The crash, between a motorcycle and a rubbish truck, happened shortly after 6.30am and closed a section of the motorway between the Western Springs off-ramp and on-ramp.
A truck breakdown is also blocking the centre lane northbound in the Waterview Tunnel.
This has resulted in thousands of morning commuters failing to turn up to work, university and school as they continue to battle the congestion.
One motorist contacted the Herald and said he had been stuck in traffic for almost two hours and counting.
Another said they were over two hours late for work because of the delays.
"We left home in Queenstown Rd, Onehunga, at 6.45am and came through the tunnel. It's now 8.50am and we are crawling on the motorway about 100m away from the Western Springs off-ramp city-bound.
"This is so frustrating. We were meant to start work at 7am at University of Auckland."
A motorist who lives in Massey said he was sitting idle in his car at the Great North Rd turnoff, a journey which usually took 15 minutes in heavy traffic but took about two hours.
He said there had been signs on the way warning there was a crash and warning motorists to expect delays.
"Some people are driving up the left side, being sneaky, trying to beat the traffic.
"One lady's car was smoking and she had to pull over."
One commuter questioned how long the crash would take to clear.
"It's Monday morning, when will the congestion be cleared by? Need to get an estimate to plan the day accordingly with the boss at work," she said.
The slow commute is causing other concerns, with motorists reporting needing the toilet and sleep as additional stresses.
"I left Avondale at 6.32am and I'm just now approaching St Lukes off-ramp. Yup, that's three hours! P.S. I'm busting to use the toilet!" one motorist stuck in traffic wrote.
Another said they have flown four hours from Cancun to Los Angeles, waited 12 hours for the next flight before flying 12-1/2 hours to Auckland, only to be stuck in traffic since 7am.
The closure is affecting traffic on SH16, SH18 and on SH20 via the Waterview Tunnel. Traffic is back to Maioro St on SH20 and is between Royal Rd and Lincoln Rd on SH16. Local roads are also congested.
The Great North Rd on-ramp eastbound has also been closed, while traffic coming through the Waterview Tunnel on the Southwestern motorway is slow moving, with some commuters reporting having to wait over half an hour just to get through the tunnel.
Motorists have been advised to take alternative routes or delay travel wherever possible.
NZTA tweeted that traffic is being diverted at Western Springs off-ramp and will be put back on to the motorway at the Western Springs on-ramp - using Great North Rd as an alternative route.
Automobile Association principal adviser of infrastructure Barney Irvine said at 7.40am, one hour after the accident, it was taking one hour and 45 minutes to get from Westgate into the CBD. Usually, at this time it takes 25 or 26 minutes.
Also at 7.40am, it was taking just under one hour to get from the airport into the CBD via the Waterview Tunnel. Usually, the trip would take 25 or 26 minutes at this time.
Auckland Transport operations centre manager Rua Pani said police were working as quickly as possible to do their investigation but they don't know when it will be cleared.
The Transport Agency thanked motorists for their patience and understanding and said it is doing all it can to assist police.
