Have you ever sat fuming in a holiday traffic jam, wishing you'd been forewarned to avoid a certain spot at a certain time?

With the summer holiday migration under way, the New Zealand Transport Agency have published maps showing where and when the worst snarl-ups are expected around the country.

The NZ Transport Agency is publishing a map to help drivers avoid congestion.

The maps detail 13 of the country's worst bottlenecks and list the times and dates traffic is expected to be at its heaviest, from Christmas through to early January, based on the experience of last summer.

National Road Policing Manager Superintendent Carey Griffiths says the maps are a useful tool in planning a summer journey.

'If you're going to travel on the days when everyone else travels, you're going to get to your destination a lot more slowly," he says.

"Accept that's the case, relax and enjoy the longer trip – or travel at non-peak times.

'What we don't want is people getting absolutely frustrated and putting themselves and other people at considerable risk.”

You can find high-resolution PDF versions of the maps on the NZTA website at http://www.nzta.govt.nz/traffic/current-conditions/docs/summer-holiday-peak-traffic-14-15.pdf