Helen Middleton

Immobilisation of the knee and ankle and its impact on drivers’ braking times: A DRIVING SIMULATOR STUDY

The purpose of this study was to investigate the effects of right leg restriction at the knee, ankle or both, on a drivers braking times. Previous studies have not investigated the effects of knee restriction on braking performance. A total of 23 healthy drivers performed a series of emergency braking tests in a driving simulator in either an above-knee plaster cast, a below-knee cast, or in a knee brace with an increasing range of restriction. The study showed that total braking reaction time was significantly longer when wearing an above-knee plaster cast, a below-knee plaster cast or a knee brace fixed at 0°, compared with braking normally (p < 0.001). Increases in the time taken to move the foot from the accelerator to the brake accounted for some of the increase in the total braking reaction time. Unexpectedly, thinking time also increased with the level of restriction (p < 0.001). The increase in braking time with an above-knee plaster cast in this study would increase the stopping distance at 30 miles per hour by almost 3 m. These results suggest that all patients wearing any lower-limb plaster cast or knee brace are significantly impaired in their ability to perform an emergency stop. We suggest changes to the legislation to prevent patients from driving with lower-limb plaster casts or knee braces.

Driver Eye Movement During A Route Navigation Information Search

In-vehicle route navigation systems are used by an increasing number of drivers throughout the world. These systems are intended to assist the driver in the driving task by providing real-time navigational instructions. However, most route navigation systems appear to have been developed on the basis of technical features, rather than from a usability/human factors viewpoint, causing concerns over their safety implications, especially for older drivers. An experimental study was carried out to test drivers’ preference of markers in an electronic map display. This was done by analysing drivers eye fixation and movement during information searching in a number of route navigation tasks. The study indicates that, in order to find the ‘correct’ road during a navigational search, participants adopt visual search strategies in which they tend to fixate, initially on text road identification markers, followed by glances to numeric and symbolic road markers. There was also significant interaction between marker type and map orientation for their influences on eye fixation. It is anticipated that by taking the driver preference for road marker type into consideration in the design of in -vehicle route displays, the system will be used more efficiently.