There have been several attempts to define the parameters influencing the aesthetic qualities of structures in architectural and engineering fields. Relationship of ?Visual Appearance vs. Structural Form? found visible and impressive in examples of bridge structures. The objective of this study is to evaluate the principles related to aesthetics of bridge structures and to make a comparative and quantitative study based on these principles. The case of Imrahor Valley Viaduct has been first overviewed with its construction technique and design parameters. Then, design dimensions of the bridge have been changed and alternative design dimensions have been analyzed with specific structural analysis programs to illustrate and compare the resultant visual effects of the studied alternatives. The study is concluded with suggestions for the quantitative researches concerning the visual appearance of bridge structures.