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OCR for page 7
CHAPTER 2. AGENCY SURVEY RESULTS
Introduction
To document the current State specifications and procedures for measuring initial
pavement smoothness, and to record both States' and paving contractors' opinions
concerning crucial smoothness specifications and smoothness measuring equipment,
two separate questionnaires on these subjects were developed and targeted for the
following organizations:
.
50 SHAs.
3 Federal Thanks agencies
IS asphalt paving contractors.
iS concrete paving contractors.
The first questionnaire, developed specifically for the SHAs, was sent to all 50
States and the three Federal Lands agencies In March, 1994. This survey included
several of the topics contained In the 1987 AASHTO and 1992 NCHRP 20-7 (Scofield
1992) State surveys, such as bump and ride quality specifications used, smoothness
measuring equipment and procedures used, and specification and equipment
assessments. Additional questions were Included that pertain to each agency's past
and planned future changes in specifications, equipment, and procedures, as well as
each agency's ability to provide roughness data for the NCHRP I-31 project.
Research team members preceded questionnaire distribution win a telephone call
so Cat He appropriate individuals within each agency could be identified.
Responses to the State survey were typically returned within 2 to 3 weeks. Complete
survey responses were receiver] from 45 States and all 3 Federal Lands agencies.
For the paving contractor survey, approved contact lists of both asphalt and
concrete paving contractors were generated via discussions with the National Asphalt
Pavement Association (NAPA) and the American Concrete Paving Association
(ACPA), respectively. From these lists, IS asphalt paving contractors and 18 concrete
paving contractors located throughout the country were identified for participation in
the June, 1994 survey. As with the State survey, research team members preceded
the contractor questionnaire with a telephone call so Cat the appropriate individuals
within each company couict be identified.
Because of the busy construction season, not all of He 36 contractors could be
contacted. As a result, only 33 questionnaires were sent out. A total of 16
contractors furnished responses to He questionnaires; 6 asphalt paving contractors, 9
concrete paving contractors, and 1 contractor involved with both asphalt and concrete
paving.
7
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Summary of State Survey Responses
The following sections present the results of State's responses to selected questions
contained In the survey. Each section pertains to the subject areas covered
sequentially in the questionnaire. Detailed responses for most of the questions not
discussed in this chapter are provided in tabular form in appendix A.
Pavement Smoothness Specifications
Currendy, most every SHA uses some form of an initial smoothness specification.
Depending largely on the pavement type, some agencies employ a bump, or surface
tolerance, specification only, whereas several more use a ride qualibr specification
supplemented by a bump specification.
. .
~ , 1,
A summary of the use of smoothness
specifications for new construction and AC overlay projects is illustrated in figure T.
As seen in this figure, 28 of the 50 responding agencies indicated using a ride
. .. .
0 ,
1 0 0 0
speclucatlon (tested using a profiling device) on newly constructed AC pavements.
Nineteen additional agencies indicated using straightedges or stringlines to ensure
adherence to bump specifications on new AC pavements.
For AC overlays, the number of agencies using a ride quality specification
dropped slightly to 19 for AC overlays on PCC, and to 26 for AC overlays on AC.
An additional 20 agencies indicated using straightedges or str~nglines as part of a
bump specification for both pavement types.
50
40
cn
._
~ 30
~4
¢
o
~ 20
z
10
O
40
Ride specification (with or without bump
specification)
Bump specification only
_._._._ 28._._ - - ~ - - ~ - - ~. - ~ - .~. - ~ - ~ - ~ - ~ -
19
...... .. . . . ............ . . .
New AC
~_
~_
_ _
_ , _ , _
r l
New PCC
l .............. . . . ............ . . . . ............ . . . ............... . . . ....... ... . . . . ............ . . . ............... . . . .....
26
20
19 20
AC/AC
AC/PCC
Figure 1. Sununary of use of smoothness specifications for various pavement types.
8
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Most highway agencies have a smoothness specification for new PCC and for PCC
overlay pavements. Forty of the 50 respondents indicated using profiling devices to
ensure PCC ride quality requirements. Five other respondents indicated using
straightedges or stringlines as part of a bump specification. The remaining 5 agencies
did not indicate the use of PCC smoothness specifications largely, it is believed,
because they do not construct PCC pavements.
In conjunction with the smoothness specifications, many highway agencies use
incentive/disincentive payment schedules. Of the 50 responding agencies, 21 and 29
indicated the use of incentive and/or disincentive pay factors on new AC and new
PCC construction, respectively. The vast majority of the incentive/disincentive pay
schedules were noted as being step-function pay schedules, with a certain percentage
paid for a specified range of smoothness.
Figures 2 Trough 4 provide a general indication of the initial smoothness
standards set by the States and Federal Lands agencies. In these figures, histograms
of the critical limits for corrective action (e.g., grinding, overlay, remove/replace),
Incentive payments, and disincentive payments, respectively, are illustrated for both
new AC and new PCC pavements. The limits are expressed in terms of profile index
11
10
9
8
~n
~7
¢ 6
a
E 4
it,
:=
~NewAC
· New PCC
-
Notes
KS (30 in/ml on~AC and~PCC)~uses~
........... . . . . . .~e.x ~bl~ing L.an. ~. . . . . . . . . .
1
O
1 3 s 7 9
... ~...
1 1 1 ~
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
~.................. ~..... ..
1 1 1 1 1 1 1 13 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
11 13 15 17 19 21
23 2s 27 29 31 33
Profilograph Corrective-Action Critical Limits, in/ml
35 37
Figure 2. Maximum roughness levels prior to requiring corrective action.
9
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8
~ ~NewAC
- 1
co !
.O 1
u
0£
¢
o
~ 3
z
4
O
4 5 6 7 8
Notes
IL (0.5 in/ml over entire project) counted
. ............. . . Y - . . _ . . . . . . . . . . .
as 1 1n/m1tor A _.
IL (4.25 in/ml over entire project) counted
. as ~.~Imi fQr P~C.~
KS (10 in/ml on AC and 15 in/ml on PCC)
uses zero blanking band.
. , ~,.,, , ,,,.,,.,, ,,.,.,., ,., ,, .,, ,.,,.,,.,, ,,.,,.! i,
9 10 11 12 13 14 15 16
Critical Limit for Profilograph-Based Incentives, in/ml
Figure 3. Minimum roughness levels prior to incurring incentive payments
10
9
8
7 ~
CO
._
~ 6
q)
so
o
z
4
1
o
_ ~NewAC
· New PCC
Notes
KS ~40j~mi on AC and 50 in/ml ~ P~C~Q
uses zero blanking band.
~. . 1
7 9 1 1 13 15 37 39 41 43 45 47 49 51
Critical Limit for Profilograph-Based Disincentives, in/ml
Figure 4. Maximum roughness levels prior to incurring disincentive payments.
10
-
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(Pl) values (as measured by a profilograph, since this was the most common device),
and they denote the m~nimurn (incentive) or maximum (corrective action and
disincentives roughness levels prior to incurring the specified consequence.
As seen in figure 2, most of the corrective action requirements fall between 7 and
15 in/ml (0.~1 and 0.24 m/km). Moreover, the limits for new AC pavements appear
to be slightly lower, or more restrictive.
Critical incentive Innits for bow new AC and PCC pavements generally range
between 3 and 7 ~n/mi (0.05 and 0.~1 m/km), as shown in figure 3. Again, however,
the critical limits are slightly more restrictive for AC pavements than for PCC
pavements. For disincentive criteria, [units of 7 and 10 ~n/mi (0.11 and 0.16 m/km)
are common, with slightly more leniency given to new PCC pavements (figure 41.
Nearly all profilograph-based bump specifications are based on a 25-ft (7.5-m)
base length. Of the 39 agencies that indicated the use of a bump specification, 36 use
a 25-ft (7.5-m) base length. Nearly two-thirds of the 36 agencies require Mat bumps
greater Man 0.3 in (7.6 mm) be ground (see figure 5), while another 31 percent
specify grinding of bumps greater than 0.4 in (10.2 mm).
Various pieces of equipment are used to enforce Me existing highway agency
smoothness specifications. The pie charts in figures 6 and 7 illustrate the breakdowns
in equipment type used for measuring initial smoothness of asphalt surfaced
pavements and concrete pavements, respectively. It should be noted that these
distributions include all of the types of equipment specified by each agency, be they
two or more profiling devices or a profiling device supplemented by a straightedge
0.5=
6%
0.4
31%
Note: Corresponding to 25-ft Base
0.3 in
63%
Figure 5. Breakdown of bump size criteria for 25-ft (7.5-m) profilograph base lengths.
11
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R It Stringline
Equipment Legend
KJ Law 690 DNC - Noncontact Inertial Profilometer
LISA - Lightweight Noncontact Inertial Profilometer
California - Califorrua Profilograph
Ames - Ames Profilograph
Rainhart- Rainhart Profilograph
Mays (vehicle) - Mays Meter installed in vehicle
Mays (trailer) - Mays Meter mounted on trailer
Law
690 DNC
3% LISA
1%
Mays (vehicle)
(trailer) 3%
7%
California
sO/^
''Ames
' 12%
Figure 6. Breakdown of roughness measuring equipment used on new AC
and AC overlay pavements.
KJ Law
690 DNC
Rolling 3% LISA
Straightedge 1%
. a,
Equipment Legend
KJ Law 690 DNC - Noncontact Inertial Profilometer
LISA - Lightweight Noncontact Inertial Profilometer
California - California Profilograph
Ames - Ames Profilograph
Rainhart- Rainhart Profilograph
Mays (vehicle) - Mays Meter installed in vehicle
Straightedge
Mays
(vehicle) \
1% \,
Rainhart
10%
Ames
10%
Figure 7. Breakdown of roughness measuring equipment used on new PCC
and PCC overlay pavements.
12
California
44%
OCR for page 13
(e.g., Iowa specifications allow the California and Ames profilographs for testing
profile, and a straightedge for testing surface tolerances In excluded areas). Hence,
for each pavement type, the total number of measuring devices far exceeded 50,
reaching to between 70 and 75.
As seen In figure 6, the devices of choice for new AC and AC overlays are the
straightedge and the California profilograph. Approximately 30 agencies use a
straightedge and approximately 20 agencies use a California profilograph in their
evaluation of initial smoothness. Moreover, 9 and 7 agencies were noted as using the
Ames profiIograph and the Mays Meter, respectively, on asphalt surfaced pavements.
A considerable difference In the equipment breakdown occurs when the subject
pavement type is new PCC (figure 71. Here, the preferred device is the California
profilograph, which is used by 33 of the 50 respondents. The straightedge is next
commonly used (23 agencies), followed by the Ames and Rainhart profilographs (7
agencies each). Unlike on AC pavements, the Mays Meter is rarely used on PCC.
As seen In table I, SHAs base the selection of smoothness specifications and
~ncentive/disincentive payment schedules on various items. For each of Tree main
pavement types, at least one-third of the agencies Indicated basing their specifications
and payment schedules on methocis other than research, engineering judgment, and
AASHTO or other specifications. Moreover, SHAs are more likely to base their
specifications and payment schedules on their own knowledge or study findings
rather than external sources. Another basis for ~ncentive/disincentive payments for
overlays (although not shown In table 1) is the percent unprovement made to
smoothness.
Table 1 also shows that the majority of SHAs base ~ncentive/dis~ncentive
payments on a portion of the unit bid, rawer than a fixed amount or other methods.
About one-half of the responding agencies base such payments for new AC on a
portion of He unit bid. This percentage is considerably higher (69 percent) for new
· · ~ ~. ~
1 ~
PCC or PCC overlays, primarily because I've pavements more commonly nave an
incentive clause.
Finally, the need for separate smoothness specifications for specific pavement
types was generally disavowed by SHAs (figure 8~. At least 50 percent of the
respondents did not feel the need for separate specifications for 9 of the 10 pavement
types listed. The exception to this finding was surface-ground PCC, which was
evenly split between the Tree possible responses. Among those pavement types for
which the majority of agencies indicated no need for a separate specification, the
highest percentages occurred with new AC pavements and raew PCC pavements.
13
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Table 1. Distribution of SHA responses to various smoothness
specification questions.
| | New PCC or |
Response I New AC I PCC Overlay I
.
Basis for selection of specified smoothness limits
Research and analysis l 10 1 .
Engineering judgment 9
Other agency specifications 4 4
AASHTO guide specification 3 5
Other 18 20
Total number of agencies responding 43
Basis on which incentive/disincentive payment amounts are determined
Fixed amount, $/yd2 1 7 | 7
Portion of the unit bid | 14 | 24
Other _ l 5 | 4
Total number of agencies responding 26 35
Basis for selection of relationship between incentive/disincentive payment and smoothness
Engineering judgment 4
AASHTO guide specification 1 3
Other agency specifications 3 4 ~
Research and analysis 6 3 .
Other 10 15
Total number of agencies responding l 24 ~32
AC Overlay
9
10
3
2
18
42
6
13
6
25
5
lo
1
2
5
10
22
1 yd2 = 0.84 m2
14
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100°/o
80%
u,
u'
o
u,
c,
~40O/O
CJ
60%
20%
0%
_ .
<, ~ ~ ~ ¢ , ~ 3 ¢ u ~ 2
v, ~
O Unknown
·No
111 Yes
Figure 8. Breakdown of responses concerning the need for separate specifications.
Specified Field Procedures
For each of the three main pavement types, smoothness progress testing is largely
performed by the paving contractor. As seen in table 2, roughly two-thirds of the
responding agencies indicated that this responsibility falls upon the contractor
for each pavement type. SHAs perform about 20 to 25 percent of this work, with the
remainder involving joint State/contractor testing.
In contrast less than 20 percent of the responding agencies indicated allowing
contractors alone to perform smoothness acceptance testing.
is performed by the highway agency, regardless of pavement type.
The bulk of this testing
The vast majority of SHAs test the entire length of paving for roughness, rather
than evaluate random samples. As evident in table 2, 76 and 86 percent of the
agencies test the entire length of AC and PCC constn~ction sections, respectively.
Similar percentages reflect the number of States that evaluate initial roughness
along O.~-mi (0.16-km) Intervals. Most others evaluate along 1-ml (~.61-m) intervals
for AC pavements and various specified lengths below 0.25 mi (0.40 km) for PCC
pavements.
15
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Table 2. Distribution of SHA responses to various roughness measuring
procedures questions.
~ New PCC or j l
Response | New AC | PCC Overlay I AC Overlay I
Party responsible for smoothness progress testing |
Contractor | 28 | 32 l
State 12 10
Over l
Totalnumber of agencies responding 1 43 1 46 l
Party responsible for smoothness acceptance testing
Contractor | 5 | 9 l
State 28
Other 7
Total number of agencies responding 1 44 | 44 l
Extent of smoothness measurement sampling
Entire paving leng*l 29 38
Random samples
Total number of agencies responding | 38 | 44 l
Unit length of paving section individually evaluated for smoothness
528 it (0.1 mi) ~23 1 36
,056 it (0~2 mi) ~1 1 O
_ _ _
Other 8
Total number of agencies responding 31 44
Time after construction in which acceptance testing is performed
_ -- . .
Within 24 has 1 11 1 8
_ _ _ ~1
Within 48 hours 1 0 1 6
Within 72 hours | 4 | 3
_ , ,
No time requirement/test as soon as possible. 1 10 l
Other | 9 | 11
~ -- - I 1
Total number of agencies responding | 34 1 42 1 ~
29
0
4
43
6
30
6
42
29
9
38
2
1
9
31
11
1
4
9
9
~4
16
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Between 40 and 47 percent of the responding States Indicated that initial
roughness testing is done within 72 hours of new construction (table 2~. Moreover,
between 26 and 33 percent of the respondents indicated having no specific time
requirement, or that testing is performed as soon as possible.
With regard to the use of computerized profiling devices, SHAs are laraeiv split
Data Reduction Procedures
~ , ~
between using Butterworth (third-order) and Cox (first-order) filters and settings
(figure 9~. Almost two-thirds of the responding agencies use one of these filtering
methods, with the remaining methods consisting of Chebyshev (third-order), moving
average, recursive (second-order), and combined Cox and moving average filters.
. . ~
Overwhelmingly, States using a profiIograph in their roughness testing place a
0.2-in (5.~-mrn) blanking band for evaluation of profiIograph traces. Table 3 shows
that, for each of the three main pavement types, approximately 86 percent of the
respondents indicate use of this blanking band limit.
Table 3 also shows that a variety of methods are used to position the blanking
band for profile trace evaluation. Visual judgment is the most common method,
followed by the computer-selected, best-fit procedure and aligrunent with previous
section. A few agencies combine visual judgment and computerized best-fit.
Cox, 1st Order
32%
Chebyshev, 3rd Moving Average
Order 5°/O Other
a/ 29%
5,0
Butterworth, 3rd
Order
29%
Figure 9. Breakdown of filter and setting types used with computerized
profiling devices.
17
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Table 3. Distribution of SHA responses to various data-reduction
procedures questions.
New PCC or
l Response | New AC | PCC Overlay |
Blanking band ~
0.1~n -3
0.2 In 19 32
Other 1 2 1 2
Total number of agencies responding ~A) ~37
Method used for positioning the blanking band
Aligr~nent with previous section ~5
Visual judgment ~16 :
Computer-selected best-fit ~9
Over ~ :
Total number of agencies responding ~3 8 :
Accuracy to which scaZIops on profiZograph traces are rounded
0.01 in ~3 :
~0.05 in ~29 :
_ _ _
Over 1 3 ~
_ _
Total number of agencies responding 1 35 all
1 In = 25.4 Am
1
8
2
2
Finally, the accuracy to which scallops on profilograph traces are rounded by
States is most often 0.05 In (~.3 mm). Approximately 82 percent of responding States
noted using this accuracy level, followed by 9 percent using 0.01 in (0.25 mm). In
addition, one State indicated using bow 0.05 in and 0.01 in (~.3 and 0.25 mm) levels,
whereas another uses 0.03 In (0.76 mm) exclusively.
Satisfaction With Current Specifications
When questioned about the adequacy of their current smoothness specifications,
most States felt Weir specifications were either adequate or in need of slight
unprovement. Of 45 responding agencies, 24 indicated Weir current specifications
were adequate, 16 indicated slight improvements should be made, and 5 indicated
their specifications should be replaced.
18
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Regarding the adequacy of their initial roughness measuring equipment, most
States are moderately satisfied to moderately dissatisfied. Figures 10 through 14
illustrate the basic statistical results of States' ratings of five equipment types. For
each type, I) different properties were rated on a scale of one (completely
satisfactory) to five (completely unsatisfactory).
Since the equipment was subjectively evaluated and since highway agencies
predominantly use the California profilograph, a comparison of property ratings
between pieces of equipment is believed to be inappropriate. More appropriate,
however, is the following discussion on the perceived merits and drawbacks of each
equipment type.
As seen in figure 10, the most apparent drawback of the California profilograph is
its ability to be correlated with other devices. There also appears to be problems In
correlating the Rainhart profilograph with other devices. In fact, not only is the
Rainhart profilograph perceived to be unsatisfactory at correlating with other devices,
but its data collection rate and data reduction effort are largely judged unsatisfactory,
much like the Ames profilograph.
4
2
1
~ Avg
l _ ............
~Avg+StdDev
..-..~..
U ~, ~ ~ c
U ~ ~o ~
Figure 10. Statistical results of California profilograph ratings
(1 = satisfactory, 5 = unsatisfactory).
19
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5 l
3.5
~ · Avg - Std Dev
4.5 , - ~ Avg . ~
4 ~ - ~ Avg + Std Dev ~|
3
~4
~ 2.5
Do;
2
1.5
1
0.5
5
4.5
4
3.5
3
~o
2.5
2
1.5
1
0.5
L . ~.
... ,..............................................
.. .............................. ............. .......... .. ............... ..............................
l . . . ............ . . . ............... . . . ............ . . . . ............ . . . ............... . . . ............ . . . . ............ . .
_ f _ _ ~
f A
.......... _._._4 i . ._
`, ~ ~ 0 5 ~ ' - ~e
D E _ a i' u ~ ~ J 2 ~v
Figure 11. Statistical results of Rainhart profilograph ratings
(! = satisfactory, 5 = unsatisfactory).
. · Avg - Std Dev . _ ~_.~ a
Avg
... . _ _ ....
Q Avg + Std Dev
_ ................................ .............. _ ` L .
_ _ ~ .~ .
_ _ .. ............................... ~ I
_ ; ' ; j jj
. ...................
................. . . . . .]
................. ...............
[ ~ ...............
O ~1 1 1 1 1 1 1 1 1 1
=^ ~-3 ~-~ ~ED ~U EN
x
Figure 12. Statistical results of Ames profilograph ratings
(] = satisfactory, 5 = unsatisfactory).
20
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5 i
r · Avg - Std Dev
4.5--- ~ Avg ......................................................
4 F - ~ Avg + S td Dev L. _._ ........... _._._._ ... _.___._._ _._._._ _._._._ ._. _ .
- - - - -- - - - t -- - - - -i - -- - -. - . - . ~- . - . - . - - . - . - . ~- . - . - . - . - ~. - . -
O.
1
O
........... ..... 4 F . . ... ]
........... _._._._ __._._._ _._._._ _._._._.
1 1 1
1 1 1 1 1 1
~ ~ =5 ~ ~S - - ~E ~u
0 ~n O ~U
Q
._
u,
s
x
Figure 13. Statistical results of Mays Meter ratings
(1 = satisfactory, 5 = unsatisfactory).
4.5~-
4
3.5
3
~o
·fi 2.5
2
1.5
1
0.5
O
o
._
~ 0
. .. · Avg - Std Dev .~.
JAvg
................................................
1
-
. _
~;
o
s
tJ
._
a'
._
1 1-- - --.-.- -.
.............. ...............
' ...............
~, ~
T ~ , I
.......... . . . .
.......... . . . .
..~ ....................................
.. ............ . . . . . .
................................
. ................................
, . .~..........
.- _ E y U, u
-_ E ~-D j C C _
E - ' . ~v
u ~3 ~ a '
Figure 14. Statistical results of inertial profiler ratings
(1 = satisfactory, 5 = unsatisfactory).
21
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The Mays Meter is generally perceived to be unsatisfactory at correlating with
both different devices and similar models (e.g., trailer-mounted versus vehicle-
mounted). In addition, there is a fair level of dissatisfaction with respect to
repeatability and its ability to identify "must grind" locations.
Finally, as seen In figure 14, the major perceived drawback of the inertial profiler
is overall cost (initial and maintenances. In general, the initial cost of this type of
equipment is between 10 and 15 times the initial cost of profilographs. Other areas of
dissatisfaction largely noted by the SHAs include durability, set-up effort, and the
level of expertise required.
Effects of Specifications
Many responses were provided to various questions regarding the effects of
smoothness specifications and ~ncentive/disincentive payments. As seen in table 4,
roughly half of the responding States have either records that show or simply believe
that increased smoothness results from their smoothness specifications. Furthermore,
although the proof is generally not available, nearly half of the SHAs indicated that
their initial smoothness specification positively impacts material/construction quality.
Interestingly, the majority of highway agencies having incentives/disincentives for
smoothness indicated they have records that show significantly smoother pavements
as a result of specifying incentive/dis~ncentive provisions. The net cost to the States
making such payments is generally not clear at this time; however, a number of
agencies did indicate increased payments associated with PCC construction.
Pavement Roughness Data
As a means of sensing the availability of both initial and extended pavement
roughness data, a series of questions were included In the survey regarding States
retention of, and ability to provide, these types of data. As seen In table 5, a fair
number of States indicated possessing iriitial and/or extended roughness records.
Most of these States also expressed their ability to provide these records, as
illustrated in figure 15.
Summary of Contractor Survey Responses
As discussed previously, a total of 16 contractors, representing all of the regions In
the continental United States, furnished responses to He contractor survey. One of
the contractors completed 2 survey forms so as to Individually reflect both their
asphalt and concrete paving experiences. The following sections provide a general
overview of the results of contractor's responses to selected questions.
22
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Table 4. Distribution of SHA responses to various questions on the impact
of smoothness specifications.
New PCC or
Response ~New AC | PCC Overlay I AC Overlay :
result of current smoothness specification on initial pavement smoothness
Records show noticeable smoothness increase 8 17 7
|| 'erceived smoothnessincrease 1 13 | 13 | 133
l I Joincreased smoothness 1 8 1 7 T 7g
l I Jot sure,too early to tell 1 6 1 3 T 5g
l I Jo specification now 1 6 1 1 T 8g
l I rotalnumberof agencies responding 1 41 1 41 T 40j
|| result of current smoothness specification on material/construction quality control j1
l | records show better quality | 2 | 4 T 11
Perceived quality increase | 16 | 20 | 15 11
l Jo increased quality ~8 1 6 T 7 11
l Cot sure; too early to tell 1 6 1 7 T 5 ill
l Jo specification currently | 7 | 2 | 9 g
l Cotalnumber of agencies responding | 39 | 39 | 38 al
I | (esuIt of incentives/disincentives on initial pavement smoothness 21
l records show significantly smoother | 12 | 19 | 11 1
pavements _ _
do difference in pavement smoothness T 2 1 2 1 0 All
i | dot sure; too early to tell | 9 | 11 | 8 :
Jo incentives/disincentives in specification ~9 ~5 ~12
. ~ 'otal number of agencies responding ~32 ~37 ~31 i
| (esuit of incentives/disincentives on overall cost to S tale j1
;igruficantly higher overall payments T 2 ~6 ~2 ||
I iignificantlyloweroverallpayments T 2 1 1 ~1 11
I dot sure;too early to tell T 17 ~23 ~16 11
. I doincentives/disincentivesin specification T 8 1 4 T 12 11
| 'otal number of agencies responding T 29 | 34 T 31 11
23
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Table 5. Distribution of SHA responses to various questions on availability
of roughness data.
| Response | New AC | New PCC/PCC Overlay | AC Overlay ||
Retention of initial pavement roughness data
Pavements 1 to 3 years old 1 13 1 10 l
Pavements 4 to 9 years old 8 14
Pavements more Man 9 years old | 6 | 9 l
_
Total number of agencies responding 27 33
Retention of extended pavement roughness data
Pavements 1 to 3 years old 4 2
Pavements 4 to 9 years old 9 9
.
Pavements more Wan 9 years old 9
Total number of agencies responding 21 20
0
7
l 7
24
3
0
8
2
30,
cn
~ 25
20
._
1
o
co
~ 10
o
0 5
Ad
o
@' Initial Roughness
Extended Roughness
14
8
25
20
1 to 3 years old 4 to 9 years old >= 9 years old All ages
Pavement Age Category
Figure 15. Ability of SHA's to provide roughness data for evaluation.
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Equipment
A majority of the contractors ~nclicated using the California profilograph In their
paving work, occasionally in conjunction with other devices. Of the 7 asphalt paving
respondents, 6 noted using the California profiIograph and 2 noted using the Ames
profilograph. Of the 10 concrete paving respondents, ~ noted using the California
profilograph, 3 noted using the Mays Meter, and 2 noted using the Ames
profilograph. Straightedges were quite common among both types of paving
contractors.
Although most contractors Indicated using only ~ device (often because of State
requirements), 4 contractors who noted the use of multiple devices had the following
preferences and corresponding reasons:
.
· California profilograph over the Ames profilograph case of data reduction.
Rainhart profilograph over the Mays Meter-repeatability and more realistic
profile.
· Ames profilograph over the California profilograph mobility and ease of
operation.
· California profilograph over the Mays Meter repeatability and quick, hard-
copy answers.
Equipment property ratings were very similar to those provided by the States.
For all of the devices (California profilograph, Ames profilograph, Rainhart
profilograph, and Mays Meter) rated by the contractors, each had mean property
ratings equal to or slightly below the mean State ratings shown in figures 10 through
13. The main drawbacks of these devices as revealed by Me contractors ratings are
as follows:
· California profilograph
- correlation with different devices.
· Ames profilograph
- data reduction effort.
identifying must-gr~nd locations.
· Rainhart profilograph
data collection rate.
data reduction effort.
· Mays Meter
equipment repeatability.
correlation with same models.
identifying must-grind locations.
Roughness Measuring Procedures
According to the contractors' responses, the contractor is generally responsible for
providing both Me progress and acceptance testing equipment on paving projects.
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Moreover, as shown In table 6, contractors are also largely Involved In the actual
roughness measuring and analyses.
All 16 contractors (including the asphalt/concrete contractor) preferred handling
the pavement roughness testing and analysis. ~ ~
~ =-~ - O , the two foremost reasons were the
contractor's ability to get immediate results and correct the pavement as necessary
and the ability to control the operation, thereby aiding the scheduling process.
Current Smoothness Specifications
On the question of whether smoothness specifications are uniformly applied by
State highway and other agencies, contractors were largely split. Four contractors
responded "yes," 4 responded "no," and 8 responded "reasonably so." In addition,
when asked whether serious attempts should be made to standardize specifications
equipment, and procedures, 14 of the 16 contractors indicated "yes." The primary
~ ~ - , ~ - - - ,
reason given was that standardized specifications and equipment will assist
contractors In obtaining consistent results. The 2 contractors opposed to
standardization believed it would either be a waste of time and money or that
specifications must be free to change with changing expectations and equipment
capabilities.
Although most contractors (15 out of 161 did not believe the emphasis on
smoothness is costly, contractors were evenly split on whether current specifications
and test procedures are adequately clear and concise (9 agreed, 7 disagreed).
Moreover, each of the 16 responding contractors agreed that obtaining smoother
pavements requires attention to other aspects of production, hereby improving the
overall quality of the highway.
Table 6. Distribution of contractor responses to various roughness measuring
procedures questions.
| Number of Responses (out of 17 total)
| Question | Progress Testing I _ I
Party responsible for operating the smoothness testing equipment
Contractor 17
State Agency
Bo~
Party responsible for doing the necessary analysis and calculations of test results
Contractor ~ 1
State Agency ~
30~ ~ 2
. . ~
Acceptance Testing
7
6
2
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With respect to ~ncentive/dis~ncentive clauses, most contractors (14 out of 16)
favored these over a fixed-bid system. The main advantages and disadvantages
given by the contractors Included the following:
Advantages
· Competitive advantage for higher quality contractors.
· Promotes quality workmanship.
An incentive to try new technologies and to upgrade QC programs.
Levels the playing field those contractors that care about quality can
potentially regain their extra costs.
The highway agency and, hence the taxpayer, benefit from cheaper bid prices
because good contractors will take advantage in the bidding process and
submit a cheaper price.
.
Disadvantages
· Disincentives are not properly balanced win incentives or with the decrease In
pavement performance.
· Specification is worthless on projects designed with characteristics restricting
the ability of the contractor to achieve the specified smoothness.
· Unbalanced bids.
· Highway agency must include Me incentive in the estimated cost of the
project. This can cause problems when funds are Ignited.
When asked if anticipated incentive/disincentive payments influence project bid
prices, Il of the 16 responding contractors indicated they do. The general response
of these contractors was Mat Hey either reduce He bid by the amount of incentive
expected or increase He bid by the amount of disincentive expected. In either case,
the contractor must assess the characteristics of each project and have a good
understanding of his capability for achieving specified levels of smoothness.
Among some of the general improvements suggested by contractors in the area of
specifications, equipment, and testing were the following:
Standardization in specifications and test procedures.
Better communication and harmony between the highway agency and the
contractor.
Clarification regarding when incentive/disincentive adjustments apply.
Universal acceptance of computer reduction of profiIograph traces, thereby
eluninating the judgment of Individuals.
Additional training of individuals performing the roughness tests and analyses.
To improve pavement smoothness, the responding contractors noted making
several operational changes In the last 5 years. Most of these changes were made In
the areas of paving equipment and procedures, subgrade quality control, paving
mixture quality control, and roughness measuring procedures. Specific changes
included buying new pavers or paver attaclunents (e.g. longer skis, material transfer
devices), maintairung more continuous paving operations, promoting better subgrade
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designs and/or preparations, and performing more intensive smoothness progress
measuring.
Suggested future changes to improve initial smoothness included new paving
equipment, training, and the use of material transfer devices.
Summary
This chapter has presented a brief discussion of the results from a questionnaire
survey on current roughness-measur~ng practices. Surveys were conducted of both
SHAs and major highway paving contractors in March and June, 1994, respectively.
These questionnaire results are a valuable indication of the current practices In
pavement roughness measurement and interpretation. The complete responses are
sumrnarwed In appendix A.
28
Representative terms from entire chapter:
smoothness specifications
