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comparison python/traffic_engineering.py @ 33:4bd7cc69b6cd

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added traffic engineering utilities with first version of LaneGroups
author Nicolas Saunier <nico@confins.net>
date Sat, 10 Apr 2010 20:46:33 -0400
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children 388a5a25fe92
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32:48e56179c39e 33:4bd7cc69b6cd
1 #! /usr/bin/env python
2 ''' Traffic Engineering Tools.'''
3
4 from math import ceil
5
6 __metaclass__ = type
7
8 #########################
9 # traffic signals
10 #########################
11
12 class Volume:
13 '''Class to represent volumes with varied vehicule types '''
14 def __init__(self, volume, types = ['pc'], proportions = [1], equivalents = [1], nLanes = 1):
15 '''mvtEquivalent is the equivalent if the movement is right of left turn'''
16
17 # check the sizes of the lists
18 if sum(proportions) == 1:
19 self.volume = volume
20 self.types = types
21 self.proportions = proportions
22 self.equivalents = equivalents
23 self.nLanes = nLanes
24 else:
25 pass
26
27 def getPCEVolume(self):
28 '''Returns the passenger-car equivalent for the input volume'''
29 v = 0
30 for p, e in zip(self.proportions, self.equivalents):
31 v += p*e
32 return v*self.volume
33
34 class IntersectionMouvement:
35 '''Represents an intersection movement
36 with a volume, a type (through, left or right)
37 and an equivalent for movement type'''
38 def __init__(self, volume, type, mvtEquivalent = 1):
39 self.volume = volume
40 self.type = type
41 self.mvtEquivalent = mvtEquivalent
42
43 def getTVUVolume(self):
44 return self.mvtEquivalent*self.volume.getPCEVolume()
45
46 class IntersectionApproach:
47 def __init__(self, leftTurnVolume, throughVolume, rightTurnVolume):
48 self.leftTurnVolume = leftTurnVolume
49 self.throughVolume = throughVolume
50 self.rightTurnVolume = rightTurnVolume
51
52 def getTVUVolume(self, leftTurnEquivalent = 1, throughEquivalent = 1, rightTurnEquivalent = 1):
53 return self.leftTurnVolume.getPCEVolume()*leftTurnEquivalent+self.throughVolume.getPCEVolume()*throughEquivalent+self.rightTurnVolume.getPCEVolume()*rightTurnEquivalent
54
55 class LaneGroup:
56 '''Class that represents a group of mouvements'''
57
58 def __init__(self):
59 self.mouvements = {'left': [],
60 'through': [],
61 'right': []}
62
63 # all the add*Mvt should add a IntersectionMovement instance
64 def addLeftMvt(self, vol):
65 self.mouvements['left'].append(vol)
66
67 def addRightMvt(self, vol):
68 self.mouvements['right'].append(vol)
69
70 def addThroughMvt(self, vol):
71 self.mouvements['through'].append(vol)
72
73 def getTVUVolume(self, leftTurnEquivalent = 1, throughEquivalent = 1, rightTurnEquivalent = 1):
74 return leftTurnEquivalent*sum([m.getPCEVolume() for m in mouvements['left']])\
75 +rightTurnEquivalent*sum([m.getPCEVolume() for m in mouvements['right']])\
76 +throughTurnEquivalent*sum([m.getPCEVolume() for m in mouvements['through']])
77
78 def checkProtectedLeftTurn(leftMvt, opposedThroughMvt):
79 '''Checks if one of the main two conditions on left turn is verified
80 The lane groups should contain left and through movement'''
81 return leftMvt.volume >= 200 or leftMvt.volume*opposedMvt.volume/opposedMvt.nLanes > 50000
82
83 def optimalCycle(lostTime, criticalCharge):
84 return ceil((1.5*lostTime+5)/(1-criticalCharge))
85
86 def computeInterGreen(perceptionReactionTime, initialSpeed, intersectionLength, vehicleAverageLength = 6, deceleration = 3):
87 '''Computes the intergreen time (yellow/amber plus all red time)
88 Deceleration is positive
89 All variables should be in the same units'''
90 if deceleration > 0:
91 return [perceptionReactionTime+initialSpeed/(2*deceleration), (intersectionLength+vehicleAverageLength)/initialSpeed]
92 else:
93 print 'Issue deceleration should be strictly positive'
94 return None