Traffic　safety　devices　are　one　of　the　most　important　tools　used　to　improve　safety　in　tunnels.　The　tunnel　retro-reflective　arch　(TA)　plays　a　crucial　role　in　stimulating　drivers,　relieving　visual　stress,　and　improving　safety.　However,　determining　the　TA　spacing　mostly　relies　on　experience　and　relevant　standards　are　lacking.　The　aim　of　this　research　was　to　evaluate　the　degree　of　influence　of　the　TA　on　driver　behavior,　visual　aspects,　and　psychology　in　different　zones　(overall　tunnel,　curved　segment,　and　middle　segment)　of　extra-long　tunnels.　To　test　the　influence　of　TAs,　four　scenarios　were　constructed,　including　three　alternatives　with　different　TA　spacings　(200,　300,　and　400　m),　and　one　no-arch　design　as　a　control　alternative.　Based　on　a　driving　simulator,　the　evaluation　indicators　related　to　driving　safety,　smoothness,　and　handling　stability　were　selected　and　analyzed.　We　acquired　data　every　50　m　as　an　analytical　unit.　The　results　show　that　the　TA　significantly　affects　driver　behavior,　visual　aspects,　and　psychology.　According　to　the　matter-element　model　result,　setting　the　TA　spacing　to　300　m　in　curved　segment　and　in　the　tunnel　overall　is　the　best　option.　In　the　middle　segment,　the　setting　spacing　of　400　m　is　ideal.　©　2020　Elsevier　Ltd