In the Netherlands, SWOV annually assesses the number of serious road injuries  based on two sources:
- Database of registered road crashes in the Netherlands (BRON). In BRON, the Ministry of Infrastructure and Water Management collects and publishes road crash databased on police registration, notifications by road inspectors of the Dutch national road authority and information from media reports. This database contains information on crash characteristics such as road and vehicle characteristics and crash circumstances. BRON does not contain reliable information about injury severity, and a lot of casualties are missing, particularly those resulting from crashes not involving a motor vehicle.
- The national hospital discharge register (LBZ). LBZ is a database maintained by Dutch Hospital Data (DHD). It contains injury data of patients discharged after hospitalisation. Examples of data that are registered are crash type, injured body parts and injury types. We assume that LBZ contains all road casualties admitted to hospital. Yet, in the database, not all casualties are identifiable as road casualties. Moreover, LBZ does not contain much information about the crash. For instance, information about crash location is entirely missing.
SWOV estimates the number of serious road injuries in the Netherlands by linking and analysing the data from both data sources, and also estimates how many serious road injuries are missing in both databases or are not recognised as such . The quality of both data sources is crucial for a reliable estimate of the number of serious road injuries. A sufficiently large number and share of casualties must be registered in BRON as well as in LBZ. Since the year 2010, the quality of, most notably, BRON has greatly decreased  and has been insufficient to allow making reliable observations concerning the developments in serious road injuries with certain characteristics (such as type of road user, age group etc) ). About 10% of serious road injuries in crashes without motorised traffic (for example cyclists crashing with a bollard or with another non-motorised road user) are to be found in BRON; and about 60% of serious road injuries in crashes with motor vehicles are thus registered . This implies that BRON registers the different types and numbers of serious road injuries (rather) incompletely and therefore presents an incomplete picture of actual road safety problems. Hospital registration (LBZ) does provide a more reliable indication of the most common characteristics of serious road injuries. About 95% of serious road injuries are registered there . The hospital registration does, however, not register the location of the crash. It is hoped that, in the future, ambulance data will add more information about crash location.