The population density in Taiwan is very high, especially in the metropolitan areas. The huge amount of motorcycles (532 motorcycles/1000 people) results in complicated traffic conditions and safety problems such as cars and motorcycles competing for lanes. Moreover, in-vehicle multimedia systems have become popular in Taiwan. A driver’s workload increases when he or she watches or listens to a multimedia program.

The analysis of official accident reports shows that, among various types of crashes in which motorcycles involved, side collisions and side-swipe collisions account for about 50% of all collisions. Normally, drivers tend to look forward while driving. Therefore, car crashed could easily happen if drivers fail to notice their surroundings when motorcycles suddenly approach. In this context, Side-Collision Avoidance Systems (SCAS) could be capable of alerting drivers and enhancing safety. However, few studies and systems reflect on traffic conditions where motorcycles are mixed in the traffic. This study employed a driving simulator to assess the effects of using SCAS and in-vehicle multimedia on drivers’ workload and driving performance (i.e., drivers’ perception reaction times, the change in heart rate and eye blinks) while moving in traffic mixed with cars and motorcycles.

A primary finding of this study was that cars equipped with SCAS could decrease drivers’ perception-reaction times effectively. The type of vehicle cutting in (car or motorcycle) had a significant influence on drivers’ perception-reaction times—drivers displayed longer perception-reaction times when a car cut in than when a motorcycle cut in. This result indicates that drivers were more attentive in the traffic flow mixed with motorcycles. In addition, the change in drivers’ eye blinks (from before a vehicle cut to after a vehicle cut in) were all negative--drivers blinked less frequently after a vehicle cut in. This finding indicates that drivers were more alert after vehicles cut in than before vehicles cut in.