The　perceptible　vibration　of　concrete　box　girders　under　traffic　loads　is　an　important　topic　in　existing　bridges,　on　which　vehicle　movement　often　cause　vibrations　too　strong　from　the　viewpoints　of　travelers.　In　this　paper,　the　results　of　an　extensive　program　of　full-scale　ambient　vibration　tests　involving　a　380 m　concrete　box　girder　bridge,　the　Cannavino　bridge　in　Italy,　are　presented.　The　human　safety　assessment　procedure　of　the　bridge　includes　ambient　vibration　testing,　identification　of　modal　parameters　from　ambient　vibration　data,　comparison　with　a　detailed　finite　element　modeling　as　validation　of　experimental　measurements,　comparison　of　peak　accelerations　to　reference　values　from　technical　standards/literature　in　order　to　estimate　the　vibration　level,　and　evaluation　of　safety　by　the　use　of　histograms.　A　total　of　nine　modal　frequencies　are　identified　for　the　deck　structure　within　the　frequency　range　of　0–10 Hz.　The　results　of　the　ambient　vibration　survey　are　compared　to　the　modal　frequencies　computed　by　a　detailed　three-dimensional　finite　element　model　of　the　bridge,　obtaining　a　very　good　agreement.　It　emerges　that　a　linear　finite　element　model　appears　to　be　capable　of　capturing　the　dynamic　behavior　of　concrete　box　girder　bridges　with　very　good　accuracy.　For　each　direction,　experimental　peak　accelerations　are　compared　to　acceptable　human　levels　available　in　technical　standards/literature,　showing　that　traffic　loads　mainly　induce　a　vertical　component　of　vibration　on　the　bridge　deck.　Finally,　the　elaboration　of　histograms　allows　to　assess　that　the　bridge　is　exposed　to　clearly　perceptible　vertical　vibrations,　requiring　the　adoption　of　suitable　vibration　reduction　devices.　©　2017,　Iran　University　of　Science　and　Technology.