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Accidents between pedestrians, bicyclists and motorized vehicles: Accident risk and injury severity

Kröyer, Höskuldur LU (2015)
Abstract (Swedish)
Popular Abstract in English

This work is focused on two accident types: accidents between motorized vehicles and pedestrians, and accidents between motorized vehicles and bicyclists. It aims at better understanding how the number of accidents is related to the number of road users; and how the speed at the site and age of the victim is related to how severe the injuries are. The work relies on several different statistical techniques to study those relations.



The results show that there is a relation between the number of road users and the numbers of accidents, that is, if there are more road users, there are more accidents. The results further suggest that the risk of an accident per road user is lower... (More)
Popular Abstract in English

This work is focused on two accident types: accidents between motorized vehicles and pedestrians, and accidents between motorized vehicles and bicyclists. It aims at better understanding how the number of accidents is related to the number of road users; and how the speed at the site and age of the victim is related to how severe the injuries are. The work relies on several different statistical techniques to study those relations.



The results show that there is a relation between the number of road users and the numbers of accidents, that is, if there are more road users, there are more accidents. The results further suggest that the risk of an accident per road user is lower at sites where the number of road user is high, compared to sites where the number of road users is low. This effect is also apparent for pedestrian fall accidents (single accidents) which allow us to reflect over the current theories regarding to why the models show this effect.



Risk values and risk curves are frequently used when working with traffic safety, where the probability of serious or fatal injuries is presented against some other variable, for example speed. The thesis suggest an alternative way to interpret those risk values and risk curves, where the approach depends on if it is from the perspective of the individual or from the perspective of the society as a whole. The results furthermore show that the speed environment and the age of the victim are closely related to the probability of sustaining serious or fatal injuries. A considerable proportion of the serious injuries occur in low speed environments, seniors suffer more serious injuries than younger pedestrians and cyclists do, and the effects differ substantially for struck pedestrians versus struck bicyclists. (Less)
Abstract
The aims of this work are to better understand (1) the relation between exposure and the risk of an accident between pedestrians and motorized vehicles and between bicyclists and motorized vehicles occurring at urban intersections and (2) how the speed environment and the victim´s age relate to the injury severity/outcome once a pedestrian or a bicyclist has been struck by a motorized vehicle. Cross sectional studies are used, and the relations are analyzed using multinomial logit models, negative binomial regression and other statistical methods.



The results show that there is a positive correlation between the exposure of pedestrians, bicyclists and motorized vehicles and the number of accidents, i.e. the more road... (More)
The aims of this work are to better understand (1) the relation between exposure and the risk of an accident between pedestrians and motorized vehicles and between bicyclists and motorized vehicles occurring at urban intersections and (2) how the speed environment and the victim´s age relate to the injury severity/outcome once a pedestrian or a bicyclist has been struck by a motorized vehicle. Cross sectional studies are used, and the relations are analyzed using multinomial logit models, negative binomial regression and other statistical methods.



The results show that there is a positive correlation between the exposure of pedestrians, bicyclists and motorized vehicles and the number of accidents, i.e. the more road users there are, the more accidents occur. The models also suggest that this relation is non-linear; the accident risk per road user is lower at sites where the exposure is greater (safety in numbers effect). Furthermore, the results show safety in numbers effect for single pedestrian accidents, which might suggest that the underlying reasons for this effect is more complex than previously assumed.



The thesis suggest an alternative way to interpret risk values and risk curves for injury severity/outcome (if one is involved in an accident), in which differences arise depending on whether the aim is to interpret the relation from an individual perspective or from the perspective of society as a whole. The results furthermore show a strong correlation between the speed environment, the age of the victim and the injury severity/outcome. A considerable proportion of the serious injuries occurs in low speed environments, seniors suffer more serious injuries than younger pedestrians and cyclists do, and the effects differ substantially for struck pedestrians versus struck bicyclists. (Less)
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author
supervisor
opponent
  • Associate Professor Kaplan, Sigal, Technical University of Denmark
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Accidents, pedestrians, bicyclists, exposure, risk, consequence, speed, age.
pages
156 pages
publisher
Lund University
defense location
Auditorium MA:5, Sölvegatan 20 A-D, Lund University, Faculty of Engineering, LTH.
defense date
2015-09-25 10:15
ISBN
978-91-7623-431-0
language
English
LU publication?
yes
id
23e842af-0bbe-4e92-b59f-f889ca6a4ba4 (old id 7792421)
date added to LUP
2015-08-31 13:33:14
date last changed
2016-09-19 08:45:12
@phdthesis{23e842af-0bbe-4e92-b59f-f889ca6a4ba4,
  abstract     = {The aims of this work are to better understand (1) the relation between exposure and the risk of an accident between pedestrians and motorized vehicles and between bicyclists and motorized vehicles occurring at urban intersections and (2) how the speed environment and the victim´s age relate to the injury severity/outcome once a pedestrian or a bicyclist has been struck by a motorized vehicle. Cross sectional studies are used, and the relations are analyzed using multinomial logit models, negative binomial regression and other statistical methods. <br/><br>
<br/><br>
The results show that there is a positive correlation between the exposure of pedestrians, bicyclists and motorized vehicles and the number of accidents, i.e. the more road users there are, the more accidents occur. The models also suggest that this relation is non-linear; the accident risk per road user is lower at sites where the exposure is greater (safety in numbers effect). Furthermore, the results show safety in numbers effect for single pedestrian accidents, which might suggest that the underlying reasons for this effect is more complex than previously assumed.<br/><br>
<br/><br>
The thesis suggest an alternative way to interpret risk values and risk curves for injury severity/outcome (if one is involved in an accident), in which differences arise depending on whether the aim is to interpret the relation from an individual perspective or from the perspective of society as a whole. The results furthermore show a strong correlation between the speed environment, the age of the victim and the injury severity/outcome. A considerable proportion of the serious injuries occurs in low speed environments, seniors suffer more serious injuries than younger pedestrians and cyclists do, and the effects differ substantially for struck pedestrians versus struck bicyclists.},
  author       = {Kröyer, Höskuldur},
  isbn         = {978-91-7623-431-0},
  keyword      = {Accidents,pedestrians,bicyclists,exposure,risk,consequence,speed,age.},
  language     = {eng},
  pages        = {156},
  publisher    = {Lund University},
  school       = {Lund University},
  title        = {Accidents between pedestrians, bicyclists and motorized vehicles: Accident risk and injury severity},
  year         = {2015},
}