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

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/s 2 while traveling from decision point to intersection Minor road 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

9. V major = 45 mph Both approach grades= 0% V minor = 25 mph L w = 12 ft L a =19 ft (PC)

10. Approach Sight Triangles

11. a= 130 ft a=142 ft t a = 4.0 s t g = 6.5 s b=b= 1.47V major t g = 1.47x45x6.5= 430 ft

12. Approach Sight Triangles

13. Departure Sight Triangles Departure sight triangles automatically considered t g 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)