Single-vehicle injury crashes on rural roads in Iceland: contribution of unforgiving roadsides to fatal and serious injuries of vehicle occupants

About 50% of the most severe crashes on rural roads in Iceland are run-off-road crashes. Many existing roads were designed before the concept of forgiving roadsides became prevailing in road design in Iceland. This research aimed to find the roadside elements that significantly increase the probabi...

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Main Authors: Audur Thora Arnadottir, Gudmundur F. Ulfarsson, Sungyop Kim
Format: Article
Language:English
Published: Technology and Society, Faculty of Engineering, LTH, Lund University 2025-01-01
Series:Traffic Safety Research
Subjects:
Online Access:https://tsr.international/TSR/article/view/26486
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author Audur Thora Arnadottir
Gudmundur F. Ulfarsson
Sungyop Kim
author_facet Audur Thora Arnadottir
Gudmundur F. Ulfarsson
Sungyop Kim
author_sort Audur Thora Arnadottir
collection DOAJ
description About 50% of the most severe crashes on rural roads in Iceland are run-off-road crashes. Many existing roads were designed before the concept of forgiving roadsides became prevailing in road design in Iceland. This research aimed to find the roadside elements that significantly increase the probability of high severity of single-vehicle injury crashes compared to low severity crashes on rural roads to prioritize safety improvements under limited budgets. In this research, 712 police records on single-vehicle injury crashes on rural state roads in Iceland in 2016–2018 were investigated. Crash data developed from police reports do not typically include information on roadside elements even though such information is often visible in photographs or written in words by police officers in their crash reports. This limits research on roadside elements and unforgiving roadsides. In this study, the original written police reports and crash photographs were reviewed. Based on this, additional data regarding the roadside elements were coded and added to the standard crash data. A binary logit model for the most severe injury in each crash was developed to statistically test the effect of roadside elements on the probability of fatal and serious injury versus low severity. The model results showed that two roadside elements, rocks and steep transverse slopes (e.g. where an access road enters a main road), hit by a vehicle in a run-off-road crash, more than doubled the probability of high severity. Road safety measures where roadside rocks are removed or steep transverse slopes are reduced, thereby making roadsides more smooth and forgiving, can be especially beneficial for safety because road users are unlikely to adapt their behavior to increased safety from such improvements. This is because such improvements are likely not easily noticed by road users; hence they reduce the probability of compensatory behavior such as increased driving speed, which could outweigh the safety benefits. The results revealed other contributing factors which more than double the probability of high severity of single-vehicle injury crashes on rural roads. Driver intoxication had the strongest effect, a problem which interestingly was limited to drivers living in Iceland. Not a single foreign tourist driver in this data was noted as being under the influence of alcohol or illegal drugs. To strengthen the analysis of the contribution of roadside elements to the severity of run-off-road crashes and to monitor the effects of improvements in the future, it is recommended that additional information on roadside elements be coded and added to the standard police record crash data.
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spelling doaj-art-746728ae77c242fa8fb9405298bc0b5e2025-01-25T05:10:49ZengTechnology and Society, Faculty of Engineering, LTH, Lund UniversityTraffic Safety Research2004-30822025-01-01910.55329/bkrk9175Single-vehicle injury crashes on rural roads in Iceland: contribution of unforgiving roadsides to fatal and serious injuries of vehicle occupantsAudur Thora Arnadottir0https://orcid.org/0009-0001-7614-6642Gudmundur F. Ulfarsson1https://orcid.org/0000-0002-0094-7531Sungyop Kim2https://orcid.org/0000-0002-1784-1813Icelandic Road and Coastal Administration, Iceland University of Iceland, IcelandUniversity of Missouri–Kansas City, the United States of America About 50% of the most severe crashes on rural roads in Iceland are run-off-road crashes. Many existing roads were designed before the concept of forgiving roadsides became prevailing in road design in Iceland. This research aimed to find the roadside elements that significantly increase the probability of high severity of single-vehicle injury crashes compared to low severity crashes on rural roads to prioritize safety improvements under limited budgets. In this research, 712 police records on single-vehicle injury crashes on rural state roads in Iceland in 2016–2018 were investigated. Crash data developed from police reports do not typically include information on roadside elements even though such information is often visible in photographs or written in words by police officers in their crash reports. This limits research on roadside elements and unforgiving roadsides. In this study, the original written police reports and crash photographs were reviewed. Based on this, additional data regarding the roadside elements were coded and added to the standard crash data. A binary logit model for the most severe injury in each crash was developed to statistically test the effect of roadside elements on the probability of fatal and serious injury versus low severity. The model results showed that two roadside elements, rocks and steep transverse slopes (e.g. where an access road enters a main road), hit by a vehicle in a run-off-road crash, more than doubled the probability of high severity. Road safety measures where roadside rocks are removed or steep transverse slopes are reduced, thereby making roadsides more smooth and forgiving, can be especially beneficial for safety because road users are unlikely to adapt their behavior to increased safety from such improvements. This is because such improvements are likely not easily noticed by road users; hence they reduce the probability of compensatory behavior such as increased driving speed, which could outweigh the safety benefits. The results revealed other contributing factors which more than double the probability of high severity of single-vehicle injury crashes on rural roads. Driver intoxication had the strongest effect, a problem which interestingly was limited to drivers living in Iceland. Not a single foreign tourist driver in this data was noted as being under the influence of alcohol or illegal drugs. To strengthen the analysis of the contribution of roadside elements to the severity of run-off-road crashes and to monitor the effects of improvements in the future, it is recommended that additional information on roadside elements be coded and added to the standard police record crash data. https://tsr.international/TSR/article/view/26486injury severityrun-off-road crashesunforgiving roadsides
spellingShingle Audur Thora Arnadottir
Gudmundur F. Ulfarsson
Sungyop Kim
Single-vehicle injury crashes on rural roads in Iceland: contribution of unforgiving roadsides to fatal and serious injuries of vehicle occupants
Traffic Safety Research
injury severity
run-off-road crashes
unforgiving roadsides
title Single-vehicle injury crashes on rural roads in Iceland: contribution of unforgiving roadsides to fatal and serious injuries of vehicle occupants
title_full Single-vehicle injury crashes on rural roads in Iceland: contribution of unforgiving roadsides to fatal and serious injuries of vehicle occupants
title_fullStr Single-vehicle injury crashes on rural roads in Iceland: contribution of unforgiving roadsides to fatal and serious injuries of vehicle occupants
title_full_unstemmed Single-vehicle injury crashes on rural roads in Iceland: contribution of unforgiving roadsides to fatal and serious injuries of vehicle occupants
title_short Single-vehicle injury crashes on rural roads in Iceland: contribution of unforgiving roadsides to fatal and serious injuries of vehicle occupants
title_sort single vehicle injury crashes on rural roads in iceland contribution of unforgiving roadsides to fatal and serious injuries of vehicle occupants
topic injury severity
run-off-road crashes
unforgiving roadsides
url https://tsr.international/TSR/article/view/26486
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AT gudmundurfulfarsson singlevehicleinjurycrashesonruralroadsinicelandcontributionofunforgivingroadsidestofatalandseriousinjuriesofvehicleoccupants
AT sungyopkim singlevehicleinjurycrashesonruralroadsinicelandcontributionofunforgivingroadsidestofatalandseriousinjuriesofvehicleoccupants