5.2 Identifying Data Requirements

There are a wide variety of uses for safety data, with many different users. As identified later in Analysis of Data and Using Data to Improve Safety, safety data can be used by policy-makers, traffic engineers, police, the health sector, the research community, insurance companies, prosecutors, vehicle manufacturers and others. Although summary data (particularly on crash fatalities) is available in most countries, more detailed information is required to fulfil the requirements of these users. Without this collection of data, it is not possible to take an evidence based approach to the management of road safety.

WHO (2010) provides discussion on the use of data for a public health approach to road safety. This document provides a comprehensive account of crash data systems, including their place in effective road safety management, and their establishment and use. It is essential reading on this topic, particularly for those working within LMICs who wish to establish or improve upon a crash data system. This document suggests a cyclic approach of:

• using data to define problems;
• identifying risk factors and priorities;
• developing strategy;
• setting targets and monitoring performance.

This process is then repeated.

WHO (2010) also provides guidance on the linkage between safety data and effective safety management (Figure 5.1), giving a framework for the collection and use of this data. The WHO document makes it clear that crash data alone is not sufficient to manage safety, but rather it must be used in combination with other sources of information. This additional information is required to better interpret risks, thereby assisting in the monitoring of performance and achievement of results.

As identified in Figure 5.1 and Box 5.1 (and further discussed in WHO, 2010; GRSF, 2009, 2013), the desired results or outcomes of road safety management are expressed as goals and targets, and occur at a number of different but related levels. These include institutional outputs from the policies, programmes and projects that have been implemented, which influence a range of intermediate outcomes. These intermediate outcomes subsequently influence final outcomes. Ultimately, these should reduce fatal and serious injury, in alignment with Safe System outcomes.

Box 5.1: Example safety data relating to road safety management

For example, analysis of data may have identified vehicle speed as a risk factor. A policy to improve compliance with speed limits will require an increase in speed enforcement. The output results of this intervention would be evidence of this increase in enforcement. Intermediate outcome measures might include the percentage of drivers exceeding the speed limit at selected locations. Changes in this measure (i.e. a reduction in speeding motorists) would help identify whether the intervention is having the desired effect. The final outcome indicators would include total deaths and serious injuries (ideally including a record of those that were identified as being speed-related), proving the ultimate benefit of this intervention.

Although crash data is a primary source of safety-related information, other data sources also serve a very important role. There is growing recognition of the use of asset data (including road design features) in road safety, and in many cases this information may already be collected and available for use. As identified later in this chapter, many countries do not have accurate information on crashes, and until such data is available, information about road design features and key safety behaviours provides an important means of identifying high risk locations and ways to address them.

Often different sources of information will be available on similar issues. Although multiple sources of information can be useful to help understand road safety issues more fully, it can also lead to confusion if the sources provide conflicting information. Differences can result from inaccuracies in data or differences in how the data is collected (see Quality and Under-reporting for further discussion of these issues). Where there is potential for confusion from the use of multiple sources of information, it is important to select a ‘single source of truth’ from a data source that will ultimately inform decision-making. Once this source of information is selected, justification needs to be provided as to why this source is preferred.

Different terms for injury severity are included throughout this manual. Definitions for different types of injury are provided in Box 5.2.

Box 5.2: Definitions for different injury levels