< Fundamentals of Transportation

Transportation networks have analogs with network processes in other systems, such as water networks, structures, and electrical networks. Some of the relationships are outlined below.

' Transportation Water: Hydrostatics Structures Electrical
Node Conservation LawFlow (q)Current (Kirchoff’s Current Law)
Fundamental Lawq = kvP = ρghF=δ (mv)/ δ (T)V=IR
k = q/vF= v δ (m)/ δ (T)V=I/G
v=q/kBernoulli’s Equation:Ohm’s Law on resistor
Constant=p+1/2ρ V2+ ρgh
P=F/A (area)
F=ma
Analogsflow (q)Pressure (P*A)δm/δTCurrent (I)
density (k)Density (ρ)Force (F)Voltage (V)
velocity (v)velocity (v)velocityConductance (G)
Equilibrium ConditionsWardrop (time equal on used pairs in parallel)Sum of horizontal (and sum of vertical) forces on a structure = 0, sum of moments = 0.Voltage drop across two components in parallel are equal

Structures

  • F= force
  • m = Mass
  • a = acceleration
  • T = Time

Transportation

  • q = flow
  • k = density
  • v = velocity

Electricity

  • V= Voltage
  • I = Current
  • R = Resistance
  • G = Conductance = 1 / Resistance

Water

  • P = hydrostatic pressure
  • ρ = fluid density =mV = mass *volume
  • g = acceleration due to gravity
  • h = height
  • c= constant
  • A = area
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