Bituminous Road BOQ — Worked Example for a 1 km × 5.5 m PMGSY Road

Bituminous (flexible-pavement) roads are the workhorse rural-road type in India — every PMGSY road, every internal panchayat road, every village inter-connectivity road follows this 5-layer spec per MoRTH + IRC 37. Initial cost is 30-40 % lower than the equivalent cement concrete road, but the lifespan is also shorter (10-15 years vs 25-40). This article walks through a complete BOQ for the PMGSY default — 1 km × 5.5 m carriageway — item by item.

Project Scenario

You're estimating a PMGSY rural road connecting two villages: 1 km length, 5.5 m carriageway (PMGSY default), 225 mm GSB + 200 mm WBM + 50 mm BM binder + seal coat + 40 mm BC wearing course, brick edging on both shoulders. Total compacted thickness ~515 mm.

Design specification at a glance

• Length: 1.0 km (1,000 m)
• Carriageway width: 5.5 m (PMGSY default)
• Sub-base GSB: 225 mm, 6.1 m wide
• Base course WBM: 200 mm, full carriageway width
• Binder course BM: 50 mm, full carriageway width
• Seal coat: over full BM surface
• Wearing course BC: 40 mm, full carriageway width
• Shoulders: 1.0 m granular each side + brick edging

The Complete BOQ — 6 Items in CPWD DSR 2023

Six items capture the full structural pavement. The live BOQ Builder evaluates these formulas in real time — change layer thicknesses, carriageway width, or skip BC for a binder-course-only finish, and the quantities update instantly.

How Each Quantity Was Computed

1. Granular Sub-Base — Item 16.78.2

GSB extends 300 mm beyond the carriageway on each side to anchor the WBM and edge restraints:

GSB width = 5.5 + 2 × 0.30 = 6.1 m
GSB volume = 1000 × 6.1 × 0.225 = 1,372.5 m³

2. Water-Bound Macadam — Item 16.4

WBM is the base course — large stone (53-90 mm) compacted with screening + watering. Full carriageway width only:

WBM volume = 1000 × 5.5 × 0.20 = 1,100 m³

WBM-Grade-III uses 53 mm aggregate as the coarse fraction. Grade-II (75 mm) is used for the first lift on weak subgrades. Grade-IV (45 mm) is used for the topmost lift before BM.

3. Bituminous Macadam — Item 16.55.1

50 mm thick binder course, full carriageway width:

BM volume = 1000 × 5.5 × 0.050 = 275 m³

BM uses VG-30 bitumen at 3.0-3.5 % by weight (per MoRTH 5th revision). The aggregate gradation is coarse — 19 mm nominal max size. Lower bitumen content than BC, so the surface is open-textured and would let water seep through if left exposed. That's why the seal coat (next item) is essential.

4. Seal coat — Item 16.41

Seal area = carriageway area = 1000 × 5.5 = 5,500 m²

Seal coat fills the surface voids of the BM with premixed fine aggregate (< 6 mm) + bitumen emulsion. Without this, the BM degrades from rainwater ingress within 6-12 months. On budget-tight PMGSY contracts where BC is skipped, the seal coat becomes the actual wearing surface — but it lasts only 2-3 years.

5. Bituminous Concrete — Item 16.57.1

40 mm thick wearing course, full carriageway width:

BC volume = 1000 × 5.5 × 0.040 = 220 m³

BC uses VG-30 bitumen at 5.0-6.0 % (much higher than BM) and finer aggregate gradation (max 13 mm). The high bitumen content + dense gradation make it watertight and abrasion-resistant. This is what vehicles actually drive on; the lower layers are structural.

6. Brick edging — Item 16.7.1

Edge length = 2 × road length = 2 × 1000 = 2,000 m

Full brick width + half brick depth, laid in cement mortar 1:6 along both shoulder edges. Protects pavement edges from raveling under wheel loads. On urban roads, brick edging is replaced by precast concrete kerb stones (DSR 16.69).

Bituminous vs Concrete — Cost & Lifespan Trade-Off

For PMGSY traffic (~150 commercial vehicles/day), bituminous wins on initial cost and has acceptable life-cycle cost. For ≥ 4,500 cv/day or specialised loading, concrete wins on life-cycle basis.

Construction Sequence (Layer by Layer)

1. Sub-grade preparation — earthwork compaction to 95-97 % modified Proctor density (NOT in this BOQ; site-specific)
2. GSB — sub-base laid, watered, rolled to 100 % MDD
3. WBM — base course in 2-3 lifts of 75 mm each, watered + power-rolled
4. Prime coat — bitumen emulsion sprayed on WBM (~0.7-1.0 kg/m²) to bond next layer; usually clubbed in BM rate
5. BM — binder course laid hot, screeded, rolled while > 100 °C
6. Seal coat — fills BM surface voids
7. Tack coat — bitumen emulsion (~0.2-0.3 kg/m²) sprayed between BM + BC
8. BC — wearing course laid hot, screeded, rolled
9. Brick edging — laid in cement mortar 1:6 along shoulder lines
10. Pavement marking + reflective studs (separately quoted)

What This BOQ Excludes

• Earthwork in cutting / embankment formation — depends on site terrain, use DSR 2.6 (area excavation) + 2.2 (banking) separately
• Prime coat (~₹15-20/m²) — small, usually clubbed in BM rate but worth verifying in your state SOR
• Tack coat (~₹8-12/m²) between BM + BC
• Road furniture — kerb stones, drains, gully gratings, signage, line marking, reflective studs
• Shoulder gravel — 150-300 mm of gravelly sand on the 1 m shoulder strip outside brick edging
• Pavement marking + reflective studs — 100 mm white centre + edge lines, ₹6-8 per running metre
• Side drains — quote separately under RCC drain BOQ
• Cross-drainage culverts — separate Hume pipe / box culvert estimates

Common Estimation Mistakes

• Forgetting the seal coat — without it, BM is exposed to water and degrades fast. Seal coat is ~₹2-3 lakh/km and routinely cut by inexperienced estimators.
• Specifying only BC with no BM — BC alone is too thin to be structural; needs BM underneath. Inverse mistake: specifying only BM (no BC) leaves the binder exposed.
• Using full BM width = GSB width — BM is laid only on the carriageway, not on shoulders. Over-estimates BM by ~10 %.
• Skipping prime + tack coats — these tiny line items (~₹40-60k/km combined) are what bond the layers. Without them, BC delaminates within 1-2 monsoons.
• Bituminous over saturated clay subgrade — black-cotton soil swells when wet, lifts pavement, cracks BC. Add lime/cement stabilisation to subgrade or use 300 mm GSB with non-woven geotextile separator.
• Using single-layer WBM — IRC 37 specifies 2-3 lifts of 75 mm. Single 200 mm lift can't be compacted to 100 % density; settles within 6 months.

What Changes for a Different Road

• 3.0 m intermediate carriageway — for upgrade-from-track roads. GSB width 3.6 m; everything else proportional.
• 7.0 m two-lane — central longitudinal joint, BM and BC volumes increase ~27 %, brick edging same (still 2 km total for both shoulders).
• NH/SH carriageway (10 m, heavy) — GSB 300 mm, WBM swapped for Dense Bituminous Macadam (DBM) 100 mm, BM 75 mm, BC 50 mm. Different DSR codes (16.56 series for DBM).
• SDBC instead of BC — for low-traffic state-PWD roads, Semi-Dense Bituminous Concrete is a 25 mm thinner wearing course (~30 % cheaper).
• Hill road / sharp gradient — bump BM bitumen content to 4 % + use polymer-modified bitumen for higher resistance to bleeding on slopes
• State-PWD SOR — switch from CPWD to your state PWD road-works SOR (typically more current for PMGSY).

Get Your Road's Cost in 30 Seconds

References & Companion Reading

• IRC 37:2018 — Guidelines for the Design of Flexible Pavements (the master spec for BT roads)
• IRC SP 72:2015 — Guidelines for the Design of Flexible Pavements for Low Volume Rural Roads
• IS 1200 Part 16:1979 — Method of Measurement for Road Works
• Sister article: Cement Concrete Road BOQ Example — for the rigid-pavement comparison
• Sister tool: Cement Concrete Road BOQ Builder
• MoRTH Schedule of Rates — the official road-works SOR (most current rates)
• CPWD DSR 2023