Monthly SPAD/TPWS Update
September 2014
Issued by Theresa Liu, Safety Intelligence Analyst, RSSB
Key statistics
All SPADs annual moving
total (AMT)
304
↑
Last month: 301
Last year: 274
20+ SPADs annual
moving total
84
17
↓
Last month: 85
Last year: 84
Multi-SPAD signals (two or
more SPADs in five years)
129
16+ SPADs annual
moving total
↑
Last month: 126
Last year: 125
↓
Last month: 19
Last year: 16
Annual moving percentage
of TPWS brake demands
SPAD risk relative to
September 2006
55% ↓
76% ↓
Last month: 56%
Last year: 62%
Last month: 78%
Last year: 63%
There were 25 SPADs during September. This is 3 greater than in September 2013. The three-year average
for the previous three September's is 22.3.
The annual moving total, which was 274 a year ago, is now 304; 3 greater than last month. An increase of
30 since last year.
Of the 25 SPADs during September: 16 involved TPWS brake demands; 10 were interventions and 6 were
activations.
Monthly performance
SPAD Numbers
33
32
26
31
29
28
22
17
19
SPAD Risk
25
23
19
400
140%
350
120%
300
100%
250
150
O N D J F M A M J J A S
76%
200
80%
60%
100%
100
40%
50
20%
0
Sep-06
0%
Sep-08
Sep-10
Sep-12
5 of September’s SPADs were risk ranked 16+; of which none were risk ranked 20+. There are currently 3
SPAD Risk Rankings outstanding for September.
The blue line in the chart above right shows the trend in underlying SPAD risk since the Sept 2006
benchmark date. At the end of September, the underlying level of SPAD risk was estimated to be 76% of
the Sept 2006 baseline.
This update regarding SPAD and TPWS performance for September 2014 is based on data available as at
the date of issue and is subject to change as further information becomes known.
The AMT refers to SPADs which have occurred in the last 12 months of the relevant period. Last month and last year are what the
respective measure was at those points.
A TPWS intervention occurs when TPWS applies the brakes before, or in the absence of, the driver doing so.
A TPWS activation occurs when a driver has already applied the brakes before the TPWS operates.