This chapter clearly demonstrates how human factors engineering (HFE) helps to improve safety, comfort, and system performance of surface transportation systems. From exploring physical and psychological individual differences, the causes and results of violated behaviors, and drivers' visual and cognitive limits, HFE contributes greatly to reducing accidents and failures caused by human and system errors, as well as enhancing human-friendly designs of in-vehicle devices and roadway elements. Studies have shown reduced mental workload of drivers when using Adaptive cruise control (ACC) system due to the driver being relieved from some elements of the driving task. The elements and symbols used on the displays should also be consistent with the allowable movements. Eye movement provides possibly the most beneficial information of where and to what extent drivers attend to various objects in and outside of their cars. Technologies for the detection of driver fatigue include: detection from visual cues like eyelid movement, gaze movement, head movement, and facial expression.