11 A pplic able bearing c a pacity c alcula tions are per the A A SHT O LRFD f or B ridge D e sign T he c alcula tion c onsider s a dead load based on c o v e r with a dead load f a c t or o f 195 In addition it applies a liv e load with a multiple presenc e f a c t or o f 12 an d a liv e load f a c t or o f 175 which is distributed a t a 115 f a c t or f or aggrega te through the c o v er dep th If the c o v er ma terial is soil this f a c t or is reduc ed to 100 T he f ollo wing are tw o ex amples o f tha t c alcula tion 1 HS25 with 24 aggrega te and asphalt c o v e r DL D ensity dep th DL F a c t or 14000 pc f 200 195 54600 psf LL P DLA MP LL F a c t or 20000 lbs 1 12 175 20 24 115 10 24 115 144 LL 337922 psf TL R equired B e aring C a pacity 54600 337922 392522 psf 2 HS20 with 48 aggrega te and asphalt c o v e r DL D ensity dep th DL F a c t or 14000 pc f 400 195 109200 psf LL P DLA MP LL F a c t or 16000 lbs 1 12 175 20 48 115 10 48 115 144 LL 98682 psf TL R equired B e aring C a pacity 109200 98682 207882 psf appendix a bearing c a p a city c alcula tion P r essure Required Required B e aring P P D D A D P P D D A D P D T ire P r essure A r ea