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Intersection Sight Distance Case C1 Ryan Miller CE 480 10/19/10

Intersection Sight Distance Case C1 Ryan Miller CE 480 10/19/10. Objective. Introduction Approach sight triangles Departure sight triangles Special situations. Introduction. Intersections with yield control on minor road Considers crossing maneuver from minor road

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Intersection Sight Distance Case C1 Ryan Miller CE 480 10/19/10

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  1. Intersection Sight DistanceCase C1Ryan MillerCE 48010/19/10

  2. Objective • Introduction • Approach sight triangles • Departure sight triangles • Special situations

  3. Introduction • Intersections with yield control on minor road • Considers crossing maneuver from minor road • Must consider both approach and departure sight triangles • Sight distances needed by drivers exceed those for stop-controlled approaches

  4. Introduction • Minor road vehicle can cross major road without stopping if no potentially conflicting vehicles on major road • Minor road vehicle assumed to decelerate at rate of 1.5 m/s2while traveling from decision point to intersection • Minorroad vehicle assumed to cross and clear intersection at 60% of design speed

  5. Approach Sight Triangles • Distance along minor street to major street (a) • Distance along major street to vehicle with right-of-way (b) • Must check both left and right directions • Use Exhibit 9-60 to find (a) • Use equations 9-2 to find (b)

  6. Approach Sight Triangles

  7. Approach Sight Triangles

  8. Approach Sight Triangles

  9. Approach Sight Triangles Vmajor= 45 mph Both approach grades= 0% Vminor= 25 mph Lw= 12 ft La=19 ft (PC)

  10. Approach Sight Triangles

  11. Approach Sight Triangles a= 130 fta=142 ft ta= 4.0 s tg= 6.5 s b=b= 1.47Vmajortg= 1.47x45x6.5= 430 ft

  12. Approach Sight Triangles

  13. Departure Sight Triangles • Departure sight triangles automatically considered • tg must meet minimum value from exhibit 9-57 (used for B3 intersection)

  14. Special Cases • Major road is divided highway with narrow median • Consider additional crossing width • Major road is divided highway with wide median • Crossing maneuver need only consider crossing near lanes • Crossing far lanes must be accomplished from stopped position (departure triangle)

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