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Submersible / Causeway Bridge

Low-water crossing per IRC SP-82 (Guidelines for Submersible Bridges) — RCC deck slab or paved-causeway over stream bed, designed to allow passage during 8-10 dry months/year + submerge safely under monsoon flood (typically 1-3 day disruptions). Three sub-types: (a) Solid causeway (paved RCC slab on stream bed); (b) Vented causeway (with hume pipes / box vents allowing low-flow water passage); (c) Submersible bridge (above-bed RCC slab on stub piers, vehicles cross till HFL). Rates: CPWD DSR Vol 1 + Vol 2 (2023).

Visual confirmation
Plan · 40 m × 5.5 m · vented causeway
stream / nallahCAUSEWAY6 × 900 mm vents (dashed = under deck)40 m5.5 m
Elevation · vented · 40 m crossing
HFL (monsoon)40 m crossing
Cross-section · 5.5 m wide vented
900 mm ventpitchingpitchingwearing coat 75 mmRCC deck 250 mm5.5 m wide
Bill of Quantities10 items · CPWD DSR Vol 1 + Vol 2 (2023)
#CodeDescriptionUnitQtyRate (₹)Amount (₹)
15.3Rcc Deck SlabReinforced cement concrete work in beams, suspended floors, roofs having slope up to 15° landings, balconies, shelves, chajjas, lintels, bands, plain window sills, staircases and spiral stair cases above plinth level up to floor five level, excluding the cost of centering, shuttering, finishing and reinforcement with 1:1.5:3 (1 cement : 1.5 coarse sand(zone-III) derived from natural sources : 3 graded stone aggregate 20 mm nominal size derived from natural sources).Cum55.0011,505.506,32,802.50
25.9.3Shutter Deck SlabCentering and shuttering including strutting, propping etc. and removal of form for — Suspended floors, roofs, landings, balconies and access platformSqm220.00927.252,03,995.00
35.22.6Steel TotalSteel reinforcement for R.C.C. work including straightening, cutting, bending, placing in position and binding all complete upto plinth level. — Thermo-Mechanically Treated bars of grade Fe-500D or more.Kg6,229.00107.856,71,797.65
419.6.2Hume Pipe Vent Np3Providing and laying non-pressure NP2 class (light duty) R.C.C. pipes with collars jointed with stiff mixture of cement mortar in the proportion of 1:2 (1 cement : 2 fine sand) including testing of joints etc. complete : — 150 mm dia. R.C.C. pipeMetre33.00556.4518,362.85
55.3Vent Headwall RccReinforced cement concrete work in beams, suspended floors, roofs having slope up to 15° landings, balconies, shelves, chajjas, lintels, bands, plain window sills, staircases and spiral stair cases above plinth level up to floor five level, excluding the cost of centering, shuttering, finishing and reinforcement with 1:1.5:3 (1 cement : 1.5 coarse sand(zone-III) derived from natural sources : 3 graded stone aggregate 20 mm nominal size derived from natural sources).Cum8.1011,505.5093,194.55
611.6Boulder Pitching[item not found: 11.6]160.000.000.00
SOR item dsr_vol1_2023:11.6 not in private subset — regenerate via scripts/boq-import-sor-subset.mjs
74.1.10Boulder Apron Pcc BondProviding and laying in position cement concrete of specified grade excluding the cost of centering and shuttering - All work up to plinth level : — 1:5:10 (1 cement : 5 coarse sand (zone-III) derived from natural sources : 10 graded stone aggregate 40 mm nominal size derived from natural sources)Cum24.006,518.601,56,446.40
816.78.2Approach GsbConstruction of granular sub-base by providing close graded Material conforming to specifications, mixing in a mechanical mix plant at OMC, carriage of mixed material by tippers to work site, for all leads & lifts, spreading in uniform layers of specified thickness with motor grader on prepared surface and compacting with vibratory power roller to achieve the desired density, complete as per specifications and directions of Engineer-in-Charge. — With material conforming to Grade-II (size range 53 mm to 0.075 mm ) having CBR Value-25Cum44.002,924.851,28,693.40
916.57.1Approach Bc WearingProviding and laying Bituminous concrete using crushed stone aggregates of specified grading, premixed with bituminous binder and filler, transporting the hot mix to work site by tippers, laying with paver finisher equiped with electronic sensor to the required grade, level and alignment and rolling with smooth wheeled, vibratory and tandem rollers to achieve the desired compaction and density as per specification, complete and as per directions of Engineer-in-Charge. — 40/50 mm compacted thickness with bitumen of grade VG-30 @ 5.5% (percentage by weight of total mix) and lime filler @ 3% (percentage by weight of Aggregate) prepared in Batch Type Hot Mix Plant of 100-120 TPH capacity.Cum11.0012,126.201,33,388.20
1010.1.1Guide Posts Ms Reflector[item not found: 10.1.1]128.000.000.00
SOR item dsr_vol1_2023:10.1.1 not in private subset — regenerate via scripts/boq-import-sor-subset.mjs
Your inputsStructure type Vented causeway · Crossing length 40 m · Deck / pavement width 5.5 m · RCC slab thk 250 mm · Stub-pier height 1.5 m · vents 6 vents · Vent ⌀ 900 mm · Guide posts + reflectors · Approach pavementTOTAL₹20,38,681
15.3₹6,32,803
Rcc Deck Slab
Reinforced cement concrete work in beams, suspended floors, roofs having slope up to 15° landings, balconies, shelves, chajjas, lintels, bands, plain window sills, staircases and spiral stair cases above plinth level up to floor five level, excluding the cost of centering, shuttering, finishing and reinforcement with 1:1.5:3 (1 cement : 1.5 coarse sand(zone-III) derived from natural sources : 3 graded stone aggregate 20 mm nominal size derived from natural sources).
55.00 Cum× ₹11,505.50
25.9.3₹2,03,995
Shutter Deck Slab
Centering and shuttering including strutting, propping etc. and removal of form for — Suspended floors, roofs, landings, balconies and access platform
220.00 Sqm× ₹927.25
35.22.6₹6,71,798
Steel Total
Steel reinforcement for R.C.C. work including straightening, cutting, bending, placing in position and binding all complete upto plinth level. — Thermo-Mechanically Treated bars of grade Fe-500D or more.
6,229.00 Kg× ₹107.85
419.6.2₹18,363
Hume Pipe Vent Np3
Providing and laying non-pressure NP2 class (light duty) R.C.C. pipes with collars jointed with stiff mixture of cement mortar in the proportion of 1:2 (1 cement : 2 fine sand) including testing of joints etc. complete : — 150 mm dia. R.C.C. pipe
33.00 Metre× ₹556.45
55.3₹93,195
Vent Headwall Rcc
Reinforced cement concrete work in beams, suspended floors, roofs having slope up to 15° landings, balconies, shelves, chajjas, lintels, bands, plain window sills, staircases and spiral stair cases above plinth level up to floor five level, excluding the cost of centering, shuttering, finishing and reinforcement with 1:1.5:3 (1 cement : 1.5 coarse sand(zone-III) derived from natural sources : 3 graded stone aggregate 20 mm nominal size derived from natural sources).
8.10 Cum× ₹11,505.50
611.6₹0
Boulder Pitching
[item not found: 11.6]
160.00 × ₹0.00
SOR item dsr_vol1_2023:11.6 not in private subset — regenerate via scripts/boq-import-sor-subset.mjs
74.1.10₹1,56,446
Boulder Apron Pcc Bond
Providing and laying in position cement concrete of specified grade excluding the cost of centering and shuttering - All work up to plinth level : — 1:5:10 (1 cement : 5 coarse sand (zone-III) derived from natural sources : 10 graded stone aggregate 40 mm nominal size derived from natural sources)
24.00 Cum× ₹6,518.60
816.78.2₹1,28,693
Approach Gsb
Construction of granular sub-base by providing close graded Material conforming to specifications, mixing in a mechanical mix plant at OMC, carriage of mixed material by tippers to work site, for all leads & lifts, spreading in uniform layers of specified thickness with motor grader on prepared surface and compacting with vibratory power roller to achieve the desired density, complete as per specifications and directions of Engineer-in-Charge. — With material conforming to Grade-II (size range 53 mm to 0.075 mm ) having CBR Value-25
44.00 Cum× ₹2,924.85
916.57.1₹1,33,388
Approach Bc Wearing
Providing and laying Bituminous concrete using crushed stone aggregates of specified grading, premixed with bituminous binder and filler, transporting the hot mix to work site by tippers, laying with paver finisher equiped with electronic sensor to the required grade, level and alignment and rolling with smooth wheeled, vibratory and tandem rollers to achieve the desired compaction and density as per specification, complete and as per directions of Engineer-in-Charge. — 40/50 mm compacted thickness with bitumen of grade VG-30 @ 5.5% (percentage by weight of total mix) and lime filler @ 3% (percentage by weight of Aggregate) prepared in Batch Type Hot Mix Plant of 100-120 TPH capacity.
11.00 Cum× ₹12,126.20
1010.1.1₹0
Guide Posts Ms Reflector
[item not found: 10.1.1]
128.00 × ₹0.00
SOR item dsr_vol1_2023:10.1.1 not in private subset — regenerate via scripts/boq-import-sor-subset.mjs
Structure type Vented causeway · Crossing length 40 m · Deck / pavement width 5.5 m · RCC slab thk 250 mm · Stub-pier height 1.5 m · vents 6 vents · Vent ⌀ 900 mm · Guide posts + reflectors · Approach pavement
Estimated total
₹20,38,681
Notes & assumptions
  • **Submersible / Causeway** is the cheapest river-crossing option for **rural seasonal streams** — designed to be overtopped 5-30 days per year during monsoon (typically 1-3 days at a time) + provide passage during the remaining 8-10 dry months. Per IRC SP-82 — adopted widely in Maharashtra, Karnataka, Gujarat, AP rural roads + MGNREGA convergence works.
  • **Three sub-types**: **Solid causeway** — RCC slab cast directly on stream bed level (no flow under it; vehicles + low water both use same surface); cheapest, suited to streams with very seasonal flow. **Vented causeway** — solid slab + hume-pipe vents at bottom allowing dry-season low flow to pass beneath; cars cross over the top; standard MGNREGA design. **Submersible bridge** — RCC slab on short stub piers raising deck 1-3 m above bed; vehicles cross till water reaches HFL (Highest Flood Level), then disruption.
  • **When to use vs minor bridge** (₹65-85L): submersible cost is 25-40 % that of an all-season minor bridge. Justified when: stream has well-defined dry season (8+ months); ADT < 200 vehicles/day; alternative route exists during monsoon submergence (5-30 days/year). Inappropriate for: SH/NH, ambulance routes, schools-on-other-side villages, year-round inhabited approaches.
  • **Cost target** for default 40 m × 5.5 m vented causeway with 6 vents + boulder pitching + approach pavement: approximately **₹15-22 lakh** per CPWD DSR 2023. Solid causeway ~₹10-15L; submersible bridge with stub piers ~₹25-35L.
  • **Boulder pitching / apron** (mandatory per IRC SP-82): hand-placed boulders (80-200 mm size) bonded with M15 PCC, 2 m wide on both banks, prevents bank erosion + protects RCC slab edges from undercutting during monsoon overtopping.
  • **Approach pavement** (20 m each side, GSB + thin BC): provides smooth entry/exit from the causeway deck level to the road formation level. Without it the road-to-causeway transition cracks within 1-2 monsoons.
  • **Excludes**: river-flow study (CWC consultation); HFL (Highest Flood Level) marker installation (₹50K-1L per bridge); navigation lighting (large rivers only); guide-bund earthwork (₹5-10L if needed for channelisation); afflux protection (additional pitching upstream).

The **Submersible / Causeway Bridge** is the most economical river-crossing option for rural seasonal streams in India — designed per **IRC SP-82** to allow passage during 8-10 dry months and submerge safely during monsoon flood (typically 5-30 days/year of disruption). Three variants: solid causeway (slab on stream bed), vented causeway (slab with hume-pipe vents for low flow), submersible bridge (slab on short stub piers above bed). Construction cost 25-40 % of equivalent all-season minor bridge — making it the standard choice for MGNREGA, State PWD rural roads, and BRO mountain crossings. Default 40 m × 5.5 m vented causeway: ₹15-22 lakh civil per CPWD DSR. This BOQ Builder generates the complete per-crossing cost.

When submersible/causeway is the right choice

**Use submersible/causeway when ALL of the following are TRUE**: (1) **Seasonal stream** — well-defined dry months (8+ months/year of low / negligible flow); (2) **Low traffic** — ADT < 200 vehicles/day, predominantly local + agricultural; (3) **Alternate route exists** — during 5-30 days of monsoon overtopping, traffic can detour via another road (even if longer); (4) **No emergency dependence** — no critical-time-sensitive services (ambulance, school bus on other side) needing year-round access. **Don't use submersible if ANY of these are FALSE** — bear the extra cost of a minor bridge ([Minor RCC T-Beam Bridge](/boq/minor-rcc-tbeam-bridge), ~₹65-85L) or PSC ([PSC Girder Bridge](/boq/psc-girder-bridge)) for all-season access. The discipline of evaluating these conditions properly is the difference between a useful structure + a costly mistake that leaves villages cut off for weeks each year.

Three variants compared

**Solid causeway** (~₹10-15L for 40 m × 5.5 m): RCC slab cast on top of leveled stream bed. Stream flows OVER the slab during dry season too (vehicles cross through 100-300 mm flowing water). Cheapest but slowest dry-season passage (water depth + algae). Best for streams with very low summer flow. **Vented causeway** (~₹15-22L for default): solid slab + hume-pipe vents at bed level (6 × 900 mm typical). Dry-season flow passes through vents under the slab; vehicles cross dry-deck top. Standard MGNREGA / State PWD choice — best balance of cost + dry-season comfort. **Submersible bridge** (~₹25-35L for default): RCC slab on stub piers raises deck 1-3 m above bed. Vehicles cross dry-deck till water reaches HFL. Best for streams with year-round low flow (no submergence for 9+ months); intermediate between true causeway + minor bridge.

Frequently asked questions
**Default 40 m × 5.5 m vented causeway** (6 × 900 mm hume-pipe vents + boulder pitching + 20 m approach pavement each side): **₹15-22 lakh** per CPWD DSR 2023. **Solid causeway** (no vents): ₹10-15L. **Submersible bridge** (stub piers raising deck 1.5 m): ₹25-35L. For comparison: equivalent all-season Minor RCC T-Beam Bridge for same crossing: ₹65-85L (3-4x more). The submersible/causeway choice is a 60-75 % cost saving but trades off monsoon-season access.
Disclaimer: Rates sourced from CPWD DSR Vol 1 + Vol 2 (2023). Indicative for estimation only — actual tender quotations are governed by market forces, locality factors and current input prices. Quantities follow IS 1200 measurement. Always verify with a local quote before finalising. © InfraLens — infralens.in