Lecture 4,Thurs Feb 8, 2018/// lecture 4 on moodle all u were absent here

Question 1

Horizontal alignment is in what view

Answer 1

Horizontal alignment is in plan view of x and z coordinates as if you are seeing it from plane

Question 2

Vertical alignment is in what view

Answer 2

Vertical alignment is in profile view of x and y coordinates as if you are looking at a mountain

Question 3

Distance is measured in terms of stations

Answer 3

station 1+258.3 is 1 km + 258.3 m which is 1258.3m

Question 4

Vertical curve components

Answer 4

Check the powerpoint of lecture 4 on moodle page 11

Question 5

Types of vertical curves

Answer 5

We always have a convention from left to right
Crest vertical curve we start with a given grade G1 then the grade decrease to get G2
Sag vertical curve we start with a given Grade G1 then the grade increases to get G2

Question 6

A parabolic function is used to define roadway
elevations at every station along the
vertical curve then we will have equal tangent curves

Answer 6

that is why at PVI we will have it as L/2

Question 7

Formula of the vertical curve to find the elevation at each point of the curve

Answer 7

It is on lecture 4 page 17

Question 8

Solve example 1, lecture pg 18

Answer 8

true

Question 9

You cant find the elevation of PVI from the equation

Answer 9

true

Question 10

when u use the equation remember to insert G1, G2 and G1 (G1 is placed 2 times in the formula), Remember to place them all as numbers not percentages

Answer 10

true

Question 11

When u find the x and the y of the lowest or highest point in the curve remember to check that the x is found between PVC and PVT because Some vertical curves will have their lowest
point at PVT since 1st derivative may not
vanish for x between that of PVC and PVT

Answer 11

true

Question 12

What are offsets

Answer 12

Offsets are ((vertical)) distance from the initial tangent off the curve

Question 13

What is Y in offsets

Answer 13

Y = offset at a distance x from PVC
formula is in slides
A=absolute value of difference in grades(expressed in %)
y3ne mmnoo3 bddak trga3 t2som 3la myye

Question 14

What is Ym in offsets

Answer 14

Ym is the mid-curve offset
formula is in slides
A=absolute value of difference in grades(expressed in %)
y3ne mmnoo3 bddak trga3 t2som 3la myye

Question 15

what is Yf in offsets

Answer 15

Yf is offset at end of vertical curve (at PVT)
formula is in slides
A=absolute value of difference in grades(expressed in %)
y3ne mmnoo3 bddak trga3 t2som 3la myye

Question 16

What are the K values

Answer 16

The K value is the measure of the curveture, meaning the horizental distance in meters required to affect 1 percent change in slope of vertical curve. K value is a constant.
The formula is found in the slides.

Question 17

What do we use the K values for

Answer 17

In case the vertical curve is a crest or a sage (meaning G1 and G2 have opposite signs),We use the K values to find the high/lowest point in the vertical curve *high if crest, lowest if sag)
Formula: abscissa of the lowest/ highest point : K * abs(G1).

Question 18

Read from slide 37 to the end, In the course we will not use grades in ssd.

Answer 18

true