MR87-1_REDUCED.pdf

INTRODUCTIONThe Department ' s current policy for selection of typeof culvert pipe to be used has been in effect for many yearsand is contained in Chapter IX ,Section 9-10 of the Surveysand Plans Design Manual .A copy of that policy is shown inAppendix A. Briefly , the policy allows corrugated metalpipemetalfor all entrances but restricts the use of corrugatedpipe for crossroad installation to roadways with lessthan 400 ADT regardles~ of surface and roadways with morethan 400 ADT that do not have a concrete or asphalticconcrete surface .Corrugated metal pipe has only been permitted forculvert installations in those areas that when the needforreplacement occurs, it is not detrimental to or does notseriously impede the flow of traffic . Examples areentrances, approaches and crossroad culverts on thosefacilities with lower traffic volumes and which do not havea high type pavemen t surface . On the remainder of thehighway system , only those culvert materials which will givethe greatest known life expectancy are permitted . Forculverts and storm water conveyance,concrete .that materialisThere were several reasons for the development of thecurrent design policy .The first being to maintaintheintegrity of the facility .It was thought that if a culvertpipehad to be replaced under a high traffic volume roadway- 1 -