Statistics showed that mental workload is among the top 10 causes of accident in Malaysia which leads to more than a thousand deaths from 2011 to 2018. Driving distraction forces the driver to focus on causes other than driving thus, this condition will increase the mental workload among the drivers. Factors that can contribute to the increment of driver’s workload includes vehicle, human-related and external factors. This study aims to assess the driver’s mental workload using two types of subjective evaluation namely the NASA TLX and Karolinska Sleeping Scale (KSS) on different types of road environment complexity.

Methods: Six healthy participants performed a simulated driving task for two different road scenes which are urban and rural road where the NASA-TLX and KSS score were recorded.
Results: Results show that the different road environment complexity affects the driver’s mental workload differently where NASA-TLX average score for urban road is higher compared to the score for rural road. On the other hand, KSS level indicates a higher score on sleepiness level when driving on the rural road compared to driving on the urban road.

Conclusion: These findings might be useful as a reference to further understanding of driver’s mental workload when driving on different type of road environment complexity.