Unusual High Tides Threaten Auckland Motorway


Unusually high tides over the next week have the potential to cause problems on Auckland’s northwestern motorway – especially for those using the cycleway.
High tides of up to 3.5m – about 0.4 metres higher than normal – will occur from today until Easter Saturday.
Tides like this occur in Auckland only every six to seven years. The area most likely to be affected is the causeway across the Waitemata harbour between the Patiki Road Interchange and the Rosebank Road bridges.

The cycleway beside the highway will be flooded, and the NZTA is advising cyclists to try to avoid using it 90 minutes either side of the high tide mark.

The transport agency expects it unlikely the motorway itself will be affected, unless weather conditions like strong winds have an impact on the tides.

It has a traffic management plan to re-direct traffic away from the causeway if there is flooding.

Water runs alongside Northwestern Motorway

The NZTA is planning to raise the causeway by 1.5 metres and increase the width of the motorway to provide extra lanes as part of the Western Ring Route development. The unusually high tides will occur throughout 2010 on the following dates.

  • Tuesday, 13 July – Monday, 19 July
  • Wednesday, 11 August – Sunday, 15 August
  • Wednesday, 8 September – Monday, 13 September
  • Thursday, 7 October – Tuesday, 12 October
  • Saturday 6th November – Wednesday 10th November




  1. Geoff says:

    The 3.6m tides earlier this month didn’t reach the motorway surface, so 3.5m should be ok. It’s only an issue if there’s lots of winds creating waves.

  2. Lti says:

    Im not sure where all this 6 to 7 years talk is coming from.

    Spring Tides happen twice a month which is aproximately 24 times per year.

    Are these spring tides extra high?

  3. max says:

    I also couldn’t find the specific reason for the 7 year cycle. However, they seem to be pretty adamant, i.e. this doesn’t seem to be a typo only.

  4. Mike says:

    It is normal to have tides higher than spring tides, they are not the highest. I believe the tides refered to are King tides however I’m not a expert.

    Raising the motorway 1.5m is going to be
    hugely expensive.
    A simple stopbank along the foreshore would be suitable for the once in a while high tides and these banks could act as a natural sound barriers.
    A stopbank also works the other way such as keeping spills out of the marine area. ( The motorway is in part next to a marine reserve)

  5. David Perry says:

    There are unusual high tides all around the globe at the moment - no-one seems to know the cause. I have noticed here in NZ that the tides have been very low and very high for about 6 months - something I haven’t seen before. (I’m a yachtie)


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