MR87-1_REDUCED.pdf

Durability o f Corrugated Me t a l Culvert s j New York St a te De p a rtme n tof Tran sporta tio n, 1 977 Survey ; The Quarterl y R&D Di gest, No . 7 ,(NYOOT Publicatio n ) .Field studies after the 1 965 survey ind icated, " ... i t a p p e a redthat meta l l o ss rates f ar exceeded t hose e stimated in the1965 survey." In 1975, a change was made in desig n po licy t opro vide greater pro tectio n o f inverts by providing a mi nimumof 8 gage plates o n inverts and coating a nd paving all 14and 16 gag e cross drains. "These changes p rovided suff i c ientmetal for an annual corros ion r ate o f 0 .004 inches, a ssumi nga 40-year design lif e and that c oating and paving protect apipe f o r 25 years . "((Having f: c l.::: c t: .:! d th ~ mCLoSU!"C::lcn t techn"l(jue 3ud sampling plan , 190 ptpes vere Eeleetcd r.o prov ide- brond eovcr .nr,c. i:.hroiir,hou t the s tll te , ft.mo n g the fiv e eor rosi venesszo nes p re.v i ol1:':J.y estf!bEs hcd . Har.n:i.tudcs of :i!etal loss were Dimil ar tot hose e ::; timated a nJ mc a sHt"!::! d in earl:i e r \.'ol.'k , but t h e distributi on of losses didno t correspond to the five zones .Figun~ 1 ShOW' D two probabi.lity curves c o rresponding to ttIO np.w 7.QU.:"!S shown :lorieun:' 2 . 'l11e~c l' ~ s l!lts inui.::ntc thnt si:'.!t~ l culverts corrode .:!t r.":