Professional bus drivers are highly exposed to physical fatigue and work-related injuries because driving task includes complicated actions that require a variety of ability and cause extreme concentration or strain. For this reason, there has always been some sense of concern regarding driver fatigue, especially for drivers of commercial vehicles. In this study, we have tried to analyze quantitative fatigue degree of urban bus drivers by measuring their physiological signals. The investigation is made up of the following approaches: a traditional questionnaire survey and video-ethnographic method with 4-way cameras. The close-circuit cameras are installed to observe the upper and lower body of real drivers when they are in driving or even resting. This approach can help to understand urban bus drivers' behaviors and fatigue-related issues. Based on the video-ethnographic investigation results above, we have got certain patterns of drivers. For these critical driving conditions, the analysis of muscle fatigue using the signal processor of electromyography (EMG) is accomplished. Totally, nine commercial bus drivers are selected as subjects who are divided into 3 groups by their statures. Four kinds of muscle are selected to be analyzed: rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA) and gastrocnemius (Gn). In consequences of the analysis of EMG signal, we found out the following results. First, pedal operation is in high fatigue on stand-by condition especially when operating clutch pedal due to its considerably high position. Second, the use of footrest is very low for real drivers, although the footrest can ease drivers' fatigue to some degree. This is because drivers generally can operate clutch pedal faster without footrest condition in traffic congestion. Third, there are two kinds of patterns in operating brake pedal and we can see different trends by region and stature.