SPAD and TPWS activity report,
Year End – 2012/13
If you would like to give feedback on any of the material contained in this
report, or if you have any suggestions for future editions, please contact:
Alexander Moor
RSSB
Block 2, Angel Square
1 Torrens Street
London EC1V 1NY
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
4
1.1
Risk in Context
4
1.2
Precursor Indicator Model
4
1.3
The risk from SPADs
5
1.3.1
Details of SPADs which reached the conflict point
5
1.3.2
Details of high risk SPADs
6
2
SPAD numbers
7
2.1
March 2013
7
2.2
Quarter 4 – 1 January to 31 March 2013
7
2.3
Year 2013/13 – 1 April 2012 to 31 March 2013
7
2.4
Changes in SPAD numbers over time
8
2.5
Monthly SPAD numbers
9
2.6
SPADs risk ranked 16+ and 20+
9
2.6.1
SPADs risk ranked 16+
9
2.6.2
SPADs risk ranked 20+
10
3
SPAD sub-categories
11
SPAD Provisional status
11
SPAD performance by route
13
SPAD numbers by route
13
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
5.3.1
SPADs normalised by millions of train miles
16
5.3.2
SPADs normalised by driver population
17
3.1
4
4.1
5
6
6.1
Further analysis of SPAD occurrence
18
SAS and SOY SPADs
18
6.1.1
SAS SPADs
18
6.1.2
SOY SPADs
19
Multi-SPAD signals
7
7.1
6.1.3
The multi-SPAD signal population – signal numbers
20
6.1.4
The multi-SPAD signal population – SPAD risk
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
24
7.2
TPWS ‘reset and continue’ (at SPADs)
25
7.3
TPWS brake demands at PSRs
26
7.4
TPWS brake demands approaching buffer stops
27
SPADs: an international perspective
28
SPAD-related events in Europe
28
8
8.1
2
20
SPAD/TPWS Report, Year End-2012/13
Executive Summary
Executive summary
Report scope
The information in this report covers SPADs which occurred on Network Rail managed
infrastructure (NRMI) during the fourth quarter of 2012/13, 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’.
Headlines

The annual moving modelled SPAD risk at the end of 2012/13 was 59% of the
September 2006 benchmark, which is a decrease from 66% at the end of 2012/13
Q3. This compares to 32% at the end of 2011/12 Q4, and 42% at the end of 2011/12
Q3.

There was one 20+ SPAD in Q4, five fewer than in Q3, which compares to two in
both 2011/12 Q3 and Q4.

The annual total of SPADs was 250 at the end of 2012/13, which is one more than at
the end of 2012/13 Q3. This compares to 276 at the end of 2011/12 Q4.
At a glance

Multi-SPAD signals
During the quarter, the number of multi-SPAD signals dropped from 131 to 127. Of
the 127 multi-SPAD signals, 78 (61%) have TPWS fitted.

Possession-related SPADs
During the quarter there were three SPADs by engineering trains. This is two fewer
than recorded in the same quarter of 2011/12, and five fewer than in Q3. There have
been 18 possession-related SPADs this financial year, which is three more than in
the 2011/12 financial year.

TPWS reset & continue
There were no post-SPAD TPWS ‘reset & continue’ incidents during the quarter.
SPAD/TPWS Report, Year End-2012/13
3
SPAD Risk
1
SPAD risk
1.1
Risk in Context
Chart 1 shows the context of SPAD risk in total system risk. 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.
Chart 1 SPAD risk as a proportion of total system risk (FWI)
1.2
Precursor Indicator Model
Chart 2 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,
December 2012 shows SPADs contributing 8.69 to a total risk of the 94.61.
Chart 2 PIM
4
SPAD/TPWS Report, Year End-2012/13
SPAD Risk
1.3
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 3 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 59% of the 2006 benchmark level.
Chart 3 Change in SPAD risk since September 2006
1.3.1
Details of SPADs which reached the conflict point
During the quarter, there were four SPADs which resulted in the train reaching the conflict
point. Details of these SPADs are show in Table 1.
Table 1 Details of SPADs which reached the conflict point
Chart 4 shows the number of SPADs where the train reached the conflict point. In 2012/13
only one SPAD reached the conflict point where TPWS was involved, which was a reset and
continue incident.
SPAD/TPWS Report, Year End-2012/13
5
SPAD Risk
Chart 4 SPADs where the train reached the conflict point
1.3.2
Details of high risk SPADs
There was one SPAD with a risk ranking of 20+ during the quarter. The details are as
follows:

SPAD risk ranking 21 – On 09 February a passenger train passed GS5850 signal at
danger on the Up Ayr Line at Smithy Lye (SC Route) by approximately 67 yards. The
main reasons for the high risk ranking of this SPAD are that: (a) this is a plain line
signal which is 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 heavily loaded passenger trains, where the potential collision
speed is 22.5 mph.
As the information is taken from initial reports, it is subject to change pending the findings of
investigations.
6
SPAD/TPWS Report, Year End-2012/13
SPAD Numbers
2
SPAD numbers
2.1
March 2013
March 2013
20 SPADs during March, which is three fewer than March 2012.
The number of SPADs in March 2013 was 2% lower than the three prior years’ average of
20.3.
Risk ranking
Three SPADs were risk ranked 16 or above (none of which were risk ranked 20+). This
compares to eight in March 2012 (none of which were risk ranked 20+).
TPWS
Five TPWS interventions (TPWS applied the brakes before, or in the absence of, driver
action).
Eight TPWS activations (the driver initiated braking before the system).
One where the TPWS brake demand type is currently unknown.
Multi-SPADs
2.2
Quarter 4
Two SPADs at multi-SPAD signals [two or more within the current five-year period].
Quarter 4 – 1 January to 31 March 2013
61 SPADs during the quarter, which is one more than the same quarter last year (2% more).
Q4 also had 5% fewer SPADs than the average for the three prior Q4s of 64.3.
Risk ranking
12 SPADs were risk ranked 16 or above (one of which was risk ranked 20+). This compares
to 23 in Q4-2011/12 (of which two were risk ranked 20+).
TPWS
26 TPWS interventions (TPWS applied the brakes before, or in the absence of, driver
action).
13 TPWS activations (the driver initiated braking before the system).
One where the TPWS brake demand type is currently unknown.
Multi-SPADs
2.3
2012/13
12 SPADs at multi-SPAD signals [two or more within the current five-year period].
Year 2013/13 – 1 April 2012 to 31 March 2013
250 SPADs during the year, which is 26 fewer than last year (9% fewer).
2012/13 also had 12% fewer SPADs than the average for the three prior years of 282.7
Risk ranking
69 SPADs were risk ranked 16 or above (16 of which was risk ranked 20+). This compares
to 77 in 2011/12 (of which nine were risk ranked 20+).
TPWS
75 TPWS interventions (TPWS applied the brakes before, or in the absence of, driver
action).
55 TPWS activations (the driver initiated braking before the system).
14 where the TPWS brake demand type is currently unknown.
Multi-SPADs
37 SPADs at multi-SPAD signals [two or more within the current five-year period].
SPAD/TPWS Report, Year End-2012/13
7
SPAD Numbers
2.4
Changes in SPAD numbers over time
As Chart 5 indicates, the current annual moving total (AMT) for all SPADs is 250, which is
close to its lowest ever point. The AMT for 16+ is currently 69, while the AMT for 20+ SPADs
is currently 16. 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 5 All SPADs – annual moving totals
Table 2 presents a summary of the change in SPAD numbers, comparing 2012/13 with
2011/12. It shows a decrease in both the All SPADs AMT and the 16+ SPADs AMT, and an
increase in the 20+ SPADs AMT. None of these are statistically significant at the 90%
confidence level.1
Table 2 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.
8
SPAD/TPWS Report, Year End-2012/13
SPAD Numbers
2.5
Monthly SPAD numbers
Chart 6 compares monthly SPAD numbers in 2012/13 with those during 2011/12 along with
the three-year average. See Appendix 6 for tables.
Chart 6 All SPADs – monthly variation
Chart 6 shows there is no clear pattern in the seasonality of SPADs.
2.6
SPADs risk ranked 16+ and 20+
2.6.1
SPADs risk ranked 16+
Chart 7 compares monthly 16+ SPAD numbers in 2012/13 with those during 2011/12.
Chart 7 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; of which four can be attributed to environmental conditions.
SPAD/TPWS Report, Year End-2012/13
9
SPAD Numbers
2.6.2
SPADs risk ranked 20+
There was one SPAD with a risk ranking score of 20+ during the quarter, which compares to
two in the same quarter in 2011/12. Details of this incident are in section 1.3.2.
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.
10
SPAD/TPWS Report, Year End-2012/13
SPAD Trends
3
SPAD sub-categories
3.1
SPAD Provisional status
Chart 8 shows the breakdown of SPADs by provisional or confirmed status. SPADs are
provisional until they have a completed investigation.
Chart 8 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 9 shows the distribution of the different SPAD classifications, in respect of the SPADs
which have occurred since the changes were introduced.
Chart 9 SPADs by sub-category
Of those which have this field completed in SMIS, 63% are A1, 26% are A2, 7% A-3 and 4%
A4. Incidents for which a sub-category has not been entered have been categorised as A1
SPADs.
SPAD/TPWS Report, Year End-2012/13
11
SPAD Trends
Chart 10 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 10 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.
12
SPAD/TPWS Report, Year End-2012/13
SPAD Performance by Route
4
SPAD performance by route
4.1
SPAD numbers by route
Table 3 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 March 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 3 Route performance – comparison of moving annual totals
The only changes in the SPAD numbers which are statistically significant are the total
numbers for Scotland and Sussex. During the last 12 months, Scotland has seen overall
SPAD numbers decrease from 29 to 14, while Sussex has seen an increase in total SPAD
numbers from 13 to 25; both sre statistically significant at the 90% confidence level.
Table 4 Route performance – comparison 16+ percentages
SPAD/TPWS Report, Year End-2012/13
13
SPAD Performance by Route
Table 4 shows the percentage of these annual totals which have a SPAD risk ranking of 16
or higher, both nationally and by route. During the 12 months to March 2012, 28% of all
SPADs had a risk ranking score of 16 or more; which is the same as a year later.
Routes where the number of 16+ SPADs has increased from March 2012 to March 2013
have their 16+ percentages highlighted in red.
14
SPAD/TPWS Report, Year End-2012/13
SPAD Performance by Railway Undertaking
5
SPAD performance by railway undertaking
5.1
Railway undertakings – passenger
First ScotRail, Northern Rail and London Overground have all had a statistically significant
decrease in SPAD numbers. The table in Appendix 9 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 11 shows the monthly numbers of SPADs by freight RUs from April 2009. This chart
presents raw SPAD numbers which have not been normalised against train miles run. There
were 20 freight train SPADs during the quarter compared with 11 in Q4 of 2011/12.
Chart 11 SPADs by freight railway undertakings
5.3
SPADs associated with engineering operations
Chart 12 shows the number of SPADs involving engineering machines. During the quarter,
there were three such SPADs. One on-track machine, one road rail vehicle, and one rail
mounted maintenance machine.
Chart 12 SPADs by engineering machines
SPAD/TPWS Report, Year End-2012/13
15
SPAD Performance by Railway Undertaking
Chart 13 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 13 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, Year End-2012/13
SPAD Performance by Railway Undertaking
5.3.2
SPADs normalised by driver population
Appendix 8 shows the annual SPAD rate per 100 drivers per month for each RU. 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.
Chart 14 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 14 Normalised SPADs per driver by age band, 10 year average
Chart 15 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 15 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 14 and Chart 15
may change slightly.
SPAD/TPWS Report, Year End-2012/13
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 16 shows the annual moving total number of SAS and SOY SPADs.
Chart 16 SAS and SOY SPADs (annual moving total)
6.1.1
SAS SPADs
Chart 17 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.
Passenger trains, which are shown in blue, constitute 39 of the 152 SPADs indicated (26%),
Chart 17 SAS SPADs by time of day
18
SPAD/TPWS Report, Year End-2012/13
Further Analysis of SPAD Occurrence
while empty coaching stock constitute 41 (27%). 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 18 shows SOY SPADs, by time of day, using data from the last three years, again
differentiated by train type.
Chart 18 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 18, than in Chart 17.
These amount to 91 of the 141 SPADs, which equates to 65%.
SPAD/TPWS Report, Year End-2012/13
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 19 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 147. There were 147 such signals listed as of a year ago and 127 as at 30
March 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 30 (23% of the multi-SPAD signal population), which is an
increase of two on a year ago. These signals are listed in Appendix 5.
Chart 19 Multi-SPAD signals – 52 weeks up to week ending 30 March 2013
A current list of multi-SPAD signals may be found at www.opsweb.co.uk. This is updated
every Monday.
6.1.4
The multi-SPAD signal population – SPAD risk
Multi-SPAD signals have traditionally been considered in terms of the number of signals
which come within the definition of multi-SPAD. However, a more radical approach could be
to consider the risk which is associated with these signals.
As at the end of the quarter, there were 127 signals listed as falling within the definition of a
‘multi-SPAD’ signal.
20
SPAD/TPWS Report, Year End-2012/13
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 20 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 20 shows, as of the end of March 2013, the most recent reset and continue incident
occurred at Brereton on 1 October 2012.
Chart 20 TPWS brake demands at SPADs
SPAD/TPWS Report, Year End-2012/13
21
TPWS
Chart 21 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.
Chart 21 SPAD risk by TPWS brake demand
At the end of 2012/13, the majority risk was from SPADs were there was no TPWS brake
demand, with 92% of the total modelled SPAD risk. The majority of these SPADs will be at
plain line signals.
22
SPAD/TPWS Report, Year End-2012/13
TPWS
Chart 22 shows the percentage of SPADs which involved any TPWS activity; the red line
indicates the annual trend. At the end of the current quarter, the moving average was 58%.
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 22 TPWS activity at SPADs
Chart 23 shows TPWS interventions, expressed as a percentage of all TPWS brake
demands at SPADs. The red and green lines represent the percentage of all SPADs with
TPWS involvement which are interventions (green line) and the moving annual percentage
(red line). From this, it may be seen that the monthly percentage does vary considerably
month on month.
Chart 23 TPWS interventions in relation to all TPWS brake demands at cat A SPADs
SPAD/TPWS Report, Year End-2012/13
23
TPWS
7.1.2
Brake demand numbers at signals at danger
Chart 24 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 24, 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 24 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.
24
SPAD/TPWS Report, Year End-2012/13
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 26 ‘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 were no post-SPAD TPWS ‘reset & continue’ incidents.
Chart 25 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 25 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.
SPAD/TPWS Report, Year End-2012/13
25
TPWS
7.3
TPWS brake demands at PSRs
Chart 26 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 26 TPWS brake demands approaching PSRs
RSSB is working on monitoring the locations at which brake demands are occurring on the
approaches to reductions in permissible speed, and drawing the industry’s attention to those
which have three or more in a 12-month period. This is being done at the request of the
TPWS Strategy Group. Current progress on this has shown insufficient information being
recorded in SMIS to uniquely identify PSRs. Work is being undertaken to resolve this, by
increasing the information stored in SMIS, and working with Network Rail and the TOCs to
uniquely identify 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.
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SPAD/TPWS Report, Year End-2012/13
TPWS
7.4
TPWS brake demands approaching buffer stops
Chart 27 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 27 TPWS brake demands approaching buffer stops
SPAD/TPWS Report, Year End-2012/13
27
Appendices
8
SPADs: an international perspective
8.1
SPAD-related events in Europe
Switzerland: 17 injured in post-SPAD collision, 10 January 2013
On 10 January, two local services collided outside Neuhausen, injuring 17 passengers. Initial
investigations suggest that the departing train passed a signal at danger. The signal in
question is fitted with a protection system, but the distance between it and points at the
station throat is too short to stop a train fouling them if it SPADs.
Portugal: Train rear-ends waiting train in platform, 21 January 2013
At 21:18 (local time) on 21 January 2013, an inter-city service struck the rear of a regional
train waiting at Alfarelos station. The inter-city train passed a signal at danger at the station
throat. There were no fatalities, but 21 people sustained minor injuries. An investigation has
been launched.
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) Q4-2012/13
Appendix 4 - Potentially severe cat A SPADs (risk ranked
20+) – Q4-2012/13
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, Year End-2012/13
Appendices
Appendix 5 - 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 30 March 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, Year End-2012/13
29
Appendices
Appendix 6 – Monthly SPAD tables
All SPADs : monthly totals
SPADs risk ranked 16+ : monthly totals
SPADs risk ranked 20+ : monthly totals
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SPAD/TPWS Report, Year End-2012/13
Appendices
Appendix 7 – SPADs per million train miles, by RU
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
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
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Appendices
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.
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SPAD/TPWS Report, Year End-2012/13
Appendices
Appendix 8 – SPADs normalised by driver population
Annual SPAD rate per 100 drivers per month
SPAD/TPWS Report, Year End-2012/13
33
Appendices
Appendix 9 – RU SPADs – year-on-year comparison
Company performance – year-on-year – All SPADs
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SPAD/TPWS Report, Year End-2012/13
Appendices
Appendix 10 – ‘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.
Improvement notices’ signals remaining multi-SPAD
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