Canadian Strategic Highway Research Program (C-SHRP)
Summary of Pavement Smoothness Specifications
in Canada and Around the World
July 1999
In April 1999, the Transportation
Association of Canada (TAC) held its
annual Spring Technical Meetings in
Toronto, Ontario. During the TAC
Pavements Standing Committee
(PSC) meeting, provincial transportation agency representatives presented their respective provinces
smoothness specifications for newly
constructed roads and highways.
This brief has been prepared from
those presentations.
BACKGROUND
Users of roads and highways expect
a certain level of comfort during their
journeys. Indeed, roads and highways are primarily designed and built
for the comfort and convenience of
the travelling public.1 The ability of
a pavement to accommodate road users at a reasonable level of comfort
defines the concept of serviceability.
First introduced in 1960, studies have
indicated that approximately 95 percent of the information defining the
serviceability of a pavement is explained by the roughness of the surface profile.2 In other words, only 5
percent of pavement serviceability is
not explained by surface roughness.
Therefore, the specification, measurement and monitoring of roughness are critical to providing roads
and highways capable of providing
adequate ride quality.
Technical Brief # 16
In addition to reduced serviceability,
roughness presents other adverse effects on road users and vehicles.
First, increased road roughness compromises vehicular safety by affecting braking and steering. Increased
roughness has also been linked to
lower operating speeds of roadways.
Finally, increased vehicle operating
costs such as fuel, oil and tire consumption as well as suspension damage result from increased road roughness.
Smoothness vs. Roughness
Hudson3 has defined roughness as “a
distortion of the pavement surface
that contributes to an undesirable or
uncomfortable ride.” A vehicle passing over a rough pavement is subjected to a harmonic or transient excitation, in turn transferring a vertical acceleration to the occupants of
the vehicle. The degree to which
roughness affects the operation of a
vehicle depends on many factors
such as the amplitude and frequency
of the pavement distortions, vehicle
suspension characteristics and vehicle speed.
Smoothness is defined as the lack of
roughness and is typically used to
describe the initial state of a pavement surface immediately after construction, but prior to trafficking.
Initial pavement smoothness is im-
1
portant since there is a direct relation between smoothness, serviceability and cost as outlined below.
Striving for High Initial
Smoothness
While minimum pavement smoothness standards contribute to acceptable serviceability over time, striving
for improved initial smoothness is a
worthwhile endeavour. Numerous
investigations have conclusively
shown that even small improvements
in initial smoothness provide significant increases in the long-term performance of the pavement surface
with respect to roughness progression
and long-term cracking.4 By reducing the progression and severity of
roughness, both annual maintenance
costs and overall life-cycle costs are
substantially reduced. Therefore,
roadbuilding agencies can afford to
offer contractors incentives (bonuses) to produce smoother pavements and be confident that the extra investment made at the beginning
of the project may be returned many
times over with the associated increase in long-term performance.
Likewise, agencies may also impose
penalties for poor initial smoothness
as reduced performance and increased maintenance costs will result.
Smoothness Measuring
Equipment
Excluding subjective measurements
made by rating panels (see below),
roughness and smoothness are measured using two types of equipment.
The first type are referred to as response-type devices measuring the
dynamic response (frequency) of a
mechanical device, typically a half or
quarter car simulator, travelling over
the pavement surface at a constant
speed. Response type devices are
simple to use, relatively low in cost
and operate at high speed. However,
frequent calibration is usually required and such devices are typically
frequency dependent, meaning that
some measured frequencies are amplified while others are attenuated.
Examples of response-type devices
include the Mays Ride Meter, PCA
Meter, Portable Universal Roughness
Device (PURD), K.J. Law Roughness
Surveyor, and the Walker Roughness
Device.
The second type of roughness/
smoothness measuring device are
referred to as profilometric devices
which measure the actual profiles of
the road surface. Accurate, scaled
reproductions of the road profile allow more flexible and case specific
evaluation of the pavement surface.
However, profilometric devices are
typically more expensive to purchase
and maintain than response type devices, operate at low speed and also
require more extensive data processing. Examples of profilometers include the California Profilograph,
Digital Instrumental Profiler (Dipstick), Longitudinal Profile Analyzer,
Inertial Profilometer and the Road
Surface Tester. Figure 1 illustrates a
California Profilograph used by the
Ontario Ministry of Transportation
(MTO).
Units of Measure
Just as there are many different types
of measuring devices, roughness and
smoothness are expressed in many
different forms. A few of the more
common measures are presented
below.
Subjective Ratings
Perhaps the most common subjective
roughness measure used in the past
throughout Canada was the Riding
Comfort Index (RCI) or Riding Comfort Rating (RCR) as determined by
a trained rating panel. Subjective ratings start with a perfect score (usually 10 or 100) and points are deducted based on the rater’s perception of the riding quality of the test
road. Like other subjective ratings,
RCI and RCR are subject to rater bias
and are difficult to compare across
multiple jurisdictions. The recent advancement of profile measuring devices and response type devices in the
last 10 years has significantly reduced, if not eliminated, the use of
subjective ratings for roughness
evaluation.
Rate of Smoothness and
Profile Index
Unlike subjective ratings, profilometric devices measure the actual
profile of the pavement surface. The
result is a series of minute crests
(“bumps”) and valleys (“depressions”) along the length of the roadway. The Rate of Smoothness is calculated by adding the amplitudes
(heights) of all bumps and depressions outside of a datum line called
Travel G uide
T op V ie w
Steering
Assem bly
0.37 m
0.88 m
Com puter
and Printer
S ide
W heel
Assem bly
M easuring
W heel
1.40 m
7.62 m
10.12 m
Figure 1: California Profilograph (Top and Side Elevation Views)
2
1.02 m
W heel
Assem bly
Blanking Band
Bump
value of 0 m/km (or mm/m) indicating no vertical deviations from the
surface along the road length. In
contrast, IRI values greater than 10
m/km represent rough, unpaved
roadways.
Depression
Reduction Length (i.e. Sublot)
CAPL25, CP and NBO
Amplitude greater than 0.8 mm
Profile Trace
The Longitudinal Profile Analyser
(APL) developed by the Laboratoire
Central des Ponts et Chaussees
(LCPC) is an inertial profilometer
consisting of a bicycle wheel, chassis
with ballast and a special low-frequency inertial pendulum that serves
as a horizontal reference. The device is mounted to a trailer and is
insensitive to movements of the tow
vehicle. In Europe, the APL trailer
is used extensively for pavement
smoothness measurement. The device is operated at 21.6 km/hr and a
summary roughness index called
CAPL 25 is calculated for each 25m
of wheel track tested. The CAPL25
index is used because the low speed
required for smoothness testing cannot record the entire frequency range
required for IRI calculation. However, IRI can be estimated from
CAPL25 through correlation factors
as shown below.
Length greater than 0.6
Figure 2: Calculation of Rate of Smoothness and Profile Index
the “blanking band” and dividing by
the length of the test section as illustrated in Figure 2. The width of the
blanking band is specified by the particular agency, typically ranging from
0 mm to 5 mm.
The Profile Index (PI) is determined
by averaging the Rate of Smoothness
of both wheelpaths for a given test
section.
Scallops (Bumps)
The Rate of Smoothness and Profile
Index measurements take the average amplitude of bumps and depressions over the length of the test section. However, individual high amplitude events known as “scallops”
(bumps) are not accounted for with
these measures. Therefore, many
smoothness specifications include a
“bump specification” to limit the occurrence and/or size of scallops in the
pavement surface. Figure 3 illustrates the procedure for measuring
scallops from profile data.
Total Cumulative
Roughness (TCR)
Whereas the Rate of Smoothness and
Profile Index measure roughness
outside of a specified blanking band,
the Total Cumulative Roughness
(TCR) is a summation of all roughness – including roughness within
the blanking band. Therefore, TCR
effectively assumes a blanking band
width of zero (0), resulting in the sum
of all slope deviations along the profile of the pavement.
International Roughness
Index (IRI)
The International Road Roughness
Experiment was held in Brazil in
1986 to correlate the various roughness measures to a standard measure, now known as the International
Roughness Index (IRI). IRI is a statistical measure that is valid for all
levels of roughness. Absolute
smoothness is denoted by an IRI
Blanking Band
Bump
Depression
Reduction Length (i.e. Sublot)
Excessive
Height
Profile Trace
10 mm
Bump
Template
7.5mm
Figure 3: Calcuation of Bump (Scallop) Height
3
CAPL25
4
6
8
13
16
IRI (m/km)
1.3
2.0
2.7
4.3
5.3
A similar roughness measure to
CAPL25 used in Belgium by the Centre de Recherches Routieres (CRR)
is called the Coefficient of Unevenness (CP). The CP measure may be
calculated from the same data used
to calculate CAPL25, however, different baselengths are used.
CANADIAN SMOOTHNESS
SPECIFICATIONS
Pavement smoothness specifications
were first introduced by individual
provinces beginning in the mid
1980’s with subsequent revisions to
the current day. While the specifications between provinces vary, the
overall goal is the same, which is to
construct smoother pavements and
thereby increase pavement serviceability. Tables 1 and 2 compare and
contrast the smoothness specifications used for the various provinces
as presented at the Pavements Standing Committee meeting during the
1999 TAC Spring Technical Meetings.
Smoothness Indicators,
Equipment and Applicability of
Specifications (Table 1)
As shown, only profilometric devices
are currently used in Canada. Most
provincial agencies utilise a
profilograph to measure smoothness
in terms of Profile Index (PI), typically measured over 100 metre segments. With the exception of
Ontario, all provinces using
profilographs calculate PI using a 5mm blanking band for both asphalt
concrete (AC) and Portland Cement
concrete (PCC) pavements. Ontario
uses a zero (0-mm) width blanking
band for AC pavements and a 5-mm
blanking band for PCC pavements.
While Manitoba uses a 5-mm blanking band for PI calculation, the Total
Cumulative Roughness (TCR) measure is calculated with a zero width
blanking band, essentially the same
as the Ontario PI measure, although
TCR is expressed in millimetres per
100 metre segment instead of
millimetres per kilometre. Quebec
uses the California Profilograph for
Portland Cement Concrete (PCC)
pavements, however, an inertial
profilometer is used to measure IRI
for AC pavements. All measuring
devices measure bump heights.
Smoothness testing is completed either by Ministry/Department forces,
private consultants or both. To ensure consistency between multiple
testing devices, calibration and correlation are important issues. To address the consistency issue, the MTO
correlates all profilometric devices in
Ontario on a single 300-metre test
section selected by the MTO each
year. Each device tests the section
three times (including the MTO’s
profilograph) and all must be within
4% of the benchmark value established at the correlation site. Each
device must remain within the 4%
benchmark throughout the season.
ASTM standard E1274 entitled
“Standard Test for Measuring Pavement
Roughness
Using
a
Profilograph” is specified by the most
provincial agencies, while Quebec
also incorporates World Bank Technical Paper 46 entitled “Guidelines
for Conducting and Calibrating Road
Roughness Measurements” for IRI
measurement.
Applicability of smoothness specifications is slightly different for each
province, however, the exclusions to
the specification are very similar.
Exclusions generally include temporary pavements, paved bridge decks
and approach sections, acceleration
4
and deceleration lanes, tight curves,
detours, areas rehabilitated with hotin-place (HIP) or cold-in-place recycling, and sections with obstructions
such as utility access points. The
western provinces (British Columbia,
Alberta and Saskatchewan) do not
exclude such sections, but rather use
lower requirements for smoothness.
Acceptance Requirements and
Pay Adjustments (Table 2)
As with applicability of the specifications, the actual smoothness requirements for acceptance of finished
pavements differ slightly between
provinces. Most provinces specify
remedial action if the PI value
reaches between 20 to 23 mm per
100-m segment. Due to its zero
blanking band, Ontario allows a
higher value for acceptable PI of 550
mm/km before remedial action. Quebec allows pavement segments with
IRI up to 1.8 m/km before remedial
action is specified. Most provinces
do allow remedial action to avoid
penalty, however, segments that are
remediated may not subsequently
qualify for bonus.
Pay adjustments based on measured
smoothness vary considerably between provinces. Most provinces provide a range of smoothness values for
which the full contract payment is
awarded. Bonuses are then awarded
for lower index values (i.e. higher
smoothness) and penalties are imposed for greater index values (lower
smoothness). An exception is Newfoundland, which does not impose
penalties (or bonuses) presently.
Newfoundland is currently developing a more comprehensive smoothness specification that is expected in
2000. Saskatchewan is the only other
province that does not offer bonus for
paving contracts, although the
smoothness requirements to achieve
bonus in British Columbia, Alberta
and Prince Edward Island are difficult to achieve. The actual values of
Table 1: Summary of Indicators, Equipment and Applicability of Specifications in Canada
Province
Year
The Western
Provinces:
British
Columbia,
Alberta,
Saskatchewan
1980’s
Smoothness
Indicator
Equipment
and Services
Profile Index
(mm/100m)
Cox
Profilograph
Bumps/Dips (mm)
Notes:
• 5mm Blanking Band
• 100 metre sublots
1993
(PCC)
Profile Index
(mm/100m)
TCR (mm/100m)
Manitoba
1997
(AC)
1999
(rev.)
Bumps (mm)
Notes:
• 5mm Blanking Band
• 100 metre sublots
Profile Index (mm/km)
Ontario
1999
(rev.)
Scallops/Bumps (mm)
Notes:
• Zero Blanking Band
• 100 metre sublots
IRI
(mm/km)
Quebec
1998
(rev.)
The Atlantic
Provinces:
New Brunswick,
Nova Scotia,
Prince Edward
Island,
Newfoundland
Notes:
• 1 km sections (AC), 500 m
sections (PCC)
• 100 metre segments
Profile Index (mm/100m)
1992 –
1999
Scallops/Bumps (mm)
Notes:
• 5mm Blanking Band
• 100 metre sublots
• DOT Services
(BC, SK)
Calibration,
Correlation
or Standard
Applicability:
• Separate specs for single lift, multiple lifts
and presence of curb and gutter
• Not Presented
Exclusions:
• No exclusions, use separate specifications
for bridges, RR crossings, etc.
• Consultant
Services (AB)
Hi-Lo Beam (AC)
3m Straight-edge
(PCC)
• Ministry
Services
California
Profilograph
• Ministry and
Contractor
Services
Inertial
Profilometer
(AC)
California
Profilograph
(PCC)
• Ministry and
Contractor
Services
• Testing Services at request of
Region or Contractor
• Start up meeting of
representatives from
contractor, project quality
assurance and profilograph
crew
• Profile measuring devices
(PMD’s) must be calibrated at
all times (distance, height)
• All Ontario PMD’s (Ministry
and Private) correlated at start
of construction season (must
remain within 4% of Ministry
benchmark)
• World Bank Technical Paper
46: Guidelines for Conducting
and Calibrating Road
Roughness Measurements
(AC)
• ASTM E1274 (PCC)
California
Profilograph
• DOT Services
(NB, PEI)
• Consultant
Services (NS, NF)
Applicability
and/or
Exclusions
• ASTM E1274
Standard Test for Measuring
Pavement Roughness Using a
Profilograph
Applicability:
• Testing completed within 1 month of
contract completion
• Top lift, outer wheelpath of each main
lane in direction of traffic
Exclusions:
• Acceleration and deceleration lanes
• readings terminated at 6m from ends of
structures, railway crossings, and existing
adjacent pavement structures
Applicability:
• Single spec for all surface courses with 2+
lifts
• Speed limit >60 km/h (except for tapers,
shoulders, accel/decel lanes, detours,
temporary pavement)
• Contracts >5000 t of surface course
Exclusions:
• Single lifts, Tight curves, Bridge decks
(<50m), Night paving
• Areas to match existing surface
• Hot-in-Place (HIP) or Cold-in-Place (CIP)
recycling
Exclusions:
• AC sections with structures such as bridge
decks are not tested.
• PCC sections with obstacles, approach
slabs to bridges or utility access points are
not tested.
Applicability: (NS)
• Full Profile Index and Bump spec for all
surface courses with 2+ lifts
• Profile Index bonus and Bump spec for 1
lift or repaving
Table 2: Summary of Acceptance Requirements and Pay Adjustments in Canada
Province
Requirements for
Acceptance/Rejection
Pay Adjustments
Full Contract
Bonus
Penalty
10 < PI < 24 mm/100m
(Multi-lift)
British
Columbia
• Correction:
• Bumps > 12 mm
• Bumps between 8-12 mm at
discretion of engineer
• Rejection:
• Sections rejected/replaced if:
• PI > 24 mm/100m (Multi-lift)
• PI > 24 mm/100m (Single-lift)
• PI > 30 mm/100m (Curb/ Gutter)
0 < PI < 10
mm/100m
(Multi-lift)
PI = 0 mm/100m
(all lift/section types)
• Bonus of $100 per 100m
0 < PI < 15
mm/100m
(Single-lift)
Alberta
15 < PI < 24 mm/100m
(Single-lift)
• Penalty of $40 to $320 per
100m
22 < PI < 30 mm/100m
(Curb/Gutter)
0 < PI < 22
mm/100m
(Curb/Gutter)
Bumps/Dips < 8 mm
• Penalty of $40 to $340 per
100m
PI = 0 mm/100m
(all lift/section types)
• Bonus of $25 per 100m
• Penalty of $40 to $320 per
100m
Bumps/Dips > 8.0 mm
• Penalty $100 per bump/dip
16 < PI < 23 mm/100m
(Tangents and Curves > 600m)
• Correction:
• No corrective measures (penalty
only) unless bumps > 12 mm
Saskatchewan
• Rejection:
• Sections rejected/replaced if:
• PI > 23 mm/100m (Tangents and
Curves > 600m)
• PI > 28 mm/100m (Other)
• Bumps > 12 mm
PI < 15
mm/100m
(Tangents and Curves
> 600m)
PI < 20
mm/100m
(Curves < 600m,
Sublots within 50m of
bridge or RR crossing
or end sublot)
No bonus offered
(penalty only)
21 < PI < 28 mm/100m
(Curves < 600m, Sublots within
50m of bridge or RR crossing or
end sublot)
• Penalty of $40 to $600 per
100m
8 < Bumps < 12 mm
• Penalty of $100 to $400 per
bump
PI < 6 mm/100m (AC)
• Correction:
• No corrective measures for AC
pavements (penalty only)
Manitoba
• Correction for PCC pavements if:
• PI > 19 mm/100m, or
• Bumps > 12 mm/7.6m
Notes:
• Repairs to section or bumps > 8mm
disqualify that section from bonus
6 < PI < 11
mm/100m (AC)
8 < PI < 14
mm/100m (PCC)
Bumps < 8mm
(AC)
PI < 8 mm/100m (PCC)
• Bonus of $59 (AC) or $185 (PCC)
per 100m
TCR < 70 mm/100m (AC)
• Bonus of $5 to $59 per 100m
Bumps < 12mm
(PCC)
• Continuous Smoothness Bonus
($100 per km)
PI > 11 mm/100m (AC)
14 < PI < 19 mm/100m (PCC)
• Penalty of $118 (AC) or $185
(PCC) per 100m
Table 2 Continued: Summary of Acceptance Requirements and Pay Adjustments in Canada
Province
Requirements for
Acceptance/Rejection
Pay Adjustments
Full Contract
Bonus
Penalty
231 < PI < 450
mm/km
PI < 230
mm/km
450 < PI < 550
mm/km
IRI < 1.1
m/km (AC)
1.3 < IRI < 1.8
m/km (AC)
Acceptance:
• for 2x2 lane-km:
• Bumps < 13 mm allowed without
pay adjustment
• for other areas:
• Bumps < 13 mm allowed
• Allow 2 bumps up to 18mm
Ontario
Quebec
• Rejection:
• Sections rejected/replaced if:
• PI > 550 mm/km
• Bumps > 13 mm repaired
Notes:
• Repairs to section disqualify that
section from bonus
• Acceptance:
(AC) • Sections accepted if:
• 7 of 10 segments
IRI ≤ 1.2 m/km, and
• 10 of 10 segments
IRI ≤ 1.4 m/km
• Rejection:
(AC) • Sections rejected if:
• IRI ≥ 1.8 m/km
(PCC) • Sections rejected if:
• PI > 240 mm/km
1.1 < IRI < 1.3
m/km (AC)
110 < PI < 160
mm/km (PCC)
• Bonus of 1% to 5% of cost of AC
(by tonnage)
PI < 110
mm/km (PCC)
• Bonus of 0.1% to 5% of cost of
PCC (by tonnage)
• Penalty of 0.5% to 15% of cost
of AC (by tonnage)
160 < PI < 240
mm/km (PCC)
• Penalty of 0.1% to 10% of cost
of PCC (by tonnage)
15.4 < PI < 23.4
mm/100m
New Brunswick
• Rejection:
• Sections rejected/replaced if:
• PI ≥ 23.4 mm/100m
• Bumps > 13.4 mm
10.5 < PI < 15.4
mm/100m
Bumps < 8.5 mm
PI < 10.4
mm/100m
• Bonus of 1% to 5% of bid price
• Penalty of 2% to 8% of bid
price
8.5 < Bumps < 13.4 mm
(or repaired)
• Penalty of $200 to $2000 per
bump
PI > 12
mm/100m
10.1 < PI < 12
mm/100m
Nova Scotia
Bumps < 8 mm
Prince
Edward Island
Newfoundland
• Rejection:
• Sections rejected/replaced if:
• PI ≥ 20.0 mm/100m
2 < PI < 20
mm/100m
• Rejection:
• Sections rejected/replaced if:
• PI ≥ 15.0 mm/100m
PI < 15
mm/100m
PI < 10.1
mm/100m
• Bonus of $0.068 to $0.338 per m2
PI < 2
mm/100m
• Bonus of $25 to $100 per 100m
N/A
• Penalty of $0.27 to $2.43 per
m2
Bumps > 8 mm
(or repaired)
• Min. Penalty of $500 (no Max.)
PI > 20
mm/100m
• Penalty of $2000 per 100m
• Repairs required
N/A
the bonuses and penalties also vary
widely and are summarised in Table
2.
A unique incentive provided by
Manitoba is called the “Continuous
Smoothness Incentive.” Under this
program, an extra bonus is awarded
for each finished kilometre with all
100-m segments that meet bonus
specifications for PI and TCR.
Repair Options
Four main options are available to
contractors to correct for inadequate
smoothness. These include diamond
grinding (usually PCC pavements),
complete removal and replacement
(mill and fill), full width overlaying,
and cold rolling. Some provinces do
not permit cold rolling (i.e. additional
rolling with the steel drum compactor after the asphalt is cold) as damage to the pavement may result.
Results of Smoothness
Specification Implementation
In general, the implementation of
smoothness specifications in Canada
has had a very positive effect on the
quality of finished pavement surfaces. Many provinces observed dramatic improvements in smoothness
during the first few years after specifications were imposed. Overall in
Canada, the incentive provided by
the bonus/penalty system appears to
convince contractors to produce
smoother pavements, which should
lead to increased performance and
reduced life cycle costs in the future.
SMOOTHNESS AROUND
THE WORLD
Examples of international smoothness specifications were also presented at the PSC meeting. It should
be stressed that the following are only
examples and may vary not only from
country to country, but within individual countries as well.
The United States
Kansas and Virginia were selected as
examples for US pavement smoothness specifications.
Like most of Canada, Kansas utilises
a profilograph to measure Profile
Roughness Index (PRI), which is the
same as PI in the Canadian specifications except that PRI is measured
in millimetres per km over 0.1 mile
(0.16 km) segments. In 1990, a
5.1mm blanking band was specified
for smoothness measurements. In
1991, Kansas changed its specifications so that PRI was calculated with
a zero (0) blanking band (as Ontario
does). The effects of removing the
blanking band were determined in
1993 and are summarised below in
Table 3.
While it is apparent that the number
of contracts receiving bonus was
drastically reduced for the first two
years after removing the blanking
band, it is clear that contractors in
Kansas have been consistently
achieving smoother pavements
(more bonus) with the zero blanking
band in more recent years. The Kansas pay adjustment schedule awards
bonuses up to $152.00 per 0.16 lane
km with PRI less than 158 mm/km
and imposes a penalty of $203.00 for
each 0.16 km segment with PRI
greater than 631.1 mm/km in addition to correcting the surface to 394
mm/km (minimum). For PRI values
within 473.1 and 631 mm/km, no
penalty is imposed, however, repairs
must be made to correct the surface
to a minimum PRI of 394 mm/km.
Virginia measures smoothness using
IRI similarly to Quebec, however, Virginia calculates a Mean Roughness
Index (MRI) which is the average IRI
of the left and right wheelpaths. Full
contract pay is achieved for MRI values between 950.1 to 1110.0 mm/km
while a constant penalty of $0.04 per
square meter is applied to MRI values greater than 1110.1 mm/km.
Bonuses range from $0.12 to $0.19
per m2 for IRI values less than 950
mm/km while segments with IRI values over 1580.0 mm/km are subjected to corrective action.
The US Federal Highway Administration (FHWA) recently held a series of workshops for contractors and
state departments to promote the
importance of initial pavement
smoothness. In addition, a “Pavement Smoothness Toolkit” was created for distribution to paving contractor to help them build smoother
pavements.
European Countries
In 1997/98, the World Road Federation (PIARC) completed a pavement
smoothness specification survey in
Europe. The results of this survey
Table 3: Comparison of Blanking Band Effects (Zero vs. 5 mm)
Compliance with Specified PRI (mm/km)
Year
1990
1990
(reanalysis)
1992
(reanalysis)
1992
1993
Blanking
Band
(mm)
Number
of 0.16 km
segments
PRI
(0-47)*
(<158)†
Bonus
%
PRI
(47.1-142)*
(158-473)†
Full Pay
5.1
0
851
842
0
0
0
%
PRI
(>142)*
(>631)†
Penalty
%
547
71
64
8
226
753
27
90
78
18
9
2
1890
57
3
1796
95
37
2
5866
4168
1467
625
25
15
4341
3499
74
84
58
42
1
1
* Ranges correspond to smoothness specifications with 5.1mm blanking band.
† Ranges correspond to smoothness specifications with zero blanking band.
8
Table 4: Comparison of Smoothness Specifications from Selected European Countries
Smoothness
Indicator and
Equipment
Country
mm2/km
Belgium
• Analyseur de profil en long
(APL)
IRI
Denmark
• Viagraphe (Danish Highspeed
profilograph)
• 100m sections
Specifications
• 25m section (urban) Speed = 21.6 km/h
CP2.5 ≤ 35
• Penalty
35 < CP2.5 ≤ 50
• 100m section (rural) Speed = 54 km/h
CP10 ≤ 70
• Rejection
• No. of Irregularities allowed:
0 ≥ 7.5mm
2 ≥ 6mm
3 ≥ 5mm
Max 9 ≥ 3mm
• New Construction
IRI
Spain
• Laser Profilometer, APL and
Dipstick
• 100m sections
• High Traffic Areas
IRI ≤ 2.5 m/km
• National Road (25m seg., 1000m section)
50% ≤ 6, 95% ≤ 13 and 100% ≤ 16 (New const.)
35% ≤ 6, 75% ≤ 13 and 90% ≤ 16 (Rehab)
cm/100m
• New specifications under development
• UT-02 (Hungarian)
• ARAN, Automatic Road
Analyzer, APL
C5 ≤ 2%
• Viagraphe
• 100m sections
• Speed = 10 km/h
• 20m section
IRI
IRI ≤ 1.4 m/km
Sweden
• RST Laser, Static Beam (3m)
6 < CAPL25 < 16
over 50% ± 3% of length
or
13 < CAPL25 < 16
over 5% of length
• Penalty
5 < UT-02 (National Roads)
10 < UT-02 (Other Roads)
• Specifications are project specific
C5, f5
Netherlan
ds
• Acceptance
• Penalty (20% price reduction)
Spec. < IRI < 4.5 m/km
IRI, RCI, CAPL25
Italy
• Acceptance
20% of job +0.5 m/km
50% of job -0.5 m/km
• Toll Free Highways (25m seg., 1000m section)
55% ≤ 4, 90% ≤ 8 and 100% ≤ 13 (New const.)
35% ≤ 6, 75% ≤ 13 and 90% ≤ 16 (Rehab)
Hungary
• No penalties but contractor
provides 5 year warranty
• Low Traffic Areas
NBO, CAPL25
• APL
CP2.5 > 50
IRI ≤ 2.0 m/km
IRI ≤ 3.0 m/km
• Toll Highways (200m segment, 4000m section)
95% (Short Wave CAPL25) ≥ 7 and 100% ≥ 6
95% (Med. Wave CAPL25) ≥ 8 and 100% ≥ 7
95% (Long Wave CAPL25) ≥ 9 and 100% ≥ 8
France
Acceptance, Penalty or
Rejection
• 200m section
IRI ≤ 2.4 m/km
• Rejection
IRI > 4.5 m/km
• Penalty
C5 > 2%
• Rejection
C5 > 2% and f5 > 5 or
C5 > 7%
• Penalty imposed after case study
• Penalty and repairs may be
cumulative
will be officially published in October of 1999 at the Kuala Lumpur
Conference. A summary table of the
8 countries surveyed is shown in
Table 4.
As shown, most European countries
utilise IRI for smoothness measurement. Perhaps the most notable difference between European and
North American specifications is the
lack of bonuses offered to European
contractors. Furthermore, the use of
contractor warranties appears much
more widely used in Europe than in
North America.
REFERENCES
1. Carey , W.N. and Irick, P.E. “The Pavement ServiceabilityPerformance Concept.” Highway Research Board Bulletin 250.
1960.
2. Haas, R. and Hudson, W.R. Pavement Management Systems.
McGraw-Hill Book Company, New York. 1978.
3. Hudson, W.R. “Generalised Roughness Index.” Paper presented
to the Annual Meeting, Transportation Research Board,
Washington, DC, January 1978.
4. National Asphalt Pavement Association (NAPA). “Pavement
Smoothness.” Information Series 111. 1996.
SUMMARY
Pavement smoothness specifications
from Canada, the United States and
Europe have been presented in this
technical brief. The methods of measurement, specifications and bonus/
penalty systems vary considerably
both within individual countries as
well as between different countries.
However, the ultimate goal of pavement smoothness specifications is
universal – to achieve smoother pavements at the time of construction,
which will provide increased pavement serviceability and performance.
This technical brief has been prepared and distributed by:
Canadian Strategic Highway Research Program (C-SHRP)
Transportation Association of Canada
2323 St. Laurent Blvd.
Ottawa, ON K1G 4J8
Tel. : (613) 736-1350
Fax : (613) 736-1395
www.tac-atc.ca/programs/cshrp.htm
ISBN 1-55187-045-2
10