Appendix A – Information Sources, Methodology And Limitations

Appendix A – Information Sources, Methodology And Limitations

Information Sources

The report utilised information held by Police Scotland to retrospectively review and assess the circumstances of fatal collisions on Scotland’s roads from 1st January 2015 to 31st December 2020. No new information was gathered but it was reviewed in the context of the aims of the project. Data was reviewed for all road deaths on Scotland’s roads over this time period.

Collision Investigation Reports

Collision Investigation reports were the main information source utilised to inform this study. Where a collision is fatal, likely to prove fatal or involves life-altering injury, Police Scotland Collision Investigators are deployed to the scene to carry out in-depth collision investigation. A report is then produced which will contain information including locus and vehicle examinations, scene photographs, collision reconstruction and speed calculations. The Collision Investigation reports provide a very detailed insight into the collision and include all relevant details and potential contributory factors. The size of and detail within a Collision Investigation report varies depending on the type and complexity of a collision.

A total of 786 Collision Investigation reports were available for the reporting period. In the majority of cases where reports were unavailable, collision investigation had not been instigated. This was often due to the collision initially appearing non-serious (and it therefore being deemed unnecessary to undertake full collision investigation) however the casualty has later died as a result of the injuries sustained. Further reasons for absence of Collision Investigation reports include there being sufficient third party evidence (including witnesses, CCTV and dashcam footage) or an absence of physical evidence around collision circumstances which would aid the investigation. In these cases, it is agreed that the existing evidence is sufficient to establish the circumstances of the collision and full collision investigation is not required. For the collisions where Collision Investigation reports were not available, data from Incidents of Note, 28 day updates and Completion Memorandums were used to populate the database and inform analysis.

Incidents Of Note/28 Day Update/Completion Memorandum

Incidents of Note (IoN) are completed following all fatal collisions on Scotland’s roads. These provide an initial overview of the circumstances including the persons and vehicles involved, road layout, external conditions and preliminary assessed contributory factors. A 28 Day Notification Memo and subsequent Completion Memorandum enhance the initial overview and provide additional detail and final conclusion, respectively. Whilst these may not be as comprehensive as full Collision Investigation reports, they provide sufficient detail to assess contributory factors and assign potential countermeasures.


STATS19 forms completed by police officers following a collision provide information on three distinct elements – circumstances, vehicles and casualties. This includes crash location, local conditions such as weather and visibility, vehicle type and demographic details of the driver/riders and casualties. The forms also provide an overview of contributory factors.

Criminal History System (CHS)

The Criminal History System (CHS) is a tool to aid the police with crime detection, prevention and administration by providing access to structured data about individuals. Records held within the system provide detailed information about an individual’s criminal history including the crime/offence and relevant disposal. This allows for analysis of the previous convictions of those at fault for fatal collisions.

977 drivers were found to be at fault for fatal collisions during the reporting period however only 201 CHS records were available. An individual’s CHS record will only be retained for three years after death, therefore the records for many of those at fault who died in the collisions will no longer be held.

Methodology And Limitations

To compile the Police Scotland Fatal Collisions database, experienced Police Scotland Roads Policing officers reviewed the data held within the aforementioned information sources. Information was extracted to populate the databases, with great attention to detail, ensuring accuracy. The officers then assigned both contributory factors and countermeasures to each fatal collision based on all of the available information.

Processes were established to ensure that the database was quality reviewed, confirming that data had been input correctly and completely prior to being made available for analysis. Although the same set of values and descriptors were used by officers to assign contributory factors and countermeasures, an element of personal interpretation exists and any repetition of this data review by different officers may provide slight variations in results.

Fatal collisions that have been definitively ruled to be a suicide or a medical death have not been included for the purposes of this report. There were however occasions where it is not conclusive that the collision was a result of a suicidal act or a medical episode and these collisions have been included in the analysis.

The percentages in this report were rounded to the nearest whole number. For example: 62.213% was rounded to 62%.

The date period covered is 1st January 2015 to 31st December 2020.

The results of this analysis should be treated as an initial indicator for ways in which to reduce fatalities and a first step in understanding the evidence on how to prevent or reduce fatalities. Prior to any countermeasure implementation, the following should be considered:

Date period covered

The date period selected for this report includes 2020, the year in which the global Covid-19 pandemic placed various restrictions on travel. The figures must therefore be considered with this borne in mind.

Cost and feasibility of countermeasure implementation

This analysis did not consider the potential cost or feasibility of each countermeasure. The focus was to apply a countermeasure that could have independently prevented the fatality from occurring. Therefore, future cost benefit analysis will likely be required to ensure that any countermeasure implementation is both cost effective and feasible.

Responsibility for countermeasure implementation

Some of the countermeasures identified may be under the direct control of Transport Scotland (e.g. hazard management; barrier placement) and Police Scotland (e.g. improved policing profile/checks) however many others will fall within the remit of other partners such as Education or Health and vehicle manufacturers.

A multi-stakeholder approach will therefore be require to ensure relevant countermeasures are implemented effectively. Some identified countermeasures relate to reserved matters that can only be legislated by the UK Government and therefore wider discussion at a UK Government level will be necessary.