A 30 km/h zone is also known as a ‘zone 30’ or a 'residential area'. The zone is mostly situated within an urban area and consists of connected access roads with a 30 km/h speed limit. The areas have a residential function where slow traffic and motorized traffic mix. For this reason speeds must be low (30 km/h maximum). For example, infrastructural measures at both road sections and intersections (think of humps, plateaus and road narrowings) can be used to realize such a low speed.

In this factsheet wrong-way driving is defined as ‘a car driving in the wrong direction on a road with separated driving directions and consequently driving into oncoming traffic '. This relates mainly to motorways. Wrong-way driving crashes are rare. The outcome, however, is often severe. Most wrong-way driving crashes occur when a driver enters a motorway exit ramp or when a driver reverses direction on a motorway. Orientation problems (especially among the elderly) or recklessness (especially among young drivers) are the most common causes.

The construction of the road network and the road design have a large effect on road safety: firstly, because these make certain conflicts impossible or unlikely (e.g. physical separation of driving direction, separate cycle lanes, obstacle-free verges); secondly, because these direct the desired traffic behaviour (recognizability, predictability). The Netherlands uses three road categories: access roads, distributor roads and through roads. Each road type has its own design principles, for both road sections and intersections.

A progressive penalty system encompasses heavier or more far-reaching sanctions being imposed as one commits more offences. A progressive penalty system is often called a progressive fines system if it involves increasingly higher financial penalties (fines), but (other) recidivism schemes such as demerit points systems can also be seen as a progressive penalty systems.