FE Exam Formulas Ch. 13 Flashcards
Purpose and Variables of…
Stopping Sight Distance
V=initial speed of vehicle
tp=driver PRT (typically 2.5s)
a=vehicle rate of deceleration (typically 11.2 ft/s2)
G=roadway grade
1.47=conversion factor from mph to ft/s
f=friction factor=a/32.2
Purpose and Variables of…
Degree of Curvature
R=radius
Purpose of…
Arc and Chord Radius
Purpose of…
Total Intersection Angle of the Compound Curve
Purpose and Variables of…
Distance from PC to PT in the Direction of the Backward Tangent
R2=radius of the sharper curve
I=Total Intersection Angle of the Compound Curve
R1=radius of the sharper curve
I1=intersection angle of the flatter curve
Purpose and Variables of…
Perpendicular Distance from the Backward Tangent to PT
R1=radius of the sharper curve
R2=radius of the sharper curve
I=Total Intersection Angle of the Compound Curve
I1=intersection angle of the flatter curve
Purpose and Variables of…
Long Tangent of the Compound Curve
R1=radius of the sharper curve
R2=radius of the sharper curve
I=Total Intersection Angle of the Compound Curve
I1=intersection angle of the flatter curve
Purpose and Variables of…
Short Tangent of the Compound Curve
R1=radius of the sharper curve
R2=radius of the sharper curve
I=Total Intersection Angle of the Compound Curve
I1=intersection angle of the flatter curve
Purpose and Variables of…
Length of Spiral Curve
Ls=length of spiral transition curve
V=design speed
R=radius
C=rate of increase of lateral acceleration
Purpose and Variables of…
Magnitude of Centripetal Acceleration
V=vehicle speed
R=radius
an=normal acceleration
Purpose and Variables of…
Minimum Radius
emax=rate of roadway superelevation
fmax=side friction factor
Rmin=minimum radius
V=design speed
Purpose and Variables of…
Horizontal Sightline Offset
S=SSD
R=radius of the centerline of inside lane
HSO=horizontal sightline offset
Purpose and Variables of…
Law of Sines
lowercase=side length
UPPERCASE=angle
Purpose and Variables of…
Elevation of Point Vertical Curve
YPVC=elevation of PVC
G1=grade of back tangent
x=horizontal distance from PVC to turning point
YPVI=elevation of point of vertical intersection
G2=grade of forward tangent
L=length of curve
Purpose and Variables of…
Tangent Offset
a=parabola constant
x=horizontal distance from PVC to turning point
Purpose of…
Difference in Grade
Purpose and Variables of…
Parabola Constant
G1=grade of back tangent
G2=grade of forward tangent
L=length of curve
Purpose and Variables of…
Rate of Vertical Curvature
A=difference in grade
L=length of curve
Purpose and Variables of…
Tangent Offset at PVI
A=difference in grade
L=length of curve
Purpose and Variables of…
Crest Vertical Curve General Equation
L=length of vertical curve
S=sight distance
A=algebraic difference in grades
h1=height of eye above roadway surface
h2=height of object above roadway surface
Purpose and Variables of…
Crest Vertical Curve General Equation
L=length of vertical curve
S=sight distance
A=algebraic difference in grades
h1=height of eye above roadway surface
h2=height of object above roadway surface
Purpose and Variables of…
Crest Vertical Curve Standard Criteria h=3.5 ft, h2=2.0 ft
L=length of vertical curve
S=sight distance
A=algebraic difference in grades
Purpose and Variables of…
Crest Vertical Curve Standard Criteria h=3.5 ft, h2=2.0 ft
L=length of vertical curve
S=sight distance
A=algebraic difference in grades
Purpose and Variables of…
Minimum Curve Length Based on Headlight Sight Distance
L=length of vertical curve
S=sight distance
A=algebraic difference in grades
