- Signals passed at danger
Signals passed at danger (SPADs)
A signal passed at danger (SPAD) occurs when a train passes a stop signal without authority to do so.We provide a summary of the SPAD report quarterly in the National Rail Trends publication.
While there are many SPADs each year, most of these have little or no potential to cause harm because they are the result of minor misjudgements of distance or of braking capability, or they occur at low speed. In most cases, the trains stop within the safety overlap provided at the signal.
The overlap is a clear section of track beyond the signal, usually 183 metres long, which provides protection against relatively minor overruns. Generally, trains have to run past the signal safety overlap before there is any potential of collision or derailment.
Can SPADs cause accidents?SPADs are only one of the potential precursors to catastrophic accidents on the railway. Under 3% of all train collisions and derailments over the last 10 years have been directly caused by SPADs. Since the introduction of the train protection and warning system (TPWS) serious SPAD incidents and the risk arising from SPADs have been greatly reduced.
What are we doing about SPADs?SPADs have always been of concern. We are continuing our efforts to reduce SPAD risk and numbers. There are many different ways of preventing SPADs or reducing their effects, including different types of train protection.
This term covers equipment fitted to trains and on the track that reduces the consequences should a train pass a signal at danger, it does this by automatically applying a train’s brakes. While such systems do not prevent SPADs, they do reduce the risks posed by SPADs.
The train protection and warning system (TPWS) has been installed across the network and is successfully reducing SPAD risk. There have been a number of incidents where TPWS has intervened to avoid a potential collision.
More information on the different types of protection available can be found in our train protection section.
SPAD risk ranking
Since March 2001, the industry has been assessing SPADs using a SPAD risk ranking (SRR) process, which considers the actual and possible consequences of each incident. The process results in SPADs being assigned a numerical ranking between 0 and 28. Those SPADs ranked at over 20 are those with the highest potential for serious consequences, while those between 16 and 19 are considered to have less serious potential. Those ranked from 1 to 15 carry little or no risk.
Over the period March 2001 to September 2006, the implementation of TPWS together with other industry improvements and initiatives (such as the removal of Mark 1 rolling stock and greater use and understanding of human factors in SPAD management) brought about a significant reduction in SPAD risk of around 80%.
September 2006 is taken to be new baseline for measuring SPAD risk, as it is representative of the system risk management in the post-TPWS implementation era. As of summer 2011, the SRR process shows SPAD risk to have reduced further, with levels standing at around 30% of the September 2006 baseline. Further information is available on the Railway Safety and Standards Board website.
SPAD investigation reports
Following the Ladbroke Grove accident, HSE produced publicly available monthly SPAD reports, from October 1999 until September 2005. After that, Transport Ministers agreed that HSE should produce quarterly SPAD reports.
We have taken over responsibility for this, and it was agreed with the Department for Transport and Ministers that these reports are no longer necessary because details are recorded in National Rail Trends, which Parliament is sent copies of. The Rail Safety and Standards Board (RSSB) still publishes monthly publicly available SPAD reports.
Last updated: 13 September 2011