Road Geometrics:1

1. ROAD GEOMETRICS : 1
A lecture by..
Er. Raghubir Singh
B.E, M.Tech (Structures)
Lecturer (Civil Engg.)
Pt.JR Govt.Polytechnic College, Hoshiarpur
Road Geometrics:1
HIGHWAY ENGINEERING
5TH SEMESTER (3 year Diploma in Civil Engineering)

2. CONTENTS
 Road geometrics: definition
 Road cross sections: Terms used and their importance
• Carriage way
• Road Shoulder
• Formation Width
• Side slopes
• Berms
• Road margins
• Right of Way
• Kerbs
• Camber
• Gradient
Road Geometrics:1

3. ROAD GEOMETRIC
The physical features of a road are known as
road geometrics.
 These physical features have direct connection
with the highway users.
These are provided in order to provide safety,
economy and comfort .
Road Geometrics:1

4. Glossary of terms used in road geometrics
Carriage way
Road Shoulder
Formation Width
Side slopes
Berms
Side Drains
Road margins
Right of Way
Kerbs
Camber
Gradient
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5. Road Sections
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6. Road Sections
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7. Carriage Way
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The portion of the roadway for the movement of vehicular traffic
is called carriageway.

8. Carriage Way
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9. Road Shoulders
• The shoulder is a strip of pavement outside an outer
lane.
• It is provided for emergency use by traffic and to
protect the pavement edges from traffic damage.
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10. Road Shoulders
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11. Formation Width
• The top width of a road embankment or the bottom
width of highway cutting is called formation width.
• It comprises of the carriageway width including traffic
separators plus shoulders on both sides.
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12. Formation Width
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13. Side Slopes
 The slopes given to the sides of the earthwork of a
road in embankment or in cutting for its stability are
called side slopes.
 Embankments - 1:1.5 , Cutting - 1:1
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14. Side Slopes
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15. Berms
 The portion of the land width left in between the toe
of the road embankment and inner edges of side
drains.
 In cutting, it is portion in between the top edge of
road cutting and the nearest edge of the spoil banks.
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16. Road Geometrics:1

17. Side drains
The function of the side drains (or ditches) is to
collect the water from the carriage way and
surrounding areas and dispose it off.
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18. Side drains
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19. Road margins
 The portion of the land width on the either side of the
roadway of a road are known as road margins.
 Road margin = Side slope + Berm + Side drain
 It may include parking lanes, cycle track,footpath or
guard rail.
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20. Right of Way
• The area of land acquired and reserved for
construction and development of a road along its
alignment is called as right of way or permanent
land.
• The width of right of way is called Road land width.
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21. Kerbs
• The boundaries between the pavement and
shoulders or footpaths are known as kerbs.
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22. Types of Kerbs
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23. Camber
The convexity provided to the surface of the carriageway
or the rise given to the centre of carriageway above its
edges on straight portion of the road is called camber.
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24. Objects of providing Camber
• To drain off the rain water from the surface of
the carriageway towards the sides of a road .
• To regulate the vehicles in their proper lanes.
• To improve the architectural appearance of the
roadway.
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25. Types of Camber
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26. Gradient
The rate of rise or fall provided to the formation of the
road along its alignment is called gradient.
 It is expressed as the ratio of rise or fall to the
horizontal distance like 1 in 300 or as percentage of rise
or fall.
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27. Objects of providing gradient
 To connect two stations situated at different levels.
 To make earthwork of road project economical.
 To provide effective drainage of rain water falling over
the road surface.
 To reduce the maintenance cost of road surface.
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28. Gradients as per recommendations of I.R.C
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29. Summary
 Road geometrics: definition
 Road cross sections: Terms used and their importance
• Carriage way
• Road Shoulder
• Formation Width
• Side slopes
• Berms
• Road margins
• Right of Way
• Kerbs
• Camber
• Gradient
Road Geometrics:1