# Fundamentals of Transportation/Horizontal Curves/Additional Problems
## Additional Questions

* Name 4 types of horizontal curves.
* 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.
* How is weather accounted for (e.g. ice) → superelevation (e)
* 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.
* 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.
* When the angle increases, does the tangent length increase or decrease
* Write the constraints on the calculation of horizontal curves
* What are the characteristics of horizontal curves
* Draw a simple horizontal curve and its components.
* Can one add T to the PI station to get the station of the PC? (No)
* How common is a horizontal curve on a vertical curve? → Depends on where you are, very common in mountainous areas. Not especially uncommon.
* 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 )
* In English Units what does station 10+25 mean? It indicates the station is 1025 feet from 0+00.
* On concrete roads there are grooves perpendicular to the direction of traffic to increase stopping road friction. Do these grooves (rumblestrips) reduce side friction?
* 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 $e$ is annual.
* Why are side friction factors for urban and rural roads different? What are different factors in rural vs. urban areas?
* Why is Radius of curvature important when building roads?
* What are some of the highest values of e and $f_{s}$ around the country?
* Why do the standards (maximums/minimums) for e and $f_{s}$ change with location?
* Label all of the forces acting on a vehicle traveling up a hill (and around a corner)
* What is curve resistance? What affects is? Why does it matter?
* What are the main variables used in curvature problems, superelevation?
* Why do engineers bank curves?
* What is centrifugal force?
* Why would an engineer want to increase or decrease the radius of curvature?
* What does superelevation represent
* What shapes do horizontal and vertical curves have. Why is this helpful for the driver
* If you want to decrease $R$, what strategies do you have?
* Is side friction the same as static friction? What does it mean?
* When the max value of $e$ is given, can a smaller number be used in the final answer → yes
* What is superelevation? How is it affected by centrifugal force?
* How does $f_{s}$ affect design speeds