Midterm 2

Question 1

series of 2 or more circular curves; any 2 successive curves having a common tangent

Answer 1

compound curves

Question 2

3 things that “define”a compound curve?

Answer 2

1. ) Simple Curve
2. ) Curvature in the same direction
3. ) Common Tangent

Question 3

where are compound curves used?

Answer 3

at grade intersections, highway sections in difficult topography, and ramps of interchanges, to avoid obstacles

Question 4

ratio of compound curves for highways

Answer 4

1.5:1

Question 5

two simple curves with equal radii turning in opposite directions with a common tangent

Answer 5

reverse curves

Question 6

What is the purpose of reverse curves?

Answer 6

to change the alignment of the highway, to redirect through lanes at channelized intersections and high speed median crossovers

Question 7

What is one downfall of reverse curves?

Answer 7

Causes sudden change in alignment which makes it hard to stay in lane

Question 8

Why is vertical alignment important

Answer 8

to determine the elevation to ensure proper drainage, and an acceptable level of safety and comfort

Question 9

What is the primary challenge of vertical curves?

Answer 9

Transitioning from one grade to another

Question 10

two types of vertical curves

Answer 10

crest and sag

Question 11

True or false: vertical curves have equal tangents making it symmetrical about the PVI

Answer 11

true

Question 12

What type of shape do vertical curves most mimic, circular or parabolic?

Answer 12

Parabolic

Question 13

how are grades selected?

Answer 13

based on the type of urban or rural, type of street, and design speed

Question 14

location at which the curve is level/where the slope is zero

Answer 14

turning points

Question 15

why are turning points important?

Answer 15

Water can collect

Question 16

number of horizontal feet needed for a 1% change in the slope; also known as vertical curvature

Answer 16

k factor

Question 17

what can the k factor be used for?

Answer 17

Finding high/lowpoints

Question 18

What is the goal of SSD considerations?

Answer 18

to find an appropriate length (L) for the curve that can accommodate the correct SSD

Question 19

Advantages of transition curve advantages

Answer 19

appearance of the highway is enhanced, reduces break in alignment, suitable zone for super elevation runoff

Question 20

curves placed between tangent and circular sections of roadway; beginning with an infinite radius to match the tangent ending with the same radius as the curveS

Answer 20

transition curves

Question 21

Curve where the radius is infinite at the tangent end and radius of circular curve at the other end

Answer 21

Spiral Curve

Question 22

Where can spiral curves be located

Answer 22

approaching a curve, leaving a curve, connect two circular curves of differential radii

Question 23

does the central angle change when reducing to a spiral curve?

Answer 23

no but the curve angle gets reduced by -2delta

Question 24

General types of roadways

Answer 24

divided and undivided

Question 25

types of undivded roadways

Answer 25

1. ) 2-lane undivided 2. ) 3-lane undivided 3. ) multi-lane undivided

Question 26

types of divided roadways

Answer 26

multi-lane divided

Question 27

number of lanes eq

Answer 27

DDHV/SFL

Question 28

what does lane width depend on

Answer 28

classification, volume, design speed

Question 29

how do you widen the pavement for simple curves?

Answer 29

widen the inside edge of traveled way only

Question 30

how to widen pavement for spiral curves

Answer 30

widen inside edge of traveled way; mark centerline midway between edges of pavement

Question 31

what is the cross slope used for?

Answer 31

necessary for proper drainage; prevents ponding on surface, determined on construction technologies, materials and equipment

Question 32

provided along the road edge to serve as an emergency lane for vehicles

Answer 32

shoudlers

Question 33

normal width of shoulder

Answer 33

10'

Question 34

portion of highway separating opposing directions of travel; dimenson between the edges of traveled way; includes shoulder width

Answer 34

median

Question 35

three types of medians

Answer 35

raised, depressed, flush

Question 36

widths of medians

Answer 36

4-84 feet

Question 37

where are median openings and what do they do?

Answer 37

3 mile intervals; provide u turn capabilities

Question 38

how much feet permits recovery of vehicles

Answer 38

30 feet

Question 39

What is a clear zone based on

Answer 39

volumes, speed, roadside slopes

Question 40

How does a curve clear zone vary?

Answer 40

you must provide 50% more Clear zone

Question 41

what do you place on shoulder if clearzone obstructions are not removable?

Answer 41

guardrails

Question 42

the boundaries between the pavement and shoulders/footpath

Answer 42

curbs

Question 43

designates traveled way cross section used on curves

Answer 43

normal crown

Question 44

between normal crown and full superelevated

Answer 44

reverse adverse crown

Question 45

super elevation transition =

Answer 45

tangent runout to superelevation run off

Question 46

gradual change from crown normal to a point where the adverse cross slope is removed

Answer 46

tangent runout

Question 47

gradual change from end of tangent runout to a cross section that is fully superelevated

Answer 47

superelevation runoff