Signals Passed at Danger – RSSB Graphic Insights
Causes and impact of SPADs
A SPAD occurs when a train passes a signal showing a stop aspect without authorisation to do so, or proceeds beyond a movement authority on a European Train Control System (ETCS) railway. To help reduce and prevent these events, we produce guidance and data insights on the causes and impact of SPADs.
Scroll to the SPAD illustration below to see one in action.
How many SPADs occur and what is the risk of a collision?
260 SPADs occurred in 2022. Around two-thirds of SPADs could potentially result in a collision involving at least one passenger train. Only a small number pass the point where an accident could occur, with a 1 in 80 likelihood of a collision occurring if they do.
What can influence the consequences from a SPAD?
SPADs can result in a range of outcomes depending on what the signal is protecting. Signals that protect junctions have the greatest consequence as other trains may be joining or crossing in front of the SPAD. The SPAD Risk Ranking Tool helps industry understand SPAD risk.
What are the causes of SPADs?
Of 125 SPADs analysed, 70% were cited as slip/lapse errors. Most SPAD events are not due to individual error and have multiple causes. The data shows that improved management of skills, ease of using equipment and quality of spoken communication can help reduce SPADs.
How do environmental factors affect SPAD risk?
More SPADs tend to occur during periods of hot weather. Previous analysis found that, during spring and summer, an increase of 1°C was associated with a rise in the underlying SPAD rate of roughly 2.5%. RSSB investigated a spike in SPAD rates during the hot summer of 2022.
Initiatives that have helped reduce SPAD risk
SPAD risk has decreased significantly since the early 2000s, however the rate of decrease has plateaued in the last 10 to 15 years.
Move the handle, and hover over the timeline for information on RSSB resources and industry support. Click the links for more information.
Further, significant reductions in SPADs are unlikely without technological solutions such as the implementation of the ETCS. Recent data analysis suggests that drivers are thought to be driving at the limit of human performance capability.
Putting SPAD risk into context
Typically, passenger trains get priority at signals and so experience fewer red aspects compared to other train types. Compared to passenger trains, Empty Coaching Stock (ECS) trains see over 4.5 times and freight trains see 2.3 times as many red signals per mile.
Click the buttons for a breakdown of SPAD rates, and hover over the graph to compare risk levels for different train types.
- Passenger Trains
- Freight & Engineering Trains
- Empty Coaching Stock
Although passenger trains experience fewer SPADS compared to other train types, they have the
highest number of SPADs per year, due to the large number operating across the network. When considering
the number of SPADs alongside the number of trains that approach a red aspect signal, passenger trains
have the lowest SPAD rate of all train types. Passenger trains also tend to run a regular and predictable
service, meaning that the day-to-day aspect of signals along a route is likely to be somewhat repetitive.
Empty coaching stock have a higher normalised rate of SPAD incidents. These events tend to occur at the beginning and at the end of the day, a time when drivers may be more prone to fatigue related errors.
Freight and engineering trains have the highest normalised rate of SPAD incidents. This is because freight train brakes take longer to apply and have lower performance than multiple unit passenger trains, providing more opportunity for drivers to misjudge stopping distances. Many of these trains also operate overnight, where fatigue may compound this challenge.