New Traveller Information Standard - Data Quality in ITS systems

Date: 4/12/2008

Source: ISO

The ISO 21707:2008 standard, “Data Quality in ITS Systems”, was published earlier in the year and specifies the format for defining the quality of data being transferred between systems in transport information applications.

It is an informative technical report and defines a set of common “terminology for defining the quality of data being exchanged between data suppliers and data consumers in the ITS domain”. In this context, data quality is defined in terms of a set of meta-data parameters, which describe characteristics of the data, such as accuracy, precision and timeliness, where “quality” refers to the “fitness of purpose” of the data for the specific application. The scope of the standard is for Traffic and Travel Information (TTI) and Traffic Information and Control Systems (TICS) for open interfaces between systems.

The data may be raw or processed, real-time or static and the data consumer may be internal or external to the organisation of the data producer. The standard only sets out a generic framework and recommends that each ITS application and data domain should define its own specific quality meta-data profile. It defines two types of data quality: “instance data quality”, which gives a measure of quality for each specific data item; and “generic data quality”, which defines a measure of quality over a period of time. For example the “reliability” parameter is defined as instance data, which is either true or false for each data item, whereas the “error probability” is defined as generic data, having an average probability over a time period.

The standard lists the following types of suggested meta-data, which are then broken down further into more specific meta-data:

o        Service completeness – the coverage of the data

o        Service availability – including the mean time to failure and the mean time to repair

o        Service grade – the standard suggests that a data supplier may wish to grade their data service in bands to help consumers decide the use to which the data may be put

o        Veracity – the expected correctness, truthfulness or error rate

o        Precision – for example, the number of decimal places

o        Timeliness – parameters relating to the time delays of the data

o        Location measurement – information on the referencing system

o        Measurement source – information on how the data is collected

o        Ownership – identification of the data owner.

ITS Radar International will monitor developments

Keywords: Traffic information, Standard