Speed Variation Analysis : A Case Study for Thailand's Roads
Research shows that vehicle speed affects the severity of all road crashes. Higher speed crashes involve more kinetic energy: the more energy that is dispersed in a crash, the more severe that crash will be. Speed also affects the likelihood of a c...
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| Format: | Report |
| Language: | English |
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World Bank, Washington, DC
2019
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| Online Access: | http://documents.worldbank.org/curated/en/641651575999780678/Speed-Variation-Analysis-A-Case-Study-for-Thailands-Roads http://hdl.handle.net/10986/33097 |
| Summary: | Research shows that vehicle speed
affects the severity of all road crashes. Higher speed
crashes involve more kinetic energy: the more energy that is
dispersed in a crash, the more severe that crash will be.
Speed also affects the likelihood of a crash occurring in
the first place. The likelihood of a serious or fatal crash
increases significantly even with small increases in vehicle
speed. Field studies demonstrate that a one percent increase
in mean average speeds results in a roughly two percent
increase in the frequency of crashes involving injury, a
three percent increase in severe crashes, and a four percent
increase in deaths. The safety of infrastructure is heavily
influenced by traffic speed, to the extent that without a
detailed understanding of speed limits and vehicle operating
speeds, it is difficult to assess the safety performance of
infrastructure at a given location. This report seeks to
highlight the central role of speed management in the Safe
System approach and how a simple speed variation can improve
safety for all types of road user. At the core of this
report lies the experience derived from iRAP assessments
undertaken under the Bloomberg Philanthropies Initiative for
Global Road Safety (BIGRS) on 867 km of national roads in
Thailand and 258 km of streets in Bangkok, between 2015 and
2019. This also involved capacity building activities with
local partner, Chulalongkorn University, which led to almost
700 specialists being trained on road safety engineering
during this period. The importance of speed in influencing
road user risk is highlighted in two case studies on
different road types in Thailand — the Outer Ring Road and
Hathai Rat Road in Bangkok — to demonstrate the effects of
different speeds on the iRAP Star Ratings. These ratings
objectively quantify the likelihood of a crash, and its
severity, whereby a person's risk of injury is highest
on a 1-star road, and lowest on a 5-star road. Among a
series of simulations and results, this report shows that
enforcing a 10 kph speed limit reduction could prevent one
in three fatal and serious injuries (FSIs) on both those roads. |
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