Pavement Roughness Studies

Transcription

1 Transportation Kentucky Transportation Center Research Report University of Kentucky Year 1962 Pavement Roughness Studies James H. Havens Kentucky Highway Materials Research Laboratory This paper is posted at UKnowledge. researchreports/1196

2 HENRY WARD COMMISSIONER OF HIGHWAYS COMMONWEALTH OF KENTUCKY DEPARTMENT OF HIGHWAYS FRANKFORT.February23, 1962 ADDRESS REPLY TO DEPARTMENT OF HIGHWAYS MATERIALS RESEARCH LABORATORY 132 GRAHAM AVENUE LEXINGTON 29, KENTUCKY D. L 7. P.4. L MEMO TO: A.. Nei.ser Assistant State Highway Engineer The attached report, "Pavement Roughness Studies," by Rolands L, Rizenbergs Research Engineer Associate, is a pro, gress report on research performed in this field during 196L Possibly the most significant effort has been the evaluation of three segments of new Interstate pavement opened to traffic during the year. A separate plot of the roughness index values for Interstate pavements has been prepared and is shown in Fig. 6, page 18. Roughness index values for component layers of Clark County, I645(7)93, are shown in page 16. These data. indicate that through careful leveling, etc., significant reduction in roughness values can be accomplished. The roughness index values for Interstate pavements have been reported previously to the Construction Division. These data \Alere requested for use in final pavement inspectl<yn prior to acceptance and before the projects had been opened to traffic. Mr. Rizenbergs has descr::.bed a pavernen.t serviceability study that resulted in the rati.ng of th1eee pavements by methods used at the AASHO Road Test: ProjecL We find, on a limited basis that there is son1e correltition. between the roughness index and present serviceability i:ndex"

3 A.. Neiser 2 February 23, 1962 We, were invited. to participate in a cooperative pavement roughness evaluation along with Michigan, Illinois, Indiana, AASHO Road Test Staff, and the Bureau of Public Roads in northern Indiana, in August, We have comparative values from methods in use by each of the groups for correlation with our values. Following this work, we have had inquiries indicating that the Indiana Joint Highway Research Project is considering obtaining roughness equip rnent patterned after the Kentucky udt. California has built two of these units, We plan to continue evaluation of projects under study and to begin roughness measurements on major projects completed during the next year, WBD:dl Enc, cc: Research Committee Members Bureau of Pablic Roads (3) Respectfully submitted, W, B, Drake Director of Research

4 3. During 1961, the equivalent of about 8 lanemiles of pavement were tested and analyzed, The largest portion of this mileage was on completed Interstate projects, In November, three pavements selected by the Bureau of Public Roads for serviceabilityindex ratings (6) were tested; and these are discussed briefly in this report, Periodic surveillance of the roughness of all of the roads presently listed in Tables land 2 is contemplated, New primary and Interstate construction will be included in the future, Thus, each respective project may be eventuau.y characterized by a history of roughness measurements.

5 RESULTS AND ANALYSES All of the data applicable to the projects under study are shown in Tables 1 and 2. A map showing the approximate locations of the completed Interstate projects is presented in Fig. l. Rating of Prim and Secondary Roads The roughness of portland cement concrete and bituminous pavements both primary and secondarys were considered in a combined plot in Fig. 2. This data was subdivided into approximately equal quartiles (containing equal number of projects) which are indicated by the "word" classification given at the bottom of Fig. 2. An overlap was allotted to each quartile in order to avoid sharp distinction between pavements having nearly the same roughness indexes. The median roughness index of 6 was computed from all the available data without any distinction as to the types or ages of pavements. There are as ma!ly roads having roughness indexes,greater than 6 as there are roads having less than this value. Accordingly, the median value was sel,ected as the midpoint for the "word" classification. Hence, the first quartile to the left and right of the median were designated "good" and "fair" respectively, and the outer quartilesa in the same respective order, were designated as 11 excellent" and "poor". The inclusion of several additional roads has increased the median roughness over that of the previous year thereby, C<\Using a shift in the quartile boundaries. 4,.

6 5 TABLE BITUMINOUS CONCRETE PAVEMENTS ROUTE PROJECT NO. and ACCEI'TAIJCE YR, " N.I!J1E OF "" COUNTY LENGTH IN MILES INTERSTATE Im" ROUGHNESS INDEX 1. i "' 1645(8)1!645{7) (9)9 Mt, Sterling Winchester Mt, Sterling Wincheeter Mt, Sterling Winchester Montgomery Clark Olark '' '" Completed in Co111p1oted 1n C111pleted in US 6 KY ROUTES US 2) Nil 77 A(2)) 1948 us 25 Nl3 FI 29{9) 19Sl Painteville Louisa London Mt, Vernon Joh.nson Laurel Oil Ruur!'acod in US 25 $B FI 7(6) 1954 US 25 SB FI 299{6) US 25 SB FI 124(4) 1946 US 25 SB Fl 23(16) 1948 London Mt, Vernon Richmond Here!!. Laxington Clay" Ferry Williatnsburg Tenn, Line Jlockc!latle Madison Fayette Madison Whitley ). 7.9 > J) o Strip Patch us 25 Nl3 1/ )22{7) Middleboro ByPass ' ll lllj 985 US 25 SB UI 538(5) Lexington Relief Rt, us 27 Nil S )66(2) Lancaster F 525(2,3,4.5 ) 1948 Nicholasville US 27 SB F lll9(5,6) 1952 US 27 SB F 544(1!,5) 1949 Lexington Nicholasville Cynthia.na. Paris F!IJ'ette Garrard Fay.,tte Jessa.rnine Huriaon Re,.ur!aced in Re,.urfaced in us )JE US )lw FI 14{12) 1953 " US )lw Fl 113(5) Sll FI 16(2) 1955 US )le F 28(5) NB F 7(5) 195 US 41 SB F 526(9) 195 US 41 SB F 526(12) 195) US 41 Sll F 526(13) 195) us 41 Sl3 F 526(1) 1951 US 45 SB F llj6(19) 1956 US 6 WB FI )(8) 195 US 6 WB us 6o :n US 6 WB US 6 WB US 62 WB us 62 Jo.'B Hodgenville Bardstown Munfordville ELtown Bcr.rling Green E' town Glasgow Hodgenville Henderson Madisonville Henderson Jijadisonville i'!ender<>on Mactisondll l!endersonl1adisonville MaYfield Wingo Louisville Paduc!lh. t4oreh.ead OIIingsville F: 1(4) & FI 8(4) 195 Ash.l!lnd FI 8(6) 1952 Grayson Fl 4(4,6) 1952 & 195) F 52J(J} 195) 195 F 53(8) 1955 F h(6} 1953 Ash.la.nd Vr:t;mon In>ington Grah.ampton Watterson Expressway Gilbertsville Paducah. Greenville Central City Nelson '' Warren Barren '"" Henderson Henderson Webster Webster Webster Grava ' Breckinridge Rowan 3.3 Boyd 7.9 Catter 89 Breckinridge ll.o Meade Jeffei'aon 8. Marshall 13.7 McCracken MuhlEnburg o ! ll 64< ) 795 8> ' ) l All lanes "5 Patch.ing

7 RESURFAOINGS US 25 NB Fl 5"17(6) 19'}1 London La\ll"el Resurfaced in 1959 Mt, Vernon US 25" NB FI 517(7) 1951 London Rockcastle o JO 648 Re9ur!aced in 1958 Mt, Vernon US 25 SB FI 88(6) 195 Berea Rockcaatle RBB\ll"f'I!Ced in 1958 Mt, Vernon US 41 SB F 526(6) 19i!B Madisonvilla Hopkin& o6 19 Resurfaced in 1957 Henderson US 41 SB F 526(7) 195 Madisonville Hopkins Resurfaced in 1958!lender son Ky, 69 SB s 473 (2) Fordsville Ohio ll.l 8o Resurfaced in 1957 Hartford Ky. 69 SB SP Hartford Ohio Reslll"faced in 1959 Centertown Ky, 229 lib s 15 (4) Barbourville Laurel Reaurf'aced in London US 119 SB F 21(5) & F 151(7) l'inevhle Bell ) 19% flarll US 127.NB F 294(2) 1954 Danville l lercer )9 7'1 Harrods bur[; US 15 WB F 244(4) 1952 Danville Boyle StEll'li'ord tjs 15 EEl F 222 (4) 1952 Bardstown Nelson Springfield US 231 SB F 125(18) OWensboro Davie as Harti'ord US 231 SB F 12$(19) 195 OWensboro Da.viess Hertford Ohio US 421 SB F 326(22) 1951 Frankfort Franklin Lexington Woodford US 421 SB so 552{2), s 552(1) Carrollton Henry )8 87 &. F 536(3) 1955 New Castle Ky. 54 EB s 462 (4) Fordsville Grayson S Leitohi'ield Ky. 8 EH SP 1235 (6) Ruaaell Springs Pulaski 9.) Somerset Ky, 9 EB s 1 (S:) Monticello Clinton Burkesville Ky. 9 EH Honticello Clinton Burkesville Ky, 9 EB F ll6 (1) Burkesville CWllbarland ) Glaev,ow TABLE I (Continued) il:oute PROJECT NO. lame OF COUNTY LENGTH ROUGHNESs INDEX',,.," " and ACSEPTANCE YR. IN MILES US 62 WB F 2(4) 1953 Versailles Anderson )2 Lawrenceburg US 62 WB F 53(6) 1953 Kuttawa Livingston Kentucky Drun Lyon us 62 E'town Hardin All lanes B1.rdsto1m US 68 WB F 163(9) 1951 Paducah Marshall Cadiz 6

8 us 6 ';.Til ;in'>c,_tcr l<wette 3.1 5n lc in;:; ton [S 6, 52, & EML oj, ;,ccroi<en 2,5 )89 6S Paducah Ky. 58 i< GO ijayfkld Graves o.2 49 Hardin Ky, 81 (J",rensboro Daviess ). '/67 All lanes CalhoW1 us 2 Nil Livingston Rockcastle Mt. V6rnon us 41 Hopkinsville Christian 13.5,66 All llllas, Constructed Nashville in 1956 us 41A Madisonville Hopkins l.h3 448 Resud'aceti in 1961, lt,l. m 77 Ubo before resurfacint;. us 41A NeboWebsLer HOJ>kins!,.2 363!te.suri'aced in R,I. 521 Co. Line before resurfacir G us 42 ';iarea\1 Gallatin 2.97 Carrollton US 6 WB MorhN>d Bath Owingsville US 6 Sll ljadiaonvule Christian 2.5 % Hopkinville All lanes RECENT CONSTRUCTION us 25 Lexington Fayette l Relief Route ' All lanes, Ocmstructed in 1959 US 25 SB Lexington Fayette All lane'!> Constructed in 1959 Relief Route us 2$ Barbourville Knox All lanes, Constructed in 196 Corbin US 27 SB Stanford Lincoln 16, 371 Somerset?ula.ski "" Constructed in 1959 us 4JA!1A Madisonville Hopkins All lanes, Canstructed in l96o ByPass Olive Hill Carter All lanes, Constructed in 196 Grayson us 127 Harrodsburg Mercer All l!l.lles, Constructed in 1961 Lawrenceburg us 15 Stanford LJ;moln All lsnea, Constructed in 195'9 Danville (WB Outer) us 421 Frankfort Franklin All lanes, Construc\ed in 1959 Thornhill ByPass us 641 & Ky. 278 Princeton Lyoo WB 346 All l!liles, Constructed in 1959, Kuttawa (3.3 mi,) 1/3 rule Ky. 34 Danville Boyle 2.6 us 27 POC BASE WITH BITUMINOUS SURFACE "" All lanes, Constructed in 196o """"' TABLE I (Continued) ROUTE PROJECT NO, YlA:JE OF COUNTY LENGTH IIOUOHNES<o INDEX " and ACGEIJAOICE YR. '" IN Mn.ES o

9 8 TABlE 2 PORTLAND CEMENT CONCRETE PAVEMENTS ROUTE PROJECT NO, NAI1E OF COUNTY LENGTH ROUGHNESS INDEX Rl>IARKS NO. HOJ\D IN MILES INTERSTATE!645:(8)47 Frankfort Franklin Completed in 1961 Louisville 1642(4)24 Frankfort Shelby Completed in ;1.96:e Louisville!643(9)37 Frankfort Shelby Completed in 1961 Louisville 1643(4)31 Frankfort Shelby CQmpleted in 1961 Louiville 1757(14)178 Williamstown Boone ),21 3 Completed in 1961 Covington 1757(13)173' Williamstown Boone Completed in 1961 Covington 1757(15)164 Williamstown GrantBoone Completed in 1961 Covington Kenton 1642(6)17 Frankfort Shelby 6,2 34 Completed in 196o Louisville Jefferson 1654(6)78 E' town Hardin All lanes, 1/3 rule, Upton t'.:ontructed in (1)169 Williamstown Boone Completed in 1961 Covington I65'Kentucky Louisville Jefferson All lanes, 1/2 dbt,, Turnpike E'town Bullitt Constructed in /J rule 1758(7)185 Williamstown Kenton 2, Completed in 1961 Covington I751 (4)15? Williamstown Grant Completed in 1961 Covington 1643(1)42 Frankfort Franklin Completed in 1961 Louisville C>helby 1758(13)181 Williamstown Kenton 1.! Completed in 1961 Coviogton us ROUTES US 25 SB London Rockcastle,9 974 Mt. Vernon US 2$E NB Pineville Bell 2,8 731 ilarbourville us 27 sa Cynthiana 2ourbon Paris US 27 SB Falmouth Harrison 6,6 532 Cynthiana Bourbon US 27 SB Alexsndria Pendleton tl Faltouth US 27 SB Somerset Pulaski Burnside US 31W SB Louisville 'lullitt E'town US 31W SB Frrmklin Simpson Tenn. Line us 42 Warsaw Gallatin All lanes Carrollton US 6o WB Smithland Livingston Paducah US 6 WB Hawesville Hancock "Owensboro US 6 WB Sturgis Crittenden Marion

10 u.s 6 Versailles Woodford l.j 41 All lanes, Constructed ByPass in 196 us 62 Paducah NcCracken Constructed in 196, ByPass (i/}l Lanes) All lanes us 6 Frankfort Franklin Y All lanes, 1/3 rule, Versailles Woodford Constructed in 1959 US 27 SB Somerset Pulaski All lanes, l/2 rule Cumberland Br. US )lw lib E' town Hardin h. 7 ),J Louisville Ky. 81 Owensboro Daviess All laners Calhoun RECENT CONSTRUCTION us 6 Shelbyville Jeffe; son All lanes Louisville (WB lane) us 6 Lexington Fayette All lanes, l/3 rule Versailles Woodford US 62 WB Lietchl'ield Ohio Beaver Dwn US 62 WB Greenville Hopkins Nortonv.i.lj_e US 68 EB Harrodsburg Fayette Lexington US 68 EB Cadiz Trigg Hopkinsville US 68 EB Cadiz Trigg Hopkinsville us 2)1 Owensboro Daviess All lanes Hartiord us 231 Hartford Oh!io 2.4 )86 Beaver Dam US 421 SB Frankfort Franklin Lexington ROUTE l'ro,ject NO. NANE OF CO'_ U't:' LENGTH.ii.()lJ<JilNEt. lfdm lill1arks NO. ROAD IN s 196 w;i TABLE 2 (Continued) 9

11 LEGEND PAVED IIII:III:Jli:J G R AD E 8 OR A IN,_ \..: ::: : zshelby s c ANKLIN, \'\'or '<<?ry:. :Georgetown '\ BA :.:.::. ' Fig. l. Map Showing Current Interstate Pavements Tested for Roughness, as of December, 1961.

12 :g 6 : 4 IL! 2 Fig. 2. Roughness Distribution of Portland Cement Concrete and Bituininous Concrete, Primary and Secondary Pavements, and Their Classification According to 196 and 1961 Records. y/%t;xc;_tfi"f/21 f:7'///fajr/ v:/7%7//l V/%7/%//":6o ////%/_// N.,. to CXl ;9; llliii")::riowij)( ).,. v.,. It) 2 g ROUGHNESS INDEX <D,._,._ " " ",._ ooooooooo.,. N q I!)G)I!)Q)Q)(DIJ)Q)Q) l cl r?ljj PAVED SINCE 1958: 8bil,mino,s C PCC PORTLAND CEMENT CONCRETE PCC BASE 8 BITUMINOUS OVERLAY BITUMINOUS LEGEND

13 12 The completed Interstate projects include 18 miles of bituminous concrete and 114 miles of portland cement concrete, Scaled diagrams of the sections are given in Figs, 3, 4, and 5; roughness indexes obtained for each lane and other pertinent information is shown thereon, It can easi.ly be seen that the degree of roughness often varied greatly within the same project; although some sections exhibited uniform roughness or smoothness throughout the project, Of course, dual" paved lanes came closer to having the same roughness, yet differences were noted in these companion lanes, Large differences were foun.d among the sections, A new low roughness index was obtained on I643(6)47, roughness index 249, and a high of 414 was found on I758{13)181, It was interesting to note that two of the smoothest projects, I643(6)47 and I643(9)37, were paved by the same contractor, Likewise, two of the roughest surfaces, I643(1)42 and I758(13)181, were paved by another contractor, It seems, therefore, that the practices, methods, and equipment, etc,, employed by the respective contractors are contributing factors since the same specifications and tolerances applied to all alike. The distribution of roughness within each project was obtained by plotting the number of 75ft, sections in each roughness Te sti.!'g and Rating of lnteetat!j:}.ghwa_l123

14 Fig. 3. Scaled Diagram, I64, FrankfortLouisville, Showing the Average Roughness Index for Each Lane within the Respective Projects and the Combined Averages for Each DualLane Pavement and Project. Note; All pavements portland cement concrete. County: Length: Year Paved: Contractor: Combined Roughness Index: SHELBY mi KELLY CONTR. CO mi. 196 KELLY CONTR. CO. 266 SHELBY JEFFERSON 6.86 mi. 196 KELLY CONTR. CO )17 EB WBcounty Length= Year Paved contractor I Combined 1643(6) FRANKLIN mi (1) (9) !!!FRANKLINSHELBY 4.32 mi sl SHELBY 5.73mi W.E. RIIIIGWALil a SONS It B. TYLER CO. W.E. RINGWALD a SONS RouQhness index gl I 64 FRANKFORT LOUISVILLE w

15 SB, 1\18 County: Length' Year Paved: Contractor: combined gj GRANT 1961 I 75 7(4) I 75 WILLIAMSTOWNCOVINGTON SHAMROCK a SCHNBDER I ) (1)169 Roughness Index: County: Length' Year Paved: Combined 1757(13) (14) (13) (7) BOONE 4.646mi mi co. gl KENTON mi R.B. TYLER co Showing the Average_Roughne ss Index for Each Lane within the Respective Projects and the Combined Averages for Each DualLane Pavement and Project. ' J; KENTON mi """ D. SALVO CONST. CO. 364 >!> Fig. 4. Scaled Di,agram, I75, WilliamstownCovington$ Note: All pavements port.lond cement concrete I BOONE Contractor: W. L. HARPER CO. FISHER CONST. Roughness Indo., mi ;lo; GRANT BOONEKENTON ;. BOONE : 5.41 mi mi. >I W. L. HARPER CO. W. L. HARPER CO.

16 I 64 MT. STERLINGWINCHESTER EB WB, I 64 5(8) (7) I (9)9C County Length: Year Paved: Conlroctor: Combined Roughness Index' mi mi HINKLE CONTR. CORP. NALLY 81 GIBSON CORP mi TALBOTT CONST. <.1' CORP. 364 Note: All pavements Bituminous Concre I e. Fig. 5. Scaled Diagram, I64, Mt. SterlingWine hester. Showing the Average Roughness Index for Each Lane within the Respective Projects and the Combined Averages for Each DualLane Pavement and Project.

17 might be attributed to the method of detecting depressions in each roughest surfaces. Perhaps some of the decrease in roughness resurfacings usually produce the greatest improvements on the course and the least on the surface course. This was expected since surface. The greatest improvemenc was noted on the second base Each successive course improved the riding quality of the of each course. The following roughness indexes were obtained: First Base Course. Second Base Course rrz Combined R.I. 47 Binder Course. 328 Surface Course 299 Winchester to Mt. Sterling, was followed closely through the paving The bituminous concrete pavement construction on I645(7)93, correlates rather well with the roughness index. The amplitude distribution plots of the percent of. 5g accelerations concentration was on pavements having the lower combined indexes. distribution. Typically, the widest distribution was found on pavements with the higher combined roughness indexes, and the largest plots portray the intensity of pavement roughness, its range, and and are arranged there according to increasing roughness index, These measured are presented. The plots are presented in the Appendix acceleration amplitude analysis in percent of the total amplitudes category versus its corresponding roughness index. Also the vertical 16 <

18 17 course that is, with a 5,,fL stringline and patching them before the next course was applied, Since this procedure was followed throughout the project, it was not possible to say just how much, if any, of the improvement is attributable directly to the stringlining. This practice was continued on project I645(8) 1; and both surfaces displayed good riding qualities. The completion of several Interstate projects established a rather definite pattern as to what may be anticipated from hightype construction wi.th regard to pavement roughness, It is of interest to differentiate Interstate construction from all other types of constructi9n and to establish a separate riding quality rating for them, Figure 6 is a plot of au of the Interstate projects thus far completed. As in Fig, 2, the projects were approximately divided into quartiles. However due to the srnau size of' the sa:rnple in.,rolved some addi= tiona! consideration was given to the range of roughness values, By comparing Figs. 2 and 6, it becomes evident that even though some improvement in. riding quauty has been attained on Interstate highways, the degree of o.mprovement is not appreciable. Only three I<iterstate projects were smoother than the smoothest primary roads, The bulk of the projects displayed about the same riding quality as most recently constructed primary roads,

19 .,. 3 : 2 ' : " :::> z EXCELLENT Fig. 6. Roughness Distribution of Portland Cernent Concrete and Bituminous Concrete Interstate Projects and their Classification According to 1961 Records. ROUGHNESS NOEX GOOD FAIR POOR PORTLAND CEMENT CONCRETE LEGEND r:=j BITUMINOUS CONCRETE I 64, I 65 a I 75 PROJECTS

20 Removal of J.ocalized Surface Ir:reg la_ri.ties_ Regardless of whether an Interstate project proved to be of good or poor riding quality, a!!. of them apparently passed the state specifications of surface quality. On most portland cement concrete pavements this was possible only after a certain amount of localized high places were ground down to within required tolerances. The Kentucky Standard Specifications require that a 1foot straightedge be used in testing surface roughness. Any high spots indicated by a variation exceeding 1/8 inch from the straightedge are to be removed by grinding or other means. To test the effects of grinding, the southbound outer lane of project l757(4)157 was tested soon after paving and after grinding of high places was finished. This lane was selected because of its high roughness, particularly the north end of the project. The resulting roughness index of 427 before, and 421 after grinding represents about 1, 4 percent difference. This reduction in the index does not necessarily reflect the improvement made by grinding since the reliability of the roughness index, from the standpoint of reproducibility, appears to be within:!:. 2 percent. Therefore, a visual inspection of the recorded acceleration traces was made and acceleration amplitudes at ground locations were measured. 19 "

21 states in Kentucky was one of the 34 participating states. condition of pavements being considered for resurfacing by the Transportation, has undertaken the task of measuring the surface Association of State Highway Officials' Committee on Highway The Bureau of Public Roads, at the request of the American.!'nt :ccord i to Se rvieablity l":dex Rating of pa ve':r'. in the roadway. These larger waves will qetermine the level of riding quality. irregularities, quite easily permits construction of large waves A 1foot straightedge, while effective in detecting localized severity of surface irregularitit' s which. are of short wave length. quality. The vehicle dynamic characteristics tend to surpass the at all surprising because localized irregularities, involving a distance of ten feet, have proportionally very little effect on riding It must be concluded then that grinding produced no detectable difference in the riding quality of this pavement. This was not done, matter of fact, on the contrary. wise, the sections of pavetnent displaying the largest passenger accelerations were not the locations where most of the grinding was attributed to the deviation from previouslyrun wheel tracks. Like Only in a few instances less acceleration resulted, which could be 2

22 on roads shorter than five miles and eight sections up to ten miles in length. The three tested roads were rated as follows: The Research Division made roughness measurements of these pavements covering the full length of both lanes. The serviceability index testing calls for six 5ft., onelane sections test was made with the CHLOE profilometer which electronically totalizes a slopevariance measurement'(61nch intervals) between two closely spaced wheels pulled in the outer or inner wheel tracks. The extent of patching ; cracking and rutting constituted the structura[ failure testing. These measurements were then inserted into an equation to arrive at a serviceability index. This index rates the pavements ranging from to 5 (the larger the index, the better the pavement). Howe,ver, the testing was interrupted and discontinued after the completion of tests on US 31E, Ky. 61 and Ky. 44. The testing involved recording of roughness and structural defects on representative sections of the pavements. The roughness i additional roads were selected, US 68, Todd County, ElktonRussellville, and Ky. 61, Bullitt County, Shepherdsville,Lebanon Jet. Accordingly, sections of two primary roads, US 31E, Nelson County, BardstownHodgenville, and US 79, Todd County, RussellvilleGuthrie, and a secondary road, Ky. 44, Bullitt County, ShepherdsvilleTaylorsville, were selected for testing. When the rating team arrived, two 21

23 22 Ro, ;hne s s Index Test Route No. WB or NB EB or SB Corli'bined Section PSI' US 31E, Bardstown (SB) Hodgenville, Nelson Co. Ky. 44, Shepher;Isville (WB) Taylorsville, Bullitt Co. Ky. 61, Shepherdsville (SB) Lebanon Jet., Bullitt Co. :{ Present Serviceability Index A serviceability index value of 1. 5 was considered on AASHO Road Test to be representative of a pavement that was no lange r serviceable and was removed from further testing. This value is presumably too low for pavements in actual service, and the present study represents an attempt to arrive at a more practical terminal value, The test sections, as rated by Kentucky's roughness index, pointed out that the 5foot sections selected were not necessarily representative, This was particularly evident on Ky. 61 where a

24 23 large difference exists between the combined roughness and the actual test section index, The Kentucky roughness index rated the pavements in the same order as the serviceability index and may, therefore, be useful as an expression of serviceability index of a pavement. An alternative would be to combine the roughness index with other parameters described the pavement structural serviceability and to meld them into an index.

25 CONCLUSIONS The completion of a number of Interstate projects has disclosed wide differences in roughness index. Between the smoothest and roughest project, a 66 percent difference in roughness was noted. However, it was possible to establish ratings for these pavements on a comparative basis. It may also be useful to arrive at some roughness index value which would describe the localized roughness qf a short pavement length, such as 3 feet. In addition, the number of individual accelerations exceeding a certain magnitude may be useq in describing or pointing out localized roughness in each project. In this study it became quite evident that the present methoq of controlling surface roughness with a 1foot straightedge fails to insure good riding quality of the pavement. Localized grinding of portland cement concrete pavements to meet the required surface tolerance produced no noticeable improvement in the roughness index. 24

26 REFERENCES 1. Field, Harvey J.; "Measurf'ments of Surface Irregularities ;nq Riding Quality of HighType Bituminous Pavements," Intradepartmental Report, Kentucky Department of Highways, December, 1949 (Unpublished). 2. Gregg, L. E. and Foy, W. S.; "Triaxial Acceleration.Analysis Applied to the Evaluation of Pavement Riding Qualities," Proceedings, Highway Research Board, Vpl 34, pp. Z+223, Foy, W.S.; "Analysis of Pavement Riding Quality," Intradepartmental Report, Kentucky Department of Highways, November, 1956 (Unpublished). 4. Rizenbergs, R. L.; "Analysis of Pavement Roughness, 11 Intr<j. departmental Report, Kentucky Department of Highways, Mar<;h, 1961 (Unpublished). 5. Drake, W. B. and Havens, J. H.; "ReEvaluation of Kentucky Flexible Pavement Design Criterion," Bulletin 233, Highway Research Board, Carey, W. N., Jr. and Irick, P. E.; "The Pavement ServiceabilityPerformance Concept," : ulletin Highway Research Board,

27 APPENDIX (Roughness Distribution Plots of Interstate Projects) Project No.!vfean Roughness Index I643(6) I642(4) I643(9)37 27 I643(4) I64 5( 8) 1 29 I645(7) I757( 14) 178 I757( 13) 173 I75,.7( 15) 16 I642(6) 17 " " " " b ' " I654(6)78 " " 352 I757( 1) I64 5( 9) 9 Q " ' " ' " 364 I758(7)185. '" 364 I757(4} I643( 1) I758( 13)

28 Number of 75' Sections N U1 U1 :::tl c ::r ::: CD Ill Ill 26 ::: 28 (/) a. CD ::X: 3 "T1 1"11 32 :::tl r )> OJ 34 2 < en " < 36 r r "11 I 4 I (JJ 42 "T1 c :::tl en 44 2 )> i 2 46 < r "., "T1 :::tl i Percent of Amplitudes )> 3.5 '..1 c: a. CD.15 ::: Ill

29 Number (JI of 75' Sections (JI N N (JI ::u c: a :::r ::J ::J Cl. "", J> c Cl..15 Cl.2 :::1 a.25 Percent of Amplitudes.1> en en r :I: "" :I: td "" < en r < td r < r I "" 1\) c: r z o s < r

30 CJf Number of 75' _f3edions (JI "fl c oq ':T :1 Ill 26 Ill 28 J> 3.5 " =.1 c CL Percent of Amplitudes (I) :z: rrl r m < c z i <, J> z, en i ().1 r U) c (I) < r r 1"11 ().1 _, ;.25 oa_.3 Ill

31 I\) :Ill 22 c: 24 f J> "CC.1 l ::II.25 PercGBnt of Amplitudes, ::u z (I), )> en :2: ttl :Ill I 4 Q) I < (I) (loa :2: c: ttl z I 1 Q) < < (loa < ;= I ttl

32 25 I 64 5(8) 1 WINCHESTER MT. STERLING MONTGOMERY COUNTY too c: :;:: u w lin 1' 2 I 15 8 Gl, 6 ii E <3: Gl.n z = u :. 2 Roughness Index.n o on O C\1 Amplitude in g's

33 Number of 75' Sections (JI u; 1\) ::u :T ::s 28 II). fll ::s Q. II) l> c: Q..H5 CD ::s. Q.2.25 Percent 1\) Amplitudes 11> CD I l> ::u ;It g z i < :1 (I) "" ::u i en c z G) I (JI z w (I) i "" ::u (Jol

34 Number of 75' Sections c:,. "" " :; <>. " %. <., I c z C') c: z ::l., l> z., " m I I\). m c: iii. :$,. ::J Percent of Amplitudes l> 3 '!!..1 c.15,.2 C!l,25 Cfle,3

35 Number of 75' Sections :: c cq ::r :: Ill Ill Ill :: III :;' r t:l :I: N Ill J> J> m 2 ft1 ft1 z :I: 4 4 (J'I z c: m z 4 c:. <, " 4 z J> I: t:l.15 ::.2 cq Ill Percent of Amplitudes ro > m om

36 Numbor of n;o' Sections N ::u 1;: :;, (') < z. 1 G) 1 1 z z I I'll ('). ;= c: z r 1 l> < C/1 en 1 U) z Pere11n t of Amplitudes l>,:1 c t :;, Q "" (1\ a>

37 Number of 75 ' Sections :: c. ::r ::s :; <>. (i') :: F r i> 31:, C/) 1 1 :Iii I 2, l> 2 1 c: llo 2 1 < < 1, 1 2 t ::r. _

38 Number of 75' Sections ;:u c :r :.,,.. ;a ;a z,. en I r.,. z., en ;a I 4 :r (1.1 I'll I r Ill r < s C'l cn.,. < c: j= 1\) z 4 r ;;; I'll en ; t ;;; 2o <Q Percent of Amplitudee

39 Number of 75' Sections ::., c: :r ::s CD. ::> CD fti z 1 z c z 1 < r l> s:: "" (J) 1 1 z C» I ()I < z C» Gl 1 z Percent of Amplitudes CD 5'..