Since many years, as a consequence of fossil fuels rarefaction and climate changes, ecology has become a major challenge of our society. In this field, many improvements could be realized on the transportation side and more precisely on passenger cars which are an important source of pollution. A quick and efficient solution to reduce fuel consumption and so, greenhouse gases emissions, is to adopt an ecological way of driving, called ecodriving. However, is ecodriving really efficient in terms of mobility and environment at a global point of view? The benefits of ecodriving have often been studied for an isolated vehicle and rarely for a whole network. The aim of this work is to estimate the effects of ecodriving on traffic congestion and fuel consumption according to the percentage of ecodrivers in the population. This has been achieved using a class of ecodriven vehicles with a car-following model (Intelligent Driver Model) and with a transport simulation software (Aimsun). Results show that the effect of ecodriving on the traffic congestion and pollution is not linearly linked to the proportion of ecodrivers and this effect varies according to the driving conditions. In some cases, ecodriving is cons-productive and fuel consumption increases. Future works will concentrate on experimental validation, on modeling the effect of ecodriving on road safety and on improving the different models.

1. Young Researchers Seminar 2011
DTU, Denmark, June 8 - 10, 2011
Young Researchers Seminar 2011
DTU, Denmark, 8 - 10, 2011
Impact of the penetration rate of
ecodriving on fuel consumption
and traffic congestion
ORFILA Olivier
IFSTTAR

2. 2
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion

3. 3
What is ecodriving ?
• No clear and objective
definition exists
• Example: “Ecodriving is a way
of driving that reduces fuel
consumption, greenhouse gas
emissions and accident rates”
(www.ecodrive.org)
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion

4. 4
Ecodriving definition
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion
Using driving rules (Saboohi 2009, Walhberg 2007,
Zarcadoula 2007)
• do not drive too fast,
• maintain steady speeds,
• do not accelerate too quickly,
• anticipate traffic flow when accelerating and
slowing down,
• shift gears sooner to keep engine speed lower,
• keep the vehicle in good maintenance.

5. 5
Ecodriving
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion
• In the literature, the benefits of ecodriving are
studied for the subject vehicle only.
• Hypothesis 1: ecodriving has an impact on the
traffic level and on the fuel consumption on the
global network
• Hypothesis 2: this impact depends on the
penetration rate of ecodriving.

6. 6
Aims of this study
Title of the presentation
Evaluate the impact of ecodriving on fuel
consumption and traffic congestion:
• On a whole network
• According to the ecodriving penetration rate
• For different road types and traffic demands

7. 7
Light duty vehicles and driver
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion

8. 8
And the role of passenger cars ?
• Fuel consumption US 2004
(IEA)
• In France, Light Duty Vehicles
represents 55% of greenhouse
gas emissions (source:
ministry of sustainable
development)
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion

9. 9
And the role of
vehicle, infrastructure
and driver?
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion
Driver:
•Desired acceleration
•Desired speed
•Engine speed,… =
ecodriving
Vehicle:
•Mass
•Engine
•Tires,…
Infrastructure:
•Geometry
•Pavement texture

10. 10
Methodology: an ecodriving
modelling
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion
Ecodriving
parameters
Ecodriven
vehicles
Normally
driven
vehicles
Traffic
demand
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
traffic state
•Congested traffic
state
2 types of roads x 3 traffic states x 11 proportions of ecodrivers x 10 replications =
660 numerical tries

11. 11
Traffic and fuel consumption
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion

12. 12
Traffic micro simulation on
interurban roads
• Intelligent Driver Model (Treiber, 2000) :
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion
Desired acceleration
Desired speed
Distance
between
vehicles
b: desired
deceleration
Speed
difference
Desired time
headway
Minimum gap
Model parameter=4

13. 13
Fuel consumption on interurban
roads
• Energy consumed
• Corrected with an efficiency ratio (Wang, 2008)
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion

14. 14
Traffic micro simulation on urban
roads
• Gipps model (Gipps, 1981) with Aimsun (TSS)
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion
0%
50%
100%
Free
Intermediate
Congested

15. 15
Fuel consumption on urban roads
• Aimsun and Alçelik model (Alçelik, 1982):
▫ 4 states are defined:
 Idling
 Cruising
 Accelerating
 Decelerating
▫ 7 parameters from the vehicle are required
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion

16. 16
Interurban roads
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion

17. 17
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
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion
Optimal proportion of ecodrivers : 100%

18. 18
Results : interurban road –
intermediate traffic
• Fuel consumption
▫ Non linear variation
▫ From 0 to 20% of ecodrivers :
-8.5%
▫ From 0 to 100% : +2.4 %
• Traffic indicator
▫ Sharp decrease : -38%
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion
Optimal proportion of ecodrivers : 20%

19. 19
Results : interurban road –
congested traffic
• Fuel consumption :
▫ Strong reduction : -35.8%
• Traffic indicator
▫ Sharp decrease : -55%
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion
Optimal proportion of ecodrivers : 30%

20. 20
Urban roads
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion

21. 21
Results : urban road – free traffic
• Fuel consumption
▫ Slow decrease : -9.8 %
• Traffic indicator
▫ Strong decrease : -19.7%
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion
Optimal proportion of ecodrivers : not defined

22. 22
Results : urban road – intermediate
traffic
• Fuel consumption
▫ Non linear variations : -7.6%
• Traffic indicator
▫ Non linear variations : -32.3%
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion
Optimal proportion of ecodrivers : not defined but 80% should be avoided

23. 23
Results : urban road – congested
traffic
• Fuel consumption
▫ Strong effect: -19.6%
• Traffic indicator
▫ Nearly steady
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion
Optimal proportion of ecodrivers : 100%

24. 24
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
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion

25. 25
Theoretical and practical
implications
• Innovative method to analyze ecodriving.
• It can be applied for several existing or future
assistance systems
• Recommandations on ecodriving
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion

26. 26
Conclusions and perspectives
Conclusions Study drawbacks
• Ecodriving is efficient at a
global point of view
• In some situations, the fuel
consumption increases with
the % of ecodrivers
• The optimal proportion of
ecodrivers varies with the
situation
• Current proportion of
ecodrivers is unknown
• The engine speed has not
been taken into account
Impact of the penetration rate of ecodriving on fuel
consumption and traffic congestion
Perspectives
• Refine the modelling
• Experimental validation