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Dive into the research topics where Helena Stigson is active.

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Featured researches published by Helena Stigson.


Accident Analysis & Prevention | 2011

Literature review of pedestrian fatality risk as a function of car impact speed

Erik Rosen; Helena Stigson; Ulrich Sander

The aim of this review was to evaluate all studies of pedestrian fatality risk as a function of car impact speed. Relevant papers were primarily investigated with respect to data sampling procedures and methods for statistical analysis. It was uniformly reported that fatality risk increased monotonically with car impact speed. However, the absolute risk estimates varied considerably. Without exceptions, papers written before 2000 were based on direct analyses of data that had a large bias towards severe and fatal injuries. The consequence was to overestimate the fatality risks. We also found more recent research based on less biased data or adjusted for bias. While still showing a steep increase of risk with impact speed, these later papers provided substantially lower risk estimates than had been previously reported.


Accident Analysis & Prevention | 2010

The Properties of Safety Performance Indicators in Target Setting, Projections and Safety Design of the Road Transport System

Claes Tingvall; Helena Stigson; Louise Eriksson; R. Johansson; Maria Krafft; Anders Lie

Road traffic Safety Performance Indicators (SPIs) are becoming increasingly used as an instrument for the planning and monitoring of safety progress. SPIs form an intermediate step between actions and final outcome in terms of casualties in road crashes. It is understood that SPIs are closely related to outcome; and that it is also possible to use them in calculations and predictions of both actions and final outcome. In the present study, it was found that some of the properties assigned to SPIs could be questioned. An assumption of linearity between SPIs and final outcome was partly rejected. It was also found that 100% fulfillment of a set of SPIs could lead to very low mortality, demonstrating the importance of handling SPIs simultaneously.


International Journal of Crashworthiness | 2009

Variation in crash severity depending on different vehicle types and objects as collision partner

Helena Stigson; Anders Ydenius; Anders Kullgren

The objective in this study of crashed cars fitted with on-board crash pulse recorders (CPR) was to present differences in average crash severity and distribution of crash severity, depending on collision partner. The investigation included both frontal and rear-end two-vehicle and single-vehicle crashes, into deformable and rigid roadside objects. In total, 544 real-world crashes involving cars fitted with CPRs were included. A difference in average crash severity was found in crashes with different collision partners. Frontal two-vehicle and single-vehicle crashes with rigid roadside objects were shown to generate the highest crash severity. In 22% of crashes with heavy goods vehicles (HGVs) and 2% of car-to-car crashes, change of velocity exceeded 45 km/h. These differences indicate the importance of focusing on compatibility. There was a statistically significant difference between frontal two-vehicle and single-vehicle crashes with deformable objects, and also between single-vehicle crashes with deformable objects and single-vehicle crashes with rigid roadside objects. Of these, the least harmful crash type was single-vehicle crashes into deformable objects. This study provides further insight into how collision partners or objects influence change of velocity and mean acceleration in the studied vehicles. Furthermore, it illustrates the importance of paying attention to compatibility issues, regarding aspects influencing both change of velocity and acceleration.


Traffic Injury Prevention | 2008

Use of Fatal Real-Life Crashes to Analyze a Safe Road Transport System Model, Including the Road User, the Vehicle, and the Road

Helena Stigson; Maria Krafft; Claes Tingvall

Objective. To evaluate if the Swedish Road Administration (SRA) model for a safe road transport system, which includes the interaction between the road user, the vehicle, and the road, could be used to classify fatal car crashes according to some safety indicators. Also, to present a development of the model to better identify system weakness. Methods. Real-life crashes with a fatal outcome were classified according to the vehicles safety rating by Euro NCAP (European Road Assessment Programme) and fitment of ESC (Electronic Stability Control). For each crash, the road was also classified according to EuroRAP (European Road Assessment Programme) criteria, and human behavior in terms of speeding, seat belt use, and driving under the influence of alcohol. Each crash was compared with the model criteria, to identify components that might have contributed to fatal outcome. All fatal crashes where a car occupant was killed that occurred in Sweden during 2004 were included: in all, 215 crashes with 248 fatalities. The data were collected from the in-depth fatal crash data of the Swedish Road Administration (SRA). Results. It was possible to classify 93% of the fatal car crashes according to the SRA model. A number of shortcomings in the criteria were identified since the model did not address rear-end or animal collisions or collisions with stationary/parked vehicles or trailers (18 out of 248 cases). Using the further developed model, it was possible to identify that most of the crashes occurred when two or all three components interacted (in 85 of the total 230 cases). Noncompliance with safety criteria for the road user, the vehicle, and the road led to fatal outcome in 43, 27, and 75 cases, respectively. Conclusions. The SRA model was found to be useful for classifying fatal crashes but needs to be further developed to identify how the components interact and thereby identify weaknesses in the road traffic system. This developed model might be a tool to systematically identify which of the components are linked to fatal outcome. In the presented study, fatal outcomes were mostly related to an interaction between the three components: the road, the vehicle, and the road user. Of the three components, the road was the one that was most often linked to a fatal outcome.


Traffic Injury Prevention | 2015

Risk of Permanent Medical Impairment (RPMI) in Car Crashes Correlated to Age and Gender

Markus Gustafsson; Helena Stigson; Maria Krafft; Anders Kullgren

Objective: As fatalities from car crashes decrease, focus on medical impairment following car crashes becomes more essential. This study assessed the risk of permanent medical impairment based on car occupant injuries. The aim was to study whether the risk of permanent medical impairment differs depending on age and gender. Methods: In total, 36,744 injured occupants in car crashes that occurred between 1995 and 2010 were included. All initial injuries (n = 61,440) were classified according to the Abbreviated Injury Scale (AIS) 2005. If a car occupant still had residual symptoms 3 years after a crash, the case was classed as a permanent medical impairment. In total, 5,144 injuries led to permanent medical impairment. The data were divided into different groups according to age and gender as well as levels of permanent impairment. The risk of permanent medical impairment was established for different body regions and injury severity levels, according to the AIS. Results: The cervical spine was the body region that had the highest number of diagnoses, and occupants who sustained injuries to the upper and lower extremities had the highest risk of medical impairment for both genders. Females aged 60 and above had a higher risk of permanent medical impairment from fractures in the extremities compared to males in the same age group and younger females. Females aged 44 or younger had a higher risk of permanent medical impairment from whiplash-associated disorders (WAD) than males in the same age group. Minor and moderate injuries (AIS 1–2) had a higher risk of permanent medical impairment among older car occupants compared to younger ones. Conclusions: Differences in long-term outcome were dependent on both gender and age. Differences between age groups were generally greater than between genders. The vast majority of permanent medical impairments resulted from diagnoses with a low risk of fatality. The results emphasize the impact of age and gender in long-term consequences from car crashes. They could be used when designing safety technology in cars as well as to improve health care by contributing to better allocation of rehabilitation resources following trauma.


Traffic Injury Prevention | 2009

Evaluation of Safety Ratings of Roads Based on Frontal Crashes with Known Crash Pulse and Injury Outcome

Helena Stigson

Objective: The objective in this study, using data from crashed cars fitted with on-board crash pulse recorders, was to present differences in average crash severity, distribution of crash severity, and injury outcomes, based on an independent safety rating of roads, also taking road type and speed limit into consideration. Furthermore, the objective was to evaluate differences in injury risk, based on the distribution of crash severity. Methods: The investigation included both frontal two-vehicle crashes and single-vehicle crashes with known injury outcome. In total, 209 real-world crashes involving cars fitted with crash pulse recorders were included. For all crashes, average mean acceleration and change of velocity of the vehicle acceleration pulse were measured and calculated. All crash spots were classified according to an independent road safety rating program (European Road Assessment Programme Road Protection Score), where the safety quality of roads is rated in relation to posted speed limits. The crash severity and injury outcome in crashes that occurred on roads with good safety ratings were compared with crashes on roads with poor safety ratings. The data were also divided into subcategories according to posted speed limit and road type, to evaluate whether there was a difference in crash severity and injury outcome within the categories. Results and Conclusions: In total, crash severity was statistically significantly lower in crashes occurring on roads with good safety ratings than in crashes occurring on roads with poor safety ratings. It was found that crash severity and injury risk were lower on roads with good safety ratings with a speed limit of above 90 km/h compared with roads with poor safety ratings, irrespective of speed limit. On the other hand, crash severity was higher on roads with good safety ratings with speed limit of 70 km/h than on roads with poor safety ratings with the same speed limit. Though it was found that a higher speed limit resulted in higher crash severity on roads with poor safety ratings, the opposite was found on roads with good safety ratings. The main reason for this was that lanes for traffic traveling in opposite directions were more often separated at higher speeds on roads with good safety ratings. On divided roads with good safety ratings, there were no crashes resulting in crash severity above the level corresponding to a 10 percent risk of sustaining serious or fatal injury. This indicates that one of the most important safety measures is divided roads.


Traffic Injury Prevention | 2014

A One Year Pay-as-You-Speed Trial With Economic Incentives for Not Speeding

Helena Stigson; Jan Hagberg; Anders Kullgren; Maria Krafft

Objective: The objective was to identify whether it was possible to change driver behavior by economic incentives and thereby reduce crash risk. Furthermore, the objective was to evaluate the participants’ attitudes toward the pay-as-you-speed (PAYS) concept. Methods: A one-year PAYS trial with economic incentives for keeping speed limits using intelligent speed assistance (ISA) was conducted in Sweden during 2011–2012. The full incentive was a 30 percent discount off the insurance premium. The participants were private insurance customers and were randomized into a test group (initial n = 152, final n = 128) and a control group (initial n = 98, final n = 68). When driving, the drivers in the test group were informed and warned visually when the speed limit was exceeded. They could also follow their driving results on a personal website. The control group was not given any feedback at all. To reflect the impact of the PAYS concept the proportion of distance driven above the speed limit was compared between the 2 groups. Results: The introduction of a PAYS concept shows that the test group significantly reduced the proportion of distance driven above the speed limit. The proportion of driving at a speed exceeding 5 km/h over the speed limit was 6 percent for the test group and 14 percent for the control group. It also showed that the effect was higher the higher the violation of speed. The result remained constant over time. Conclusions: It was shown that a PAYS concept is an effective way to reduce speed violations. Hence, it has the possibility to reduce crash severity and thereby to save lives. This could be an important step toward a safer road transport system. The majority of the participants were in favor of the concept, which indicates the potential of a new insurance product in the future.


Traffic Injury Prevention | 2014

Long-Term Medical Consequences for Child Occupants 0 to 12 Years Injured in Car Crashes

Katarina Bohman; Helena Stigson; Maria Krafft

Objective: There is limited knowledge of the long-term medical consequences for children injured in car crashes. Thus, in the event of injury, the aim of the study was to specify patterns and risks of injuries resulting in permanent medical impairment of children (0–12 years) for different body regions and injury severity levels, according to Abbreviated Injury Scale (AIS). The aim was also to compare the impairment outcome with adults. Methods: Data were obtained from the Folksam insurance company, including reported car crashes from 1998 to 2010 with at least one injured child 0–12 years of age. In all, 2619 injured children with 3704 reported medical diagnoses were identified. All injuries were classified according to the AIS 2005 revision. If the child had not recovered within 1 year postinjury an assessment of permanent medical impairment (PMI) was made by one or several medical specialists. Results: In all, 55 children sustained 59 injuries resulting in PMI of which 75 percent were at AIS 1 or AIS 2. The head and cervical spine were the body regions sustaining the most injuries resulting in PMI. Sixty-eight percent of all injuries resulting in PMI were AIS 1 injuries to the cervical spine, with the majority occurring in frontal or rear impacts. Given an injury to the cervical spine, the risk of injuries resulting in PMI was 3 percent, and older children (≥6 years) had a significantly higher risk (3% versus 1%) than younger children. The head was the second most commonly injured body region with injuries resulting in PMI (12/59), which were predominantly AIS 2+. In addition, mild traumatic brain injuries at AIS 1 were found to lead to PMI. Whereas for children the injuries leading to PMI were primarily limited to the head and cervical spine, adults sustained injuries that led to PMI from a more diverse distribution of body regions. Conclusion: The pattern of injuries resulting in permanent medical impairment is different for children and adults; therefore, safety priorities for children need to be based on child data. The majority of those injuries leading to PMI were at lower AIS levels. Furthermore, AIS 1 cervical spine and AIS 1+ head injuries should be given priority concerning mitigation of long-term consequences for children.


Traffic Injury Prevention | 2011

Census Study of Fatal Car-to-Car Intersection Crashes in Sweden Involving Modern Vehicles

Cecilia Sunnevång; Ola Boström; Anders Lie; Helena Stigson

Objective: Intersections are challenging for many road users. According to US, European, and global statistics, intersection-related crashes with fatal outcome represent approximately 20 percent of all traffic fatalities. The aim of this study was to use Swedish data to investigate and characterize fatal car-to-car intersection crashes for modern cars equipped with frontal and side air bags. Method: The Swedish Transport Administration (STA) national database on fatal crashes was searched to find vehicle-to-vehicle intersection crashes involving modern cars that occurred between 2003 and 2009 that resulted in fatal injuries for at least one of the involved passengers. From all intersection crashes, the car-to-car crashes from the sample were analyzed at an occupant level. Occupant location in the target vehicle with respect to impact direction as well as AIS3+ injuries to body regions was examined for the total car-to-car sample. Crashes involving a target vehicle equipped with front and side air bags were then selected for an in-depth study. Results: In the STA database, 39 vehicle-to-vehicle crashes matched the search criteria. Of 39 crashes, 17 involved a heavy goods vehicle (HGV) as the striking vehicle, and 17 were car-to-car crashes. All car-to-car crashes were side impacts, occurring at rural intersections, involving 20 (12 female and 8 male) fatally injured occupants, 15 of whom were 61 years or older and classified as senior occupants. A majority of fatally injured occupants sustained combined AIS3+ injuries to more than one body region. Conclusions: All modern car-to-car crashes with a fatal outcome occurring at Swedish intersections from 2003 to 2009 were side impacts. The crashes were characterized by a senior front seat driver, traveling with a front seat passenger, hit on the left side at approximately 70 km/h. In this study all fatal crashes occurred at severities beyond those currently evaluated in side impact rating procedures but were within survivable limits for a non-senior occupant in a majority of cases.


Accident Analysis & Prevention | 2017

Modelling the effect on injuries and fatalities when changing mode of transport from car to bicycle

Philip Nilsson; Helena Stigson; Maria Ohlin; Johan Strandroth

BACKGROUND Several studies have estimated the health effects of active commuting, where a transport mode shift from car to bicycle reduces risk of mortality and morbidity. Previous studies mainly assess the negative aspects of bicycling by referring to fatalities or police reported injuries. However, most bicycle crashes are not reported by the police and therefore hospital reported data would cover a much higher rate of injuries from bicycle crashes. The aim of the present study was to estimate the effect on injuries and fatalities from traffic crashes when shifting mode of transport from car to bicycle by using hospital reported data. METHODS This present study models the change in number of injuries and fatalities due to a transport mode change using a given flow change from car to bicycle and current injury and fatality risk per distance for bicyclists and car occupants. RESULTS show that bicyclists have a much higher injury risk (29 times) and fatality risk (10 times) than car occupants. In a scenario where car occupants in Stockholm living close to their work place shifts transport mode to bicycling, injuries, fatalities and health loss expressed in Disability-Adjusted Life Years (DALY) were estimated to increase. The vast majority of the estimated DALY increase was caused by severe injuries and fatalities and it tends to fluctuate so that the number of severe crashes may exceed the estimation with a large margin. CONCLUSION Although the estimated increase of traffic crashes and DALY, a transport mode shift is seen as a way towards a more sustainable society. Thus, this present study highlights the need of strategic preventive measures in order to minimize the negative impacts from increased bicycling.

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Anders Kullgren

Chalmers University of Technology

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Johan Strandroth

Swedish Road Administration

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Matteo Rizzi

Chalmers University of Technology

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Anders Lie

Swedish Transport Administration

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Claes Tingvall

Swedish Road Administration

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