Summary of Pavement Smoothness Specifications in Canada and Around the World

Transcription

1 Canadian Strategic Highway Research Program (C-SHRP) Summary of Pavement Smoothness Specifications in Canada and Around the World July 1999 Technical Brief # 16 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. 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 Hudson 3 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 important 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. 1

2 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 Top View 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 Guide Side 0.37 m Steering Assembly Computer and Printer 0.88 m Wheel Assembly Measuring 1.40 m Wheel 1.02 m 7.62 m m Wheel Assembly Figure 1: California Profilograph (Top and Side Elevation Views) 2

3 Blanking Band Bump 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 Depression Reduction Length (i.e. Sublot) Amplitude greater than 0.8 mm Length greater than 0.6 Profile Trace Figure 2: Calculation of Rate of Smoothness and Profile Index 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 Excessive Height 10 mm Blanking Band 7.5mm 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. CAPL25, CP and NBO 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. Depression Reduction Length (i.e. Sublot) Bump Template Figure 3: Calcuation of Bump (Scallop) Height Profile Trace 3

4 CAPL25 IRI (m/km) 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 5- mm 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 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 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 4

5 Table 1: Summary of Indicators, Equipment and Applicability of Specifications in Canada Province Year Smoothness Indicator Equipment and Services Calibration, Correlation or Standard Applicability and/or Exclusions The Western Provinces: British Columbia, Alberta, Saskatchewan 1980 s Profile Index () Bumps/Dips (mm) 5mm Blanking Band 100 metre sublots Cox Profilograph DOT Services (BC, SK) Consultant Services (AB) Not Presented Applicability: Separate specs for single lift, multiple lifts and presence of curb and gutter Exclusions: No exclusions, use separate specifications for bridges, RR crossings, etc. Manitoba Ontario Quebec 1993 (PCC) 1997 (AC) 1999 (rev.) 1999 (rev.) 1998 (rev.) Profile Index () TCR () Bumps (mm) 5mm Blanking Band 100 metre sublots Profile Index (mm/km) Scallops/Bumps (mm) Zero Blanking Band 100 metre sublots IRI (mm/km) 1 km sections (AC), 500 m sections (PCC) 100 metre segments 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) 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. The Atlantic Provinces: New Brunswick, Nova Scotia, Prince Edward Island, Newfoundland Profile Index () Scallops/Bumps (mm) 5mm Blanking Band 100 metre sublots California Profilograph DOT Services (NB, PEI) Consultant Services (NS, NF) ASTM E1274 Standard Test for Measuring Pavement Roughness Using a Profilograph 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

6 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 (Multi-lift) British Columbia Alberta Correction: Bumps > 12 mm Bumps between 8-12 mm at discretion of engineer PI > 24 (Multi-lift) PI > 24 (Single-lift) PI > 30 (Curb/ Gutter) 0 < PI < 10 (Multi-lift) 0 < PI < 15 (Single-lift) 0 < PI < 22 (Curb/Gutter) Bumps/Dips < 8 mm PI = 0 (all lift/section types) Bonus of $100 per 100m PI = 0 (all lift/section types) Bonus of $25 per 100m Penalty of $40 to $340 per 100m 15 < PI < 24 (Single-lift) Penalty of $40 to $320 per 100m 22 < PI < 30 (Curb/Gutter) Penalty of $40 to $320 per 100m Bumps/Dips > 8.0 mm Penalty $100 per bump/dip Saskatchewan Correction: No corrective measures (penalty only) unless bumps > 12 mm PI > 23 (Tangents and Curves > 600m) PI > 28 (Other) Bumps > 12 mm PI < 15 (Tangents and Curves > 600m) PI < 20 (Curves < 600m, Sublots within 50m of bridge or RR crossing or end sublot) No bonus offered (penalty only) 16 < PI < 23 (Tangents and Curves > 600m) 21 < PI < 28 (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 Manitoba Correction: No corrective measures for AC pavements (penalty only) Correction for PCC pavements if: PI > 19, or Bumps > 12 mm/7.6m Repairs to section or bumps > 8mm disqualify that section from bonus 6 < PI < 11 (AC) 8 < PI < 14 (PCC) Bumps < 8mm (AC) Bumps < 12mm (PCC) PI < 6 (AC) PI < 8 (PCC) Bonus of $59 (AC) or $185 (PCC) per 100m TCR < 70 (AC) Bonus of $5 to $59 per 100m Continuous Smoothness Bonus ($100 per km) PI > 11 (AC) 14 < PI < 19 (PCC) Penalty of $118 (AC) or $185 (PCC) per 100m

7 Table 2 Continued: Summary of Acceptance Requirements and Pay Adjustments in Canada Province Requirements for Pay Adjustments Acceptance/Rejection Full Contract Bonus Penalty Ontario 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 PI > 550 mm/km Bumps > 13 mm repaired 231 < PI < 450 mm/km PI < 230 mm/km 450 < PI < 550 mm/km Quebec 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 (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) IRI < 1.1 m/km (AC) 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) 1.3 < IRI < 1.8 m/km (AC) 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 New Brunswick PI 23.4 Bumps > 13.4 mm 10.5 < PI < 15.4 Bumps < 8.5 mm PI < 10.4 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 Nova Scotia 10.1 < PI < 12 PI < 10.1 Penalty of $0.27 to $2.43 per m 2 Bumps < 8 mm Bonus of $0.068 to $0.338 per m 2 Bumps > 8 mm (or repaired) Prince Edward Island Newfoundland PI 20.0 PI < PI < 20 PI < 15 PI < 2 Bonus of $25 to $100 per 100m N/A Min. Penalty of $500 (no Max.) PI > 20 Penalty of $2000 per 100m Repairs required N/A

8 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 $ per 0.16 lane km with PRI less than 158 mm/km and imposes a penalty of $ for each 0.16 km segment with PRI greater than mm/km in addition to correcting the surface to 394 mm/km (minimum). For PRI values within 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 to mm/km while a constant penalty of $0.04 per square meter is applied to MRI values greater than mm/km. Bonuses range from $0.12 to $0.19 per m 2 for IRI values less than 950 mm/km while segments with IRI values over 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) PRI PRI PRI Blanking Number (0-47)* ( )* (>142)* Band of 0.16 km (<158) ( ) (>631) Year (mm) segments Bonus % Full Pay % Penalty % (reanalysis) (reanalysis) * Ranges correspond to smoothness specifications with 5.1mm blanking band. Ranges correspond to smoothness specifications with zero blanking band. 8

9 Table 4: Comparison of Smoothness Specifications from Selected European Countries Country Belgium Smoothness Indicator and Equipment mm 2 /km Analyseur de profil en long (APL) Specifications 25m section (urban) Speed = 21.6 km/h CP m section (rural) Speed = 54 km/h CP10 70 Acceptance, Penalty or Rejection Penalty 35 < CP Rejection CP2.5 > 50 Denmark IRI Viagraphe (Danish Highspeed profilograph) 100m sections No. of Irregularities allowed: 0 7.5mm 2 6mm 3 5mm Max 9 3mm No penalties but contractor provides 5 year warranty Spain France IRI Laser Profilometer, APL and Dipstick 100m sections APL NBO, CAPL25 New Construction IRI 2.0 m/km High Traffic Areas IRI 2.5 m/km Low Traffic Areas 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 Toll Free Highways (25m seg., 1000m section) 55% 4, 90% 8 and 100% 13 (New const.) 35% 6, 75% 13 and 90% 16 (Rehab) Acceptance 20% of job +0.5 m/km 50% of job -0.5 m/km Acceptance 6 < CAPL25 < 16 over 50% ± 3% of length or National Road (25m seg., 1000m section) 50% 6, 95% 13 and 100% 16 (New const.) 35% 6, 75% 13 and 90% 16 (Rehab) 13 < CAPL25 < 16 over 5% of length Hungary cm/100m UT-02 (Hungarian) New specifications under development Penalty 5 < UT-02 (National Roads) 10 < UT-02 (Other Roads) Italy Netherlan ds Sweden IRI, RCI, CAPL25 ARAN, Automatic Road Analyzer, APL Viagraphe 100m sections C5, f5 IRI RST Laser, Static Beam (3m) Specifications are project specific 20m section 200m section C5 2% Speed = 10 km/h IRI 1.4 m/km IRI 2.4 m/km Penalty (20% price reduction) Spec. < IRI < 4.5 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

10 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 Serviceability- Performance Concept. Highway Research Board Bulletin Haas, R. and Hudson, W.R. Pavement Management Systems. McGraw-Hill Book Company, New York Hudson, W.R. Generalised Roughness Index. Paper presented to the Annual Meeting, Transportation Research Board, Washington, DC, January National Asphalt Pavement Association (NAPA). Pavement Smoothness. Information Series 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) Fax : (613) ISBN