Internationally, people aged 65 and over are forming a rapidly increasing proportion of society (Heenan, 1993). New Zealand is no exception. By 2001, it is estimated that older people (people over the age of 65) will account for 11% of the New Zealand population (Statistics New Zealand, 1998). As the baby boom generation advances through their later years, and as life expectancy continues to improve, it has been predicted by Statistics New Zealand that by the year 2031, this figure will literally double, swelling to 22% (Statistics New Zealand, 1998). Tomorrow's aged population will be accustomed to the high levels of motorisation that have developed in the latter part of last century. With demographers predicting the number of older persons increasing both in total and as a proportion of the whole population (Land Transport Safety Authority, 1994), people aged over 65 will form a rapidly increasing proportion of New Zealand's road users. As such, it is important that as people age they can continue to travel and enjoy their mobility as freely and safely as other road users (Transportation Research Board, 1988).