In　this　study,　a　comparative　analysis　of　the　impact　of　the　attack　angle　and　windscreen　height　on　the　vortex-induced　vibration　(VIV)　in　a　streamlined　closed-box　girder　was　conducted　using　a　1:50　scaled　model　of　a　coastal　cable-stayed　bridge　through　wind　tunnel　tests　and　numerical　simulations　covering　a　range　of　attack　angles　and　windscreen　heights.　The　simulations　were　validated　through　experimental　data,　grid　sensitivity　analysis,　and　time-step　independence.　The　results　revealed　that　the　VIV　amplitude　increased　with　increasing　attack　angle　because　of　the　interaction　between　vortices　from　the　traffic　lane　and　those　in　the　wake　region.　Specifically,　under　a　+5◦　attack　angle,　pronounced　VIV　was　observed　in　the　section,　with　the　maximum　torsional　VIV　amplitude　reaching　up　to　4.1　times　the　code-specified　limit.　Spectral　analysis　revealed　that　within　different　wind　speed　lock-in　ranges,　the　vibrations　consistently　corresponded　to　the　torsional　fundamental　frequency　mode.　Further　insight　from　proper　orthogonal　decomposition　(POD)　based　on　singular　value　decomposition　(SVD)　revealed　that　the　large-amplitude　torsional　VIV　of　the　section　was　caused　by　separated　vortices　over　the　traffic　lane　persistently　transferring　energy　to　the　wake　Kármán　vortices,　forming　large-scale　vortices　that　could　lock　in　with　the　torsional　mode　of　the　main　girder.　Windscreens　on　both　sides　of　the　section　effectively　reduce　the　VIV　amplitude　through　distinct　mechanisms:　the　windward　screen　delays　flow　separation.　Moreover,　the　leeward　screen　altered　the　path　of　the　vortices　toward　the　wake　region.　When　the　windscreen　height　reached　4.5　m,　the　vortex　movement　path　to　the　leeward　side　was　completely　blocked,　fully　suppressing　the　VIV.　The　effect　of　windscreen　height　on　VIV　was　closely　linked　to　lift,　surface　pressure,　and　their　correlation.　These　findings　provide　valuable　insights　into　wind-induced　vehicular　safety　measures　and　VIV　suppression　strategies　for　sea-crossing　bridges.　©　World　Scientific　Publishing　Company.