Harsh braking by truck drivers: A comparison of thresholds and driving contexts using naturalistic driving data

Frequent harsh braking is an example of risky driving behaviour by truck drivers. This study explored how threshold values on longitudinal deceleration affect the detection rate of harsh braking events across driving contexts. Naturalistic driving data from the EU project UDRIVE was used to study the behaviour of 24 Dutch truck drivers. Harsh braking events were identified through longitudinal deceleration using an initial threshold of 3.0 m/s2. The maximum deceleration in each event was used to stratify the events, covering a range of threshold values found in previous studies. In total 2031 events were found. For each speed limit the mean event rate was calculated across drivers. The event rate at urban roads (30, 50 km/h) was significantly higher than at rural roads (60, 80 km/h), which in turn was significantly higher than at highways (100, 120+ km/h). Drivers with a high event rate at urban roads also showed a high event rate at rural roads and highways, but only for thresholds up to 4.0 m/s2. Finally, we found distinct event rate distributions when we manipulated the threshold value. Our results suggest that driving context influences harsh braking behaviour, and that drivers have distinct driving styles. We discuss the implications for in-vehicle monitoring systems and driver coaching.