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National Road Database (NRD)

The NRD is a digital database of just about all roads in the Netherlands. All roads that are managed by road authorities: the state, provinces, municipalities, and water boards are included, but only if they have a street name or number. This means that separate footpaths and bicycle tracks and unsurfaced roads are also included if they have a street name. If a road has a dual carriageway, they are processed in the database as separate road segments.

The geometry of the NRD is identical to the centre lines of the TOP10maps database of the Dutch Ordnance Survey. Therefore the geometrical accuracy is the same as maps with a scale of 1:10,000.

The NRD is a network consisting of junctions joined together by road segments.

A junction can be:

• a location in the network where traffic exchange can take place,
• the end of a no through road,
• the location where a road segment crosses a municipality border.

A logical consequence of this method is that a large number of road segments are essential to form such a network.

The NRD 2005, therefore, consists of 895,789 road segments and 643,071 junctions.

Figure 1. Example of road segments and junctions

Use

The NRD is particularly important because it links various data sources to one another:

• road crashes are linked to the NRD;
• registrations of road features make use of the NRD;
• road authorities link their traffic counts to the NRD.

That makes it possible to analyse road safety in relation to the traffic volume and the features of the infrastructure.