DEPARTMENT OF CIVIL ENGINEERING

Sub-Railway and Bridge Engineering

Topic-Culvert and Cause Ways

Sem-5^th

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BY

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Er. Jyoti Shankar Mohanty

( Lect. In Civil Engineering Department)

AY:2021-2022

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Causeway and culvert

• The causeway may be proposed on streams of flashy nature with high frequency of short duration floods or at sites where construction of submersible bridges is not economically viable. Culverts are the structures constructed across the drainage below the highway and railways for easy access for humans and animals.
• Culverts are constructed with various materials and to different designs. The popular forms are :
• Temporary stone scuppers
• Stone slab culverts with abutments and piers
• RCC slab culverts with abutments and piers
• RCC Box culverts
• RCC Pipe culverts
• Armco Pipe (metal pipe) culverts
• Masonry arch culverts

• Temporary Stone Scuppers In hill roads, it is customary to cut the roads from the hill-face and to open up the road immediately thereafter to traffic. Further improvements such as construction of the pavement are taken up gradually. In such cases, it is the practice to construct temporary stone corbelled scuppers immediately after the road is cut. These are eventually replaced by permanent structures.

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Stone Slab Culverts with Abutments and Piers Where good quality stone slabs are available like granite slabs, they can be used for superstructure of culverts, with suitable masonry abutments. Spans of such slabs are necessarily small, say upto one metre. Such culverts can be constructed for rural roads (Other District Roads and Village Roads).

RCC Slab Culverts -RCC slab culverts with masonry abutments and piers can be constructed for individual spans upto 6 m.

RCC Box Culverts- RCC Box culverts are ideal for in-situ constructions for opening of size upto 5 m. They can be constructed in square boxes or rectangular boxes, depending upon site conditions. Single or multiple boxes can be constructed. The advantage lies in the elimination of the stout abutment sections which are unavoidable in slab construction.

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RCC Pipe Culverts- Reinforced cement concrete pipe culverts are ideal for dealing with small discharges. The advantages are : (a) They are very economical, since a circular section is the most ideal for withstanding forces from all around.

(b) Since the pipes do not need very elaborate bedding, the cost further comes down.

(c) Pipe culverts do not demand structural design for individual cases. Pipes are standardised, in terms of mix, thickness and reinforcement.

(d) Pipes can be cast under strictly controlled conditions at a Central plant and thus their quality is assured

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The disadvantages with pipes are that they cannot be used for large openings. A minimum cover of at least half the diameter of the pipe is to be ensured over the pipes. In India, RCC pipes of the NP 3 class are suitable for highway loadings. For rural roads (Village Roads and Other District Roads), NP 2 pipes are suitable. Two conditions of bedding are followed :

Culverts, Causeway and Bridges

1. Granular bedding , which consists of forming and grading the bed with sand or any granular material passing 4.75 mm sieve. The thickness of the bedding layer should be minimum 75 mm. Such a bedding is suitable for fills upto 4 m height.
2. Concrete cradle bedding (Figure 7.7), which consists of a concrete bed of M-15 grade concrete. The thickness of the bedding layer should be minimum 250 mm. Such a bedding is used for height of fills above 4 m.
3. Single pipe or a row of pipes can be used. The distance between pipes should be at least half the diameter of the pipe subject to a minimum of 450 mm. the pipes are kept sufficiently below the floor of the deepest bed. Pipe culverts are generally designed to flow full. Suitable head-walls are needed to protect the embankment fills. The slope of the floor is kept to a minimum of 1 : 1000.

• Masonry Arch Culverts-
• Brick or stone masonry arches were very popular forms for culverts till recently. The disadvantage with this form is the unavoidable humps in the longitudinal profile that result. It can also give employment to skilled masons. It is a labour intensive form of construction.
• TYPES OF BRIDGES AND THEIR SUITABILITY –
• Bridging is a specialized filed of engineering science. India has very high degree of sill and expertise in this field, gathered from bridging its mighty rivers. The types of superstructure commonly adopted and the site conditions for which they are suitable are indicated .

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• CAUSEWAYS –
• Paved Dips, also known as bed level causeways, are structures consisting of gentle and shallow depressions in the road where the water is allowed to flow over the road. The full road width is paved with a cement concrete bed, and curtain walls are provided on the upstream and downstream sides to prevent scour.

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• Vented Causeway
• Vented causeways are structures provided with vents (usually pipes) to take care of dry weather perennial flows and which allow water to overflow the paved bed on occasions of high rainfall.

Thank You