place," police said.

Another logging truck was on its way to collect the truck's load.

Rail: Britomart Station re-opens

Meanwhile, Auckland's Britomart Station has reopened for limited rail services.

Auckland Transport has advised that Britomart is now partially open, but limited train services are operating to the station every 20 minutes.

Platforms 3, 4 and 5 at Britomart will be open for some services, while Platforms 1 and 2 will remain closed as it was not possible to move the derailed train overnight.

Southern and Eastern lines will operate to Britomart, but the Western line services will be terminating at Newmarket - connecting with the Southern line service to Britomart.

The Onehunga train shuttle is also operating between Penrose and Onehunga and there will be limited replacement buses running between Britomart and The Strand and Britomart and Newmarket. These buses will depart from stop 7020 at the corner of Commerce and Quay Sts.

Commuters are advised that due to the reduced frequency, trains and buses will be busier than usual.

The derailment crippled the busy station after three of six carriages derailed as a train arrived at the station at 9.45am yesterday.

The six-carriage train had 33 people on board but no one was injured.

Some passengers described the accident as a sudden shake "like an earthquake".

The station was closed overnight as the Transport Accident Investigation Commission looked into the incident.

Investigators mapped, recorded and gathered evidence from the site to make sure the re-railing crew had all the information they needed to get the train back on track.

It is not yet known when the train will be put back on the rails.

Yesterday afternoon, commuters told the Herald the closure had added as much as an hour to their trip home.

Louise Caro was aware of the closure of the station before arriving but was annoyed at the confusing planner provided by Auckland Transport detailing what bus she needed to catch.

She was on her way home from work to Morningside and expected the interim transport options would mean her commute was at least an hour longer.

"I would normally be home by 5.10pm but God knows how long it will take me now. I may have to get my husband to come get me.

"It should be fixed by tomorrow, it is just one train for God's sake. I'm frustrated."

She was lucky she lived in central Auckland and feared for the length of commute for people in the fringes of the city.

About 12 Auckland Transport staffers were at the two entrances directing people to the Newmarket and The Strand stations via buses.

Andrew Blomfield was travelling home to Papakura and said the closure was "bit of a pain in the arse".

Praveen Sivapalan said he didn't know much longer it would take for him to get home to Howick but expected it would add another half an hour at best.

At worst it could be more than an hour, he said.

An Auckland Transport spokesman said there would be delays and changes to where the trains departed and arrived last night and through to the morning.

The station was to be closed overnight as the Transport Accident Investigation Commission looked into the incident.

The commission arrived at the scene about 3pm and was now in control of the station, Auckland Transport media relations manager Mark Hannan said.

Transport Accident Investigation Commission senior communications adviser Simon Pleasants said investigators would be mapping, recording and gathering evidence from the site to make sure the re-railing crew had all the information they needed to get the train back on track.

"The commission opens an inquiry when it believes the circumstances of an accident or incident have - or are likely to have - significant implications for transport safety, or when the inquiry may allow the commission to make findings or recommendations to improve transport safety."