Construction of roads, bridges,culverts.pptx

Construction of roads, bridgesculverts

1. Construction of roads, bridges/culverts

2. Road A  road  is a wide way leading from one place to another, especially one with a specially prepared surface which vehicles can use.

3. The proper planning ,design and fixing up of visible dimension of road for providing optimum speed, comfort and maximum safety to road user at a minimum operation cost is road geometrics.

4. Components of road  CARRAIGE WAY  SHOULDER  CAMBER  CURBS  GRADIENT

5. Carriage way: The paved portion of the highway or the road over which the traffic is meant to move is called the pavement or the carriageway. The pavement width is dependent on the  width of the traffic lanes  and the  number of lanes planned for construction.

6. Shoulders:   These are provided along the road edge . This area serves the purpose of accommodating vehicles that are compelled to be taken out of the pavement or the roadway. These also act as a service lane for the vehicles that have broken down.

7. Camber: camber is the slope that is provided in the transverse direction of the pavement or carriageway. The cross slope helps to drain off the rainwater from the road surface. Inadequate cross slope results in the flooding of water over the pavement, which results in deterioration of the highway.

8. Curb: The boundary between the pavement and the shoulder is called as curbs. Curbs are desirable to be constructed for urban roads.

9. Gradient: It is defined as the rate of rising or falls along the length of the road with respect to the horizontal is known as Gradient of  Road . In another word, it is the longitudinal slope provided to the formation level of the road along its alignment.

10. Purpose of Providing Gradient to the Roads To connect the two stations or points with each other, which are located at different levels. To provide  effective drainage of rainwater,  especially when the  pavement  is provided with the curbs. To construct the side drains economically.

11. Cross section of typical road

12. Types of roads 1. WBM Roads Water Bound Macadam (WBM) roads contain crushed stone aggregate in its base course. The aggregates are spread on the surface and rolled after sprinkling water. WBM roads provide better performance compared to earthen, gravel, murrum , and kankar roads. WBM roads are laid as layers of about 10cm thickness of each layer. They are very rough and may disintegrate immediately under traffic.

13. 2 . Bituminous Roads Bituminous roads are prevalent roads around the world. They are the most used roads in the world. This road types are low in cost and suitable for driving conditions. The thickness of bituminous roads depends upon the subgrade soil conditions.

14. 3. Concrete Roads Cement concrete is used to construct the pavements in case of concrete roads. These are very popular and costlier than all other types of roads. They are not flexible, so they require less maintenance. Concrete roads are suitable for high traffic areas. They are laid with joints and time of construction is more.

15. Bridges A  bridge  is a  structure  built to  span  a physical obstacle, such as a  body of water ,  valley , or  road , without closing the way underneath. It is constructed for the purpose of providing passage over the obstacle, usually something that is otherwise difficult or impossible to cross .

16. Classification of bridges  Functions : aqueduct, viaduct, highway, pedestrian etc.  Materials of construction : reinforced concrete, prestressed concrete, steel, composite, timber etc.  Form of superstructure : slab, beam, truss, arch, suspension, cable-stayed etc.  Inter-span relation : simple, continuous, cantilever.  Method of construction : pin-connected, riveted, welded etc.  Span : short, medium, long, right, skew, curved.  Type of service and duration of use : permanent, temporary bridge, military

17. Basic components of bridge The two basic parts are: Substructure - includes the piers, the abutments and the foundations. Superstructure - consists of the deck structure itself, which support the direct loads due to traffic and all the other permanent and variable leads to which the structure is subjected.

18. Piers The piers are vertical structures used to support deck or the bearings provided for load transmission to underground soil through foundation. These structures serve as supports for the bridge spans at intermediate points.  The pier structure has mainly two functions: Load transmission to the Foundation Resistance to the horizontal forces

19. Abutments Abutments are vertical structures used to retain the earth behind the structure. The dead and the live loads from the bridge superstructure is supported by the bridge abutments.

20. Wing walls: Structures constructed as an extension of the abutments to retain the earth present in the approach bank are called wing walls. This portion will otherwise have a natural angle of repose. 

21. Approach: The approach slab provides a transition between roadway pavement and the bridge. The approach slab acts as an intermediate bridge to span the portion of embankment directly behind the abutment/ backwall which was excavated to construct the abutment/ backwall .

22. Culvert: A  culvert  is a structure that allows water to flow under a road, railroad, trail, or similar obstruction from one side to the other. Typically embedded so as to be surrounded by soil, a culvert may be made from a  pipe ,  reinforced concrete  or other material. Types:  Pipe culvert, box culvert and arch culvert are the common types used under roadways and railways.