transportation pe review - christian brothers universityfacstaff.cbu.edu/~gmcginni/classes/ce 318...
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TransportationTransportation PE ReviewPE Review
Horizontal and Vertical Curves
Azimuths and Bearings
But first, a little plane surveying…..
See Page 78-12
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Computation of Bearings
See Page 78-12
Latitudes and Departures
See Page 78-12
N = y = Latitude = L cos B
E = x = Departure = L sin B
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Deflection Angles
See Page 78-13Take the difference between the two bearings to compute the deflection angle.
Horizontal Curve ElementsSee Page 79-2
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Horizontal Curve EquationsSee Page 79-2
Stationing on a Horizontal Curve
See Page 79-2STA PT = STA PC + L 79.11
STA PC = STA PI – T 79.12
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Superelevation See Page 79-8
Definitions:
Tangent runout (TR) aka tangent runoff and crown runoff Point out glitch in text!
Superelevation runoff (L)
Superelevation runoff rate aka transition rate
Equations:Required e:
Side friction factor:
See Page 79-7
Superelevation
Equations:Tangent runout and SE runoff distances:
See Page 79-8
For circular curves, the SE runoff should be developed 60 to 90% on the tangent and 40 to 10% on the curve. Most state agencies use a rule of 2/3 on the tangent and 1/3 on the curve.
Read the problem statement carefully to determine how to determine the superelevation!
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Stopping Sight Distance ValuesSee Page 79-10
Horizontal Sight Distance
See Page 79-10
These equations assume that S <= L and level terrain!
Decision sight distance should be added when appropriate.
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Required lengths of Vertical CurvesSee Page 79-13
K-Values What?See Page 79-13
K = L/A
Where A = G2 – G1 G2 – G1 is always positive!
K-values are used to simplify the selection of a stopping sight distance for a crest or sag vertical curve.
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Design Controls: Crest Vertical CurvesSee Page 79-15
Design Controls: Sag Vertical CurvesSee Page 79-16
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Highway Capacity and LOSSee Page 74
Nomenclature:ADT (Average Daily Traffic) vpd
D (Density) pcpmpl
DDHV (Directional Design Hourly Volume) vph (highest demand direction)
DHV (Design Hourly Volume) vph (both directions)
E (Passenger Car Equivalent for Heavy Vehicles)
f (Adjustment factors) [for lane widths, lateral clearances, etc.]
FFS (Free Flow Speed) mph
BFFS (Base Free Flow Speed) mph
K (ratio of DHV to ADT)
PHF (Peak Hour Factor)
V (Volume) pcphpl v (rate of flow during peak 15-min. period)
S (Speed) mph
Highway Capacity and LOS
See Page 74-5
Symbols:T (Trucks and Buses) for basic freeway segments
R (Recreational vehicles)
Equations:PHF = (Actual Hourly Volume)/(Peak rate of flow)
Peak rate of flow = 4(peak 15-minute flow rate)
Heavy Vehicle Factor:
Peak 15-minute passenger-car equivalent flow rate:
See Page 74-8
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Highway Capacity and LOS
See Page 74-8Equations:
v/c ratio (volume capacity ratio) = v/c
FFS (Free Flow Speed):
Adjustment factors (f) are determined from HCM.
Density:See Page 74-7
Adjustment factors to BFFS