Most　existing　road　infrastructures　were　constructed　before　the　emergence　of　automated　vehicles　(AVs)　without　considering　their　operational　needs.　Whether　and　how　AVs　could　safely　adapt　to　as-built　highway　geometry　are　questions　that　remain　inconclusive,　and　a　plausible　concern　is　a　challenge　from　vertical　alignments.　To　fill　this　gap,　this　study　uses　a　virtual　simulation　to　investigate　the　available　sight　distance　(ASD)　of　AVs　on　vertical　alignments　subject　to　the　current　highway　geometric　design　specification　and　its　implications　for　speed　limits.　According　to　the　scenario　generation　framework,　several　scenarios　featuring　vertical　geometric　elements　and　lidar　sensors　were　created　and　tested.　Moreover,　the　maximum　speed　for　adequate　ASD　is　calculated　to　determine　the　AV　speed　limit,　considering　safe　sight　distance　and　speed　consistency　requirements.　The　results　indicate　that　crest　curves　are　not　disadvantaged　in　ASD　compared　with　either　sag　curves　or　tangent　grades.　Only　equipped　with　multichannel　lidar　and　advanced　perception　algorithms　enabling　a　lower　detection　threshold　would　a　level　4　AV　be　compatible　with　the　as-built　vertical　alignment　with　a　design　speed　(Vd)　of　100　km/h.　However,　a　level　3　AV　can　only　adapt　to　the　vertical　profile　with　Vd　=　60　km/h.　The　findings　of　this　study　should　be　of　interest　to　the　road-oriented　operational　design　domain　and　support　road　administrators　in　regulating　AV　safe　speeds.　1939-1390　©　2023　IEEE.