2. for the Design Values Above in #1, the Rectangular Spiral Component Xs Is Most Nearly

1. On HW5, designers now change the length of spiral Ls to 600 ft, while setting the radii Rc for Curve 1 and 2 to 1200 ft. The design velocity Vdes that will give a "jerk" of 2.0 ft/sec^3 is most nearly:

@ Vd = (Rc*Ls*C)^1/3 = 76.993 mph

a. 72 mph

*b. 77

c. 82

d. 87

2. For the design values above in #1, the rectangular spiral component Xs is most nearly:

@ must be slightly less than 600, DELTAs=Ls/(2*Rc) radians, and by the infinite series: Xs = Ls*(1 – DELTAs^2/(5*2!) + DELTAs^4/(9*4!)-+...) = 596.26

*a. 596

b. 598

c. 600

d. 602

3. On our HW5, which will compute the correct value of station for the T.S. for the second curve (Sta TS2)?

@ Sta TS2 = Sta ST1 + (TTL2-Ts1-Ts2), must compute the straight line distance on TTL2.

a. Sta PI1 + Ts1 + Ts2

b. Sta PI2 – Ts1

c. Sta 40+00 – TTL2 + Ts1 + Ts2

*d. Sta ST1 + (TTL2-Ts1-Ts2)

4. On railroads and other fixed guideway route systems, spirals are absolutely needed because of:

@ the "infinite jerk" force build up at the PC without spirals.

a. national design standards

*b. rapid lateral force build-up

c. a natural spiral in the tracks

d. rail spacing and geometry

5. If the spiral design values of problem #1 were used to insert spirals into Curve 2 of SR25, the length of the remaining circular curve is most nearly:

@ DELTAc=DELTA(32 deg) – 2*DELTAs = 0.058. Lc=Rc*DELTAc =

70.2 feet

*a. 70 ft

b. 100 ft

c. 130 ft

d. 160 ft

6. In any spiral, the Short Tangent on the "incoming" spiral is measured between which two points? 1 PI 2 TS 3 CS 4 ST 5 SPI 6 SC

@ between the SPI and SC, 5, 6.

a. 2, 5

b. 3, 6

*c. 5, 6

d. 3, 5

7. If someone drives the full superelevation of our HW6 Curve 1 at 65 mph, the side friction factor experienced by the driver is most nearly?

@ edesign = .091 R=1500, substitute in the superelevation equation:

.091 + f = (65)^2/(15*1500) = 0.096

a. 0.05

*b. 0.10

c. 0.15

d. 0.20

8. If someone now drives the full super on Curve 1 at 70 mph on wet pavement, which is correct?

@ f computes to 0.13. This is above AASHTO's safe limit of 0.10 at 70 mph, but below fmax = .30 for sliding on wet pavement.

a. the driver slides off the curve before reaching 70 mph.

b. the driver is still on the pavement and is safe according to AASHTO

*c. the driver is not safe by AASHTO standards, but is still on the pavement

d. the driver is at the point of impending sliding off the road.

9. The minimum curve radius (Rmin) allowed by AASHTO for Curve 1 of HW6 is most nearly?

@ .f safe at 60 mph is 0.12 by interpolation of the fsafe line. e design is pushed to emax = .10, solve the superelevation equation for R = 1090 (or look at the edesign chart)

*a. 1000 ft

b. 1500

c. 2000

d. 1500

10. If the edesign on our HW6 were set to 10% with a Rate of Rise of 300:1, the required length of transition (Ltrans) is most nearly:

@ Total rise in outside edge = (.02+.10)*12=1.44 ft. Ltrans = 300*1.44 = 432 ft.

a. 280 ft

b. 330

c. 380

*d. 430

11. For the above design choices, the horizontal distance separating cross sections A-A and B-B is most nearly?

@ With a ROR of 300:1, the outside edge rises 0.24 ft, solve for x: x/.24=300/1, x=72 ft.

a. 65 ft

*b. 70

c. 75

d. 80

12. For the above design choices, the difference in elevation between the inside and outside pavement edges in full superelevation is most nearly:

@ with a full super of 0.10, the outside edge is .10 x 12 = 1.2 above and the inside edge is 1.2 below baseline. Vertical difference = 2.4 ft.

a. 1.2 ft

b. 1.8 ft

*c. 2.4 ft

d. 3.0 ft

13. Why is 80% of a transition placed before the PC of a curve without spirals in Florida?

@ to match the natural spiral of a driver who starts turning the wheel before the PC

a. to meet national AASHTO design codes

b. for water drainage off pavement in storms

*c. match driver's natural spiral

d. to keep the vehicle in the center of the traffic lane.

14. Which best describes a Mass Diagram's shape(going left to right) if a project starts in cut, increases to a maximum cut depth, reduces to zero cut/fill, moves into fill of constant depth to end project. 1 MD starts above axis 2 MD is level 3 MD point of inflection 4 MD starts at zero cumulative 5 MD goes down 6 MD minimum point 7 MD maximum point 8 MD starts below the axis 9 MD goes up

@ 4 MD starts at zero, 9 MD increases in cut, 3 MD point of inflection at max cut, 7 maximum point at transition cut to fill, 2.

a. 8, 9, 3, 6, 5

b. 1, 9, 2, 3, 5

*c. 4, 9, 3, 7, 2

d. 1, 5, 3, 6, 9

15. Which describes the SR25 HW7 earthwork volumes after applying a shrinkage factor of 50%?

@ About 1000CY of cut material over expanded fills.

*a. about 1000 CY of extra cut material

b. expanded fills about double cut volume

c. cut volume is about double expanded fills.

d. the cut and fill volumes are about equal.

16. If the shrinkage factor were reduced to 30%, how would the MD diagram change?

@ with lower shrinkage, the expanded fills would be less, and cuts would exceed fills by larger margins moving the MD sloping higher (more cut than fill).

a. the mass diagram would move "down" to lower cumulative values

b. the mass diagram would do a parallel shift upwards

*c. the MD would move "up" to higher cumulative amounts.

d. the MD would do a parallel shift downward.

17. If the FHD were increased on a project, which quantities would be certain to go UP in cost? 1 $a Roadway Excavation 2 $b Borrow Excavation 3 $c Overhaul Compensation 4 $d Waste Excavation

@ Rdwy Excavation would go up, all others would likely decrease.

a. 2, 3, 4

b. 1, 4

*c. 1 only

d. 2 only

18. At the LEH, which line item costs are equal? 1 $a Rdwy Exc 2 $b Borrow Exc 3 $d Waste Exc 4 $c Overhaul Compensation

@ At the Limit of Economic Haul, option #1 of paying $a Rdwy Exc and $c Overhaul Compensation equals option #2 of $b Borrow and $d Waste

a. 1+2 = 3+4

*b. 1+4 = 2+3

c. 1+3 = 2+4

d. 1 = 2+3+4

19. What does the contractor agree to do for material inside the Free Haul Distance?

@ contractor will do it for $a cost. No Overhaul Compensation needed.

*a. Cut and Fill at $a cost only.

b. Complete the fill and waste the remaining cut.

c. Perform the cut and fill at no cost

d. Waste and Borrow

20. Why is borrow excavation $b usually more expensive than Roadway Excavation $a material?

@contractor must buy the borrow pit land.

a. haul distance

b. material testing

*c. land cost

d. excavation equipment