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One important variable to distinguish traffic systems from other engineering or industry systems is human factor. It is vital for traffic engineers to consider drivers’ comfort as well as physical risk in transportation design as that is one of the prime objectives of the transportation services. Present standards for sight distance design at a stop controlled intersection focus on mathematical principles based on the concept of acceptable gap. As an attempt to evaluate the formulized design standard from the subjective perspective of drivers, this paper examines the effects of intersection sight distance (ISD) on drivers’ physiological reaction, as measured by the heart rates during turning. In the designed experiment, drivers were asked to make right turns at stop-controlled intersections with varying sight distances. Some of the intersections have sufficient sight distance according to AASHTO design standards, while others do not. Drivers’ heart rates were measured during the “turning” stage which is defined as the time from stop at stop sign to the moment when they finish the turning maneuver. Statistical analyses were performed upon the reduced data to explore the relationship between ISD and drivers’ heart rate during turning. The results reveal that ISD does have statistically significant impact over drivers’ heart rates which would influence their subjective evaluation of roadway design. Intersections with sight distance greater than the design value in AASHTO do incur less stress to drivers. This research opens a new direction to evaluate and optimize traffic designs based on human-oriented criterion.