Quality Assurance Handbook for Rural Roads Volume-I - pmgsy

1400 : CEMENT CONCRETE CAUSEWAYS
189
Quality Assurance Handbook for Rural Roads
Under this section quality aspects of different submersible structures viz., Irish/ Flush Causeway, Vented
Causeway and Submersible Bridges for rural roads are dealt with:
A. Methodology
A1 Flush Causeway
1. Choose flush causeway (Paved dip) to cross a shallow water course by adopting general guidelines
given in clause 1401.0 of MORD Specifications for Rural Roads.
2. Keep top level of floor of causeway same as that of bed of water-course.
3. Build cut-off walls in brick masonry on stone masonry or plain cement concrete with suitable
formwork as per provisions given in sections 600, 700, 800 and 900 respectively of this Manual.
4. Excavate for laying of foundation of u/s and d/s cut-off walls. Keep it sufficiently deep to avoid
exposure due to scouring. Adopt a PCC footing of 150 mm thickness in M15 grade, laid on a layer
of 100 mm thick lean concrete (M10)
5. Adopt a plain cement concrete slab of minimum thickness 200 mm in a minimum grade of M30 as
paved dip. Provide construction joints 4-6m apart and seal them with polysulphide.
6. Provide u/s and d/s protection works, apron, pitching as per requirement.
7. Provide guide posts/stones at required spacing.
A2 Vented Pipe Causeways
1. Choose vented pipe causeway to cater to low flows through circular vents which overtop during
monsoon. Usually RCC pipes (NP3 or NP4) are used for providing circular vents.
2. Follow the same methodology as detailed in section 1100 of this Manual for laying of RCC Pipes.
3. For headwalls or other ancillary works, adopt the requirements given in Section 1300.
4. Take foundation and head walls sufficiently deep to avoid exposure to scouring in erosive strata.
Batter the d/s side headwall on the outside and round the corners.
5. Adopt rectangular or arch on type vents instead of circular pipe as per local practice.
6. Raise end portion of face walls and protect entire top of causeway by well desirable non-erodible
wearing coat.
A3 Submersible Bridges
For design and construction of submersible bridges, adopt prevailing practice in the State or
Guidelines given in IRC:SP:20.
1. Make the deck slabs heavy to withstand drag, uplift and lateral force due to overflow and upstream
pressure.
2. Fix the location and levels of pier cap, abutment cap, pedestals and anchorage arrangements to
ensure proper alignment.