Effects on Driving Performance of Long-term Exposure to a Seatbelt Reminder System: Findings from the Australian Tac Safecar Project

The TAC SafeCar study evaluated the impact of three Intelligent Transport System technologies, alone and in combination, on driver performance: Intelligent Speed Adaptation, Following Distance Warning and a Seatbelt Reminder system for all seated occupants. The project had several aims: to evaluate the technical operation of these technologies; to assess the acceptability to drivers of them; and to evaluate, in an on-road setting, the impact of them, alone and in combination, on driver performance and safety. Twenty-three fleet car drivers (15 treatment and 8 control drivers) participated in the on-road study. Each participant drove a SafeCar for at least 16,500 kilometres. The SafeCar project was the first to evaluate the effects on driving performance of long-term exposure to a Seatbelt Reminder system. The results, reported in this paper, revealed that driver and passenger interaction with the Seatbelt Reminder system led to large and significant decreases in the percentage of trips where occupants were unbelted, in the percentage of total driving time spent unbelted, and in the time taken to fasten a seatbelt in response to the seatbelt warnings. The Seatbelt Reminder system was rated by drivers as being useful, effective and socially acceptable, and use of it led to a decrease in drivers’ subjectively reported mental workload. Based on the results of the study, use of the Seatbelt Reminder system is estimated to save the Australian community approximately AUD $335 million per annum in reduced HARM costs. These findings were yielded even though initial seatbelt wearing compliance rates in the community were high, suggesting that Seatbelt Reminder systems can be effective in improving seatbelt compliance among occupants who already have high wearing rates. INTRODUCTION There is clear evidence that seatbelts are effective in reducing trauma to vehicle occupants in crashes, and in saving lives (Krafft et al., 2006; Glassbrenner, 2004; Eby et al., 2005). Consequently, new passenger vehicles are routinely fitted with them. In many jurisdictions around the world there is legislation that mandates the use of seatbelts by all vehicle occupants. Despite the existence of this legislation, however, there are many occupants who choose not to wear seatbelts. Within the European Union (EU) Member States, for example, the average wearing rate for front seat occupants is 76 percent; for rear seat occupants, it is 46 percent (Krafft et al., 2006). In Australia, the comparable rates are 95 and 90 percent (Transport Accident Commission, 2007), respectively, even though the use of seatbelts by all seated occupants is actively enforced there by police. In the US, around 80 percent of front-outboard vehicle occupants use their seatbelt (Glassbrenner, 2004). Even though Australia has a relatively high rate of seatbelt use, around 33 percent of occupants killed each year in car crashes are unbelted (Fildes et al., 2002). In Sweden, the comparable figure is 40 percent (Krafft et al., 2006). The reasons why vehicle occupants fail to wear seatbelts are many and varied. For some, it is a deliberate choice. For others, it is that they simply forget (see Harrison, Senserrick & Tingvall, 2000). In Australia, non-users appear mainly to be inconsistent users (rather than consistent nonusers), who wear seatbelts in most day-to-day driving activity and tend not to only in slow or residential driving situations (Harrison, Senserrick & Tingvall, 2000).