In-vehicle monitoring to investigate older drivers’ speeding and rapid deceleration behaviour

Abstract

This study sought to monitor driving of 380 drivers aged 75+ yrs for a week and 190 for up to a year. Volunteers’ vehicles were instrumented to monitor speed, distance and deceleration. Participants undertook cognitive and visual assessments at baseline and 12 months. We examined drivers’ involvement in speeding events (averaged over 30s), and rapid deceleration events (RDEs) (>750milli-g) for 362 vehicles (182 over 12 months). We used two safety outcomes: speeding as this increases crash risk and injury severity, and RDEs as an indicator of a near crash. We examined how measures of cognitive and visual function affected speeding and near crashes. Speeding was common, involving 99% of 177 participants; however, as a rate per distance driven, speeding decreased with age. Although speeding was less frequent for drivers with lower cognition and visual scanning, poor function was not predictive of speeding per distance driven. This suggests older drivers with poorer function decrease speeding by driving less. High-range speeding (average 10+km/h above the limit) was infrequent. Drivers involved in high-range events drove approx. twice the kms as those not involved. Drivers with reduced cognitive function were involved in fewer high-range events per distance driven. This suggests older drivers with poorer cognition and visual attention may drive more cautiously. Of 177 participants, 64% were involved in 1+ RDEs over 12 months. Drivers who experienced a decline in contrast sensitivity over the year were at increased risk of RDEs per distance. As other researchers have found a relationship between reduced contrast sensitivity and increased crash risk, our finding supports the use of RDEs as a surrogate safety measure. While the majority of older drivers drive less distance and with increased care to increase their safety, there is a need for policy makers to maintain speed control measures and further consider the health of older drivers, specifically deterioration in eyesight.