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IRC SP 16 : 2019Guidelines for Surface Evenness of Highway Pavements

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ASTM E1926

CurrentFrequently UsedCode of PracticeTransportation · Roads and Pavement

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IRC SP 16:2019 is the Indian Standard (IRC) for guidelines for surface evenness of highway pavements. IRC SP:16 defines how smooth a road must be — using IRI (International Roughness Index) as the primary measure. New NH bituminous surface must achieve IRI ≤2.5 m/km, concrete ≤2.0 m/km. Surface evenness is increasingly linked to contractor payment (bonus/penalty system).

Guidelines for measurement and acceptance criteria for surface roughness/evenness of highway pavements using IRI, BI, and profilograph.

Quick Reference — IRC SP 16:2019 Pavement Surface Evenness

Key reference values — verify against the current code edition / project specification.

✓ Verified 2026-05-15

Reference	Value	Clause
Subject	Surface roughness/evenness measurement & acceptance	Scope
Roughness index	IRI / Bump Integrator (BI), mm/km	Metric
New flexible (good)	Low IRI target (e.g. ≤ ~2000 mm/km BI class)	Acceptance
Measurement	Bump integrator / profilograph / laser profiler	Method
Use	Construction acceptance + PMS monitoring	Application

⚠ Indicative reference values from the code/standard practice; binding figures are those in the current edition and the project specification.

Overview

Status: Current
Usage level: Frequently Used
Domain: Transportation — Roads and Pavement
Type: Code of Practice

International equivalents

ASTM E1926 · ASTM (US)

Typically used with

IRC 37 IRC 58 IRC 15

Also on InfraLens for IRC SP 16

25Key values 8Tables 13FAQs

Practical Notes

! IRI is now the standard roughness measure for NH/expressway — replacing the old Bump Integrator.

! Contractor payment bonus/penalty linked to IRI achievement — incentivizes quality construction.

! IRI <2.0 m/km is 'very good' ride quality — achievable with slip-form paver for concrete.

! For NHAI and MoRTH projects, stringent adherence to IRI values is paramount. A 'no compromise' approach is often adopted during project execution.

! Ensure that the contractor has calibrated and certified equipment for IRI, BI, and profilograph measurements. Regular checks are crucial.

! Site engineers must understand that IRI and BI are statistical measures over a length. Individual bumps might not always reflect the overall index, but significant deviations must be addressed.

! Profilograph is excellent for identifying localized surface defects like dips and humps. These are often easier to rectify than widespread roughness.

! The choice of measurement method (IRI, BI, or Profilograph) depends on the project stage and contractual requirements. Always refer to the specific contract documents.

! Smoothness achieved during the compaction of the asphalt layer significantly impacts the final IRI/BI. Proper roller patterns and adequate compaction effort are key.

! For PMGSY roads, while IRI values might be slightly relaxed compared to national highways, consistency and uniformity of the surface are still critical for user comfort and vehicle longevity.

! Irregularities introduced during utility crossings, drainage installations, or pavement joints are common culprits for high roughness. Proactive planning and meticulous execution at these points are essential.

! Temperature variations can affect asphalt pavement surfaces. Measurements should ideally be taken under stable temperature conditions to avoid erroneous readings.

! Don't just rely on the raw data. Analyze the profilograph traces for the type and location of defects to understand the root cause of roughness.

! Feedback from the measurement team to the construction supervisors should be timely and specific, allowing for prompt corrective actions.

! Consider the drainage aspects. Even with good surface evenness, if water ponding occurs due to minor undulations, it can lead to premature pavement distress.

! Contract clauses often specify penalties for non-compliance with surface evenness. This provides a strong incentive for the contractor to maintain quality.

! Post-construction surveys are vital. Any significant deterioration in evenness during the initial service period should be investigated.

! During overlay projects, ensuring a smooth surface on the existing pavement before applying the new layer is critical for achieving a good final profile.

Frequently referenced clauses

Cl. 3 — Measurement methods (Bump Integrator, IRI, Profilograph)

Cl. 4 — Acceptance criteria for new construction

Cl. 5 — Maintenance intervention levels

Cl. 2 — Definitions

Cl. 3.1 — Introduction to Surface Evenness

Cl. 4.1 — International Roughness Index (IRI) - Principle

Cl. 5.1 — Beachyevenness Index (BI) - Principle

Cl. 6.1 — Profilograph - Principle

Cl. 7 — Equipment Specifications for Roughness Measurement

Cl. 8.1 — Acceptance Criteria for IRI

Cl. 9.1 — Acceptance Criteria for BI

Cl. 10.1 — Acceptance Criteria for Profilograph

Cl. 12.1 — Responsibilities of the Contractor and Engineer

surface evennessroughnessIRIunevenness indexride qualityIRC SP

Engineer's Notes

In Practice — Editorial Commentary

When IRC SP 16 is your governing code

IRC SP 16 specifies guidelines for surface evenness of highway pavements — methodology for measuring + acceptance criteria for pavement riding quality. Surface evenness directly affects ride comfort, vehicle wear-and-tear, fuel efficiency, and safety. It's measured by International Roughness Index (IRI) and 3 m / 7 m straightedge tolerance.

Use IRC SP 16 when: - Acceptance testing of newly-constructed flexible / rigid pavement - Periodic condition assessment of operational highway - Forensic investigation of riding quality complaints - BOT / EPC contract acceptance per quality KPI - Pavement maintenance prioritisation (worst-IRI sections targeted first)

Surface evenness metrics: - International Roughness Index (IRI) — m/km; lower = smoother; standard global metric - 3 m straightedge — maximum deviation under 3 m straightedge; mm; rapid local check - 7 m straightedge — for runway / longer-wavelength evenness; mm - Bump integrator — older mechanical method; less common now

IRI categories (typical interpretation):

| IRI (m/km) | Surface quality | Use | |---|---|---| | < 1.5 | Excellent | New expressway / runway | | 1.5-2.5 | Good | Standard new highway | | 2.5-3.5 | Acceptable | Operational highway after 5 years | | 3.5-5.0 | Poor | Maintenance needed | | > 5.0 | Very poor | Reconstruction needed |

Reference values you'll actually use

Acceptance criteria (per IRC SP 16:2019):

| Pavement type | Initial (newly constructed) | After 5 years | Reconstruction trigger | |---|---|---|---| | Bituminous Concrete (BC) on highway | ≤ 2.5 m/km | ≤ 3.5 m/km | > 5.0 m/km | | Pavement Quality Concrete (PQC) | ≤ 2.0 m/km | ≤ 3.0 m/km | > 5.0 m/km | | Surface dressing (rural) | ≤ 4.0 m/km | ≤ 5.0 m/km | > 7.0 m/km | | Airport runway (BC) | ≤ 1.5 m/km | ≤ 2.0 m/km | > 3.0 m/km |

3 m straightedge tolerance (acceptance): - BC newly laid: ≤ 5 mm under 3 m - PQC newly laid: ≤ 5 mm under 3 m - After 5 years: 8-10 mm typical (acceptable) - > 12 mm: maintenance needed

Measurement equipment: - Class 1 (high precision): laser-based vehicle-mounted IRI meter (e.g., MERLIN, ROMDAS) - Class 2 (medium): vehicle-mounted accelerometer-based IRI meter - Class 3 (low): 3 m / 7 m straightedge for spot checks - Class 4: subjective rating (visual)

Frequency of measurement: - New construction: every km after final compaction (acceptance) - Operational highway: annual (per NHAI / state PWD) - Pre-maintenance survey: every section

Speed of measurement: - Class 1 / 2 vehicle: 30-100 km/h continuous; per-100 m IRI reported - Straightedge: stationary; 1 reading per 30 m (random)

Tolerance ranges for cumulative deviation: - Maximum deviation: ≤ 5 mm under 3 m straightedge (initial) - Mean deviation: per project spec; typically ≤ 2-3 mm

Cost of testing: - Class 1 IRI survey: ₹500-1500 per km - Class 2: ₹200-500 per km - Class 3 straightedge: ₹50-200 per km (spot only) - Annual NHAI corridor monitoring: significant project but per-km cost low

Maintenance trigger thresholds: - BC pavement: IRI > 3.5 m/km — plan periodic resurfacing - IRI > 5.0 m/km — major rehabilitation or reconstruction - Specific defects (rutting > 25 mm, longitudinal cracks > 3 m/m): targeted repair regardless of IRI

Companion codes (must pair with)

IRC:111:2009 — bituminous mix design + construction.
IRC 15:2017 — concrete road construction.
IRC SP 75:2008 — Roller Compacted Concrete.
IRC SP 76:2015 — white-topping.
IRC:37:2018 — flexible pavement design.
IRC:58:2015 — rigid pavement design.
IRC SP 27:2009 — airfield pavement design (stricter IRI).
IRC 81:1997 — Benkelman Beam Deflection (structural evaluation).
IRC SP 17:2019 — performance evaluation.
IRC:82:2015 — maintenance of bituminous road surfaces.
IRC SP 11:2015 — handbook of quality control for road + runway construction.
IS 73:2013 — paving bitumen.
IS 9013:1978 — water permeability of concrete.
ASTM E1926 — international IRI standard.
World Bank IRI calibration protocols.

Common pitfalls / what reviewers flag

1. No IRI measurement at acceptance. Surface looks OK visually but IRI > 3.5; ride quality poor. Mandatory IRI for acceptance. 2. IRI calculated from inadequate data. Single straight-edge measurement; insufficient. Use Class 1/2 vehicle-mounted. 3. Inadequate paver setup. Paver speed too high; segregation; rough surface. Calibrate paver per design. 4. Compaction too late. Mix cools; can't compact properly; rough surface. Paving + compaction in continuous schedule. 5. No grinding / texturing of high spots. Paver leaves hump; uneven. Diamond grinding for correction. 6. Joint quality poor. Construction joints have offsets; bumps. Carefully prepare joints. 7. Existing surface roughness propagates. Overlay over rough existing; bumps continue. Mill + level existing first. 8. Acceptance below standard. Contractor pressured to accept inadequate IRI; long-term complaints. Strict acceptance + retrofit if needed. 9. No periodic IRI monitoring. Pavement degrades undetected; user complaints + complaints. Annual IRI for all corridors. 10. Climate effect ignored. Hot weather → mix flow → rutting → IRI deterioration. Match mix to climate (modified bitumen). 11. Subgrade settlement causes future IRI rise. Inadequate subgrade preparation; long-term IRI rise. Subgrade quality essential. 12. No documentation of as-built IRI. Future references for trend analysis impossible. Mandatory record.

Where it sits in pavement quality + maintenance

Pavement quality cascade:

1. Construction acceptance: - IRI ≤ specification at handover - 3 m straightedge tolerance - Visual / texture / cross-camber checks 2. Periodic monitoring (per IRC SP 16): - Annual IRI survey on highways - Trend tracking 3. Maintenance prioritisation: - Worst-IRI sections targeted first - Cost-benefit of repair vs reconstruction 4. Maintenance / repair: - IRI 2.5-3.5: routine maintenance (crack sealing, surface dressing) - IRI 3.5-5.0: periodic resurfacing (BC overlay) - IRI > 5.0: major rehabilitation or reconstruction 5. Performance evaluation: - Did maintenance improve IRI as expected? - Refine maintenance strategy

For NHAI / state PWDs: - Asset management database tracks per-km IRI history - Maintenance budget allocated based on IRI distribution - Concession agreements (BOT) have IRI targets in performance clauses

International benchmark: - US Federal Highway Administration: target IRI < 1.7 m/km for new construction - European Union: target IRI < 1.5 m/km for highways - India: target IRI < 2.5 m/km for new highways (BOT contracts often < 2.0)

IRC SP 16:2019 brings Indian highway acceptance + monitoring in line with international best practice. Modern Indian highway construction increasingly delivers IRI < 2.0 m/km, providing world-class ride quality.

International Equivalents

Similar International Standards

ASTM E1926ASTM (US)

HighCurrent

Standard Practice for Computing IRI from Longitudinal Profile Measurements

IRI is an international standard measure — calculation method is identical worldwide.

Key Differences

≠IRC SP:16: ≤2.5 m/km for BC. US state DOTs: typically ≤1.5-2.0 m/km for new interstate.

Key Similarities

≈IRI calculation is identical globally per World Bank technical paper. Same measure everywhere.

Parameter Comparison

Parameter	IS Value	International	Source
New surface IRI limit	≤2.5 m/km (BC)	≤1.5-2.0 m/km (interstate)	US State DOTs

⚠ Verify details from original standards before use

Key Values25

Quick Reference Values

IRI limit (new BC surface)≤2.5 m/km

IRI limit (new PQC surface)≤2.0 m/km

IRI (good road)<3.0 m/km

IRI (poor road)>5.0 m/km

Measurement5m profilograph or laser profilometer

Maximum allowable IRI for NH/SH flexible pavements (new construction)3.00 m/km

Maximum allowable IRI for NH/SH flexible pavements (reconstruction/overlay)3.50 m/km

Maximum allowable IRI for MDR/ODR flexible pavements (new construction)3.50 m/km

Maximum allowable IRI for MDR/ODR flexible pavements (reconstruction/overlay)4.00 m/km

Maximum allowable IRI for Local Roads flexible pavements (new construction)4.00 m/km

Maximum allowable IRI for Local Roads flexible pavements (reconstruction/overlay)4.50 m/km

Maximum allowable IRI for Expressways (new construction)2.50 m/km

Maximum allowable BI for new flexible pavements (all categories)15.00 mm/km

Maximum allowable BI for existing flexible pavements (all categories)20.00 mm/km

Minimum length of pavement section for IRI testing (single unit)100 m

Minimum length of pavement section for BI testing (single unit)100 m

Length of sample for IRI test100 m

Length of sample for BI test100 m

Minimum average speed for profilometer testing20 kmph

Maximum speed for profilograph testing15 kmph

Tolerance for longitudinal profile measurements (long wavelength)± 2.0 mm

Tolerance for longitudinal profile measurements (short wavelength)± 1.0 mm

Acceptance criteria for deviation from design profile (Profilograph)± 3 mm in any 3m segment

Reporting frequency for IRI/BIPer 100 m segment

Reporting frequency for ProfilographPer 100 m segment

Key Formulas

IRI = Sum of absolute vertical movements of simulated wheel / Total distance travelled

BI = Sum of absolute vertical deviations from a 3.0m straightedge / Total length tested

Longitudinal Profile Deviation (mm) = Measured Profile Value - Design Profile Value

Local Roughness Index = Maximum deviation in any 3.0 m length

Tables & Referenced Sections

Key Tables

Table 1 — IRI acceptance limits for new construction

Table 2 — Roughness categories

Table 1 — Recommended Maximum Allowable IRI Values for New Flexible Pavements

Table 2 — Recommended Maximum Allowable IRI Values for Reconstruction/Overlay of Flexible Pavements

Table 3 — Recommended Maximum Allowable BI Values for New Flexible Pavements

Table 4 — Recommended Maximum Allowable BI Values for Reconstruction/Overlay of Flexible Pavements

Table 5 — Acceptable Deviation Limits for Profilograph Measurements

Table 6 — Minimum Testing Frequencies and Sample Sizes

Frequently Asked Questions13

What is IRI?+

International Roughness Index — measures road surface roughness in m/km. Lower = smoother. IRI 1.5 = airport runway smooth. IRI 2.5 = good NH. IRI 4.0 = acceptable state highway. IRI >6.0 = needs resurfacing. Measured by laser profilometer at 80 km/h.

What is the primary objective of IRC SP 16:2019?+

The primary objective of IRC SP 16:2019 is to provide guidelines and establish acceptance criteria for the surface evenness (or roughness) of highway pavements. It aims to ensure a smooth and comfortable ride for road users and to minimize premature pavement deterioration caused by uneven surfaces. The code promotes the use of standardized methods like IRI, BI, and profilographs for measuring and assessing pavement evenness.

What are the key parameters used to measure pavement evenness according to IRC SP 16?+

IRC SP 16:2019 primarily uses three key parameters: the International Roughness Index (IRI), the Beachyevenness Index (BI), and profilograph measurements. IRI quantifies longitudinal roughness over a length, BI provides a similar measure based on a straightedge, and profilographs offer a detailed graphical representation of the longitudinal profile, identifying specific irregularities.

What is the difference between IRI and BI?+

IRI is a statistically derived index simulating the response of a standard vehicle suspension to pavement roughness over a specific length, measured in meters per kilometer (m/km). BI, on the other hand, is a more direct measure of deviations from a 3.0-meter straightedge, expressed in millimeters per kilometer (mm/km). While both assess evenness, IRI is the more commonly accepted international standard for ride quality.

How is a profilograph used for pavement evenness assessment?+

A profilograph is an instrument that measures and records the longitudinal profile of the pavement surface. It generates a graphical trace showing deviations from a true surface. This trace can then be analyzed to identify localized defects such as dips, humps, and bumps, and to determine the overall evenness and the severity of individual irregularities. It provides a more detailed view compared to IRI or BI.

What are the typical acceptance criteria for IRI values for national highways?+

For National Highways (NH) and State Highways (SH) with flexible pavements, IRC SP 16:2019 specifies maximum allowable IRI values. For new construction, the generally recommended maximum IRI is 3.00 m/km. For reconstruction or overlay projects, a slightly higher value of 3.50 m/km may be acceptable, depending on the specific contract and existing conditions.

Why is pavement evenness important for road user comfort and vehicle maintenance?+

Pavement evenness directly impacts ride comfort. Rough roads transmit vibrations and jolts to occupants, leading to fatigue and discomfort. Furthermore, uneven surfaces cause increased stress on vehicle suspensions, tires, and structural components, leading to accelerated wear and tear and higher maintenance costs for vehicles. Good evenness translates to a safer and more pleasant travel experience.

What are the responsibilities of the contractor regarding surface evenness?+

The contractor is primarily responsible for achieving the specified surface evenness throughout the construction process. This involves using appropriate construction techniques, ensuring proper compaction, skilled finishing operations, and employing calibrated equipment for measurements. They must rectify any sections that do not meet the acceptance criteria before final handover.

How does IRC SP 16:2019 address different categories of roads?+

The code differentiates acceptance criteria based on road categories, such as National Highways, State Highways, Major District Roads (MDR), Other District Roads (ODR), and Local Roads. Expressways generally have the most stringent requirements. The aim is to balance the required level of service and user expectations with the economic considerations for different road classes.

What are the implications of non-compliance with surface evenness specifications?+

Non-compliance with surface evenness specifications can lead to significant consequences for the contractor. These typically include financial penalties, as stipulated in the contract. In severe cases, the engineer may reject the work, requiring the contractor to undertake remedial measures or even reconstruct the affected sections at their own expense, impacting project timelines and costs.

Can surface evenness be measured on concrete pavements as well?+

While IRC SP 16:2019 focuses heavily on flexible pavements, the principles of surface evenness and the measurement techniques like IRI and profilographs are also applicable to concrete pavements. Specific criteria and acceptable deviations for concrete pavements are usually detailed in other relevant IRC codes or project-specific specifications.

What is the role of the Engineer in relation to surface evenness?+

The Engineer's role is to oversee the construction and ensure compliance with the specifications, including surface evenness. They are responsible for reviewing measurement data, approving or rejecting pavement sections based on the criteria, instructing the contractor on remedial actions, and ultimately certifying that the finished pavement meets the required standards for ride quality and durability.

How frequently should surface evenness measurements be taken?+

IRC SP 16:2019 specifies minimum testing frequencies. Generally, measurements for IRI and BI are taken for every 100-meter segment of the pavement. Profilograph testing may also be conducted on similar segments. The exact frequency and sampling strategy should be clearly defined in the project contract documents.

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IRC SP 16 : 2019Guidelines for Surface Evenness of Highway Pavements

PDF Google Compare IRC Portal

Link points to Internet Archive / others. Not hosted by InfraLens. Details

ASTM E1926

CurrentFrequently UsedCode of PracticeTransportation · Roads and Pavement

PDF Google Compare IRC Portal

Link points to Internet Archive / others. Not hosted by InfraLens. Details

Guidelines for measurement and acceptance criteria for surface roughness/evenness of highway pavements using IRI, BI, and profilograph.

Quick Reference — IRC SP 16:2019 Pavement Surface Evenness

Key reference values — verify against the current code edition / project specification.

✓ Verified 2026-05-15

Reference	Value	Clause
Subject	Surface roughness/evenness measurement & acceptance	Scope
Roughness index	IRI / Bump Integrator (BI), mm/km	Metric
New flexible (good)	Low IRI target (e.g. ≤ ~2000 mm/km BI class)	Acceptance
Measurement	Bump integrator / profilograph / laser profiler	Method
Use	Construction acceptance + PMS monitoring	Application

⚠ Indicative reference values from the code/standard practice; binding figures are those in the current edition and the project specification.

Overview

Status: Current
Usage level: Frequently Used
Domain: Transportation — Roads and Pavement
Type: Code of Practice