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XXXVSCUOLAESTIVADIFISICAMATEMATICA,
RAVELLO,Settembre2010.
MathematicalModelsofTrafficFlow:Macroscopicand
MicroscopicAspects
.MRsacelU(inevsrtie´deiNc)eMichelRascle
LaboratoireJADieudonne´,
Universite´deNiceSophia-Antipolis
ParcValrose06108NiceCedex02,France
http://math.unice.fr/
∼
rascle/
M11thOctober2010
taehamitacloMedslforTffiaclFwo11htOtcobre02101/56
Introduction
Broadsubject!Somanyaspectsoftrafficmodeling,e.g.
.MRFully(cellularautomata,numericalschemes...)orsemi-discrete
(ODE,delayedODE...)/Macroscopic(PDE(hyperbolic
(conservationlaws?Hamilton-Jacobi?Withdiffusionand/or
relaxation?)
OrMesoscopic(kineticdescription)?
Multiscale(structureoftrafficjams,”phasetransitions”,
homogenization,hybridschemes...)
(I):Instability,e.g.stopandgowaves/(S):Stability:preserve
nonnegativespeed(!)and(hopefully!)nocrash...
ODEdescriptionmuchbetterfor(I)andPDEfor(S)...Howtofind
therightcombination?Relatedquestion:ifnecessary,givepriorityto
ODEanduse”modifiedequationathigherorder”fordescribing
specificeffects?
Junctions,linkwithhomogenization.Networks.Hybridschemes...I
won’tcovereverything!
sacelU(inevsrtie´deiNc)eaMhtmeaitacloMedslforTffiaclFwo11htOtcobre02102/65
Outline
Introduction
.MRDiscrete/FluidModels
TheFluidModel(WithoutRelaxation)
I
TheEulerianSystem
I
RiemannProblem.Waves
I
Motivations.Lagrangianversion
I
LinkwithMicroscopicModels(FLM)
I
LagrangianGodunovScheme
I
Passingtothelimit(s)
Junctions
saclI
Onanetwork
I
IngoingHalf-RiemannProblem
I
OutgoingHalf-RiemannProblem
I
RiemannProblematajunction
I
2-1Junction:Homogenization
I
HomogenizedSupply
I
Conclusiononjunctions
eU(inevsrtie´deiNc)eaMhtmeaitacloMedslforTffiaclFwo11htOtcobre02103/56
Outline...
.MRWithRelaxation:TravelingWavesandOscillations
I
Motivations
I
Remark:WhithamSubcharacteristiccondition
I
Smooth”simplewaves”aregenericallyTravelingWaves
I
J.Greenberg’sworkperiodicsolutionsforARG.Extensions...
I
AnExample:theIntelligentDriverModel
I
AdditionalRemarks.Conclusion
Commentsandreferences
sacelU(inevsrtie´deiNc)eaMhtmeaitacloMedslforTffiaclFwo11htOtcobre02104/56
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de
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4
LagrangianGodunovScheme
Passingtothelimit(s)
Junctions
Onanetwork
IngoingHalf-RiemannProblem
OutgoingHalfRiemannProblem
WithRelaxation.TravelingWavesandOscillations
Conclusiononjunctions
HomogenizedSupply
2-1Junction:Homogenization
RiemannProblematajunction:Principle...
2
Linkwithmicroscopicmodels(FLM)
Motivations.Lagrangianversion
TheEulerianSystem
TheFluidModel
Remark:WhithamSubcharacteristicCondition
Smooth”simplewaves”aregenericallyTravelingWaves
J.Greenberg’speriodicsolutionsforARG.Extensions
Discrete/FluidModels
.MR(Fullyor)1/2discrete:FollowtheLeaderModels...
Carlength:
l
=Δ
X
.Spacing:
τ
j
:=
x
j
+1
−
x
j
;
s
j
=1
/ρ
j
=
τ
j
/
l
:
specificvolume,density.
x
˙
j
=
v
j
=
⇒
s
˙
j
=
v
j
+1
l
−
v
j
v
˙
j
=
F
(
x
j
,
x
j
+1
,
v
j
,
v
j
+1
)
(
e
.
g
.
)=
α
v
m
V
0
(
x
j
+1
−
x
j
)
v
j
+1
−
v
j
+
β
(
V
e
(
x
j
+1
−
x
j
)
−
v
j
)
jlll
)1.2(
Convectivepart(fastreaction)+(slow)relaxationpart...
Examples,seealsoGazis-Herman-Rotheryand...
I
α
=0
,β>
0:Bando’sOptimalVelocityModel
I
α>
0
,β
=
m
=0:Aw-Klar-Materne-Rascle,SIAP2002
I
α>
0
,β>
0
,
m
=0:J.Greenbergand/orAw-Rascle,SIAP2000-2004
I
IntelligentDriverModel(IDM):Helbing-Treiber,
∼
2000
√v
˙
j
=
a
[1
−
v
jm
−
(
s
b
(
v
j
)
−
v
j
s
(
v
j
+1
−
v
j
)
)
2
];
s
b
(
v
):=
s
0
+
s
1
v
+
s
2
(
v
)
j
sacelU(inevsrtie´deiNc)eaMhtmeaitacloMedslforTffiaclFwo11htOtcobre02108/56
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λ:2dna0<v:1:sexodaraP]!esrowllitsnoisuffiD[!!ledomelbirretasiWP)59,meiuqeR(oznagaDI...+ρx∂)ρ(0p˜−=:...+ρx∂)ρ(0p1−ρ−=vx∂v+vt∂,0=)vρ(x∂+ρt∂()scimanyDsaGfc(mahtihW-enyaP:redrOdnoceSI[)RWL(sdrahciR-mahtihW-llihthgiL:redrOtsriFI:diulF:citeniK∂
t
ρ
+
∂
x
(
ρ
v
)=0
,
v
=
V
(
ρ
)
,
V
0
(
ρ
)
<
0
,
(
ρ
V
)”
<
0
,
Fundamentaldiagram:flux
q
=
ρ
V
(
ρ
).
RiemannPb:
ρ
(
x
,
0)=
ρ
±
for
±
x
>
0:
-centeredrarefactionwaves(acceleration)if
v
−
<
v
+
,
-shockwaves(braking)if
v
−
>
v
+
.Veryrobust,(too)stable.Figures.
↔
Hamilton-Jacobi]
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