no82 2010
Collisions with roadside structures
   Last year, 4,914 deaths were recorded in all traffic accidents, a decrease of 241 from 5,155 the previous year: this marked the first drop below 5,000 in 57 years, since 1952.

From the 2008 traffic accident statistics available most recently as compiled data, 1,710 of the total 5,155 fatalities were killed while in the car, as large as the number (1,721) who were killed while walking
(Table 1).

Of the 1,710 victims, 508 were involved in collisions with traffic safety facilities such as guard fences, signposts and other roadside structures. This accounts for nearly 30% of all the fatal occupants involved and nearly 10% of the total deaths.

In this issue of ITARDA Information, we focus on vehicular collisions with roadside structures to seek ways to reduce the injury by analyzing the characteristics of this type of accident and each roadside structure, using traffic accident data before 2008.

1. Statistics for collisions with roadside structures
2. Analysis of collisions for each structure
3. Relationship between location of impact and fatality rate
4. Why do vehicles crash into roadside structures?
5. Examples of accidents
  (1) Summary of the analysis

* Collisions with roadside structures are a dangerous type of accident that causes a relatively large number of deaths with fatality rates as high as those of vehicle-to-vehicle head-on collisions.

* Driver fatality rates are low in collisions with guard fences compared to collisions with other structures and do not rise significantly at higher vehicle speeds. This is because a guard fence is a traffic safety facility that ensures safe and smooth flow of traffic as well as occupant protection.

* As for the location of impact on the vehicle, driver fatality rates are higher when the vehicle crashes into a structure on its side. Fatality rates are particularly higher when striking a utility pole partly because its thin tall shape greatly deforms only a small part of the vehicle roof.

* Analysis of the causative factors leading to collisions with roadside structures shows that "driving errors" account for 40 to 50% for each type of structure. Even if collisions are caused by the same error,
the degree of injury to the driver will depend on the structure that the uncontrolled vehicle crashes into.

(2) To reduce injuries

* Drivers must understand the danger of collisions with roadside structures, and always drive safely.
Even if a car runs off the road at the same speed or due to the same error, some types of structures will cause more serious injury. Always be careful not to run off the road while driving.

* Guard fences are effective road facilities in reducing the injury to car occupants and should be installed in all locations that need them.

* Vehicles must be made safer against side collisions with roadside structures in which the occupants are more likely to be killed. A strengthened vehicle body can protect the passenger compartment,
and a side curtain airbag is effective for protecting the occupants' heads.

Institute for Traffic Accident Research and Data Analysis (ITARDA)