Understanding Passenger Influences on Driver Behaviour: Implications for Road Safety and Recommendations for Countermeasure Development

Monash University Accident Research Centre - Report #180 - 2001

Authors: M.A. Regan & E. Mitsopoulos

Full report in pdf format [1MB]

Abstract:

Several epidemiological studies have shown that the crash risk of drivers is affected, positively or negatively, by the presence of passengers. Little is currently known, however, about the behavioural interactions between drivers and passengers that moderate these effects. The present study proposed to investigate the potentially constructive roles that passengers can play to positively influence the behaviour of drivers, to enhance driver and passenger safety in the Australian Capital Territory (ACT). This involved a literature review, an analysis of ACT crash data pertaining to passengers, administration via telephone of a survey to 872 ACT residents exploring the roles that passengers currently play in the driving situation, and the conduct of three focus groups involving 28 ACT residents. The findings shed light on the role types that passengers currently play in influencing, positively and negatively, their safety and that of their driver - from the perspective of both passengers and drivers. The outcomes of this study formed the basis for a set of recommended countermeasures designed to enhance the safety of both passengers and drivers in the ACT.

Executive Summary

Background and Overall Objective

Passengers comprise a substantial proportion of the road toll. However, passengers' safety is almost entirely in the hands of the driver. Traditionally, the driver has been the main focus of road safety campaigns and programs. The passenger's influence on the driver's behaviour has been virtually overlooked in the development of such campaigns. Little is currently known about the patterns of communication that exist between drivers and passengers, and the effect this interplay has on driver behaviour to influence safety. If the behavioural interactions that take place between drivers and passengers were better understood, it would be possible to develop countermeasure strategies for enhancing the positive role of passengers and minimising the negative role of passengers on driver behaviour. These countermeasures would be expected to have considerable safety benefits for drivers and passengers alike.

The NRMA-ACT Road Safety Trust commissioned the Monash University Accident Research Centre (MUARC) to research the potentially constructive roles that passengers can play to positively influence the behaviour of drivers, and from this research, to make recommendations for countermeasures that are designed to enhance driver and passenger safety in the ACT. This study was partitioned into five parts: a review of the literature on the interaction between drivers and passengers; a summary of ACT crash data pertaining to passengers; administration via telephone of a survey; the conduct of three focus groups; and recommendations for countermeasure development and future research.

Literature Review

The purpose of the literature review was to gain an understanding of the research that has been conducted to date on the effect of passengers on driver behaviour, the behavioural mechanisms underlying this effect, and of any road safety initiatives that target passengers.

Epidemiological studies have served to show that the risk of drivers being involved in a casualty crash is affected by the presence of passengers. However, the effect of passengers on driver behaviour is not uniform across all drivers for all of the types of passengers that drivers might carry. It seems that the direction and magnitude of the effect of passenger presence on driver crash risk is contingent upon the following factors at least: the age of the driver, and the sex of the driver relative to the sex of the passenger. For young drivers at least, the age of the passenger is another factor that has been found to influence what sort of an effect the presence of passengers will have on them. There is consensus across studies that particular driver-passenger combinations increase driver crash risk while other combinations have either no effect or reduce the risk. It has been found that the crash risk of young drivers is elevated further when carrying their peers as passengers, but is reduced when carrying an adult or a child as a passenger compared with carrying no passengers. The crash risk of older drivers in general, was reduced in the presence of passengers. Young male drivers were reported to have a higher crash risk in the presence of passengers than young female drivers, and male passengers were found to place young drivers, male and female, at a greater risk of a crash than female passengers. The number of passengers was also found to influence the direction and magnitude of the passenger effect for young drivers. The fatal crash risk of young drivers was reported to increase with two or more passengers provided the passengers are peers of the young driver. The crash risk of young drivers, male and female, also was shown to increase with each additional male passenger. A beneficial effect of carrying two or more female passengers was observed for young drivers but for female drivers only.

Behavioural studies have revealed the relationship between the driver and the passenger as another critical determinant of the effect of passengers on driver behaviour and therefore, driver and passenger safety. It was reported that friends or peers as passengers are generally a negative influence on the behaviour of the young driver, particularly the young male driver, thus compromising safety. This is thought to be due to an increased propensity by the young driver to take risks in response to peer pressure. Inattentiveness to the driving task due to distraction caused by social interaction among peers might also play a role. In contrast, passengers who are the young driver's children, spouse/partner, or parents were found to promote safer driving practices through the young driver's increased sense of responsibility and respect for the life of others. Further, it was thought that the beneficial effect of passengers on the safety of elderly drivers might be due to the passenger warning the driver of imminent hazards in consideration of elderly drivers' generally compromised perceptual and cognitive abilities.

There are three road safety initiatives that concern passengers. First, New Zealand and 15 US states have a passenger restriction as part of Graduating Licensing. All jurisdictions with passenger restrictions permit young newly licensed drivers to carry passengers if the young driver is being supervised by a fully licensed driver who is over the age of 20 or 21. An evaluation of the New Zealand passenger restriction revealed fewer crashes involving passengers among young drivers with a restricted licence compared with young drivers licensed before the introduction of graduated licensing. The Californian passenger restriction has been evaluated also. Preliminary results showed a reduction in the proportion of deaths and injuries among teenage passengers. Passenger restrictions have been criticised on the grounds that rates of compliance might be low, and that compliance will force young passengers to drive themselves thus increasing their exposure to a crash. It has been argued, however, that even if all teenage passengers were to comply by driving themselves a large proportion of lives would still be saved each year. The second initiative, the Norwegian "Speak Out" campaign, was designed to encourage teenage passengers to speak out to their teenage drivers about excessive speeding and other unsafe driving practices. An evaluation showed a reduction in the proportion of fatalities and serious injuries among passengers aged 16 to 19 years but not among drivers aged 16 to 19 years. It is possible that the effect of the campaign was to discourage passengers from driving with drivers who did not act on their advice to drive more safely. A third initiative, the Transport Accident Commission of Victoria's "If you don't trust the driver, don't get in" campaign was targeted primarily at young passengers and was an advertisement televised in Victoria for a period in the late 1990s. It was designed to make young passengers realise that they have a choice and that they do not have to travel with drivers whose responsibility or judgment they question.

ACT Crash Data

A summary of the available and relevant data on casualty crashes involving passengers in the ACT from 1995 to 1999 was undertaken. The aim of this activity was to gain an understanding of the characteristics of these crashes. The main findings were:

  • Between 1995 and 1999, 35% of vehicle occupants who were killed or seriously injured in a crash were passengers.
  • In single vehicle crashes, driver and passenger casualties were most prevalent among males, and among 16 to 24 year olds.
  • In single vehicle crashes where both the driver and at least one passenger was killed or seriously injured, the most prevalent driver-passenger combination was 16 to 24 year old male drivers carrying 16 to 24 year old male passengers. These trends are consistent with similar trends reported elsewhere in the literature.

Telephone Survey

A total of 872 ACT residents who were at least 16 years of age, and who were drivers, passengers or both completed the survey. The aims of the telephone survey were:

  • To collect some background information on participant's experience and travel exposure as a driver, and their exposure as a passenger, in addition to some demographic information on participants' main passenger and their main driver.
  • To determine the types of roles that passengers currently play to influence driver behaviour from the perspective of the driver and also from the perspective of the passenger.
  • To determine to what extent the types of roles that passengers play are affected by the following variables: the age of the driver, the age of the passenger, the relationship between the driver and the passenger, and the sex of the driver relative to the sex of the passenger.

The critical findings were:

  • Passengers currently play a number of role types: passengers determine whether their driver engages in risky driving behaviours (e.g. driving too close to the car in front) either implicitly through their physical presence or explicitly by telling the driver; they determine whether their driver engages in anti-social driving behaviours (e.g. spinning the wheels, or drink driving) either implicitly or explicitly; and, they determine whether their driver drives responsibly (e.g. notifying the driver of approaching traffic hazards). In addition, passengers talk to their driver either socially or to keep their driver awake, and they do things for their driver to alleviate the driver's workload (e.g. answering the mobile phone).
  • If acted upon by the driver, role types potentially encouraging risky driving behaviours and anti-social behaviours are the most likely to have negative safety implications.
  • From the perspective of the driver it was found that:
    • The extent to which role types were played was affected by passenger age, driver-passenger relationship, and the sex of the driver relative to the sex of the passenger, but not by driver age.
    • The mere physical presence of a 16 to 24 year old passenger was more likely to stimulate the driver to engage in risky and anti-social driving than the presence of a passenger aged 55 years or older.
    • A 16 to 24 year old passenger was more likely to tell the driver to take risks, to engage in anti-social driving, to talk to the driver, and to do things for the driver than a passenger aged 55 years or older.
    • A 16 to 24 year old passenger was no less likely than a passenger aged 55 years or older to be responsible by telling the driver about approaching hazards, how to reach the destination, and so on.
    • A friend as a passenger was generally more likely to stimulate the driver, either through physical presence or by telling the driver, to engage in anti-social driving behaviours than the presence of the driver's child or spouse. A friend of the driver was also more likely to talk to the driver than the driver's spouse.
    • The physical presence of a male passenger was more likely to stimulate a female driver to practice anti-social driving than the physical presence of a female passenger.
    • A male passenger of a female driver was more likely to tell the driver to engage in risk taking and anti-social driving behaviours than a female passenger of a male driver and a female passenger of a female driver
  • From the perspective of the passenger it was found that:
    • The extent to which role types were played was affected by driver age only - a pattern of effects in contrast to that revealed from the driver's perspective.
    • Passengers in general, felt that they were more likely to stimulate, either through physical presence or by telling the driver, a driver aged 55 years or older to engage in anti-social type behaviours than a driver aged 25 to 54 years.
    • Passengers in general, felt that they were more likely to do things or talk to a driver who was aged 25 to 54 years than a driver who was aged 55 years or above.
  • The mismatch in outcomes between the driver's perspective and the passenger's perspective suggests that passengers appear to be unaware that they are having the effects on drivers that drivers say that passengers are having on drivers. This is one of the most important findings emerging from the present study.

Focus Groups

A total of three focus groups were held in the ACT involving a total of 28 ACT residents who were drivers, passengers, or both. The aims of the focus groups were:

  • to further examine the roles passengers currently play and driver's perceptions and reactions to these role types;
  • to discuss the roles that passengers should be playing to assist the driver to drive more safely; and
  • to discuss possible strategies for best implementing and promoting these roles in the community.

The key findings were:

  • Passengers currently play several roles: navigating, adjusting the radio and other dials, keeping the driver company by talking, warning the driver of approaching hazards, and alerting the driver to the speed at which they are travelling.
  • Whether passengers will play a given role, and how drivers perceive and react to these roles, was said to depend on the relationship between the driver and the passenger, and for the younger participants in particular, the age and sex of the driver relative to the passenger. For example:
    • Passengers were said to be more likely to intervene when the driver is a family member than when the driver is a work colleague or an acquaintance.
    • Younger participants commented that they would be more likely to intervene as a passenger or take advice as a driver, from their parents than from their friends.
    • Younger drivers said that they drive more cautiously when carrying their parents, older passengers and children as passengers due to a greater sense of responsibility.
    • Young participants, males in particular, commented that as a passenger they would never discourage their male peers from engaging in risky driving behaviours, and might even explicitly encourage such behaviours.
    • As a driver, many of the young males commented that they would also engage in risky driving practices to show off even if not explicitly asked to by their male peers travelling as passengers.
  • Roles that participants believed that passengers should be playing included: warning the driver of approaching hazards, navigating, adjusting the radio and other dials, and keeping quiet in high workload times. Essentially, any intervention from passengers must be constructive and should occur before the event rather than after the event.
  • Participants generally agreed that road safety strategies involving a constructive role for passengers could be implemented. These strategies:
    • Need to be along the lines of "look after the driver" and "help the driver in these ways" rather than "passengers should do this or that".
    • Need to be well promoted to raise public awareness of the potential benefits and dangers of carrying passengers.
    • Need to be implemented through education at the learner driver stage to encourage young passengers to query their driver about driving behaviours that appear to be unsafe, and to encourage young drivers to expect such intervention and to consider it.
    • Need to pay particular attention to the potentially negative influence of young male friends as passengers of young drivers who are susceptible to this influence.

Recommendations for Countermeasure Development and Future Research

Recommendations for countermeasure development were derived from the findings of the current study. To assist in this process, the authors convened a discussion among a small group of experienced and respected Melbourne-based road safety and aviation safety researchers and practitioners. An integrated package of recommended countermeasures for the ACT were derived from the meeting and were categorised as follows:

  • Promotion:
    • Any promotional campaign introduced in the ACT should aim to raise community understanding and support of the increased and decreased risks associated with carrying certain types of passengers.
    • Such a campaign would need to target passengers, drivers and parents of young drivers.
    • The key elements of the campaign would be to make people aware of the potentially negative and positive influences that passengers have on driver behaviour, and to empower people to speak up as passengers if they feel that the driver is compromising their safety.
  • Education:
    • Educational materials and programs that re-iterate the key messages of the promotional campaign need to be introduced also.
  • Training:
    • Consideration should be given to incorporating into pre-driver and driver training programs principles of Crew Resource Management (CRM) that are relevant to the enhancement of communication and teamwork between drivers and passengers to enhance safety. CRM is a type of training that has been adopted widely throughout the aviation industry to enhance communication and teamwork within the aircraft cockpit to optimise flight safety.
  • Licensing:
    • Consideration should be given to incorporating information into the preparatory handbooks for learner drivers in the ACT and items into the ACT traffic knowledge test for learner drivers, that pertain to the positive and negative influences of passengers on driver behaviour and safety.
    • The ACT government should consider introducing a passenger restriction for newly licensed probationary drivers.
  • Enforcement:
    • Consideration should be given to doubling the number of demerit points incurred by probationary drivers or implementing an alternative penalty system for probationary drivers who commit a traffic offence while carrying passengers. Such a penalty regime could be introduced following the expiration of the passenger restriction period to deter young drivers from partaking in high-risk activities when carrying passengers.
  • Research:
    • Further research is necessary before the recommended countermeasures can be fully developed and implemented. For example, it would be necessary to conduct focus testing of the themes and messages that underpin any proposed promotional campaign, including the likely reaction of young drivers and parents to passenger restrictions.
    • Further research would need to be conducted to quantify the costs and benefits of the proposed countermeasures.
    • An evaluation study would be necessary after the implementation of the countermeasure program to determine the program's effectiveness in reducing young passenger and driver fatalities and serious injuries in the ACT.

Both the papers that were reviewed and the work carried out by the authors highlighted the need for further research in several areas. These included:

  • Research into determining the relative contributions of distraction and risk taking factors in giving rise to the increased crash risk of young drivers carrying their peers as passengers.
  • An examination of the influence on safety of the personality of the driver and of the passenger.
  • Research into the effect of the number of passengers on the extent to which particular role types are played by passengers.

Sponsoring organisation:  NRMA-ACT Road Safety Trust