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IRC SP 73 : 2015Manual of Specifications and Standards for Two-Laning of Highways with Paved Shoulders

Q: What is the primary objective of providing paved shoulders in two-laning projects according to this IRC manual?

The primary objective is to enhance road safety and operational efficiency. Paved shoulders provide a stable area for vehicles to pull over in emergencies, act as a buffer zone, and allow for safe overtaking maneuvers. They also contribute to the structural integrity of the road by reducing stress on the main carriageway and preventing edge deterioration, thus extending the service life of the highway.

Q: What are the minimum requirements for lane width and paved shoulder width specified in this manual?

The manual specifies a minimum lane width of 3.60 meters (Clause 4.1.1.1) for two-laning. For paved shoulders, the minimum width stipulated is 1.50 meters (Clause 4.1.2.1). These dimensions are crucial for safe vehicular movement and maneuverability, especially in challenging traffic conditions.

Q: How does the manual address the strength requirements of the subgrade for two-laning with paved shoulders?

The manual mandates a minimum California Bearing Ratio (CBR) of 4% for the subgrade (Clause 5.2.1). If the existing subgrade does not meet this requirement, it necessitates strengthening measures such as soil stabilization, improving the subgrade by excavation and replacement with better material, or providing a thicker sub-base layer to ensure adequate load-bearing capacity and prevent pavement distress.

Q: What are the typical pavement layer thicknesses prescribed for the different strata in this manual?

The manual outlines minimum layer thicknesses for various pavement components. For instance, the Granular Sub-Base (GSB) requires a minimum thickness of 150 mm (Clause 5.3.3.1), Granular Working Base (GWB) a minimum of 100 mm (Clause 5.3.4.1), Dense Bituminous Macadam (DBM) a minimum of 50 mm (Clause 5.3.5.2), and Asphalt Concrete (AC) a minimum of 25 mm (Clause 5.3.7.1). These thicknesses are designed to distribute traffic loads effectively.

Q: What is the importance of drainage design in the context of two-laning with paved shoulders?

Drainage is critically important because water ingress into pavement layers can lead to a significant reduction in their strength and stability, causing premature failure such as rutting, cracking, and pumping. The manual emphasizes proper camber and the provision of adequate drainage structures (Clause 6.1) to efficiently remove surface water and prevent its accumulation, especially under the paved shoulders.

Q: Are there specific material requirements for the bituminous layers used in paved shoulders?

Yes, the manual specifies material requirements for Bituminous Macadam (BM), Dense Bituminous Macadam (DBM), and Asphalt Concrete (AC) in Chapter 7. This includes guidelines on the aggregate gradations, binder types and properties, and the mix design requirements to ensure durability and performance of the paved shoulders under traffic and environmental conditions.

Q: What are the key quality control measures recommended in this manual for pavement construction?

The manual emphasizes a robust quality control system, outlined in Chapter 9, which includes regular testing of materials and executed works. This involves checking the CBR of the subgrade, compaction density of GSB and GWB layers, aggregate gradations, bitumen content and properties, and the surface regularity and skid resistance of bituminous layers. Table 9.1 lists specific tests and their frequency.

Q: How does the manual address the design speed considerations for two-laning projects?

The manual provides different design speeds based on terrain types in Table 4.1. For rural and plain/rolling terrain, the design speed is typically 80 kmph, while for mountainous and steep terrain, it is reduced to 50 kmph. These speeds dictate geometric design parameters like sight distances, curve radii, and superelevation, ensuring safe vehicular operation.

Q: What is the purpose of having both paved and unpaved shoulders in some cases?

While the manual focuses on paved shoulders, it acknowledges the existence of unpaved shoulders in some contexts (Clause 4.1.2.2) for reasons of cost-effectiveness or specific project requirements. Unpaved shoulders primarily serve as run-off-road areas and can accommodate occasional slow-moving vehicles, but paved shoulders offer superior structural support and safety benefits due to their stability and load-carrying capacity.

Q: What are the recommended camber values for different road sections?

Camber is essential for surface drainage. The manual specifies minimum camber values in Table 4.4. For rural sections, a minimum camber of 2.0% is recommended, while for hilly sections, a higher camber of 3.0% is advised to facilitate rapid runoff of rainwater and prevent pooling on the road surface.

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IRC SP 73:2015 is the Indian Standard (IRC) for manual of specifications and standards for two-laning of highways with paved shoulders. This IRC manual is a vital resource for engineers undertaking the two-laning of existing highways, with a specific emphasis on the provision of paved shoulders. It details design considerations, material specifications, construction methodologies, and quality assurance procedures. The inclusion of paved shoulders is critical for enhancing road safety by providing emergency stopping space, facilitating safe overtaking maneuvers, and improving the overall structural integrity and longevity of the pavement. The document aims to standardize practices, ensuring a consistent and high-quality outcome for such road improvement projects across India.

This manual provides comprehensive specifications and standards for the two-laning of existing highways, focusing on the incorporation of paved shoulders. It covers all aspects of design, construction, and quality control necessary for upgrading single or intermediate lane carriageways to a two-lane configuration with the added benefit of paved shoulders for improved safety and operational efficiency.

Quick Reference — IRC SP 73:2015 Two-Laning with Paved Shoulders

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

✓ Verified 2026-05-15

Reference	Value	Clause
Subject	Specs & standards for 2-laning highways with paved shoulders	Scope
Carriageway	2-lane (7.0 m) + paved shoulders	Geometry
Design speed	By terrain (ruling/minimum)	Geometry
Pavement	Flexible (IRC 37) / rigid (IRC 58) as specified	Design
Use	NHAI/MoRTH 2-lane-with-PS project standard	Application
Read with	IRC SP 84 (2-lane) / IRC SP 87 (4-lane)	Cross-ref

⚠ 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

AASHTO LRFD Bridge Design Specifications (USA)Austroads Guide to Pavement Technology (Australia)Design Manual for Roads and Bridges (DMRB) (UK)

Also on InfraLens for IRC SP 73

20Key values 11Tables 10FAQs

Practical Notes

! The design speed should be chosen conservatively based on the terrain and the ability of the existing road geometry to accommodate it after widening.

! Adequate drainage is paramount to prevent water ingress into the pavement layers, especially under paved shoulders, to maintain their structural integrity and prevent premature failure.

! The selection of appropriate aggregate gradations for GSB and GWB layers is critical for load distribution and preventing pumping action of fines.

! Compaction of all pavement layers must be meticulously controlled to achieve the specified densities, which directly impacts the load-bearing capacity and durability of the road.

! The construction of paved shoulders should be coordinated with the main carriageway construction to ensure seamless integration and consistent quality.

! Provisions for drainage outlets from paved shoulders, such as scuppers or weep holes, are essential to prevent water accumulation.

! The use of quality control tests at regular intervals throughout the construction process is non-negotiable to ensure compliance with specifications.

! Material sourcing for aggregates and bitumen should be from approved quarries and refineries to guarantee the required quality.

! Strict adherence to traffic management plans is necessary to ensure the safety of construction workers and the traveling public.

! Regular maintenance of paved shoulders, including cleaning of drains and repair of any surface distress, will significantly extend their service life.

! The existing subgrade's CBR value should be assessed thoroughly, and if it falls below the minimum requirement, strengthening measures like soil stabilization or a thicker sub-base layer should be implemented.

! Consideration should be given to the longitudinal and cross-sectional drainage during the design phase to effectively manage surface water runoff.

! The choice of bitumen grade should be based on the climatic conditions and the anticipated traffic loading.

! The construction of the paved shoulder should commence after the main carriageway pavement layers are in place to allow for proper compaction and bonding.

Frequently referenced clauses

Cl. 4.1Geometric Design Standards for Two-Laning

Cl. 4.1.1Lane Width

Cl. 4.1.2Shoulder Width and Type

Cl. 5.1Subgrade Preparation

Cl. 5.2Subgrade Strength and Compaction

Cl. 5.3Pavement Layers Specifications (GSB, GWB, DBM, BM, AC)

Cl. 6.1Drainage Requirements

Cl. 7.1Material Specifications for Bituminous Layers

Cl. 8.1Construction Procedures for Paved Shoulders

Cl. 9.1Quality Control and Assurance

Cl. 10.1Traffic Management during Construction

Cl. 11.1Maintenance Requirements for Paved Shoulders

highway engineeringroad constructionpavement designtwo-laningpaved shouldersIRC codesroad specificationstraffic safetyIndian roadsinfrastructure developmentIRC

Engineer's Notes

In Practice — Editorial Commentary

When IRC SP 73 is your governing code

IRC SP 73 (2015) is the Manual of Specifications and Standards for Two-Laning of Highways with Paved Shoulders — the comprehensive technical reference for upgrading existing 2-lane highways to 2-lane with paved shoulders (2-lane + PS). This intermediate upgrade is widely applied on Indian NH/SH where full 4-laning is not yet justified by traffic.

Use IRC SP 73 when you are: - Doing DPR for NH 2-lane upgrade with paved shoulders - Specifying technical standards for 2-lane + PS construction - Specifying intermediate-capacity highway upgrade - Cross-referencing NH 2-lane + PS specifications - Doing traffic capacity intermediate analysis

2-lane + PS vs full 4-lane: - 2-lane + PS: 2 lanes + 1.5-2.5 m paved shoulders both sides; AADT 5,000-15,000 PCU/day - 4-lane: full 2 lanes per direction; AADT > 15,000 PCU/day - Cost: 2-lane + PS is ~60-70 % of 4-lane cost - Performance: 2-lane + PS handles moderate traffic adequately - Future-proofing: 2-lane + PS can be expanded to 4-lane later

What IRC SP 73 covers: - 2-lane + PS geometric design (cross-section, alignment, junctions) - Pavement design (flexible + rigid) - Bridge + culvert standards - Drainage system - Safety appurtenances - Construction methodology + quality assurance - Performance-based maintenance contracts - Cost-effective + sustainable approach

2-lane + PS design framework

Cross-section (typical 2-lane + PS): - Carriageway: 7.0 m (2 lanes × 3.5 m) - Paved shoulders: 1.5-2.5 m each side - Earthen shoulders: 1.0 m each side beyond paved - Total formation width: 12-14 m - ROW: typically 30-45 m

Vs full 2-lane (no PS): - Standard 2-lane: 7.0 m carriageway + 2.5 m earthen shoulder each side - 2-lane + PS: 7.0 m carriageway + 1.5-2.5 m PAVED + 1.0 m earthen shoulder each side - Difference: paved shoulder provides emergency stopping + slow-vehicle accommodation + breakdown lane

Capacity benefits of paved shoulders: - Stopped vehicles don't block main lane (improves capacity) - Slow vehicles can use shoulder (improves speed) - Emergency vehicles can access (safety) - Cyclists / pedestrians can use shoulder (safety) - 5-15 % capacity gain over 2-lane without PS

Geometric design: - Per IRC:73:1980 (rural highways) + IRC SP 73 - Design speed: - Plain terrain: 80-100 km/h ruling; 65 km/h minimum - Rolling terrain: 65-80 km/h - Mountainous: 50 km/h (per IRC:52:2019) - Sight distances: per IRC:66:1976 - Horizontal curves: per IRC:38:1988 - Vertical curves: per IRC:SP-23:1993

Pavement design: - Per IRC:37:2018 - Cumulative ESAL design: 15-year horizon; 30-100 msa typical for 2-lane + PS - Layer system: - Subgrade (CBR ≥ 8 %) - Granular sub-base / stabilised - DBM per IRC:29:2019 - BC wearing per IRC:107:2013 - Total bituminous: 150-220 mm typical

Paved shoulder pavement: - Similar layer system to main carriageway - May be slightly thinner if traffic loading lower - Continuous with main carriageway for seamless transition

Junctions + intersections: - At-grade intersections + rotaries - Per IRC:65:2017 (rotaries) or signalised - Service roads not typical (rural context) - Bus bays + lay-bys provided as needed

Drainage (per IRC:SP-42:2014): - Cross-fall + edge drainage - Median drainage if median present - Cross-drainage culverts - Subsurface drainage at cuts

Safety appurtenances: - Crash barriers: at hazard locations - Signage per IRC:67:2012 - Markings per IRC:35:2015 - Speed-limit zones at sensitive locations

Reference values + specifications

Carriageway: - Width per lane: 3.5 m - Total carriageway: 7.0 m - Camber: 2.5-3 %

Paved shoulder: - Width: 1.5-2.5 m (varies by traffic + design speed) - Cross-fall: 2.5 % outward from carriageway - Pavement: similar to main lane (or marginally thinner) - Construction: typically same materials

Pavement design parameters: - Cumulative ESAL (15-year): 30-100 msa - Bituminous thickness: 150-220 mm - Asphalt grade: VG-30 standard - Concrete (rigid): M40 minimum - Sub-base granular: per IRC:36:2010

Geometric design: - Design speed plain: 80-100 km/h - Sight distances: per design speed - Curve radius: R = 230 m (V=80); 360 m (V=100) - Super-elevation: max 7 %

Drainage: - Cross-fall: 2.5 % from crown - Longitudinal drains: every 50-100 m - Cross-drainage: per IRC:SP-13:2004 - Subsurface drainage: at cut sections

Safety: - Crash barriers at hazard locations - Median fencing where applicable - Lighting at intersections + service road approaches - Speed signs at sensitive locations - Markings per IRC:35:2015 - Signs per IRC:67:2012

Bridge + structures: - Bridge cross-section: matches 2-lane + PS - Design vehicles: Class A + 70R per IRC:6:2017 - Pier + abutment per IRC:78:2014 + IRC:83:2018 - Per IRC:5:2015 framework

Construction: - Earthwork + subgrade preparation per IRC:36:2010 - Pavement layers per IRC:37:2018 - Bituminous mix per IRC:29:2019 - Surfacing per IRC:107:2013 - Bridge construction per IRC codes - Quality control per IRC:SP-57:2015

Maintenance: - Performance-based contracts (typically 5-10 years) - Annual visual inspection - 5-year detailed pavement assessment - Joint sealing on rigid pavement - Surface dressing every 5-7 years - Major overlay every 10-15 years - 20-25 year design horizon

Cost-benefit: - 2-lane + PS: 60-70 % cost of 4-lane - Service life similar (with proper maintenance) - Capacity adequate for AADT < 15,000 - When AADT exceeds threshold, expand to 4-lane

Future expansion to 4-lane: - Cross-section can be expanded - ROW often adequate (30-45 m sufficient) - Pavement may need strengthening for higher traffic - Bridge widening + median addition - Reduces capital cost vs greenfield 4-lane

Companion codes (must pair with)

IRC:SP-84:2019 — NH 4-laning Manual.
IRC:SP-99:2013 — 6-laning Manual.
IRC:SP-87:2013 — Older 4-laning Manual.
IRC:73:1980 — Rural Highway Geometric Design.
IRC:38:1988 — Horizontal Curves.
IRC:37:2018 — Pavement Design.
IRC:29:2019 — DBM/DBC Specifications.
IRC:107:2013 — BC Wearing Course.
IRC:58:2015 — Rigid Pavement.
IRC:36:2010 — Earth Embankment.
IRC:75:2015 — High Embankments.
IRC:SP-21:2009 — Intersection + Grade Separated Structures.
IRC:65:2017 — Traffic Rotaries.
IRC:35:2015 — Road Markings.
IRC:67:2012 — Road Signs.
IRC:103:2012 — Pedestrian Facilities.
IRC:SP-13:2004 — Small Bridges + Culverts.
IRC:SP-42:2014 — Road Drainage.
IRC:5:2015 — Bridge General Features.
IRC:6:2017 — Bridge Loads.
IRC:78:2014 — Bridge Foundations.
IRC:83:2018 — Direct Foundations.
IRC:112:2020 — Concrete Bridges.
IRC:24:2010 — Steel Bridges.
IRC:SP-19:2001 — Road DPR Manual.
IRC:SP-57:2015 — Quality Systems.
IRC:SP-44:1996 — Road Safety Audit.
IRC:SP-55:2014 — Work Zone Traffic Management.
IS 456:2000 — Plain + Reinforced Concrete.
IS 800:2007 — Steel Construction.
NHAI Manual of Standards.
MoRTH Specifications for Road and Bridge Works.

Common pitfalls / what reviewers flag

1. Insufficient paved shoulder width. 1.0 m only; emergency stopping inadequate. Per IRC SP 73: 1.5-2.5 m. 2. Earthen shoulder beyond paved omitted. Paved shoulder ends; vehicle drops off. Earthen shoulder mandatory. 3. Cross-fall on shoulder wrong direction. Water flows toward carriageway. Shoulder slopes outward. 4. Pavement of shoulder thinner than carriageway. Shoulder fails under occasional truck use. Similar or slightly thinner pavement spec. 5. No median where required. Two-way traffic mixing; head-on conflicts. Median for high-volume 2-lane + PS. 6. Drainage at shoulder edge missing. Water collects at PS/earthen interface. Edge drainage required. 7. Cost-cutting at structures. Bridges still need full 2-lane + PS cross-section. 8. Geometric standard relaxed. Sub-standard curves justified as 'temporary'; safety issue. Adhere to design standards. 9. Construction quality variable. Multiple contractors; quality varies. Per IRC:SP-57:2015 consistent. 10. No road safety audit. In-service crashes high. Per IRC:SP-44:1996. 11. Future 4-lane expansion not provided. ROW inadequate; structures don't allow expansion. Plan for future. 12. Junctions inadequate. At-grade intersections poorly designed; capacity issues. Per IRC:SP-21:2009. 13. No maintenance budget. Performance-based contract underfunded. Adequate budget. 14. Environmental clearance delayed. Per IRC:SP-93:2017. 15. Land acquisition issues. ROW disputes; project delayed. Pre-DPR coordination.

Where it sits in NH-project lifecycle

NH 2-lane + PS project — IRC SP 73 touchpoints:

1. Pre-feasibility: existing 2-lane condition; demand; upgrade timing.

2. DPR (per IRC SP 73 framework): - Geotechnical + hydrological - Traffic study + ESAL forecast - Pavement design + cross-section - Bridge + culvert design - Drainage system - Safety appurtenances - Cost-benefit analysis - Environmental clearance

3. Tender + award: - Per NHAI EPC / HAM contracts (typically) - Performance-based maintenance (5-10 year) - Quality requirements per IRC:SP-57:2015

4. Construction: - Earthwork + structural foundation - Pavement layers per IRC:37:2018 - Bridge construction - Paved + earthen shoulders - Safety appurtenances - Traffic management during construction

5. **Quality control + acceptance.

6. Operations + maintenance: - Performance-based contract - Annual visual inspection - Periodic detailed assessment - 20-25 year design life

7. Future expansion to 4-lane (when traffic justifies): - ROW available - Pavement strengthening / overlay - Median addition - Bridge widening - Cost-effective vs new alignment

IRC SP 73 is the intermediate-capacity NH manual — bridging the cost-benefit gap between 2-lane and 4-lane. Applied on hundreds of NH projects across India where AADT growth supports intermediate upgrade.

International Equivalents

Similar International Standards

AASHTO LRFD Bridge Design Specifications (USA)

MediumCurrent

Austroads Guide to Pavement Technology (Australia)

MediumCurrent

Design Manual for Roads and Bridges (DMRB) (UK)

MediumCurrent

Key Differences

≠

Key Similarities

≈

Parameter Comparison

Parameter	IS Value	International	Source
Lane Width
Minimum Paved Shoulder Width
Subgrade CBR Requirement
Design Speed (Plain Terrain)
Compaction Density (GSB)

⚠ Verify details from original standards before use

Key Values20

Quick Reference Values

minimum lane width3.60 m (Clause 4.1.1.1)

minimum shoulder width paved1.50 m (Clause 4.1.2.1)

minimum shoulder width unpaved2.50 m (Clause 4.1.2.2)

design speed rural80 kmph (Table 4.1)

design speed plain rolling80 kmph (Table 4.1)

design speed mountainous steep50 kmph (Table 4.1)

cbr requirement subgradeMinimum 4% (Clause 5.2.1)

layer thickness gsbMinimum 150 mm (Clause 5.3.3.1)

layer thickness gwbMinimum 100 mm (Clause 5.3.4.1)

layer thickness dbmMinimum 50 mm (Clause 5.3.5.2)

layer thickness bmMinimum 25 mm (Clause 5.3.6.1)

layer thickness asphalt concreteMinimum 25 mm (Clause 5.3.7.1)

minimum camber rural section2.0% (Table 4.4)

minimum camber hilly section3.0% (Table 4.4)

traffic volume threshold for 2 laningConsidered based on existing conditions and projected growth (Implied in Scope)

compaction density subgrade97% of MDD (Clause 5.2.2)

compaction density gsb98% of MDD (Clause 5.3.3.3)

compaction density gwb98% of MDD (Clause 5.3.4.3)

compaction density dbm93-97% of theoretical density (Clause 5.3.5.5)

compaction density asphalt concrete93-97% of theoretical density (Clause 5.3.7.5)

Key Formulas

SSD = v*t + v^2 / (2*g*(f + sin(theta)))

ISD = 2.5 * SSD

OSD = v*t2 + 2*S*v + v^2 / (2*a) + v^2 / (2*g*(f + sin(theta)))

Theoretical Density = (100 / ((P_agg / rho_agg) + (P_bitumen / rho_bitumen)))

Tables & Referenced Sections

Key Tables

Table 4.1: Design Speed for Different Terrain Types

Table 4.2: Ruling Gradients

Table 4.3: Sight Distance Requirements

Table 4.4: Camber Values for Different Road Sections

Table 5.1: CBR Requirements for Subgrade

Table 5.2: Granular Sub-Base (GSB) Gradation and Properties

Table 5.3: Granular Working Base (GWB) Gradation and Properties

Table 7.1: Requirements for Bituminous Macadam (BM) Mix

Table 7.2: Requirements for Dense Bituminous Macadam (DBM) Mix

Table 7.3: Requirements for Asphalt Concrete (AC) Mix

Table 9.1: Quality Control Tests for Pavement Layers

Frequently Asked Questions10

What is the primary objective of providing paved shoulders in two-laning projects according to this IRC manual?+

The primary objective is to enhance road safety and operational efficiency. Paved shoulders provide a stable area for vehicles to pull over in emergencies, act as a buffer zone, and allow for safe overtaking maneuvers. They also contribute to the structural integrity of the road by reducing stress on the main carriageway and preventing edge deterioration, thus extending the service life of the highway.

What are the minimum requirements for lane width and paved shoulder width specified in this manual?+

The manual specifies a minimum lane width of 3.60 meters (Clause 4.1.1.1) for two-laning. For paved shoulders, the minimum width stipulated is 1.50 meters (Clause 4.1.2.1). These dimensions are crucial for safe vehicular movement and maneuverability, especially in challenging traffic conditions.

How does the manual address the strength requirements of the subgrade for two-laning with paved shoulders?+

The manual mandates a minimum California Bearing Ratio (CBR) of 4% for the subgrade (Clause 5.2.1). If the existing subgrade does not meet this requirement, it necessitates strengthening measures such as soil stabilization, improving the subgrade by excavation and replacement with better material, or providing a thicker sub-base layer to ensure adequate load-bearing capacity and prevent pavement distress.

What are the typical pavement layer thicknesses prescribed for the different strata in this manual?+

The manual outlines minimum layer thicknesses for various pavement components. For instance, the Granular Sub-Base (GSB) requires a minimum thickness of 150 mm (Clause 5.3.3.1), Granular Working Base (GWB) a minimum of 100 mm (Clause 5.3.4.1), Dense Bituminous Macadam (DBM) a minimum of 50 mm (Clause 5.3.5.2), and Asphalt Concrete (AC) a minimum of 25 mm (Clause 5.3.7.1). These thicknesses are designed to distribute traffic loads effectively.

What is the importance of drainage design in the context of two-laning with paved shoulders?+

Drainage is critically important because water ingress into pavement layers can lead to a significant reduction in their strength and stability, causing premature failure such as rutting, cracking, and pumping. The manual emphasizes proper camber and the provision of adequate drainage structures (Clause 6.1) to efficiently remove surface water and prevent its accumulation, especially under the paved shoulders.

Are there specific material requirements for the bituminous layers used in paved shoulders?+

Yes, the manual specifies material requirements for Bituminous Macadam (BM), Dense Bituminous Macadam (DBM), and Asphalt Concrete (AC) in Chapter 7. This includes guidelines on the aggregate gradations, binder types and properties, and the mix design requirements to ensure durability and performance of the paved shoulders under traffic and environmental conditions.

What are the key quality control measures recommended in this manual for pavement construction?+

The manual emphasizes a robust quality control system, outlined in Chapter 9, which includes regular testing of materials and executed works. This involves checking the CBR of the subgrade, compaction density of GSB and GWB layers, aggregate gradations, bitumen content and properties, and the surface regularity and skid resistance of bituminous layers. Table 9.1 lists specific tests and their frequency.

How does the manual address the design speed considerations for two-laning projects?+

The manual provides different design speeds based on terrain types in Table 4.1. For rural and plain/rolling terrain, the design speed is typically 80 kmph, while for mountainous and steep terrain, it is reduced to 50 kmph. These speeds dictate geometric design parameters like sight distances, curve radii, and superelevation, ensuring safe vehicular operation.

What is the purpose of having both paved and unpaved shoulders in some cases?+

While the manual focuses on paved shoulders, it acknowledges the existence of unpaved shoulders in some contexts (Clause 4.1.2.2) for reasons of cost-effectiveness or specific project requirements. Unpaved shoulders primarily serve as run-off-road areas and can accommodate occasional slow-moving vehicles, but paved shoulders offer superior structural support and safety benefits due to their stability and load-carrying capacity.

What are the recommended camber values for different road sections?+

Camber is essential for surface drainage. The manual specifies minimum camber values in Table 4.4. For rural sections, a minimum camber of 2.0% is recommended, while for hilly sections, a higher camber of 3.0% is advised to facilitate rapid runoff of rainwater and prevent pooling on the road surface.

QA/QC Inspection Templates

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IRC SP 73 : 2015Manual of Specifications and Standards for Two-Laning of Highways with Paved Shoulders

PDF Google Compare IRC Portal

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

AASHTO LRFD Bridge Design Specifications (USA) · Austroads Guide to Pavement Technology (Australia) · Design Manual for Roads and Bridges (DMRB) (UK)

CurrentFrequently UsedCode of PracticeTransportation · Roads and Pavement

PDF Google Compare IRC Portal

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

Quick Reference — IRC SP 73:2015 Two-Laning with Paved Shoulders

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

✓ Verified 2026-05-15

Reference	Value	Clause
Subject	Specs & standards for 2-laning highways with paved shoulders	Scope
Carriageway	2-lane (7.0 m) + paved shoulders	Geometry
Design speed	By terrain (ruling/minimum)	Geometry
Pavement	Flexible (IRC 37) / rigid (IRC 58) as specified	Design
Use	NHAI/MoRTH 2-lane-with-PS project standard	Application
Read with	IRC SP 84 (2-lane) / IRC SP 87 (4-lane)	Cross-ref

⚠ 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