Evaluation of the In-Service Safety Performance of Safety-Shape and Vertical Concrete Barriers
REPORT NUMBER
TRP-03-259-11
AUTHORS
Daniel Albuquerque, Dean Sicking
PUBLICATION DATE
2011-12-16
ABSTRACT
Roadside concrete barriers have been widely used to protect errant motorists from hitting roadside hazards or obstacles. Two concrete barrier profiles, vertical and safety-shape, have been used for this purpose. The safety-shape profile has been shown to produce excessive vehicle climbing which tends to increase rollover propensity. On the other hand, the vertical profile does not cause vehicle climbing, but it does produce higher lateral forces which may produce higher injury levels.
The objective of this research is to investigate which barrier profile is the safest based on real-world vehicle crash data. The safest barrier profile is defined as the one that produces lower injury levels. Rollover propensity was also used as a second indicator of barrier performance since rollovers may also affect injury severity.
Bridge-related crash data was collected from State maintained highways in the State of Iowa. It was found that rollovers are twice more likely to occur in crashes involving safety-shape barriers as compared to vertical barriers. It was also found that crashes that involved safety-shape barriers resulted in higher injury levels as compared to crashes that involved the vertical barriers. Therefore, it is believed that the expanded use of vertical barriers would improve overall highway safety.
KEYWORDS
Highway Safety, Roadside Appurtenances, Roadside Safety, Concrete Barriers, Accidents, Rollover, Injury Severity