Research Trends and Results

Preparation of countermeasure proposal technology
document based on past traffic safety
countermeasures
TAKEMOTO Azuma, Researcher
OZAKI Yuta, Researcher
KAMIYA Sho, Guest Research Engineer
YABU Masayuki, Head
Advanced Road Design and Safety Division, Road Department(Key words) Traffic safety countermeasures, countermeasure proposal, black spot, arterial road
1. Introduction
Although the numbers of fatalities and injuriescaused by traffic accidents have tended to fall in
recent years, every year, more than 800,000 people arekilled or injured in traffic accidents, and this statistic
continues to be high as an absolute value.
The fall of the number of traffic accidents is theresult of the promotion of traffic safety education andthe improvement of vehicle safety accompanied bydiverse traffic safety countermeasures on the road side.
At places where road managers take traffic safety
countermeasures, each one has its unique road traffic
environment and site conditions, and the causes ofaccidents also vary widely, so a problem faced by
officials in charge of these locations is that they mustrack their brains to propose countermeasures for eachone.
So in order to support the proposal of traffic safety
countermeasures appropriate to the causes of accidents
in order to implement effective traffic safety
countermeasures,
acountermeasureproposaltechnology document has been prepared based on past
countermeasure projects.
2. Preparing the countermeasure proposal technology
document
To propose traffic safety countermeasures forarterial roads, generally, based on the results of theorganization of accident data etc., studies areconducted—[1] to set the forms of accidents to focus
on, [2] to hypothesize accident occurrence processes,[3] to analyze causes of accidents (hypothesizingerrors by people involved and road traffic
environments that induce errors), [4] to study
countermeasure policies, and [5] to propose
countermeasure works.
The countermeasure proposal technology document
was prepared with the structure shown in the figure sothat it can serve as reference material that roadmanagers use when proposing countermeasures alongwith the study process.
To select the forms of accidents (location of eachaccident and combinations of people involved) to be

Figure. Structure of the Countermeasure Proposal
Technology Document

entered in the countermeasure proposal technology
document, statistical traffic accident data of theInstitute for Traffic Accident Research and Data
Analysis were used to aggregate forms of accidents foreach accident category and to select about 50 cases as
frequent forms of accidents. And from among accident
occurrence
processes,
causesofaccidents,
countermeasure policies, and countermeasure work
methods that are hypothesized for each form ofaccident, past proposals of countermeasures at about8,000 locations accumulated in the Accident
Countermeasure Database of the NILIM (locations
defined as black spots in 2003 or in 2008, and wherecountermeasures were taken) were used to abstract
appropriate combinations from the hypothesizing ofaccident occurrence process to the proposal ofcountermeasure works. And in addition, past
countermeasure proposals for each form of accident
were organized to simplify hypothesizing causes ofaccidents unique to each location. The table presents
an example of the organization of right turn accidents
at intersections.
3. Conclusion
This technology document will be completed andupdated as necessary in response to the state of theexecution of traffic safety countermeasures in thefuture.

Research Trends and Results
Table. Example from the Countermeasure Proposal Technology Document Concerning Right Turn Accidents at Intersections
Study process
Form ofaccident

Type oflocation[1] Setting the forms ofaccidents to focus on
Form of accident

Vehicle right-turning
Accident
collides with a vehicle
while Intersecti
coming straight from theturningon
opposite direction at anrightintersection[3] Analyzing causes of accidents[4] Studying countermeasure policies[5] Proposing
countermeasure works

PersonPerson’s error hypothesized in Example of a road traffic environment
involved the accident occurrence processthat induces error by a person

Example of countermeasure policy

Typical countermeasure
works[2] Hypothesizing accident occurrence processes
Example of accident
occurrence process

A right-turning vehicle
turning right into theintersecting road between
vehicles traveling in the
opposing lanes collides in
the intersection with avehicle traveling in theopposite lane

Image diagram

RightturningvehicleTurns right while unable toadequately check the oncoming
vehicleTraveling at a speed delaying
Oncoming avoidance of the accident evenvehicle after noticing the right-turning
vehicleBecause of vehicle turning right from Improve the visibility of vehicles
the opposite direction, it is difficult approaching from the opposite direction
to check the opposite lane
when turning right
Because the right turn waiting
Guiding the traveling position of the rightlocation is not good, it is difficult to turning vehicle to appropriate locations
check the opposite lane
inside the intersectionBecause it is a descending slope,vehicles tend to travel too fast

Removing the descending slope or making
it gentler
Alerting the driver

Right-turn lane (newlycreated or location
improved)
Channel indicator (rightturn)Intersection center
indicator
Improving longitudinalalignment
Road surface indicators
Illegal signboards