SPAD and TPWS activity report
Quarter 1 – 2013/14
Alexander Moor
020 3142 5487
Mail to: spad@rssb.co.uk
The report may be downloaded from the RSSB website: www.rssb.co.uk.
 Rail Safety and Standards Board Limited 2013
Contents
Executive summary
3
1
SPAD risk
5
1.2
Precursor Indicator Model
5
1.3
The risk from SPADs
6
SPAD numbers
8
2.1
June 2013
8
2.2
Quarter 1 – 1 April to 30 June 2013
8
2.3
Changes in SPAD numbers over time
9
2.4
Monthly SPAD numbers
10
2.5
SPADs risk ranked 16+ and 20+
10
SPAD sub-categories
12
SPAD Provisional status
12
SPAD performance by route
14
SPAD numbers by route
14
SPAD performance by railway undertaking
15
5.1
Railway undertakings – passenger
15
5.2
Railway undertakings – freight
15
5.3
SPADs associated with engineering operations
15
Further analysis of SPAD occurrence
18
SAS and SOY SPADs
18
2
3
3.1
4
4.1
5
6
6.1
Multi-SPAD signals
7
7.1
8
20
Train Protection and Warning System
21
TPWS brake demands at signals
21
7.1.1
Brake demand numbers associated with SPADs
21
7.1.2
Brake demand numbers at signals at danger
23
7.2
TPWS ‘reset and continue’ (at SPADs)
24
7.3
TPWS brake demands at PSRs
25
7.4
TPWS brake demands approaching buffer stops
26
SPADs: an international perspective
27
New Look
We have been looking at making some changes to the report, with the aim of:



Making the key points easier to see at a glance
Simplifying some of the more complicated items that were easy to misinterpret
Adding useful information that was previously not included
The Executive Summary and Context sections are an example of this, and we would
welcome any feedback on these to spad@rssb.co.uk
Within the report last quarter is used to refer to the end of 2012/13 Q4, and last year
to the end of 2012/13 Q1.
2
SPAD/TPWS Report, Q1-2013/14
Executive summary
Key statistics
All SPADs annual moving
total (AMT)
16+ SPADs AMT
SPAD risk relative to
September 2006 benchmark
268 ↑7.2%
72 ↑
58% ↓
Last quarter: 250
Last year: 257
Last quarter: 70
Last year: 71
Last quarter: 60%
Last year: 36%
Multi-SPAD signals (two or
more SPADs in five years)
20+ SPADs AMT
AM percentage of TPWS brake
demands which were
interventions
126 ↑
13 ↓
58% ↑
Last quarter: 122
Last year: 136
Last quarter: 16
Last year: 10
Last quarter: 56%
Last year: 43%
Quarterly performance
SPAD numbers
SPAD risk relative to
September 2006 benchmark
16+ and 20+ SPADs
16+
27
66%
20+
77
62
68
61
5
Q2
Q3
Q4
Q1
2 12/13 3
4 13/14
5
The 68 SPADs in Q1 was above the
Q1 average of 64.7 for the previous
three years. The annual moving total
has seen an increase both compared
to the last quarter and the same time
last year.
4
6
SAS
14
11
SOY
5
Q2
Q3
Q4
Q1
Q212/13Q3 Q4 13/14
Q1
Due to the small numbers involved,
there is large variation in the number
of 16+ and 20+ SPADs between
quarters. Note that the 16+ category
also includes 20+ SPADs.
Q1
Q1
1
Q2
Q3
2 12/133
4
Q1 13/14 included seven passenger
train SPADs which passed the conflict
point, which is the main reason for the
increase from a year ago, when this
figure was four.
There was one suspected post SPAD TPWS ‘reset & continue’ incident
during the quarter, which occurred on 9 June 2013 at Shoeburyness.
10
Multi-SPAD signals
8
5
Q1
2
TPWS reset & continue
SAS & SOY SPAD numbers
13
Q1
5
13/14
12
1
1
Q4
44%
36%
13
Q1
58%
21
18
50
60%
7
4
5
Of the 126 multi-SPAD signals, 77 (61%) have TPWS fitted. These signals
carry a lower risk, as TPWS is designed to stop the train before it reaches
the conflict point.
9% of SPADs in the last five years have been at Multi-SPAD signals.
Q1
Q1
Q2
Q3
Q212/13Q3
Q4
Q4
Q1
Q1
13/14
Analysis of the AMTs shows Q1-Q3
12/13 were a peak for SOY SPADs,
which are now returning to their prepeak level. Similar analysis on SAS
SPADs shows they been consistent in
recent quarters, following a large
decrease between 11/12 and 12/13.
SPAD/TPWS Report, Q1-2013/14
3
Context
Most recent notable incidents resulting from SPADs
Passenger train derailment
Passenger train collision
TPWS reset and continue
28 Aug 2010
3 Oct 2009
9 Jun 2013
Guildford
Darlington
Shoeburyness
Non-passenger train
derailment
Non-passenger train
collision
7 Nov 2011
16 Oct 2003
Healey Mills Yard
Norton Bridge
Last three SPADs resulting in fatalities
Ladbroke Grove
Southall
Watford Junction
5 Oct 1999
19 Sep 1997
8 Aug 1996
Collision: 31 fatalities
(29 passengers and 2 workforce)
Collision: 7 passenger fatalities
Collision: 1 passenger fatality
Historic performance
SPAD risk relative to September
2006 benchmark
SPAD numbers (AMT)
879
Seasonality (10 year average)
500%
268
11990
58%
2013 1
2003
2013
Between March 2003 and September
2006 there was a significant reduction
in SPAD risk following the installation
of TPWS.
Since 1990 annual SPAD numbers
have decreased by almost 70%, with
the long term trend continuing to show
a decrease.
J
F M A M J
J
A
S
O N D
In the last 10 years, average monthly
SPADs numbers have seen peaks in
April and July/August.
Contribution to total accidental system risk
Total accidental system risk
Non-Movement
Train accident risk
10 year moving total SPAD
fatalities for last 50 years
Non-SPAD
Train
Accident
SPAD
Movement
SPAD risk contributes 10.0% of train accident risk, and 0.6% of total system
risk. While this is a relatively small level of risk, SPADs are an important
precursor due to their ability to cause a multi-fatality accident.
4
1963
2013
1
There have been no fatalities as a result
of SPADs in almost 14 years, with
Ladbroke Grove having the highest
number of fatalities since St John's
Lewisham in 1957.
SPAD/TPWS Report, Q1-2013/14
SPAD Risk
1
SPAD risk
1.1
Precursor Indicator Model
Chart 1 shows the precursor indicator model (PIM) for train accident risk. In September 2006,
SPADs contributed 14.1 of the 100 total risk benchmark, relative to this benchmark, May
2013 shows SPADs contributing 8.38 to a total risk of the 86.86.
Chart 1.
PIM
SPAD/TPWS Report, Q1-2013/14
5
SPAD Risk
1.2
The risk from SPADs
SPAD risk is calculated across the network using a consistent and objective measure applied
by the SPAD risk ranking tool (SRRT). The risk ranking score assigned to each SPAD is then
used to track changes in SPAD risk over time (see Appendix 1 for a definition and Appendix
2 for the methodology).
Chart 2 shows the annual moving total number of SPADs (red line), along with SPAD risk
(green line). This is modelled using the individual components of SPAD risk ranking scores,
based on a rolling 12-month period. It indicates that, at the end of the year, the risk from
SPADs is 58% of the 2006 benchmark level.
Chart 2.
6
Change in SPAD risk since September 2006
SPAD/TPWS Report, Q1-2013/14
SPAD Risk
Chart 3.
SPADs where the train reached the conflict point
1.2.1
Details of high risk SPADs
There were two SPADs with a risk ranking of 20+ during the quarter. The details are as
follows:

SPAD risk ranking 23 – On 11 April a passenger train passed SE7022 signal at
danger on the Up Ashton Line line at Stalybridge (LNW Route) by approximately 1400
yards. The main reasons for the high risk ranking of this SPAD are that: (a) the train
passed the potential conflict point, and (b) the consequences had a collision occurred,
could have been relatively high due to the possibility of a rear-end collision involving
two peak loaded passenger trains, where the potential collision speed is 22.5 mph.

SPAD risk ranking 22 – On 20 April a passenger train passed WH72 signal at danger
on the Up Fast line at West Hampstead (EM Route) by approximately 328 yards. The
main reasons for the high risk ranking of this SPAD are that: (a) this is a plain line
signal and so not required to be fitted with TPWS, and (b) the consequences had a
collision occurred, could have been relatively high due to the possibility of a rear-end
collision involving two peak loaded passenger trains, where the potential collision
speed is 50 mph.
As the information is taken from initial reports, it is subject to change pending the findings of
investigations.
SPAD/TPWS Report, Q1-2013/14
7
SPAD Numbers
2
SPAD numbers
2.1
June 2013
Table 1.
SPAD numbers: June 2013
June 2013
25 SPADs during June, which is seven greater than June 2012.
The number of SPADs in June 2013 was 1% lower than the three prior years’ average of
25.3.
Risk ranking
Eight SPADs were risk ranked 16 or above (none of which were risk ranked 20+). This
compares to six in June 2012 (four of which were risk ranked 20+).
TPWS
Six TPWS interventions (TPWS applied the brakes before, or in the absence of, driver
action).
Eight TPWS activations (the driver initiated braking before the system).
None where the TPWS brake demand type is currently unknown.
Multi-SPADs
Six SPADs at multi-SPAD signals [two or more within the current five-year period].
2.2
Quarter 1 – 1 April to 30 June 2013
Table 2.
SPAD numbers: Quarter 1 2013/14
Quarter 1
68 SPADs during the quarter, which is 18 more than the same quarter last year (36% more).
Q1 also had 5% more SPADs than the average for the three prior Q1s of 64.7.
Risk ranking
21 SPADs were risk ranked 16 or above (two of which were risk ranked 20+). This compares
to 18 in Q1-2012/13 (of which five were risk ranked 20+).
TPWS
26 TPWS interventions (TPWS applied the brakes before, or in the absence of, driver
action).
19 TPWS activations (the driver initiated braking before the system).
None where the TPWS brake demand type is currently unknown.
Multi-SPADs
8
19 SPADs at multi-SPAD signals [two or more within the current five-year period].
SPAD/TPWS Report, Q1-2013/14
SPAD Numbers
2.3
Changes in SPAD numbers over time
As Chart 4 shows, the current annual moving total (AMT) for all SPADs is 268, which is 12%
higher than the all-time low of 239 in September 2012. The AMT for 16+ is currently 70, while
the AMT for 20+ SPADs is currently 13. Given the low number of 20+ SPADs, you would
expect the 20+ AMT to be subject to more statistical uncertainty than the 16+ or total figures.
Chart 4.
All SPADs annual moving totals
Table 3 presents a summary of the change in SPAD numbers, comparing end Q1 2013/14
with Q1 2012/13. It shows an increase in the All SPADs AMT, the 16+ SPADs AMT and the
20+ SPADs AMT. None of these are statistically significant at the 90% confidence level.1
Table 3.
All SPADs annual moving totals
1
Statistical significance testing can help to indicate whether a genuine change has occurred or whether the data
could be the result of chance fluctuations. Throughout this report, the term statistically significant refers to a
change that is significant at the 90% confidence level; that is, we can be reasonably confident that there has been
a real improvement or deterioration.
SPAD/TPWS Report, Q1-2013/14
9
SPAD Numbers
2.4
Monthly SPAD numbers
Chart 5 compares monthly SPAD numbers in 2013/14 with those during 2012/13 along with
the three-year average. See Appendix 6 for tables.
Chart 5.
All SPADs – monthly variation
Chart 5 shows there is no clear pattern in the seasonality of SPADs.
2.5
SPADs risk ranked 16+ and 20+
2.5.1
SPADs risk ranked 16+
Chart 6 compares monthly 16+ SPAD numbers in 2013/14 with those during 2012/13.
Chart 6.
SPADs risk ranked 16+ – monthly variation
In the last 3 years about 28% of SPADs have been risk ranked 16+, although there is large
variation in this percentage between months. There were a particularly high number of 16+
SPADs during November 2012/13; of which four can be attributed to environmental
conditions.
10
SPAD/TPWS Report, Q1-2013/14
SPAD Numbers
2.5.2
SPADs risk ranked 20+
There were two SPAD with a risk ranking score of 20+ during the quarter, which compares to
five in the same quarter in 2012/13. Details of these incidents are in section 1.2.1.
SPADs risk ranked 20+ are taken forward to Operations Focus Group (OFG) and individual
Operational Safety Reduction and Mitigation (OPSRAM) group meetings, and are also
reported to the RSSB Board.
SPAD/TPWS Report, Q1-2013/14
11
SPAD Trends
3
SPAD sub-categories
3.1
SPAD Provisional status
Chart 7 shows the breakdown of SPADs by provisional or confirmed status. SPADs are
provisional until they have a completed investigation.
Chart 7.
SPADs by provisional/confirmed
SPADs are subdivided into four different types: A1, A2, A3 and A4. These differing
sub-categories cover, in that order, the scenario of a ‘classic’ SPAD; that of a signal being
imperfectly displayed/part obscured; an incorrect authority being given and a train
experiencing compromised braking performance. Full descriptions are given in Appendix 2.
Chart 8 shows the distribution of the different SPAD classifications, in respect of the SPADs
which have occurred since the changes were introduced.
Chart 8.
12
SPADs by sub-category
SPAD/TPWS Report, Q1-2013/14
SPAD Trends
Of those which have this field completed in SMIS, 64% are A1, 26% are A2, 6% A-3 and 4%
A4. Incidents for which a sub-category has not been entered have been categorised as A1
SPADs.
Chart 9 shows the contribution to SPAD risk of each SPAD sub-category, with the risk for
each month modelled using the individual components of SPAD risk ranking scores, based
on a rolling 12-month period.
Chart 9.
SPAD risk by sub-category
Since the middle of 2012, the modelled risk from A2 classified SPADs has increased
significantly. Over the same period, the annual moving total of A2 SPADs has remained
relatively stable, indicating an increased risk per event for these types of SPADs.
A2 classified SPADs are those for which, according to available evidence, the stop aspect,
indication or end of in-cab signalled movement authority concerned was not displayed or
given correctly, but was preceded by the correct aspects or indications.
SPAD/TPWS Report, Q1-2013/14
13
SPAD Performance by Route
4
SPAD performance by route
4.1
SPAD numbers by route
Table 4 presents performance by route for ‘all SPADs’ and those risk ranked 16+. The
percentage changes are based on a comparison between the annual moving totals at the
end of June 2012 and 2013. If any of the changes in SPAD numbers are statistically
significant (at the 90% confidence level), this is indicated in the right-hand column.
Table 4.
Route performance – comparison of moving annual totals
The only changes in the SPAD numbers which are statistically significant are the 16+
numbers for Anglia. During the last 12 months, Anglia has seen the number of 16+ SPADs
decrease from 13 to 5, which is statistically significant at the 90% confidence level.
Table 5 shows the percentage of these annual totals which have a SPAD risk ranking of 16
or higher, both nationally and by route. In the 12 months to June 2012, 28% of all SPADs
had a risk ranking score of 16 or more; while in the 12 months to June 2013, this was 26%.
Table 5.
Route performance – comparison 16+ percentages
Routes where the number of 16+ SPADs has increased from June 2012 to June 2013 have
their 16+ percentages highlighted in red.
14
SPAD/TPWS Report, Q1-2013/14
SPAD Performance by Railway Undertaking
5
SPAD performance by railway undertaking
5.1
Railway undertakings – passenger
The table in Appendix 10 shows the current annual total, and the annual total 12 months
previously, classified by railway undertaking (RU). Appendix 7 presents SPAD data for each
RU, by calendar year, which has been normalised by millions of train miles run, and
compares this with the national average for all RUs.
5.2
Railway undertakings – freight
Chart 10 shows the monthly numbers of SPADs by freight RUs from July 2011. This chart
presents raw SPAD numbers which have not been normalised against train miles run. There
were 13 freight train SPADs during the quarter compared with 8 in Q1 of 2012/13.
Chart 10. SPADs by freight railway undertakings
5.3
SPADs associated with engineering operations
Chart 11 shows the number of SPADs involving engineering machines. During the quarter,
there were two such SPADs, both on-track machines.
Chart 11. SPADs by engineering machines
SPAD/TPWS Report, Q1-2013/14
15
SPAD Performance by Railway Undertaking
Chart 12 indicates the number of possession-related SPADs, broken down by whether the
movement concerned was entering, leaving or within a possession at the time of the SPAD.
Chart 12. Possession-related SPADs
5.3.1
SPADs normalised by millions of train miles
Appendix 7 shows the SPAD performance of individual RUs, normalised by millions of train
miles (MTM) run. This is calculated from SPAD numbers and their SPAD risk rankings, along
with train mileage data.
This table compares the performance of each RU, in terms of the numbers of SPADs per
million train miles run, to the national rate. It highlights those which have achieved SPAD
rates better than the appropriate national rate in respect of ‘All SPADs’ and ‘16+ SPADs’, as
well as those which have exceeded the national rate in either one, or both of these
categories.
The main part of the table is divided into two. Passenger train operators are shown
separately from freight train operators. This allows separate group rates to be shown for
these two types of operators and should enable more meaningful comparisons to be made.
16
SPAD/TPWS Report, Q1-2013/14
SPAD Performance by Railway Undertaking
5.3.2
SPADs normalised by driver population
Chart 13 shows the average number of SPADs per driver (x1000), normalised by the number
of drivers in each age band. Age band data has been collected from industry surveys.
Chart 13. Normalised SPADs per driver by age band, 10 year average
Chart 14 shows the average number of SPADs per driver (x1000), normalised by the number
of drivers in each experience band. Experience band data has been collected from industry
surveys.
Chart 14. Normalised SPADs per driver by experience, 10 year average
The experience data in many cases refers only to experience at the drivers’ current
company, and so in cases where a driver has moved between train companies, they may fall
into a lower experience band than their actual experience. Normalisation data for age and
experience is collected separately, so it is not currently possible to do analysis on whether
one of these is a more dominant factor. This is something we will try to collect in future.
Normalisation data has only been collected from about 80% of the industry; if companies
have different age and experience profiles, the SPAD rates shown in Chart 13 and Chart 14
may change slightly.
SPAD/TPWS Report, Q1-2013/14
17
Further Analysis of SPAD Occurrence
6
Further analysis of SPAD occurrence
6.1
SAS and SOY SPADs

A SAS SPAD is one where a stationary train starts against a signal at danger. This
may be at a platform starting signal, or at any other signal at which a train is stopped.

A SOY SPAD is one which occurs when a train starts away from a yellow signal, but
then fails to stop at the next (danger) signal.
Chart 15 shows the annual moving total number of SAS and SOY SPADs.
Chart 15. SAS and SOY SPADs (annual moving total)
6.1.1
SAS SPADs
Chart 16 shows SAS SPADs, by time of day, using data from the last three years. The types
of trains involved are differentiated by the colour-coded sections of the bars.
Chart 16. SAS SPADs by time of day
18
SPAD/TPWS Report, Q1-2013/14
Further Analysis of SPAD Occurrence
Passenger trains, which are shown in blue, constitute 40 of the 120 SPADs indicated (33%),
while empty coaching stock constitute 37 (31%). As could be expected, passenger trains are
shown as having had no SAS SPADs during the period between midnight and 06:00, as
there are few such trains running during these hours.
During the morning and evening peak periods, trains tend to be more numerous, especially
on urban commuter routes; this increases the number of occasions when trains are exposed
to red signals, and therefore the opportunities for trains to SPAD.
6.1.2
SOY SPADs
Chart 17 shows SOY SPADs, by time of day, using data from the last three years, again
differentiated by train type.
Chart 17. SOY SPADs by time of day
It is apparent that the incidence of SOY SPADs decreases after the evening peak, becoming
very low during the early hours of the morning, before increasing during the morning peak.
The pattern on this chart is more in line with what would be expected bearing in mind the
changes in exposure to red signals during the peak hours mentioned above.
There are a greater proportion of passenger trains represented in Chart 17, than in Chart 16.
These amount to 83 of the 116 SPADs, which equates to 72%.
SPAD/TPWS Report, Q1-2013/14
19
Further Analysis of SPAD Occurrence
Multi-SPAD signals
6.1.3
The multi-SPAD signal population – signal numbers
A multi-SPAD signal is defined as one which has had two or more SPADs in the preceding
five years. Chart 18 plots the number of signals classified as multi-SPAD throughout the last
year, along with the annual moving average. This shows that the number of listed signals has
been as high as 136. There were 136 such signals listed as of a year ago and 126 as at 29
June 2013.
Prioritisation of SPAD mitigation measures can be difficult when there are a large number of
signals on the weekly multi-SPAD list. Whilst all multi-SPAD signals require attention, there is
a degree of random chance that a signal will be subject to a second SPAD within five years.
However, there is less likelihood that a third SPAD will occur at random within five years at a
given signal. Analysis is therefore undertaken to identify signals that have had three or more
SPADs in the last five years, in order to determine those that require more immediate
attention. Those multi-SPAD signals which have accrued three or more SPADs within five
years currently number 25 (18% of the multi-SPAD signal population), which is a decrease of
two on a year ago. These signals are listed in Appendix 5.
Chart 18. Multi-SPAD signals – 52 weeks up to week ending 30 June 2013
A current list of multi-SPAD signals may be found at www.opsweb.co.uk. This is updated
every Monday.
20
SPAD/TPWS Report, Q1-2013/14
TPWS
7
Train Protection and Warning System
7.1
TPWS brake demands at signals
7.1.1
Brake demand numbers associated with SPADs
A TPWS brake demand (BD) which occurs in connection with a SPAD may be classed as
either an ‘activation’ or an ‘intervention’. Although these terms are sometimes considered to
be interchangeable, they do have their own distinct meanings. Definitions of ‘activation’ and
‘intervention’ may be found in Appendix 2.
Chart 19 shows the breakdown of TPWS involvement at SPADs by month. All SPADs are
shown, grouped by their TPWS involvement, broken down as follows:






Activations (The driver applied the brakes before TPWS)
Interventions (TPWS applied the brakes in the absence of (or prior to) the driver)
Unknown (Although TPWS applied the brakes, it is unknown whether it was an
activation or an intervention.)
Reset and continue (The driver reset the TPWS without the signaller’s permission and
continued forwards.)
No brake demand This was either because:
o TPWS is not fitted to either the train or the signal (or both)
o The length of overrun was so short that that the TPWS did not initiate a brake
demand, but it would have done so if the train had gone slightly further.
o The Train Stop Override or the temporary isolation switch had been operated.
Failure – No TPWS BD (The TPWS did not initiate a BD because of a failure (such as a
power supply outage).
Chart 19 shows, as of the end of June 2013, the most recent suspected reset and continue
incident occurred on 9 June at Shoeburyness.
Chart 19. TPWS brake demands at SPADs
Chart 20 shows the contribution to SPAD risk for each type TPWS brake demand, with the
risk for each month modelled using the individual components of SPAD risk ranking scores,
based on a rolling 12-month period.
SPAD/TPWS Report, Q1-2013/14
21
TPWS
Chart 20. SPAD risk by TPWS brake demand
At the end of Q1 2013/14, the majority of risk was from SPADs were there was no TPWS
brake demand, with 78% of the total modelled SPAD risk. The majority of these SPADs will
be at plain line signals.
Chart 21 shows the breakdown of TPWS activity at SPADs; the blue line indicates the
annual trend in the percentage of SPADs which involved a TPWS brake demand, and the
orange line the percentage of these SPADs which were interventions. At the end of the
current quarter, 60% of the SPADs in the previous year involved a TPWS brake demand,
and of these 58% were interventions, a 15% increase from the same time last year. The
percentage of all signals which are fitted with TPWS is approximately 28%. This indicates
that TPWS-fitted signals are overrepresented in the SPAD data, which highlights that TPWS
has been fitted where SPADs are more likely to occur.
Chart 21. TPWS activity at SPADs
22
SPAD/TPWS Report, Q1-2013/14
TPWS
7.1.2
Brake demand numbers at signals at danger
Chart 22 shows monthly brake demand figures in respect of trains activating the overspeed
sensor (OSS) for a signal at danger. The bars also indicate those which occurred at the
TPWS+ loop (where fitted). The chart shows that brake demands decrease around the end
of each year and into the following year, then increase towards a peak each summer.
TPWS brake demands, especially those on the approach to signals at danger, are
considered to be precursors to SPADs. It would be reasonable to expect there to be a
similarity between the seasonal pattern shown in Chart 22, and that for SPADs. The black
line on this chart shows the number of SPADs each month. However, there does not seem to
be any correlation between this line and the numbers of TPWS brake demands at OSSs
approaching signals at danger.
Chart 22. TPWS brake demands approaching signals at danger (no SPAD)
One possible reason for this marked seasonal variation is that drivers alter their braking
technique when approaching signals at danger according to the prevailing conditions, and
that slowing down earlier would reduce the numbers of overspeed trips approaching signals
at danger.
The increase in numbers for 2012 against previous years is primarily the result of moving to
SMIS as the data source, resulting in a greater number of events being captured than with
the previous process.
SPAD/TPWS Report, Q1-2013/14
23
TPWS
7.2
TPWS ‘reset and continue’ (at SPADs)
TPWS is designed to initiate an emergency brake application on a train which either passes
a TPWS fitted signal at danger, or approaches one at a speed such that a SPAD is likely to
occur.
A TPWS ‘reset & continue’ incident occurs when a train SPADs a signal, is stopped by
TPWS, but the driver then resets the TPWS and continues forwards without the signaller’s
authority. When this happens, the protection which was provided by TPWS is reduced. The
consequences of this type of event are still mitigated to some extent, because of the train
having been brought to a stand prior to moving off, as well as by the interlocking, which
resets conflicting signals to danger. Thus, if a collision and/or derailment were to occur,
following a TPWS ‘reset & continue’ incident, the speed of the train(s) involved would be
lower than if there had been no TPWS involvement.
Since the installation of TPWS was completed in early 2004, there have been 27 ‘reset &
continue’ incidents. None of these have resulted in either a collision or a derailment, although
in one instance the SPAD train did damage some points by running through them.
During the quarter there was one suspected post-SPAD TPWS ‘reset & continue’ incident,
which occurred 9 June at Shoeburyness.
Chart 23 looks at the frequency of TPWS ‘reset and continue’ incidents. The red line
represents the proportion of TPWS interventions that are ‘reset & continue’ events. This has
been based on a measure of the previous 50 TPWS interventions, on a shifting scale. The
blue peaks and troughs represent the number of days between each intervention.
This measure now stands at 0%.
Chart 23. TPWS ‘reset and continue’
Although the frequency of ‘reset and continue’ events is low, the industry must remain
vigilant to the risk from such events.
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SPAD/TPWS Report, Q1-2013/14
TPWS
7.3
TPWS brake demands at PSRs
Chart 24 shows the monthly number of TPWS brake demands at the OSS approaching
permanent speed reductions (PSRs). This shows that these have been occurring at the rate
of about 30 to 40 per month, with no noticeable trend over time.
Chart 24. TPWS brake demands approaching PSRs
Prior to 2012, all TPWS brake demand data was collected from control logs, with details
added from SMIS. Following the changes which were made to SMIS recently, whereby more
information is collected by SMIS, the data is now collected directly from SMIS. The increase
in unwarranted brake demands shown since January is likely to have come about as a result
of there now being more comprehensive data in SMIS that was previously collected from the
control logs. The number of unwarranted events will be monitored to ensure that SMIS
captures train protection demands and not AWS brake demands or events that only involve a
power-up test.
SPAD/TPWS Report, Q1-2013/14
25
TPWS
7.4
TPWS brake demands approaching buffer stops
Chart 25 shows the monthly number of TPWS brake demands at OSS loops approaching
buffer stops since mid-2007. The annual moving average indicates that the number of these
brake demands had levelled out at between five and six per month. However, a slight
increase has been evident from March 2010, with the moving average showing around eight.
Chart 25. TPWS brake demands approaching buffer stops
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SPAD/TPWS Report, Q1-2013/14
Appendices
8
SPADs: an international perspective
Argentina: Trains collide, 3 dead, hundreds injured, 11 June 2013
At 07:00 (local time) on 11 June 2013, a commuter train struck the rear of another which was
standing at signal near Castelar station, killing three and injuring over 300 others. A SPAD is
suspected.
Australia: Collision between two freight trains at Dry Creek, SA, 11 October 2011
At 01:05 (local time) on 11 October 2011, an empty ore train operated by Specialised Bulk
Rail Pty Ltd (SBR) passed a signal at danger near Dry Creek Junction, South Australia. It
subsequently struck a loaded grain train, operated by Genesee and Wyoming Australia Pty
Ltd, which was travelling in the opposite direction and traversing the points at Dry Creek
Junction, in order to enter Dry Creek North Yard.
The collision was at low speed and there was no injury to the crew of either train. However,
there was significant damage to the cab of the ore train’s leading locomotive and to the grain
wagons involved in the collision.
The Australian Transport Safety Bureau (ATSB) found that the collision occurred because
the ore train passed Signal 13 at danger. The SPAD was a result of the trainee driver and
supervising driver of the ore train becoming distracted on the approach to the preceding
signal, which was displaying a caution aspect, indicating that Signal 13 ahead was red.
SPAD/TPWS Report, Q1-2013/14
27
Appendices
Report scope
The information in this report covers SPADs which occurred on Network Rail managed
infrastructure (NRMI) during the first quarter of 2013/14, comparing it with previous quarters
and years.
Note: Following the recent reissue of Railway Group Standard GO/RT3119, the term ‘SPAD’
now refers to those events which were previously labelled as a ‘category A SPAD’.
Appendix 1 and 2
Appendix 1 and 2 can be found as a separate file on the website, alongside this report.
Appendix 3 - Potentially significant cat A SPADs (risk
ranked 16-19) Q1-2013/14
Table 6.
Potentially significant cat A SPADs (risk ranked 16-19) Q1-2013/14
Appendix 4 - Potentially severe cat A SPADs (risk ranked
20+) – Q1-2013/14
Table 7.
Potentially severe cat A SPADs (risk ranked 20+) – Q1-2013/14
Full details of all SPADs for the review period, plus historic data from January 1998, is available at www.opsweb.co.uk
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SPAD/TPWS Report, Q1-2013/14
Appendices
Appendix 5 - Signals with 3 or more SPADs during last 5
yrs. (at 29 June 2013)
Table 8.
Signals with 3 or more SPADs during last 5 yrs. (at 31 March 2013)
This appendix lists those signals which have been passed at danger three (or more) times during the five-year
period ending 29 June 2013. Lists of those signals which fall within the standard definition of a multi-SPAD signal
(2 or more occasions in five years) are produced every week and posted at www.opsweb.co.uk
SPAD/TPWS Report, Q1-2013/14
29
Appendices
Appendix 6 – Monthly SPAD tables
Table 9.
All SPADs : monthly totals
Table 10. SPADs risk ranked 16+ : monthly totals
Table 11. SPADs risk ranked 20+ : monthly totals
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Appendices
Appendix 7 – SPADs per million train miles, by RU
Table 12. SPADs risk ranked 20+ : monthly totals
This table is divided into three sections: All SPADs, 16+ SPADs and 20+ SPADs. The
national SPAD rates for each risk ranking band are also shown, highlighted in yellow. Those
RUs which have a SPAD rate which is lower than the national rate for both ‘all SPADs’ and
for ‘16+ SPADs’ are coloured green. Those with one such rate lower than the national rate,
and one higher are coloured orange, whereas those with both rates higher than the national
rate are coloured red. The ‘20+ SPAD’ rates are not reflected in the colour coding, due to the
small number of events per company.
The infrastructure companies’ SPADs are not normalised as it would be inappropriate to do
so in view of the limited number of miles accrued by these undertakings. Instead, raw SPAD
SPAD/TPWS Report, Q1-2013/14
31
Appendices
numbers are given. Alstom’s SPAD figures are also raw SPAD numbers, as the miles
accrued are small.
In accommodating franchise changes, RSSB has measured relevant RUs’ past performance,
where possible (by considering the current RU’s predecessors’ SPADs), in order to provide a
benchmark reference for future comparison. This estimation is considered to be realistic; it is
based on SMIS data since January 1998. However, it has not been possible to allocate train
miles data accurately prior to the franchise changes in respect of the some of the present
RUs. This means that some of the figures are shown as blanks. In addition, there is currently
no mileage data available for Heathrow Connect, hence their 2012 data is also blank.
Appendix 8 – ‘T22’ and ‘IN’ signals
The signals listed below are those which were cited in the two post-Ladbroke Grove
Improvement Notices, and which remain classified as multi-SPAD as at the end of March
2013.
Table 13. Improvement notices’ signals remaining multi-SPAD
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SPAD/TPWS Report, Q1-2013/14
Appendices
Appendix 9 – SPADs normalised by driver population
Table 14. Annual SPAD rate per 100 drivers per month
The colour codings indicate whether an individual company’s SPAD rate is significantly better
(green) than the average group rate, or significantly worse (red), at the 90% confidence level.
SPAD/TPWS Report, Q1-2013/14
33
Appendices
Appendix 10 – RU SPADs – year-on-year comparison
Table 15. Company performance – year-on-year – All SPADs
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SPAD/TPWS Report, Q1-2013/14