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j�..� Desihn of Pavement Structures
<br /> Table 4.3. Effective roadbed soil resilient modulus values, MR (psi),that may be used in
<br /> the design of flexible pavements for lots-volume roads. Suggested values
<br /> depend on the U.S.climatic region and tho relative quality of the roadbed soil.
<br /> Relative Quality of Roadbed Soil
<br /> U.S.
<br /> Climatic
<br /> Region Very Poor Poor Fair Good 'Very Good
<br /> I 2.80G• 3,700 5.000 6,800 9.500
<br /> li 2,700 3,400 4,500 5.500 7,300
<br /> NI 2,700 3,000 4,000 4,400 5,700
<br /> IV 3,200 4,100 5,600 7,S,00 11,700
<br /> V 3,100 3.700 = '00 6,000 3,200
<br /> V1 2,200 :.'.00 CO 4.-,-X 5,700
<br /> ~ee see as ietr. tr, s:
<br /> . :cdt:_as of.h: rD3-dbed Soil CTe`.' .01:_ . I:,,: Ib j 2:: Z ._-1CSS-' ....:Bch:s1,GT='..:-'T-'.::ver
<br /> �. . p c=tn t ceriLnshould not r_used in iieu of
<br /> IL' t prccec.,=described her-_
<br /> Trc<_e de:''n re"uircments are ased i.^. conj;:=:t. 3
<br /> wit: the ccn-imm6onal chart in fable 4.4 and the
<br /> T-e primary design :eauirements for agZ..regate- dcsic:nnomc`-zaphs for (Ficure4.?.)and
<br /> sunac..d roads (17) include: rutting(Fig-.a-e 4.3). An example of the application of
<br /> certain steps of this procedure is presented in Table
<br /> 4.5.
<br /> O the predicted future traffic, wlg (Section
<br /> 2.1.2), for the period, Step]: Select four levels of aggregate base thickness,
<br /> DBS,which should bound the probable solution.For
<br /> (2) the lengths of the seasons(Section 2.3.1; or this,four separate tables,identical to Table 4.?,should
<br /> criteria in Section 4.1.1 may be used if better be prepared.Enter each of the four trial base thickness,
<br /> infortraticn is not available), DBS,in the upper left-hand comer of each of the four
<br /> tables (DBS = 8 inches is used in the example).
<br /> (3) seasonal resilient moduli of the roadbed soil
<br /> (Section 2.3.1 or general criteria in Section Step 2: Enter the design serviceability loss as well as
<br /> 4.1.1 may be used if better information is not the allowable rutting in the appropriate boxes of each
<br /> available), of the four tables.
<br /> (4) elastic modulus.ELS(psi),of aggregate base Step 3: Enter the appropriate seasonal resilient
<br /> la,.er, (Sec:ion 2.3.3), ( asttc)moduli of the roadbed(M,,)and the aUrcgate
<br /> base r ater:a , t:v.� (psi), in Colum.:ts 2 an] 3, resrcc-
<br /> - , ate tttei}, of l' b,, .4. The bast mo l us ca':.c� ty re bC
<br /> t:) clastic modulus, E` (, st), of cgcrcr :
<br /> ,uo�asc i�}.r��.cuo. �.-.3), pro :rt:or:. I to t!"e rc-tiient
<br /> sot! .:r. ci.. ,,:::,,t;1. A con .:,::: .z, of
<br /> : si s�r�i ":bill i. S, .�P�I (Sc ::n ps: '.t:s „1 u: t'._ e .a;t i' .. `:ot�e.,_ a ;
<br /> CQilt.11 nt t:a':?..., :s Of suct'.l�C Tnat�..:=1
<br /> (7) allowablc rutting, RID (inches), in surface prostd.some i;:ci l,:cal(utt`:cea�tro::r.:c^ta!r,:.aturu
<br /> layer(Section L2.2), and effects).
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