MOD 2-HIGHWAY GEOMETRICS.pptxhchxhcufufucuf

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1. MODULE 2 HIGHWAY GEOMETRICS TRANSPORTATION ENGINEERING

2. Geometric design of highway Geometric design of highway is concerned with the physical dimensions and layout of visible features of the highway Visible features are alignment, sight distances and intersections Geometric design of highway is to be done to provide optimum efficiency in traffic operations with maximum safety at reasonable cost TRANSPORTATION ENGINEERING

3. Geometric design of highway (contd) Geometric design of highway is related with following elements: Cross-sectional elements Sight distance considerations Horizontal alignment details Vertical alignment details Intersection elements TRANSPORTATION ENGINEERING

4. Objectives of geometric design Gives maximum efficiency in traffic operation Gives maximum safety to users Saves time of travel Increases speed of vehicles Increases no: of vehicles on road Reduces cost of construction TRANSPORTATION ENGINEERING

5. Topography or Terrain: The topography or terrain conditions influence the design speed, than in turn governs the designing of highway elements. The classification of topography is based on the cross slope of the country as Plain, Rolling, Mountainous and Steep. TRANSPORTATION ENGINEERING FACTORS AFFECTING GEOMETRIC DESIGN

6. TRANSPORTATION ENGINEERING

7. 2. Design speed The design Speed of the vehicle depends upon the type of Topography or Terrain Classification and the road over which it moves. The design speed of the vehicle helps in deciding the: cross-section element, width, clearance, side distance, radius of the curve, super elevation, transition, gradient etc TRANSPORTATION ENGINEERING

8. 3. Traffic Factor Traffic factors include vehicle characteristics and human characteristics. To design highway elements standard size of the vehicle is considered (car) in case of mixed traffic operation. Human characteristics include the physical, mental, and psychological characteristics of drivers and Pedestrians. TRANSPORTATION ENGINEERING

9. 4. Highway Capacity Defined as the maximum no: of vehicles that can pass over a given section of roadway during a given time period under prevailing traffic conditions It is expressed in terms of Passenger Car Units (PCU) TRANSPORTATION ENGINEERING

10. 5. Environmental factors Environmental factors such as aesthetics, air pollution, noise pollution, and landscaping also govern the design of Highway elements. TRANSPORTATION ENGINEERING

11. CROSS-SECTION OF HIGHWAY TRANSPORTATION ENGINEERING

12. Cross-section of Highway (contd..) TRANSPORTATION ENGINEERING

13. Important terms TRANSPORTATION ENGINEERING 1. RIGHT OF WAY

14. 2. ROAD MARGIN TRANSPORTATION ENGINEERING 3. FORMATION WIDTH OR ROADWAY WIDTH

15. The portion of roadway constructed for the movement of vehicle traffic TRANSPORTATION ENGINEERING 4. CARRIAGE WAY OR PAVEMENT

16. TRANSPORTATION ENGINEERING 5. SHOULDER

17. The slopes given to the sides of earthwork of a road in embankment or in cutting for stability. TRANSPORTATION ENGINEERING 6. SIDE SLOPES 7. BERMS

18. TRANSPORTATION ENGINEERING 8. SPOIL BANK 9. KERBS

19. TRANSPORTATION ENGINEERING 10. FORMATION LEVEL 11. CAMBER OR CROSS-SLOPE

20. TRANSPORTATION ENGINEERING 12. GRADIENT OF ROAD Gradient of Road is defined as the rate of rising or falls along the length of the road with respect to the horizontal alignment

21. TRANSPORTATION ENGINEERING 13. DRAINAGE The pavement must be completely impermeable so that seepage of water into the pavement layers does not take place and the geometrical pavement surface should be such that it helps and remains out of the water from the surface quickly.

22. SIGHT DISTANCE TRANSPORTATION ENGINEERING

23. TYPES OF SIGHT DISTANCE TRANSPORTATION ENGINEERING STOPPING SIGHT DISTANCE (SSD) OVERTAKING SIGHT DISTANCE (OSD) INTERMEDIATE SIGHT DISTANCE (ISD)

24. 1. STOPPING SIGHT DISTANCE (SSD) TRANSPORTATION ENGINEERING SSD = v.t + v 2 / 2gf Where, v – speed in m/s 2 t – reaction time taken f - coefficient of friction g- acceleration due to gravity

25. 2. OVERTAKING SIGHT DISTANCE (OSD) TRANSPORTATION ENGINEERING

26. 3. INTERMEDIATE SIGHT DISTANCE (ISD) TRANSPORTATION ENGINEERING It is a sight distance that is provided only when it is difficult to provide overtaking sight distance (in horizontal curves). As per IRC, intermediate sight distance (ISD) should be equal to twice the stopping sight distance (SSD). ISD= 2 X SSD

27. SUPER ELEVATION TRANSPORTATION ENGINEERING

28. Objectives of Super elevation TRANSPORTATION ENGINEERING