Question 1

What is the radius of a 10.6° roadway curve (in feet)?

Accepted Answer

The radius of a 10.6° roadway curve is 540.53 ft. Solution: Use the degree of curve equation R = 5729.58 ft / D_a Given, D_w = 10.6° R = 5729.58 / 10.6 = 540.53 ft

Question 2

What is the degree of curve of a roadway curve with a radius of 500 feet (in degrees)?

Accepted Answer

The degree of curve of a roadway curve with a radius of 500 feet is 11.4°. Solution: Use the degree of curve equation D_a = 5729.58 ft / R Given, R = 500 feet D_a = 5729.58 / 500 = 11.4°

Question 3

What is the length of the arc for the given curve?
Radius 245.00
Tangent in N 20°30' E
Tangent out N 30°30' E

Accepted Answer

The length of the arc for the given curve is 42.76 feet.
Solution: Use the Horizontal Circular Curve formula
L = R x r (expressed in radians)
Where L = length of arc
R = radius = 245.00
r = central angle
Step 1: Convert angle from degrees into radians
Angle in radians = (angle in degrees) x ?/180
= (30.30 - 20.30) ?/180 = 0.1745 radians
Step 2: Determine length of arc
L = R x r
= 245.00 (0.1745) = 42.76 ft

Question 4

Why is a correction factor applied to roadway earthwork volume calculations for alignments that include a horizontal curve?

Accepted Answer

A correction factor is applied to roadway earthwork volume calculations for alignments that include a horizontal curve to account for the eccentricity of the curved area. The correction factor is applied to volume calculations to compensate for soil shrinkage. The "corrected" volume represents the amount of material in a "natural state" that is required to fill compacted roadway embankments. Additionally, a swell compensation factor may be required if rock or large stones used to construct an embankment.

Question 5

What is the minimum spiral curve length transition for a new roadway with a radius of 1000 feet and a design speed of 45 miles per hour (mph), assuming a 2 ft/sec3 lateral acceleration increase rate?

Accepted Answer

The minimum spiral curve length transition for a new roadway with a radius of 1000 feet and a design speed of 45 mph is 143.5 feet. Solution: Use American Association of State Highway Transportation Officials (AASHTO)Equation for minimum length of spiral transition curve LS1U1B1sS1U1B0 = 3.15 x (design speed)S1U1P13

Question 6

What is the approximate optimal length for a transitional spiral curve when using a 2,400 feet (ft) circular curve and a design speed of 70 miles per hour (mph)?

Accepted Answer

The approximate optimal length for a transitional spiral curve when using a 2,400 ft circular curve and a design speed of 70 mph is 225 ft. Solution: Use the transitional spiral curve formula L = 1.6 (design speed)³ / radius of the circular curve Given, Design speed = 70 mph Radius of circular curve = 2,400 ft L = 1.6 (70 mph)³ / 2400 ft = 228.66 ft (use 225 ft)

Question 7

Which of the following is not a type of horizontal roadway curve?

Accepted Answer

"Superelevation" is not a type of horizontal roadway curve. Superelevation is described as banking of a roadway curve to counterbalance the centrifugal force of a vehicle moving through the horizontal curve. Because of the additional side friction that is developed between a vehicle's tires and the road surface, superelevation allows a vehicle to negotiate curves more safely at higher speeds than if the roadway was flat.

Question 8

Which of the following equations are used to compute latitudes and departures of traverses?
1. Departure = latitude/ tan bearing
2. Latitude = cos bearing x length of course
3. Departure = sin bearing x length of course

Accepted Answer

The following equations are used to compute latitudes and departures of traverses:
• Latitude = cos bearing x length of course
• Departure = sin bearing x length of course
The correct formula for tan bearing is tan bearing = Departure/Latitude

Question 9

Which of the following reasons provides an explanation of why reverse circular curves are seldom used in roadway design?

Accepted Answer

The reason why reverse circular curves are seldom used in roadway design is that the instantaneous change in direction could result in an unsafe driving conditions and traveler discomfort. Although a very popular feature of roller coasters, the instantaneous curvature change of reverse circular curves does not allow sufficient space for a superelevation transition for cross-slopes.

Question 10

In which of the following situations might a compound circular curve be used in roadway design?

Accepted Answer

A compound circular curve may be used in the design of a low-speed roadway in hilly terrain. Due to the high costs associated with constructing compound circular curved roadways, they are normally used in areas were simple curves are not cost effective. The recommended speed limits for compound circular curves are lower than those of simple and spiral curves.

Question 11

What is the total length of a project that begins at Sta 70+00.00 and ends at Sta 226+45.23?

Accepted Answer

the total length of a project that begins at Sta 70+00.00 and ends at Sta 226+45.23 is 15,645.23 feet.
Solution:
End of the project=226+45.23=22,645.23 ft
Beginning of the project=70+00.00=7,000.00 ft
Total length of project = 15,645.23 ft

Question 12

The elevation of Sta 10+00 on a 2.5% grade line is 204.00 feet (ft) and the elevation of Sta 20+00 on a 3% line is 200.00 ft. What is the station at which the two grade lines intersect?

Accepted Answer

The two grade lines intersect at Sta 16+00. Solution: Use Asymmetrical Vertical Curve properties to solve for Point of Intersection (PI) Given G₁ = 2.5 G₂ = 3 Step 1: Calculate elevation difference between the points 204.00 ft - 200.00 ft = 4.0 ft Step 2: Use grade lines to show the elevation distance and solve for location of PI G₁ x- G₂ (separation - x) = -elevation distance 2.5 x - (3) (10 - x) = -4.0 ft à 2.5 x - 30 + 4 x = -4 à 6.5 x = 26 x = 4 Sta point of intersection = 10+00 + 4+00= 16+00

Question 13

What is the elevation of the point of vertical tangency for an equal-tangent sag vertical curve with the following given information? G₁ = -2%, G₂ = +4%, L= 300 ft, PVC Sta = 100+00, PVC Elev = 100.00 ft

Accepted Answer

the elevation of the point of vertical tangency for the given equal-tangent sag vertical curve is 103 ft. Solution: Use the general parabolic formula for a vertical curve y = ax² + bx + c Where a = (G₂ - G₁ )/2L Given, G₁ = -0.02 G₂ = +0.04 L = 300 ft a = (0.04 - (-0.02))/2(300) = 0.0001 x = curve length = L = 300 ft b = G₁ = -0.02 c = PVC elevation = 100 ft y = 0.0001 (300) ² + (-0.02) (300) + 100 = 9 - 6 + 100 = 103 ft

Question 14

The approximate location of the low point of a 400 ft sag vertical curve is at which of the following stations? Assume g₁ = -3.2%, g₂ = 1.8%, PVI is located at Sta 100+00.

Accepted Answer

The station of the low point is approximately 100+56. Solution: Use the sag vertical curve formula X = -g₁ / r = -g₁ L / (g₂ - g₁ ) Where L = 400.00 ft = 4 Sta g₁ = -3.2 g₂ = 1.8 X = - (-3.2)(4) / (1.8)-(-3.2) = 2.56 Sta Low point location is 256 feet from beginning of the vertical curve = [(100+00.00)-(2+00.00)] + (2+56.00) = 100+56.00

Question 15

Which of the following is not one of the four American Association of State Highway and Transportation Officials (AASHTO) requirements for vertical curves?

Accepted Answer

The answer "appropriate for terrain" is not one of the four AASHTO requirements for vertical curves. The four requirements that AASHTO lists for vertical curves are as follows:
• Safe - ample sight distances are provided
• Comfortable to navigate - gravitational and vertical centripetal forces are managed
• Pleasing in appearance - long vertical curves rather than short vertical curves
• Adequate for drainage - 0.5% minimum grades in areas receiving snow and 0.3% in other areas

Question 16

Which of the following factors is used to determine locations of the high and low points of vertical curves on roadways?

Accepted Answer

All of the factors listed are used to determine the locations of the high and low points of vertical roadway curves. Catch basins and stormwater inlet structures are installed at the lowest point of a roadway - the location of these structures is often dependent on the elevation of downstream drainage structures. Adequate clearances must also be provided for overhead structures and underground infrastructure.

Question 17

Which of the following is not a type of vertical roadway curve?

Accepted Answer

"Peak" is not a type of vertical roadway curve. Vertical curves, which are used to prevent abrupt vertical changes, can be classified two different ways. The first way is based on the location of the vertex of the curve with respect to the beginning and ending of the curve (symmetrical or asymmetrical). The second classification is based on the grades leading into and away from the vertical curve (sag or crest). The equation used to solve unknown dimensions and elevations of vertical curves is the parabolic formula.

Question 18

When designing the alignment of a roadway, which of the following factors is a general consideration in obtaining the proper mix of horizontal and vertical curves in the final design?

Accepted Answer

All of the listed factors are considered in obtaining the proper mix of horizontal and vertical curves in the final alignment design of a roadway. Because of the magnitude of effort put into constructing a roadway, alignments must take important factors such as these under consideration during the design phase. Other factors that play a role in the final alignment include existing and future land development, subsurface conditions, and political interests.

Question 19

Which of the following grade changes is generally considered acceptable when designing a sag or crest vertical point of intersection without a vertical curve?

Accepted Answer

A 1% grade change is generally considered acceptable when designing sag or crest vertical point of intersection without a vertical curve when design speeds are < 45 miles per hour. For design speeds > 45 miles per hour, a grade change of 0.5% or less is generally acceptable. When grade changes are constructed without a specified vertical curve, the actual point of intersection is typically adjusted to be smooth in the field.

Question 20

A Stormwater Management Plan typically required when constructing a roadway in which of the following conditions?

Accepted Answer

A Stormwater Management Plan is typically required when the proposed roadway may cause a significant increase in flow or volume of water to existing drainage facilities or waterways. Stormwater Management Plans may also be required when the proposed roadway is located in an area known to experience drainage or flooding problems.

Quiz 19: Transportation

What is the radius of a 10.6° roadway curve (in feet) ?

What is the degree of curve of a roadway curve with a radius of 500 feet (in degrees) ?

What is the length of the arc for the given curve? Radius 245.00 Tangent in N 20°30' E Tangent out N 30°30' E

Why is a correction factor applied to roadway earthwork volume calculations for alignments that include a horizontal curve?

What is the minimum spiral curve length transition for a new roadway with a radius of 1000 feet and a design speed of 45 miles per hour (mph) , assuming a 2 ft/sec3 lateral acceleration increase rate?

What is the approximate optimal length for a transitional spiral curve when using a 2,400 feet (ft) circular curve and a design speed of 70 miles per hour (mph) ?

Which of the following is not a type of horizontal roadway curve?

Which of the following equations are used to compute latitudes and departures of traverses? 1. Departure = latitude/ tan bearing 2. Latitude = cos bearing x length of course 3. Departure = sin bearing x length of course

Which of the following reasons provides an explanation of why reverse circular curves are seldom used in roadway design?

In which of the following situations might a compound circular curve be used in roadway design?

What is the total length of a project that begins at Sta 70+00.00 and ends at Sta 226+45.23?

The elevation of Sta 10+00 on a 2.5% grade line is 204.00 feet (ft) and the elevation of Sta 20+00 on a 3% line is 200.00 ft. What is the station at which the two grade lines intersect?

What is the elevation of the point of vertical tangency for an equal-tangent sag vertical curve with the following given information? G₁ = -2%, G₂ = +4%, L= 300 ft, PVC Sta = 100+00, PVC Elev = 100.00 ft

The approximate location of the low point of a 400 ft sag vertical curve is at which of the following stations? Assume g₁ = -3.2%, g₂ = 1.8%, PVI is located at Sta 100+00.

Which of the following is not one of the four American Association of State Highway and Transportation Officials (AASHTO) requirements for vertical curves?

Which of the following factors is used to determine locations of the high and low points of vertical curves on roadways?

Which of the following is not a type of vertical roadway curve?

When designing the alignment of a roadway, which of the following factors is a general consideration in obtaining the proper mix of horizontal and vertical curves in the final design?

Which of the following grade changes is generally considered acceptable when designing a sag or crest vertical point of intersection without a vertical curve?

A Stormwater Management Plan typically required when constructing a roadway in which of the following conditions?

Quiz 19: Transportation

What is the radius of a 10.6° roadway curve (in feet) ?

What is the degree of curve of a roadway curve with a radius of 500 feet (in degrees) ?

What is the length of the arc for the given curve? Radius 245.00 Tangent in N 20°30' E Tangent out N 30°30' E

Why is a correction factor applied to roadway earthwork volume calculations for alignments that include a horizontal curve?

What is the minimum spiral curve length transition for a new roadway with a radius of 1000 feet and a design speed of 45 miles per hour (mph) , assuming a 2 ft/sec3 lateral acceleration increase rate?

What is the approximate optimal length for a transitional spiral curve when using a 2,400 feet (ft) circular curve and a design speed of 70 miles per hour (mph) ?

Which of the following is not a type of horizontal roadway curve?

Which of the following equations are used to compute latitudes and departures of traverses? 1. Departure = latitude/ tan bearing 2. Latitude = cos bearing x length of course 3. Departure = sin bearing x length of course

Which of the following reasons provides an explanation of why reverse circular curves are seldom used in roadway design?

In which of the following situations might a compound circular curve be used in roadway design?

What is the total length of a project that begins at Sta 70+00.00 and ends at Sta 226+45.23?

The elevation of Sta 10+00 on a 2.5% grade line is 204.00 feet (ft) and the elevation of Sta 20+00 on a 3% line is 200.00 ft. What is the station at which the two grade lines intersect?

What is the elevation of the point of vertical tangency for an equal-tangent sag vertical curve with the following given information? G1 = -2%, G2 = +4%, L= 300 ft, PVC Sta = 100+00, PVC Elev = 100.00 ft

The approximate location of the low point of a 400 ft sag vertical curve is at which of the following stations? Assume g1 = -3.2%, g2 = 1.8%, PVI is located at Sta 100+00.

Which of the following is not one of the four American Association of State Highway and Transportation Officials (AASHTO) requirements for vertical curves?

Which of the following factors is used to determine locations of the high and low points of vertical curves on roadways?

Which of the following is not a type of vertical roadway curve?

When designing the alignment of a roadway, which of the following factors is a general consideration in obtaining the proper mix of horizontal and vertical curves in the final design?

Which of the following grade changes is generally considered acceptable when designing a sag or crest vertical point of intersection without a vertical curve?

A Stormwater Management Plan typically required when constructing a roadway in which of the following conditions?

What is the elevation of the point of vertical tangency for an equal-tangent sag vertical curve with the following given information? G₁ = -2%, G₂ = +4%, L= 300 ft, PVC Sta = 100+00, PVC Elev = 100.00 ft

The approximate location of the low point of a 400 ft sag vertical curve is at which of the following stations? Assume g₁ = -3.2%, g₂ = 1.8%, PVI is located at Sta 100+00.