Blockers and enablers to learning from SPAD investigations

Research has identified some of the blockers to learning from SPAD investigations. These are shown below together with the enablers that can help overcome them. It’s worth considering whether these are issues for your company.

Blocker:  SPAD investigations that do not establish why the signal was displaying a danger aspect

A study of a spike in SPADs in Period 3 2018 showed that this was a problem in 23% of investigations. Maintaining ‘proceed’ aspects wherever possible is the best way to prevent SPADs, so it’s vital to record the reason the signal was displaying a danger aspect.


  • Build-in the need to identify the ‘reason for red’ in your investigation materials, including: training, procedures, draft remits, report templates and audits.
  • Try to go beyond just the basics when recording the reason. Explanations like ‘train in section ahead’ are fine, but it’s helpful to include further information— was this because of delays, a problem with the train ahead, or just part of normal operations?
  • RSSB has a system called Red Aspect Approaches to Signals (RAATS). This looks at the number of times a signal is approached at red; check whether your signal is on the RAATS database and what the data shows (log-in needed).

Blocker:  Incorrectly classifying driver errors as intentional rule breaking

Intentional rule breaking (or violations) leading to SPADs are rare, occurring in around 7% of incidents (RSSB research project T1128).


  • Use RSSB’s 10-incident factor framework guidance (available from Rail Industry Standard for Accident and Incident Investigation).
  • Collect all the facts before deciding if the action was an error or an example of intentional rule breaking. Then identify what sub-category it falls into; if it’s still not clear, discuss with your manager.
  • When reviewing the actions or failings of others’, remember that you are judging with the benefit of hindsight. Try substituting yourself or others you know into the same situation, how confident are you that the outcome would be different?

Blocker:  Seeing a SPAD as a driver issue and not looking for other contributing factors, such as equipment or organisational issues  

Problems with equipment occur in around 40% of SPADs, but these are not always picked-up by investigators. Issues range from dirt on a signal, to an Automatic Warning System (AWS) magnet being an unusually long distance from the signal. One company reported 90% of recommendations focussed on the driver, 8% on the signal and 2% on company systems and processes.


  • Research shows between 4 to 8 incident factors contribute to most SPADs, this gives a rough guide of the number to look for (RSSB research project T1128).
  • Train investigators to look at the underlying causes. RSSB offers a training course in accident and incident investigation based around the requirements of RIS-3119-TOM.
  • Give investigators enough time to do it properly.
  • If underlying causes are not related to the driver’s competence, it should mean less work is needed with the driver.
  • Ensure the investigation remit covers organisational and equipment issues.
  • To avoid overlooking potential issues, the investigation should review items in the 10-incident factor framework and work systematically to rule them out based on evidence.

Blocker:  Recommendations that do not address causes

Investigations make generic recommendations such as ‘re-briefing the driver’ that do not fully address causes.


  • Correctly identifying causes will drive good recommendations.
  • Properly mapping causes to recommendations.
  • Using the investigating SPADs page should help.
Haven’t found what you’re looking for?
Get in touch with our Principal Human Factors Specialist for further information.
Philippa Murphy
Tel: 020 3142 5641
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