Crash data quality for road safety research: Current state and future directions

Crash databases are one of the primary data sources for road safety research. Therefore, their quality is fundamental for the accuracy of crash analyses and, consequently the design of effective countermeasures.

Although crash data often suffer from correctness and completeness issues, these are rarely discussed or addressed in crash analyses. Crash reports aim to answer the five “W” questions (i.e. When?, Where?, What?, Who? and Why?) of each crash by including a range of attributes. This paper reviews current literature on the state of crash data quality for each of these questions separately.

The paper also examines the accuracy of crash databases from a number of countries and demonstrates specific examples of crash database errors from four databases: STATS 19 (UK), FARS (US), Australian Road Deaths Database and the Attica Tollway crash database (Greece).

The researchers say the most serious data quality issues appear to be: inaccuracies in crash location and time, difficulties in data linkage (e.g. with traffic data) due to inconsistencies in databases, severity misclassification, inaccuracies and incompleteness of involved users’ demographics and inaccurate identification of crash contributory factors.

The paper shows that the extent and the severity of data quality issues are not equal between attributes and the level of impact in road safety analyses is not yet entirely known. The paper highlights areas that require further research and provides some suggestions for the development of intelligent crash reporting systems.