“…Considerable research has been performed to reveal the mechanisms of fatigue cracking in OSDs by investigating the design (Connor & Fisher, 2006;Kozy, Connor, Paterson, & Mertz, 2011;Nader & Baker, 2014;Wang, Feng, & Duan, 2009) and fabrication procedures (Sim, Uang, & Sikorsky, 2009;Wolchuk, 2014;Ya, Yamada, & Ishikawa, 2011). Adding an extra concrete layer results in decreased traffic-induced stress in some fatigue-prone points of OSDs (Walter, Olesen, Stang, & Vejrum, 2007), and reduced stress leads to a diminished risk of fatigue cracking.…”