ChengDu University Invited Conference

Institut français des sciences et technologies des transports, de l’aménagement et des réseaux

www.ifsttar.fr

Institut français

des sciences et technologies

des transports, de l’aménagement

et des réseaux

Transportation system complexity

: Optimal driving strategies

Olivier OrfilaTongJi University (High End Foreign Expert)IFSTTAR-COSYS-LIVIC (Senior Researcher)[email protected]


www.ifsttar.fr

What are our objectives?

• We want to mitigate a wide range of transportation issues (congestion, pollution, safety, etc)

• In our case: Reduce the negative impact of road transport on health and environnement:

• Reduce greenhouse gases emissions (GHG);

• Reduce pollutants emissions;

• Reduce energy use;

• All of this without increasing travel time nor road insecurity.


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Regulation is pressing!

• Emissions

standards:

• Increasing

constraints

• COP21 :

• Limit global

warming to 2°C

targetting 1.5°CHistorical fleet CO2 emissions performance and current or proposed passenger vehicle standards (ICCT, International Council on Clean Transportation):


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What about passenger cars?

• Fuel use data in the US (IEA)

• In France, 55% of GHG

emissions are due to light duty

vehicles (source : MEEM,

french ministry of ecology)


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Role of infrastructure,

vehicles and drivers

Drivers :•Driving•Use choice, maintenance, client choices

Vehicle :•Mass, aérodynamics•Engine•ADAS•Tires,…

Infrastructure :•Geometry•Road texture•Urban planning•ITS


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USE CASE OF OPTIMAL

DRIVING: ECODRIVING

First part


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A few energy reach the

wheel and we are still

spoiling it!

Ecodriving =

cooking leftovers

Ecodriving definition proposal


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Ecodriving definition

« Ecodriving is a strategy to reduce fuel use by following several

advice: do not accelerate strongly, reduce speed, keeping low

RPMs, anticipate traffic. » M. Barth, K. Boriboonsomsin, 2009. Energy and

emissions impacts of a freeway-based dynamic eco-driving system

« Ecodriving should not be confused with hypermiling wich

neglects safety to reduce fuel use while ecodriving has no trade-

off » J. N. Barkenbus, 2010. Eco-driving: An overlooked climate change initiative

« Ecodriving aims at following a vehicle safely in order to reduce

energy use on the long term » M.A.S. Kamal, M. Mukai, J. Murata and T.

Kawabe, 2010. On board eco-driving system for varying road-traffic environments

using model predictive control


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Ecodriving definition proposal• Ecodriving is a set of driving technics, dealing with all driving tasks,

aiming at minimizing the energy losses and/or emissions rate of thedriven vehicle, from an origin to a destination, without trading-offsafety nor total travel time.

• Note: Ecodriving is a real time multi objective optimization process.


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Some ecodriving research

questions• Can ecodriving famous golden rules, taken

one by one:• Reduce the energy used by the concerned

vehicle?

• Reduce the emissions rates of the concernedvehicle?

• Improve road safety for the concerned vehicle?

• Reduce congestions?

• Increase comfort?

• Reduce traffic noise?

• And what about a whole network?


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IFSTTAR ecodriving research

methodology• Ecodriving optimization• Ecodriving modelling

• Ecodriving assistance

systems

• Impact of ecodriving

Smart and Green ACC

ddriver

Tdriver

V

d

Vi

g

SAGA Mode

Target Speed

Target Acc.

Error Flag

Accuracy

Dyn. Limit

Func. Limit

70

Vdriver

eHorizon

Fuel use in congested urbantraffic

Fuel use in nearly congestedinterurban roads

δ

ωmax2

Olivier Orfila, Guillaume Saint Pierre, Cindie Andrieu. (2012) « Gear Shifting BehaviorModel for Ecodriving Simulations Based on Experimental Data », EWGT2012

H. T. Luu, 2011, Développement de méthodes de réduction de la consommation en carburant d’un véhicule dans un contexte de sécurité et de confort : un compromis entre économie et écologie. Thèse de doctorat, Université d’Evry

Orfila O., Saint Pierre G., Messias M. (2014), « Development of an ecodriving assistance application for nomadic devices performing real-time and post trip coaching for road vehicles », TRA 2014, Paris, La Défense.

O. Orfila, 2011, Impact of the penetration rate of ecodriver on traffic and fuel consumption, YR2011, Copenhaguen


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Methodology: an ecodriving

modelling

Impact of the penetration rate of ecodriving on fuel consumption and traffic

congestion

Ecodrivingparameters

Ecodrivenvehicles

Normallydriven

vehicles

Trafficdemand

Road network

Traffic micro simulation

Fuel consumption

Traffic indicator(mean speed)

%

•IDM (Intelligent Driver Model) Treiber, 2000

•Gipps model 1981 (AIMSUN)

•Interurban•Urban

•Free traffic state

•Intermediate trafficstate

•Congested trafficstate

2 types of roads x 3 traffic states x 11 proportions of ecodrivers x 10 replications = 660 numerical tries


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Traffic micro simulation on urban

roads

• Gipps model (Gipps, 1981) with Aimsun (TSS)


congestion

0%

50%

100%

Free

Intermediate

Congested


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RESULTS:

Interurban roads


congestion


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Results : interurban road – free

traffic• Fuel consumption

• Slight and steady decrease

• Fuel consumption reduces

by 7.7%

• Traffic indicator

• Slight decrease (9.1%)

• 2 minutes lost on a 20

minutes travel


congestion

Optimal proportion of ecodrivers : 100%


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Results : interurban road –

intermediate traffic• Fuel consumption

• Non linear variation

• From 0 to 20% of ecodrivers

: -8.5%

• From 0 to 100% : +2.4 %


• Sharp decrease : -38%


congestion



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Results : interurban road –

congested traffic• Fuel consumption :

• Strong reduction : -35.8%


• Sharp decrease : -55%


congestion



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RESULTS:

Urban roads


congestion


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Results : urban road – free traffic

• Fuel consumption

• Slow decrease : -9.8 %


• Strong decrease : -19.7%


congestion

Optimal proportion of ecodrivers : not defined


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Results : urban road –

intermediate traffic• Fuel consumption

• Non linear variations : -7.6%


• Non linear variations : -

32.3%


congestion

Optimal proportion of ecodrivers : not defined but 80% should be avoided


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Results : urban road – congested

traffic• Fuel consumption

• Strong effect: -19.6%


• Nearly steady


congestion



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Conclusions

• Ecodriving is efficient at a global point of

view for energy use only.

• The optimal proportion of ecodrivers varies

with the situation.

• In some situations, the fuel

consumption increases with the

proportion of ecodrivers


congestion


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Proposed solutions for

ecodriving

• Short term: promote ecodriving on

identified situations

• Middle term: giving real time advice to the

driver

• Long term: develop a strategy to manage

a whole network.

• Change subsystem definition


congestion


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STUDYING TRANSPORTATION

SYSTEM COMPLEXITY

Second part


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Transportation system and life cycle

Automotive

industry

energy

production

infrastructure

construction

multimodality

recycling

depolluting

maintenance

highways –

periurban

roads

urban

networks

rural

networks

Usage


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Decomposing the transportation

system

• Structural analysis:

• Physical structures

• Administrative structures

• Studying interaction between elements


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Road transportation system

Physical

• Infrastructure:

• Road, power supplies,

power stations, public

transport stations, ITS,…

• Vehicles:

• Private cars, shared cars,

trucks, buses, bikes,

motorbikes,…

• Users:

• drivers, pilots,…

Administrative

• Government

• Local collectivities: • Province, City, District,

• Private companies:• vehicle sharing, vehicle renting,

infrastructure managers

• Associations:• User association, road

association, vehicle manufacturers association

• Laboratories:• Resaerch centers, universities

We should think about

interactions and scales!


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HOW TO DEFINE A

SUBSYSTEM LIMITS

Third part


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Defining the subsystem limits

• Selecting a subsystem is a complex task

that generally consists in finding the good

study scale (select the right numbers of

actors, select the right study area such as

a street, a quarter, a city, a province or a

country).

• A wrong selection leads to suboptimal

solutions or cons-productive results.


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Isolated system, closed system,

opened system?

• Isolated system: that is totally separated from other systems and that does not interact with others.

• Closed system: system exchanging energy with other systems

• Opened system: system exchanging energy and matter with other systems


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Co-evolution

• Host, parasitic co-evolution: metaphoric,

Road (host) and car (parasitic)

• Combined co-evolution:

• Antagonistic : Taxis and private cars service,

buses and trains.

• Symbiosis : commercial centers and cars,

thermal engine and fuel.

• Diffuse co-evolution: ITS, as related to

several transportation means.


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Conclusion

• When trying to mitigate very important issues we might first have to:

• have a good overall vision of the global tranportation system and subsystems and their interactions

• define the subsystem in accordance with transportation system decomposition and by interacting with transportation actors.

• make research studies to proove the concept efficiency


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THANK YOU VERY MUCH FOR

YOUR ATTENTION!

ChengDu University Invited Conference

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