How Passenger Cars Protect their Drivers and Should Cars be Protected from their Drivers: from Airbags to Automated Driving

Tapio Koisaari

Research output: ThesisDoctoral ThesisCollection of Articles


This thesis examined not only the effectiveness of the currently available safety devices for passenger cars (introduced by 2018) but also crashes that cannot be prevented by current safety technology. The research was carried out as a statistical analysis using Finnish databases as material. The material of the Finnish Crash Data Institute (OTI) was used exclusively as the crash data. In the publications, this crash data was combined with appropriate Finnish databases as needed. All four publications were quantitative observational studies. The first three studies were retrospective cross-sectional studies regarding passenger car safety technology, but the first one also included a case-control part. The last of these studies was a prospective cohort study, where the follow-up period for those with attention deficit-hyperactivity disorder (ADHD) had been going on for a considerable period of 40 years. The results of the studies were presented as odds ratios (OR) for the case-control and cohort studies, and as the prevalence for the cross-sectional studies. According to the results, the airbags contributed little to eye injuries (the prevalence of possible eye injuries was fewer than 4 injuries per 10,000 injured), but the non-use of the seat belt increased the odds of both head injuries (OR 2.50, 95% confidence interval [1.59; 3.97]) and death (OR 5.89 [3.33;10.9]). In addition, the injury (-29% [-27%;-31%]) and fatal (-58% [-45%; -69%]) crash rates were significantly lower for passenger cars having electronic stability control (ESC) than for older, non-ESC cars. If the ESC cars mentioned above are compared to newer cars having almost all available active safety devices, the analysis showed that the incidence of at-fault fatal crashes could be reduced by another 20-27% per kilometre, i.e. down to 0.48-0.53 crashes per billion kilometres when sudden disease attacks and suicides were not taken into account. Crashes that are most difficult to prevent using current safety technology are suicides, crashes caused by active but erroneous driver control, and crashes occurring in bad weather or road conditions. In addition to the above, shortcomings in usability, consumer resistance, and behavioural adaptation may be risks in the future. However, the results of this dissertation showed that currently, the most significant negative behaviour regarding safety devices was the non-use of safety devices. Non-medicated ADHD is an example of a single factor leading to highly complex cause-and-effect relationships regarding risk-taking. In the results, ADHD combined not only with increased mortality but also with elevated criminality (OR 24.3 [3.21; 184]) and drunk driving (OR 5.61 [2.30; 13.6]). The purpose of the example was not to stigmatize people with ADHD but to show how a disease with perinatal exposure factors can lead to crashes that are difficult to prevent.
Translated title of the contributionKuinka autot suojaavat kuljettajiaan ja pitäisikö autoja suojata kuljettajiltaan: turvatyynyistä ajamisen automaatioon
Original languageEnglish
QualificationDoctor's degree
Awarding Institution
  • Aalto University
  • Tammi, Kari, Supervising Professor
  • Tervo, Timo, Thesis Advisor, External person
Print ISBNs978-952-60-8858-7
Electronic ISBNs978-952-60-8859-4
Publication statusPublished - 2019
MoE publication typeG5 Doctoral dissertation (article)


  • road crashes
  • passive safety
  • active safety
  • traffic medicine


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