Abstract
With the rising popularity of private automobiles, the number of driver's license holders in Taiwan increases year by year. It has now reached more than 50% of the population in Taiwan. However, traffic accidents due to poor driving awareness or skills are still quite common, in which "improper lane changing" is the main cause of fatal accidents on the highway. Advanced Driver Assistance System (ADAS) was hence developed to solve this problem, among which the Lane Change Assist (LCA) and the Blind Spot Detection System (BSDS) had become mature and been used widely. In the meantime, relevant standards for the LCA are developed by ISO. Nevertheless, so far there is no agreement on the design of warning signals used in LCA. Currently, a variety of warnings of LCA may lead to misunderstanding of the representations or conflicts with prior knowledge, even though the information to be conveyed is exactly the same. Thus, this study aims to investigate the effect of situation awareness level of warnings in LCA on driving performance and workload, so as to enhance safety through designs that help drivers receive the information more effectively and accurately. Ten males and ten females who belong to the high-risk groups of traffic accidents (20-26 years old) with more than two years of driving experience were recruited (including driving on the highway). Besides, those who are too conservative or too risky were excluded by using the Driving Anger Scale. A driving simulator was used to perform driving tasks on a highway. Participants had to change lanes with the use of LCA presented in four situation awareness levels (no warning, perception, comprehension, or projection). The differences in objective parameters (steering wheel rate, success rate of task execution, and reaction time) and perceived workload (NASA-TLX) were analyzed, in order to identify the design that is most helpful for driving safety. The interaction between driver’s gender and warning level were also investigated to see whether the recommended warning levels are different between the two groups. The results showed that the warning system provides the greatest help when the neighboring vehicle appears in the blind spot area. Besides, drivers had the last reaction time and completion time under the LCA warning of the third level (projection). LCA of both the second (comprehension) and third levels yielded significantly better performance than the first level (perception) and the case without LCA. However, the difference between the second and third levels is not significant. According to the subjective responses, males preferred the second level, while females preferred the third level. Therefore, it is recommended to provide LCA with multiple levels of situation awareness, so as to enable the driver to choose the preferred one. Overall, the findings of this study have the potential to benefit developers of LCA by facilitating the designs that better meet the needs of drivers and help reduce traffic accidents.