NCPA - National Center for Policy Analysis

Risk Homoeostasis Theory and Road Safety?

May 21, 2002

Risk homoeostasis (also called risk compensation) theory predicts that, as safety features are added to vehicles and roads, drivers tend to increase their exposure to collision risk because they feel better protected. Gerald Wilde, a Canadian professor emeritus of psychology, found evidence for it and suggests that it should be used to form road safety strategies.

There are four possible approaches to reducing the target level of risk for drivers: rewarding particular safe behaviors, rewarding drivers who have not crashed, punishing particular unsafe behaviors, and punishing drivers for having crashed. The third option, which is used predominantly in most societies, has not been found to be especially effective. However, incentives for crash-free driving (the second approach) have been shown to be useful.

  • The promise of free renewal of the driver's license in California in return for crash-free driving was followed by a 22% reduction in crashes in the first year and by a 33% reduction in the second.
  • Norwegian beginner drivers, who were promised by their insurance company complete reimbursement plus interest of the insurance surcharge for young drivers, responded by a 35% reduction in crashes.
  • German truck drivers who were given the prospect of a cash bonus for every half year of crash-free driving subsequently caused many fewer crashes; this incentive program has been in effect for over 30 years without any dwindling in its power to prevent accidents.

Anyone wishing to reduce car wrecks on the road to zero can do so by never using the roads, but that person would also miss all the benefits of road travel. A person learns to assess risk by perceiving the outcomes of decisions.

Source: Gerald J. S. Wilde, "Does Risk Homoeostasis Theory Have Implications For Road Safety?" British Medical Journal, May 11, 2002.

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