If you're heading away on holiday for Christmas, it would pay to take a look at our road safety route planner first.

The New Zealand Herald has built an interactive that calculates the road toll on your summer driving route, using data on fatal crashes over the past 20 years.

The statistics are sobering; 7431 people have died on New Zealand roads in that time and experience suggests more will lose their lives in crashes this summer.

Memorials for these victims haunt the sides of the roads. But the roadside crosses we notice are a small fraction of the number of people who died instead of reaching their destination.

Our interactive shows many of New Zealand's most lethal routes are to and from Auckland. The drive north is the worst and includes included the segment from Warkworth to Whangārei where in 20 years 162 people have been killed on just 101km of road. On average, this is one person every 623m of road.

The number of fatalities on a given road over the past 20 years does not always reflect the risk posed by driving on that road today.

NZ Transport Agency senior road safety manager Fabian Marsh says safety measures, including median barriers, roundabouts, raised safety platforms and speed management, have been deployed as part of safe-system transformations of a number of crash hotspots. These have resulted in significant reductions in serious road trauma.

The road toll has been increasing since 2013 but, looking back 20 or even 40 years, there has been a significant reduction. The worst year was 1973 when, with a population of just over three million, 843 people died on the roads.

Marsh also notes many fatal crashes have occurred at locations where there has not previously been a fatal crash.

NZTA's top tips for safe holiday driving

• Check your car is in good "health" before you head off: Check your tyre pressure and tread, windscreen wipers, indicators and lights.

• Take extra care when travelling in holiday periods because of increased traffic volumes, congestion, tiredness and people driving in unfamiliar environments.

• Drive to the conditions: whether it's the weather, the road you're on, the time of day or amount of traffic.

• Avoid fatigue: Take regular breaks to stay alert.

• Keep a safe following distance from vehicles in front so you can stop safely.

• Be patient: Overtaking is unlikely to make a significant difference to your journey time due to the amount of traffic expected over the weekend.

• Allow plenty of time: Remember you are on holiday, so there's no need to rush.