# Fundamentals of Transportation/Horizontal Curves/Additional Problems

1. Name 4 types of horizontal curves.
2. When are the non-simple types most used? Why are reverse curves so bad? → Special applications, including mountains, restricted right-of-way, or anywhere that a simple curve cannot be feasibly used.
3. How is weather accounted for (e.g. ice) → superelevation (e)
4. Explain m? When would m and M be equal? Are the equations for “m” used in determining the placement of buildings or billboards on existing roadways? → Used as a justification to keep stuff off the side of the road. May be used in roadway construction to avoid unmovable objects, or when placing objects to avoid unmovable road.
5. When should you design speed for curves rather than the curve for speed? → If it is new construction, design the radius to serve the desired speed. If you are setting speed limits, set the speed based on the existing curve.
6. When the angle increases, does the tangent length increase or decrease
7. Write the constraints on the calculation of horizontal curves
8. What are the characteristics of horizontal curves
9. Draw a simple horizontal curve and its components.
10. Can one add T to the PI station to get the station of the PC? (No)
11. How common is a horizontal curve on a vertical curve? → Depends on where you are, very common in mountainous areas. Not especially uncommon.
12. Are most horizontal curves designed using circles? → (In US, almost uniformly yes. It is also easier for driver, who just needs to set the steering wheel, constant readjustment is not required )
13. In English Units what does station 10+25 mean? It indicates the station is 1025 feet from 0+00.
14. On concrete roads there are grooves perpendicular to the direction of traffic to increase stopping road friction. Do these grooves (rumblestrips) reduce side friction?
15. What is maximum superelevation when a road is really icy? → superelevation cannot change seasonally (it would be too expensive to jack up the road). So Max ${\displaystyle e}$ is annual.
16. Why are side friction factors for urban and rural roads different? What are different factors in rural vs. urban areas?
18. What are some of the highest values of e and ${\displaystyle f_{s}}$ around the country?
19. Why do the standards (maximums/minimums) for e and ${\displaystyle f_{s}}$ change with location?
20. Label all of the forces acting on a vehicle traveling up a hill (and around a corner)
21. What is curve resistance? What affects is? Why does it matter?
22. What are the main variables used in curvature problems, superelevation?
23. Why do engineers bank curves?
24. What is centrifugal force?
25. Why would an engineer want to increase or decrease the radius of curvature?
26. What does superelevation represent
27. What shapes do horizontal and vertical curves have. Why is this helpful for the driver
28. If you want to decrease ${\displaystyle R}$, what strategies do you have?
29. Is side friction the same as static friction? What does it mean?
30. When the max value of ${\displaystyle e}$ is given, can a smaller number be used in the final answer → yes
31. What is superelevation? How is it affected by centrifugal force?
32. How does ${\displaystyle f_{s}}$ affect design speeds