ROUGHNESS INDEX MEASURED1 WITH LINE LASER …docs.trb.org/prp/15-5005.pdf · 3 the laser through pavement texture introduces non-representative values of International 4 ... using

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ROUGHNESS INDEX MEASURED WITH LINE LASER AND TRIPLE POINT LASER IN 1

TEXTURED AND NON-TEXTURED STRIPS 2 3 4

By 5 6 Bernard Igbafen Izevbekhai, P.E., Ph.D. Corresponding Author 7 Research Operations Engineer 8 Minnesota Department of Transportation 9

1400 Gervais Avenue Maplewood MN 55109 10 E-mail: [email protected] 11 Phone: 651 3665454 Fax: 6513665461 12 13

Jed Ohiremen Tamunodienye Ig-Izevbekhai 14 Case Western Reserve University 15

College of Arts and Sciences 16 10900 Euclid Avenue 17

Cleveland OH 44106 18 E-mail: [email protected] 19 Phone: 6515871924 20

21 Manshean (Sharon) Wong 22

Student Worker Paraprofessional 23 Minnesota Department of Transportation 24 1400 Gervais Avenue Maplewood MN 55109 25

E-mail: [email protected] . 26

Phone: 651 3665520 Fax: 6513665461 27

28

29

30

31

# of Words = 4889 32 # of Tables =4 *250= 1000 33 # of Figures =6 *250= 1500 34 Equivalent Words =7389 35

36 Submitted for to the 2015 Transportation Research Board Conference for Presentation and 37 Publication 38

mailto:[email protected]

Izevbekhai, Ig-Izevbekhai & Wong 2

ABSTRACT 1 Practitioners have often wondered if during ride measurement with inertial devices, motion of 2 the laser through pavement texture introduces non-representative values of International 3 Roughness Index (IRI) particularly in certain textures. In response to this problem, a special 4

texture study created a non-textured strip by a recession of the middle 4 ft of a texturing broom 5 dragged longitudinally behind the paver. The study measured IRI, other surface properties in the 6 adjacent textured and non-textured strips using a lightweight profiler outfitted with the line laser 7 (ROLINE) and Triple Laser arranged in tandem. IRI measurements were performed after 8 sufficient concrete strength gain and repeated as soon as the joints were sawn. The same 9

measurements were repeated after the joints were deployed. 10 Results showed a significant difference between IRI of textured strip and that of non-11 textured strip. Further analysis indicated that though texture appeared to affect IRI, the effect is 12 amplified by laser type used, as the triple laser appeared to exhibit higher IRI in comparison to 13

the ROLINE. Although the ROLINE is not a reference profiler that is unaffected by texture, the 14 prevalence of ROLINE and Triple Laser in construction acceptance testing is sufficient reason to 15

be concerned about the difference inherent in the results obtained. CHI –squared and t-test 16 statistical analysis showed that laser type induced comparable and even higher IRI anomalies 17

than the experimental drag texturing. Texture and laser-induced-IRI-anomaly can be minimized 18 by measuring smoothness after true joint deployment has occurred. 19

20


INTRODUCTION 1 Certain pavement smoothness specification had resulted in some undesirable riding conditions 2 including the “chatter phenomena” that could not be penalized due to the use of the profile 3 indices and blanking band filters. Other factors such as anomalous ride quality due to certain 4

textures led the industry to enquire about the effects of texture on ride at that time. Additionally, 5 contractors had expressed concern that that the zero blanking bands may result in strict penalties 6 since texture effects on ride measurement had not been quantified for a corrective algorithm. To 7 address this issue, many agencies changed from a two tenths blanking band to a zero blanking 8 band specification and subsequently to an International Roughness Index (IRI) specification. 9

A poll conducted showed that above every other requirement, most people want smooth 10 riding pavements (1). A study performed by the Smith et al (2) for NCHRP (Report I-31 of 1997) 11 correlated increase in service life to various percentage improvements in ride quality. The study 12 showed that some Portland cement concrete (PCC) sections in Alabama experienced increases of 13

11%, 28% and 56% respectively in service life for 10%, 25% and 50% increase in ride quality. 14 Minnesota PCC experienced 6%, 15% and 30% increase in service life with the respective ride 15

quality improvements. Recent published MnDOT reports showed that smooth pavements remain 16 smoother and the rate of deterioration of poorly riding pavements is higher (3). It is therefore 17

evident that pavement smoothness should be a major infrastructure goal. To evaluate pavement 18 performance through ride quality it is important to ensure that measured ride quality is indicative 19 of actual pavement condition and that any error is quantified after the source has been identified. 20

Some of these sources of errors have been indicated in previous research work (4). A Minnesota 21 Department of Transportation (MnDOT) 2002 investigation created non-textured strips between 22

astro-turf textured finished strips on a paving project on US trunk Highway 212 between Olivia 23 and Bird Island. A lightweight profiler and a California Profilograph were used to measure ride 24 quality, on each strip before and after joint-establishment. Results showed consistent deviation of 25

10 to 20 inches per mile of IRI between the textured and un-textured strips. Subsequent 26

diamond-ground surface exhibited 5 inches per mile lower IRI than the non-textured surface. A 27 ProVAL Power spectrum density analysis showed similar high preponderant wavelengths 28 attributed to joints and string lines (4). With advancements in wave analysis frequency 29

fragmentation and intrinsic mode decomposition mode decompositions, we are now better able 30 to quantify roughness inducing factors. 31

The quest for a corrective algorithm for the effect of texture on IRI led to the development 32 of a suggested texture ride optimization software (4) that was superseded by an implementation 33

of IRI in program delivery as well as a combined IRI specification for construction acceptance 34 (5) (6). Although a transition was made from Profile Index (PI) in program delivery to IRI, the 35 challenge of the degree to which texture influences measured smoothness had not been fully 36 solved. Lightweight profiler used in 2002 was at that time equipped with a single laser (4). 37 Studies later conducted (7) observed an anomalous difference between IRI measured with point 38

lasers and that measured by line lasers in the same profiler. Given the equal usage of line lasers 39 and point lasers, a comprehensive evaluation of the effect of texture must include the various 40

laser types on adjacent textured and non-textured segments. Current research addresses this 41 issue with applicable experimental design. 42 43

EXPERIMENTAL DESIGN AND EQUIPMENT USED 44 The test section consisted of 1005 feet of the outside lane on northbound Interstate Highway 35 45 near Midway Road in Duluth Minnesota. The southern limit of test section was approximately 46


96.4 feet from northern limits of Midway Bridge approach-panel on this Interstate Highway 1

(FIGURE 1). This section was part of a major construction project SP 098-139 of a pavement of 2 10-inch thick dowelled concrete with non-skewed joints at 15 ft interval. The paving was 3 followed by finishing and broom drag texturing. In the test section, the broom was indented at 4

the middle (between wheel paths thus creating a 4 ft wide non-textured strip between two 4 ft 5 wide textured strips. Texturing was followed closely by the application of a uniform layer of 6 Alpha Methyl Styrene curing compound. When sufficient strength gain had occurred in 8 hours, 7 a lightweight profiler was able to get on the pavement. The first set of smoothness measurements 8 were conducted on the textured strip as well as the non-textured strip. MnDOT had equipped the 9

lightweight profiler with a tandem arrangement of the Triple Laser accelerometer and the line 10 laser (ROLINE) accelerometer as shown in FIGURE 2 with inset of magnified laser rays and 11 beam. In this arrangement, the two accelerometers measured IRI simultaneously followed by 2 12 repeat runs in each strip. These “Pre-Saw” ride measurements were identified as: 13

mndotI35midwayDLpresawBWPnontxt (runs 1-3).erd +5 ft from CL of road (non-14 textured). 15

mndotI35midwayDLpresawRWPtxt(runs 4-6).erd +8 ft from CL of road (broom 16 textured) 17

(The names and file extensions were so chosen for continuity and easy access in a myriad of 18 project and research files). As soon as the transverse sawing was performed (3:00 AM next day), 19

longitudinal sawing commenced and was completed at approximately 7:00 AM. Joints were 20 washed and generally cleaned of excess slurry. Another set of IRI measurements was conducted 21 on the textured and non-textured sections. Post –Sawing Ride Files were identified as: 22

mndotI35midwayDLpostsaw7.9.2013BWPnontxt.erd Runs 7-9).erd +5 ft from CL (non-23 textured) 24

mndotI35midwayDLpostsaw7.9.2013RWPtxt.erd (Runs 10-12) +8 ft from CL of road 25 (textured w/ broom) 26

27

28 FIGURE 1: Location of Test Section on Highway 35 near Duluth Minnesota 29

30 31


1 FIGURE 2 Lightweight Profiler outfitted with two lasers, accelerometers and Circular 2 Track Meter ASTM E-2157. 3 4

FIGURE 3 1000-ft of textured and non-textured strips & close-up view 5 6

Ride was measured with the International Roughness Index (IRI). The International Roughness 7 Index is based on the suspension algorithm of the quarter car (8) travelling at 50 miles per hour. 8

Vertical acceleration of the Quarter Car is associated with displacements that are summed over 9 the travelled distance as inches/mile or m/km. IRI is neither a slope of the profile nor a 10 summation of slopes of elements of the profile but the average rectified value of the slope power-11 spectrum-density (PSD). 12

Creation of Adjacent Strips Close Up View of Adjacent Strips

Circular

Track

Meter

6

Texture measurements were conducted with the Circular Track Meter (ASTM E-2157) in 1

order to evaluate the texture configuration associated with the textured and non-textured 2 segments. The circular track meter, uses a charge coupled device (CCD) laser-displacement 3 sensor to measure the profile of an 11.2-inch diameter circle. The CCD is mounted on an arm 4

that rotates at 3.15 inches above the surface. It is driven by a DC motor at a tangential velocity of 5 19.7 ft. /min in a counterclockwise direction. Measurements were performed in conformance to 6 the ASTM E 2157 standard. Accordingly, three measurements were made at each test cell 7 location. The output data is segmented into eight 4.4 inches arcs of 128 samples each. The 8 precision for the given standard deviation of the eight measurements on the test cell is 0.001 9

inches. Outputs given by the device is mean profile depth (MPD) of the eight segments. By 10 using the in-house Visual basic Program PARSER developed for visualizing basic texture output 11 texture wavelength and texture orientation were evaluated. 12 13

RESULTS AND ANALYSIS 14 Comparison of Texture Configuration Properties 15 Mean Profile Depth (MPD) and an unscaled texture profile were obtained directly from the 16 CTM. Additionally, texture direction, asperity interval and texture orientation were considered 17

necessary for adequate characterization of the texture configuration. Asperity interval is defined 18 as characteristic wavelength of a repeating texture patterns. The turf or broom drag texture used 19 is an anisotropic texture with longitudinal asperities represents a longitudinal texture. Texture 20

orientation (spikiness) (8) is the measure of the skewness of the amplitude distribution function 21 of a texture. It is positive or negative texture depending on the skewness from equation 1. 22

PARSER provided 128 texture depth measurements for each segment for each of three separate 23 runs. Skewness was computed as in equation 1. 24

Skewness or Texture orientation = ∑ (Yi−Y)̅̅ ̅N

i=1

3

(N−1)S3 (1) 25

where Y = depth measured from reference 26

N = Sample size 27 S = Sample standard deviation 28

29 Texture orientation is a measure of texture spikiness in pavement surfaces. Negative textures are 30 characterized by peaks and rounded valleys that indicates appearance of asperities projected 31 above surface; while positive textures exhibit flat peaks and sharp valleys that indicated as 32

depressions in surface (8). MPD values were obtained for various measurement points at 0.00, 33 100+00, 500+00 and 600+00 at various offsets thus evaluating the textured and adjacent non-34 textured strips. Tables 1 and 2 thus show the MPD values obtained at station 0+00 and 500+00 in 35 these strips. The MPD for the non-textured strip ranged from 0.18 to 0.35 mm while the MPD for 36 the textured strip ranged from 0.81 to 1.03 mm. These measurements were performed 2 weeks 37

after paving prior to opening to traffic but not without some light construction traffic. 38 Consequently, if texture loss would have occurred it will be proportionately higher in the 39

textured strips. Values obtained for asperity interval showed that the textured segment had lower 40 asperity intervals of 3.01 to 3.38 mm while the broom texture showed asperity interval of 3.85 to 41 5.07 mm. 42 43


Probability density function plotted by using frequency of peak heights shows that that spiky 1

surface has positively skewed distribution, and non-spiky surface has negatively skewed 2 distribution. Values obtained showed that the non-textured segments had a somewhat neutral 3 texture orientation while some were slightly positive generally ranging from –0.15 to +0.34. The 4

textured segments exhibited a range of -0.48 to -0.10 indicating a more negative texture. Table 1 5 and Figure 4 show results of texture measurements and subsequent analysis for one of many 6 sections in the study area. Table 1 shows mean profile depth (MPD), texture skewness and texture 7 wavelength of the textured and non-textured strips. Evidently, the non-textured surface was not 8 void of asperities, having been finished with the paver and float in some areas and the paver in 9

others. Typically, texturing is performed for adequate skid resistance but it occasionally provides 10 negative texture that imparts other surface benefits. 11 12

Pavement Smoothness Evaluation 13 A gradual decrease in the difference between IRI of textured and non-textured strip is indicated by 14 the Triple Laser measurement (Tables 2 &3) from paving to joint deployment. Initially before 15

sawing, there is a difference of 10.5 inches per mile which became 7.5 inches/mile after sawing. 16 The reduction in the net effect of texturing is attributed in part to changes in the megatexture and 17

stress relief from built-in warp and curl due to the joint sawing. After standard joint sawing to 18 (1/3

rd of the pavement thickness) the space beneath the joint is expected to crack to the slab 19

bottom and provide load transfer through aggregate interlock. This phenomenon is referred to as 20

“joint deployment”. Though it can be accelerated by heavy equipment, such loads may cause 21 uncontrolled cracking. Consequently prior to traffic loading, shrinkage of the concrete and 22

restraint of the base (or interlayer) facilitate joint deployment. 23 However, the crack propagation (joint deployment) was evident 2 weeks after paving in this test 24 section. After joint deployment, a difference of 6.27 inches per mile was observed. The ROLINE 25

in all cases exhibited a lower IRI value than the Triple Laser. This justifies the fact that the 26

bridging of the texture asperities by a line laser may be more representative of tire footprint that is 27 not necessarily influenced by the texture asperities. Initially before sawing, ROLINE showed an 28 IRI difference of 6.2 inches per mile between textured and non-textured strips. After sawing this 29

difference became 6.43 inches/mile. Crack deployment resulted in a difference of 3.37 inches per 30 mile. TABLE 3 shows that the difference in IRI arising from the sawing of the joints is almost 31

insignificant in the ROLINE but remarkable with the Triple Laser. Examining the actual IRI 32 values, the Triple Laser started at 57 inches per mile in the non-textured strip and decreased 33

slightly to 56.47 in/mile after joints were sawn but changed to 57.8 inches per mile when the joints 34 were deployed in the non-textured strip. These numbers are within margin of error. In the 35 textured strip, the Triple Laser started at 67.53 inches per mile and decreased slightly to 63.97 36 after joints were saw but increased slightly to 64.07 inches per mile when the joints were 37 deployed. The ROLINE started (pre-saw) at 57.0 inches per mile in the non-textured strip and 38

changed slightly to 57.5 inches per mile after joints were sawn but increased slightly to 63.93 39 inches per mile when the joints were deployed in the non-textured strip. In the textured strip, the 40

ROLINE started (pre-saw) at 63.2 inches per mile and increased slightly to 63.93 inches/ mile 41 after joints were sawn and changed slightly to 62.17 inches per mile when the joints were 42 deployed. These show that laser type and texturing were more influential to the changes than the 43 joints and the deployment. Relative importance of texture and laser is evaluated with statistical 44 tools in a later section. 45


TABLE 1 Texture Test Results of Non-Textured and Textured Strips at Stations 0.00 ft. and 500 ft 1

Peaks Texture Orientation Texture Wavelength

(mm)

Mean Profile Depth

(mm)

Non

Textured

Textured Non

Textured

Textured Non

Textured

Textured Non

Textured

Textured

Test 1 (Sta.0) 35 24 -0.079 -0.414 3.186 4.646 0.24 1.02

Test 1 (Sta.0) 35 24 -0.100 -0.434 3.186 4.646 0.24 1.01

Test 1 (Sta.0) 36 22 -0.148 -0.481 3.098 5.068 0.23 1.03

Average 35.33 23.33 -0.109 -0.443 3.157 4.787 0.236 1.02

Test 1 (Sta.0) 36 28 0.038 -0.409 3.098 3.982 0.19 0.82

Test 1 (Sta.0) 35 29 -0.028 -0.420 3.186 3.845 0.18 0.81

Average 35.5 28.5 0.005 -0.414 3.142 3.914 0.185 0.815

Test 1 (Sta.500) 34 28 0.0018 -0.413 3.2799 3.983 0.23 0.85

Test 2 (Sta.500) 34 24 0.0052 -0.398 3.2799 4.646 0.23 0.86

Test 3 (Sta.500) 37 27 -0.0034 -0.389 3.0139 4.130 0.23 0.84

Average 35 26.33 0.0112 -0.400 3.1912 4.253 0.23 0.85

Test 1 (Sta.500) 35 26 0.175 -0.099 3.186 4.289 0.34 0.86

Test 2 (Sta.500) 33 26 0.239 -0.109 3.379 4.289 0.34 0.85

Test 3 (Sta.500) 35 26 0.344 -0.101 3.186 4.289 0.35 0.85

Average 34.33 26 0.253 -0.103 3.250 4.289 0.343 0.853

1 inch = 25.4mm 2


(a) PARSER- Profile of Non-textured Strip (Station

0)

(b) PARSER Profile of Textured Strip (Station 0)

(a) PARSER- Profile of Non-textured Strip (Station

500)

(b) PARSER Profile of Textured Strip (Station 500)

FIGURE 4: PARSER –Recreated profile on station 500 (a) non-textured (b) textured 1

1980200020202040206020802100212021402160

0 50 100 150

Ele

va

tio

n

CTM Sector Location

1900

1950

2000

2050

2100

2150

2200

0 20 40 60 80 100 120

Ele

va

tio

n

CTM Sector Location

Ele

va

tio

n


TABLE 2 Triple Laser and ROLINE Pre-Saw and Post-Saw Test IRI (inches/mile) 1

Non-textured Strip Triple Laser ROLINE Difference

Non-textured Strip (Pre-Saw)

mndotI35midwayDLpresawBWPnontxtr1 57.2 57.2 0

mndotI35midwayDLpresawBWPnontxtr2 57.1 56.6 0.5

mndotI35midwayDLpresawBWPnontxtr3 56.7 57.2 -0.5

Mean 57.00 57.00 0.00

Textured Strip (Pre-Saw)

mndotI35midwayDLpresawRWPtxt4 69 63.5 5.5

mndotI35midwayDLpresawRWPtxt5 68 62.1 5.9

mndotI35midwayDLpresawRWPtxt6 65.6 64 1.6

Mean 67.53 63.20 4.23

Mean Difference (Textured -Non-textured) 10.53 6.20 4.23

Non-textured Strip Post-Saw

mndotI35midwayDLpostsaw7.9.2013BWPnontxt1 56.1 57.7 -1.6



Mean 56.47 57.50 -1.03

Textured Strip (Post-Saw)

mndotI35midwayDLpostsaw7.9.2013RWPtxt4 65.3 63.1 2.2

mndotI35midwayDLpostsaw7.9.2013RWPtxt5 62.5 64.4 -1.9

mndotI35midwayDLpostsaw7.9.2013RWPtxt6 64.1 64.3 -0.2

Mean 63.97 63.93 0.03

Mean Difference (Textured -Non-textured) 7.50 6.43 1.07

2 TABLE 3: ROLINE and Triple Laser IRI Post-Joint Deployment IRI 3

File Triple Laser

IRI (in/mile)

ROLINE

IRI(in/mile)

Diff

(in/mile)

Non-Textured Strip Post-Joint Deployment

DLpostpro7.17.2013BWPnontxtr1 57.70 58.00 -0.30



Mean (Non-Textured) 57.80 58.80 -1.00

Textured Strip Post-Joint Deployment

DLpostpro7.17.2013RWPtxtr4 66.40 62.30 -1.23



Mean (Textured) 64.07 62.17 -1.23

Nontex. post crack propagation (Textured-

Non-textured)

6.27 3.37 -0.23

63.36 inches/mile = I m/km 4


1

TABLE 4: Average IRI Pre-Saw, Post Saw and Post Joint Deployment 2

Strip Pre-Saw IRI

(in/mile)

Post-Saw

IRI (In/mile)

Post Joint Deployment

(in/mile)

Triple Laser Mean Non-Textured 57.00 56.47 57.80

Triple Laser Mean Textured 67.53 63.97 64.07

ROLINE Mean Non-Textured 57.00 57.50 58.80

ROLINE Mean Textured 63.20 63.93 62.17

Difference Triple Laser 10.53 7.5 6.27

Difference ROLINE 6.20 6.43 3.37

3

4 5

6 7

8 FIGURE 5 IRI in pre-saw, post-saw and post-joint-deployment9

55

57

59

61

63

65

67

69

Triple Laser Mean

Non-Textured

Triple Laser Mean

Textured

ROLINE Mean

Non-Textured

ROLINE Mean

Textured

IRI

(in

ches

/ m

ile)

Pre-Saw IRI (in/mile)

Post-Saw IRI (In/mile)

Post Joint Deployment (in/mile)

12

1

2 FIGURE 6 IRI difference between textured & non-textured strips 3

4 5

STATISTICAL ANALYSIS OF EFFECTS OF LASER-TYPE, TEXTURE, SAWING & 6 JOINT-DEPLOYMENT. 7

8 This section examines texture the CHI squared (χ

2) test and the t-test (10) as the chosen statistical 9

tools to evaluate the relative importance of texture and laser in influencing IRI. 10 The χ

2 test (Equation 2) first calculates a χ

2 statistic using the formula: 11

12

∑ ∑(𝐴𝑖𝑗−𝐵𝑖𝑗)

2

𝐵𝑖𝑗

𝑐𝑗=1

𝑟𝑖=1 (2) 13

14 where: 15

Aij = actual frequency in the i-th row, j-th column 16 Bij = expected frequency in the i-th row, j-th column 17 r = number or rows c = number of columns 18

19 A low value of χ

2 is an indicator of independence. As can be seen from the formula, χ

2 is always 20

positive or 0 only if Aij = Eij for every i, j. 21 This test returns the probability that a value of the χ

2 statistic at least as high as the value 22

calculated by the above formula could have happened by chance under the assumption of 23

independence. This test uses the χ2 distribution with an appropriate number of degrees of 24

freedom (df). 25

26 df= (c-1) (r-1) (3) 27

28 where 29 c = number of columns (c >1) and 30 r = number of rows (r >1) 31

3

4

5

6

7

8

9

10

11

Triple Laser ROLINE

IRI

Dif

fere

nce

(in

ches

/mil

e) Pre-Saw IRI (in/mile)

Post-Saw IRI (In/mile)

Post Joint Deployment (in/mile)


The χ2

statistic was first calculated in the comparison of the textured strip IRI to the non-textured 1

strip IRI. Subsequently it was calculated between the pre-joint deployment and the post joint 2 deployment IRI and between laser types. The results are shown in the first 2 rows of Table 5. It 3 is evident that proximity to 1 is an indication of similarity in this case or dependence where 4

applicable. In subsequent rows the χ2 statistic was obtained for other combinations of laser type 5

and texture. The results are shown in the 3rd

column. It shows that the laser type used has more 6 influence on the IRI than the joint sawing and deployment. The t-test, based on the difference 7 between means considered data spread and computed probability of overlap. The final formula 8 for the t-test is shown in equation 4: 9

𝑡 =[(𝑥1+𝑥2)−𝑑]

𝑆𝐸 (4) 10

11 where 12

𝑥1 is the mean of textured or laser 1 as applicable, 13

𝑥1is the mean of non-textured or laser 2 respectively) 14

d is the hypothesized difference between population means, and 15 SE is the standard error of the mean. 16 17

The p-value is the probability of observing a sample statistic as extreme as the test statistic. Since 18 the test statistic is a t-score, the t- distribution was used to assess the probability associated with 19

the t-score, with the degrees of freedom computed below (Equation 5). If the sample findings are 20 unlikely, given the null hypothesis, the researcher rejects the null hypothesis. Typically, this 21 involves comparing the p-value to the significance level, and rejecting the null hypothesis when 22

the p-value is less than the significance level. The t-value will be positive if the first mean is 23 larger than the second and negative if it is smaller. To test the significance, risk level (called the 24

alpha level) (α) was set to 0.05. In the t-test, the degree of freedom is given by 25 26

df= (2n-2) (or df = cr-2) (5) 27 where 28 n is the population or 29

c is number of columns and 30 r is the number of rows 31

32 Given the alpha level and degree of freedom (df), the t-value, was obtained from a standard 33 table of significance. This test directly returned a p-value that was compared to a pivot of 0.05. 34 It shows that joint sawing and joint deployment are not significant in the IRI distribution. It also 35 shows that the laser type used has more influence on the IRI than the joint sawing and 36

deployment based on this level of significance. 37

Table 5 elucidates the relative importance of the various factors (laser type, joint 38

condition and texturing) on IRI. The various factorials shown in columns 1 and 2 were subjected 39 to the two statistical tests described previously and the results ranked in columns 5, 6 &7. The 40 combined ranking formed the basis of evaluation of the similarity or dissimilarity between 41 various combinations of laser types test strips and joint conditions. Joint condition refers to pre-42 sawing, post sawing and post-joint deployment in this context and not to degree of distress. It is 43 therefore evident that irrespective of joint condition, the Triple Laser and the ROLINE 44 measurements on textured strips to a 95% confidence level are dissimilar in spite of the fact that 45


ROLINE vs Triple Laser in the non-textured strips showed some similarity. It can also be 1

deduced that the laser type may be more influential than the textured versus non-textured strips 2 in the introduction of anomalies to ride measurements. However, in the non-textured strips the 3 Triple Laser versus ROLINE appears similar to a 95% confidence level. The ROLINE on the 4

texture strip vs the ROLINE on the non-textured strip was also found to be dissimilar. Texturing 5 appears to have an effect but this effect is amplified by the laser types and by the 6 correspondingly different laser effects. Table 5 arranges the tests in order of significance based 7 on each test and sums the rankings into a final rank of which the lowest number is the most 8 significant. It identifies laser type and texture as very significant as accentuated by the laser 9

effect being insignificant in the non-textured strip. 10 11

TABLE 5 Comparison of Significance of Texture and Laser Combinations 12 RANK * = Combined X

2 and T Rank (Arithmetic Sum) 13

14

15 CONCLUSION AND RECOMMENDATION 16

Conclusions 17 A special texture study was performed on Interstate 35 in July 2013, in Duluth Minnesota. It 18 created adjacent textured and non-textured strips and measured IRI using a lightweight profiler 19 outfitted with the Line Laser and Triple Laser arranged in juxtaposition. The research also 20 measured geometries of the textured and non-textured strips. Smoothness measurements were 21 performed as soon as the lightweight profiler could ride on the concrete and repeated again as 22

TEST VARIABLE P- Value

RANK*

EFFECT

X2

T-TEST X2 T RANK*

Triple Laser

Textured Vs Non-

textured

Texture &

Laser

0.381 2.5E-8 2 1 3 Clearly

Significant

Triple Laser Vs

ROLINE

(Textured)

Laser

(Texture)

0.229 0.037 1 3 4 Clearly

Significant

ROLINE Textured

Vs ROLINE Non

Textured

Texture

with

ROLINE

0.478 0.03 3 2 5 Clearly

Significant

Post Deployment

Vs Pre-Joint ( All

Strips)

Deployment

0.714 0.165 4 5 9 Significant

Triple Laser Vs

ROLINE (Non-

Textured)

Laser (No

texture)

0.98 0.039 6 4 10 Non-

Significant

Post-Joint Vs Pre-

Joint Sawing

0.948 0.276 5 6 11 Non-

Significant

ROLINE Vs

ROLINE (Non

Textured)

Reference

1 1 7 7 12 Reference


soon as the joints were sawn. The same measurements were repeated after the joints were 1

deployed. The textured strips exhibited more negative orientation than the non-textured 2 segments, implying that the broom imparted negative textures on the surface. The non-textured 3 strip exhibited texture isotropy while the texture scan showed that the textured strip exhibited 4

asperity alignment in the longitudinal direction. The broom texturing process appeared to have 5 imparted a more negative texture orientation (skewness) to the generally neutral orientation of 6 the non-textured strip. Results showed an IRI difference of 10.75 inches per mile between the 7 non-textured and the textured strips adjacent strips with the triple point laser but 6.2 inches a per 8 mile with the line laser before joint sawing. The difference after sawing of joints were 9

respectively 7.5 and 6.43 inches per mile after joint sawing and subsequently 6.27 and 3.37 10 inches per mile after joint deployment Evidently, IRI measurements conducted after observable 11 deployment of the joints indicated largely reduced difference between textured and non-textured 12 strip IRI Results show a significant difference between IRI of textured strip and that of non-13

textured strip. Further analysis indicated that though texture appears to affect IRI this effect is 14 amplified by laser type used as the triple laser appears to indicate higher IRI in comparison to the 15 ROLINE. Although the ROLINE is not a reference profiler from which we may establish IRI 16

values unaffected by texture, the prevalence of the ROLINE and Triple Laser in construction 17 acceptance testing is sufficient reason to be concerned about the difference inherent in the results 18

obtained. Difference obtained between joint sawing and join t deployment is expected to be very 19 significant in many concrete paving projects including unbonded overlays with non-woven 20 geotextile stress-relief layers. In this design the lesser restraint delays effective joint deployment 21

occasionally beyond the time of pavement acceptance smoothness measurements. 22

23

Recommendations 24 The effect of texturing can therefore be minimized by measuring smoothness for acceptance at 25 least two weeks after paving. However, adequate accommodation for texture may be interpolated 26

from the values obtained in this study. The point at which acceptance IRI measurements are 27 performed should be recorded and such acceptance tests must be performed with similar quality 28

assurance and quality control devices so that anomalous laser effects are minimized. 29 Based on findings of this research, a cursory assessment of the degree of joint deployment should 30

be noted (where possible) during the pavement acceptance smoothness testing. 31 Additionally, the texture type and configuration will affect IRI to various degrees. 32 Consequently, further research is recommended to examine different texture types and different 33

texture aggressiveness with the various laser types including the single laser which is still 34 common in network monitoring. 35 36

ACKNOWLEDGEMENTS 37 Robert Orthmeyer, Senior Pavement Engineer of Federal Highway Administration facilitated the 38

unique outfitting of MnDOT’s lightweight profiler with ROLINE and Triple Laser to enable this 39 research work. MnDOT’s Steve Olson and John Pantelis performed on-site testing. MnDOT 40 District 1, MnDOT’s Maureen Jensen and Curtis Turgeon were instrumental to the 41 conceptualization and realization of the research. Additionally, Gerard Geib (MnDOT) provided 42

very helpful review. 43

44 45 46


REFERENCES 1 1) Swanlund M. Enhancing Smooth Pavements. FHWA Public Roads September /October 2

2000 Vol 64 No. 2 3 4

2) Smith, K.L.; Smith, K.D.; Evans, L.D; Hoerner, T.E; Darter, M.I. Smoothness 5 Specifications for Pavements (Final Report 1997) National Co-operative Highway 6 Research Board, National Research Council. (NCHRP 1-31 7

8 3) Snyder M.B.: Lessons Learned From MnROAD Proceedings of the 9th International 9

Conference on Concrete Pavements The Golden Gate to Tomorrow's Concrete 10 Pavements Organized by ISCP San Francisco, California, USA August 17-21, 2008. 11 12

4) Izevbekhai, B.I (2006) a field investigation of the influence of pavement texture on 13

Pavement Smoothness measurements. MnDOT MnROAD Reports. URL: 14 http://www.mrr.dot.state.mn.us/research/pdf/2007mrrdoc009.pdf Accessed 7/3/2012 15 16

5) W. James Wilde. Implementation of an International Roughness Index for MnDOT 17 Pavement Construction and Rehabilitation Report MN/RC-2007-09 18

19 6) W. James Wilde and Thomas J. Nordstrom MnDOT Combined Smoothness 20

Specification URL http://www.lrrb.org/media/reports/201015.pdf. Accessed 10/13/12 21

22 7) Izevbekhai, B.I. and E. Lukanen Laser induced Roughness Index Anomalies in 23

Longitudinal Box car Configurations URL: 24 http://www.mrr.dot.state.mn.us/research/pdf/2011MRRDOC008.pdf. Accessed 09/01/13 25 26

8) Izevbekhai, B.I. Tire Pavement Interaction Noise of Concrete Pavements. Dissertation 27 for Doctor of Philosophy in Civil Engineering. University of Minnesota. May 2012. 28

29 9) Sayers, M.W. On The Calculation OF International Roughness Index from 30

Longitudinal Profiles Transportation Research Board 500 Fifth Street, NW 31 Washington, DC 20001 USA URL: Http://www.trb.org/Publications/Pages/262.aspx 32 33

10) Izevbekhai, B.I. Watson, M.W Evaluation of Concrete Texturing Practices in 34 Minnesota: URL: http://www.lrrb.org/media/reports/200846.pdf. Accessed 10/12/13 35

36

DISCLAIMER 37 This paper does not express the opinion of Minnesota Department of Transportation, Federal 38

Highway Administration or other agency. It is the result of research and analysis conducted by 39 the authors, whose opinions are solely expressed. 40

http://www.lrrb.org/media/reports/201015.pdf

http://www.mrr.dot.state.mn.us/research/pdf/2011MRRDOC008.pdf.%20Accessed%2009/01/13

http://www.lrrb.org/media/reports/200846.pdf.%20Accessed%2010/12/13

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ROUGHNESS INDEX MEASURED1 WITH LINE LASER …docs.trb.org/prp/15-5005.pdf · 3 the laser through pavement texture introduces non-representative values of International 4 ... using