Road　surface　roughness　is　an　important　indicator　for　evaluating　the　service　quality　and　performance　of　asphalt　pavements;　the　traditional　evaluation　index　for　this　indicator　is　the　international　roughness　index　(IRI).　In　this　study,　in　order　to　comprehensively　evaluate　the　riding　comfort　induced　by　pavement　roughness,　indoor　laboratory　tests　and　field　tests　were　conducted　on　the　threshold　value　of　the　IRI.　The　laboratory　tests　used　a　driving　simulation　chamber,　and　the　field　tests　used　12　typical　roads　in　the　Miyun　District　in　Beijing,　China.　Three　different　evaluation　techniques　were　used:　a　questionnaire;　a　vibration　acceleration　method　(aw,　the　weighted　root-mean　square　acceleration);　and　a　psychological　and　physiological　index　root-mean　square　of　the　successive　differences　(RMSSD)　method.　The　evaluation　techniques　were　employed　in　order　to　analyze　the　threshold　value　of　the　IRI　for　both　the　laboratory　and　the　field　tests.　The　evaluation　revealed　two　significant　results.　For　a　constant　driving　speed,　as　the　IRI　value　increased,　the　evaluation　indicator　aw　increased,　and　the　value　of　the　RMSSD　decreased　linearly.　For　a　constant　IRI　value,　as　driving　speed　increased　both　the　evaluation　indicator　aw　and　the　RMSSD　value　increased.　Furthermore,　the　fitting　results　showed　that　the　correlation　coefficient　R2　between　the　IRI　and　the　driving　speed　reached　0.9525　for　the　outdoor　test,　indicating　a　high　relativity.　The　methods　for　the　evaluation　of　the　IRI　threshold　value　that　were　explored　in　this　study　are　very　promising,　having　the　potential　to　improve　pavement　construction　and　maintenance　efforts.　(c)　2020　American　Society　of　Civil　Engineers.