MR87-1_REDUCED.pdf

CONCLU S I ONS AND RECOMMENDAT IONSIt isapparentfromthequantity ofzinc-coatedcorrugatedsteelpipe(CSP)beingreplacedbytheDepartment ' s own forces and the quantity being replaced bycontract, that a major problem exists with the durability ofCSP. In 1986 , the Department ' s personnel placed 37 , 583linear feet of CSP at a cost of $968 , 890. Also, the CSPwere replaced or lined by contract on 94 . 653 miles ofroadway at a cost of S450~094 .TheDepartment ' s culvert type selection policy allowsas much or more use of CSP as the adjoining Statessurveyed, except Kansas .Inselectedrelocate.Missouri , roadbeds and highway corridors areand designed with no foreseeable intent toAt the present time, approximately 25 percent ofthe Department ' s roadbeds are already 50 years or older and74 percent are over 25 years of age. Current field reportsshowthat CSP is being replaced as early as 20 years of agedue to rusting out of the lower portion of the flowline(invert) .Zinc- coatedcorrugated steel pipe is less durable thanRCP with Missouri soils and drainage .The mode offailureis different for the two types of pipe .nearly always due to a material failure ,Failure of CSP isrusting out of theinvert .Failure of Rep is normally due to disjointed pipesections , a mechanical failure .- 3 -