Research Trends and Results

Studying the application of probe data to traffic safetymeasuresOZAKI Yuta, Researcher
YATA Junichi, Guest Research Engineer
YABU Masayuki, HeadAdvanced Road Design and Safety Division, Road Department(Key words) Traffic safety measure, probe data

Figure 1. Relationship of Frequency of Abrupt
Decelerations of 0.3G or more with Number ofAccidents Causing Death or Injury
700

y = 3.0796x
R² = 0.4428

600
decelerations in 2011
*Abrupt※2011年の急減速

Frequency of abrupt deceleration of0.3G以上急減速発生回数（回/年）
0.3G or more (times/year)500
4003002001000050100150

Accidents
causing death or injury
死傷事故件数（件/5年）(accidents/5 years)

200※2008年～2012年の事故*Accidents from 2008 to 2012

Figure 2. Number of Abrupt Emergency Decelerations
and Number of Accidents Causing Death or Injury of
Each Basic Road Link of DRM on Arterial Roads
Accidents causing death or injury ※Accidents from 2008 to 2012
Frequency of abrupt deceleration of 0.3G or more
※Abrupt decelerations in 2011

※Nos. on lateral axis are numbers assigned to DRM links in theinbound direction in each section of the route.

Frequency of abrupt deceleration of
0.3G or more (times/year)

2. Relationship of abrupt deceleration data withaccidents
Figure 1 used abrupt deceleration data from probe
data provided by Honda Motor Co., Ltd. to organizeand prepare a distribution map of the relationship ofthe frequency of abrupt deceleration of 0.3G or higher
with the number of accidents causing death or injury
at every basic road link of DRM in a certain region(below, called “DRM link”). Figure 1 shows that therelationship of the frequency of abrupt deceleration
with the number of accidents causing death or injury is
greatly scattered and it is difficult to discover a fixed
correlation.
So it was decided to narrow the focus to a specified
route to compare the frequencies of abrupt
deceleration and the numbers of accidents causing
death or injury at each DRM link to confirm thecorrelation. In Figure 2, the relationships of thefrequency of abrupt deceleration with the number ofaccidents causing death or injury at each DRM linkare organized in parallel by focusing on a certain
section of an arterial road. Overviewing therelationship of the two phenomena in Figure 2 showsthat at locations where the number of accidents
causing death or injury is higher than it is at other
DRM links, abrupt decelerations tend to occur often,
and at locations where accidents causing death or

injury are rare, abrupt decelerations tend to occurrarely.
Examining each section in detail reveals that there
are characteristic links where, even though accidents
do not occur very often, at No. 17 in Figure 2 forexample, the frequency of abrupt decelerations is far
higher than it is at surrounding DRM links.

Number of accidents causing deathor injury (accidents/5 years)

1. Introduction
Traffic safety countermeasure projects are carried
based on a PDCA cycle consisting of identifying blackspots, analyzing causes of the accidents and planningcountermeasures, implementing countermeasures,
evaluating their effectiveness, and studying and taking
supplementary countermeasures, in order to take more
effective countermeasures. In the PDCA cycle, it isstandard procedure to identify black spots andevaluate countermeasure effectiveness based on
accident data. But because traffic accidents occur
rarely, a long period of time is required to collectstable accident data.
So at the National Institute for Land andInfrastructure Management, the data properties ofvarious kinds of probe data are organized in order tostudy methods of effectively identifying black spots.

3. Conclusions
In abrupt deceleration data, a correlation withaccidents was seen in certain narrow sections. But
even in sections which are narrow to a certain degree,
there are many locations where the frequency ofemergency deceleration occurrences in relation toaccidents is much higher than at surrounding locations.
It is assumed that the characteristics of occurrence ofabrupt decelerations of this kind are also impacted by
the road structure etc. In the future, factors such as
road structures which impact the characteristics of theoccurrence of abrupt decelerations of this kind will beclarified, and the analysis of its relationship withaccidents and other studies of its application to theabstraction of accident hot spots will be carried out.