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  1. 1. Curves, island,interchanges and freeway REPORTED BY: JOSEPH R. POLICENA
  2. 2. Table of content Widening of curves Islands  Island is included in the design by the ff purposes Interchange  Function of freeway interchanges  Types of interchange  Four-way interchanges  three-way interchanges  two-way interchanges Freeway entrance and exit Page 2
  3. 3. Widening of curves Page 3
  4. 4. Provision for a wider roadway is necessary onsharp curve for two lanes pavement under the ff. reason 1. To force the drivers to shy away from the pavement edge. 2. To increase the effective transverse vehicle width for non- tracking of front and rear wheel. Page 4
  5. 5. Provision for a wider roadway is necessary onsharp curve for two lanes pavement under the ff. reason 3. To give additional width due to the slanted position of the front wheel to the roadway center line. 4. For a 7.2m wide roadway, an additional width of 30cm is necessary on an open curve highway. Page 5
  6. 6. Islands Is a define area between traffic lanes for controls of vehicle movement and for pedestrian refuge. Within an intersection, median is considered as an island. Page 6
  7. 7. Island is included in the design by the ff puRposes1. Separation of vehicles flow2. Separation of conflicts3. Reduction in excessive pavement areas4. Reduction of traffic and indications of proper use of intersection Page 7
  8. 8. Island is included in the design by the ff puRposes5. Arrangement to favor a prominent turning movement6. Location to traffic control devices Page 8
  9. 9. General types and shapes of an island Page 9
  10. 10. General types and shapes of an island Page 10
  11. 11. General types and shapes of an island Page 11
  12. 12. Interchange a road junction that typically uses grade separation, and one or more ramps, to permit traffic on at least one highway to pass through the junction without directly crossing any other traffic stream. It differs from a standard intersection, at which roads cross at grade. Page 12
  13. 13.  The High Five in Dallas, Texas, USA: an extreme example of interchange design. This is a complicated five-level stack Page 13 interchange due to the proximity of frontage roads.
  14. 14. Function of freeway interchanges To provide separation between two or more traffic arteries. To facilitate easy transfer of vehicles from one entry to the other or between local roadways and the freeway. Page 14
  15. 15. Use of overpass or underpass? UNDERPASS Depends on topography, economy and any other minor factors Underpass better for deceleration/acceleration, cost and advance warning OVERPASS Overpass better aesthetics Page 15
  16. 16. Types of interchange Page 16
  17. 17. Four way interchanges1. Cloverleaf interchange –  typically a two-level, four-way interchange where all left turns are handled by loop ramps (right turns if traveling on the left). Page 17
  18. 18.  A typical cloverleaf interchange in Ohio, United States Page 18
  19. 19. Advantage of cloverleaf they require only one bridge, which makes such junctions inexpensive as long as land is plentiful A major shortcoming of cloverleafs, however, is weaving and the consequent low capacity of this design. Page 19
  20. 20. Objections to the cloverleaf interchange design It requires large area of land At higher design speed, more time is consumed just to transverse the longer loops Vehicles making left turn execute 270° right turn and travel greater distance becoming very unpleasant and hazardous due to sharp curves and steep grades. Page 20
  21. 21. Objections to the cloverleaf interchange design Vehicles leaving the curve loop in one quadrant weave those entering the adjacent loop from the through road way. Page 21
  22. 22. Four way interchanges2. Stack interchange –  whereby left turns are handled by semi- directional flyover/under ramps. Page 22
  23. 23.  A multi-level stack interchange in Shanghai, China Page 23
  24. 24. Disadvantages Expensive creates an eyesore among local residents, leading to considerable (Not In My Back Yard) opposition Page 24
  25. 25. Four way interchanges3. Cloverstack interchange –  Its ramps are longer to allow for higher ramp speeds, and loop ramp radii are made larger as well. The large loop ramps eliminate the need for a fourth, and sometimes a third level in a typical stack interchange, as only two directions of travel use flyover/under ramps. Page 25
  26. 26. 1st level 2nd level 1st level 3rd level2nd level Two way cloverstack Three way cloverstack Page 26
  27. 27. advantages cheaper to build than stack interchanges less of an eyesore for local residents weaving is also eliminated Page 27
  28. 28. disadvantages require a lot of land to construct the loop ramps are not as efficient as flyover/under ramps in terms of traffic flow Page 28
  29. 29. Four way interchanges4. Turbine interchange (whirlpool)  requires fewer levels (usually two or three) while retaining semi- directional ramps throughout, and has its left-turning ramps sweep around the center of the interchange in a spiral pattern in right-hand driving. Page 29
  30. 30.  The Circle Interchange in Chicago, a notable turbine interchange Page 30
  31. 31. 2nd level 2nd level 3rd level1st level 1st level Two way turbine Three way turbine Page 31
  32. 32. Four way interchanges5. Roundabout interchange –  The ramps of the interchanging highways meet at a roundabout or rotary on a separated level above, below, or in the middle of the two highways. Page 32
  33. 33. Page 33
  34. 34. Other/hybrid interchanges1. windmill interchange  is similar to a turbine interchange, but it has much sharper turns, reducing its size and capacity Page 34
  35. 35. Page 35
  36. 36. Other/hybrid interchanges2. diverging windmill  increases capacity by altering the direction of traffic flow of the interchanging highways, making the connecting ramps much more direct. Page 36
  37. 37. Page 37
  38. 38. Other/hybrid interchanges3. Divided volleyball  create a wide median between the carriageways of the two interchanging highways, using this space for connecting ramps. Page 38
  39. 39. Page 39
  40. 40. Other/hybrid interchanges4. Full diamond  large, multi-level interchanges that use flyover/under ramps to handle both right and left ramps. Page 40
  41. 41. Page 41
  42. 42. Hybrid interchange near Rotterdam, Netherlands. Hybrid interchange near Cross-Harbour Tunnel, Hong Kong. Page 42
  43. 43. Three way interchanges Trumpet interchange  have been used where one highway terminates at another highway. These involve at least one loop ramp connecting traffic either entering or leaving the terminating expressway with the far lanes of the continuous highway. Page 43
  44. 44. A trumpet interchange on theOttawa River Parkway Page 44
  45. 45. Three way interchanges Directional T interchange  uses flyover/under ramps in all directions at a three-way interchange. A semi-directional T does the same, but some of the splits and merges are switched to avoid ramps to and from the passing lane. Page 45
  46. 46. Semi-directional-Tinterchange in Lausanne,Switzerland Page 46
  47. 47. Three way interchanges Full Y interchange  typically used when a three-way interchange is required for two or three highways interchanging in semi- parallel/perpendicular directions, but it can also be used in right-angle case as well. Their connecting ramps can spur from either the right or left side of the highway, depending on the direction of travel and the angle. Page 47
  48. 48. Page 48
  49. 49. Two way interchanges Diamond interchange  interchange involving four ramps where they enter and leave the freeway at a small angle and meet the non-freeway at almost right angles. Page 49
  50. 50. Page 50
  51. 51. Diamond interchange in Ohio, UnitedStates Page 51
  52. 52. Two way interchanges Parclo interchange/folded diamond  also known as a partial cloverleaf, is an interchange usually involving four to six ramps, two of which are loop ramps, which connect to the non-highway. Page 52
  53. 53. Page 53
  54. 54. Parclo A-4 interchange inOntario, Canada. Page 54
  55. 55. Two way interchanges Diverging diamond interchange  similar to a traditional diamond interchange, except that it uses directional lanes for the non-highway to cross over each other on either side of the highway, altering the direction of travel on the over/underpass through the use of traffic lights. Page 55
  56. 56.  This allows all turns to and from the highway to be made without crossing the opposite direction of travel, increasing the capacity when compared to a typical diamond interchange. Page 56
  57. 57. One set oftraffic signal Page 57
  58. 58. Page 58
  59. 59. References: Highway engineering by Clarkson H. Oglesby & R. Gary Hicks Elements of roads and highways by Max Fajardo www.highway researchinterchangesInterch ange (road) - Wikipedia, the free encyclopedia.htm Page 59