Présentation au colloque "La modélisation des flux au service de l'aménagement urbain", Lille, 14/06/2012

1. Eval-PDU: urban traffic and its environmental impacts
modelling to assess Urban Mobility Master Plan.
Conception of a methodology based on the Nantes’ case
Fouillé L., Broc J.-S., Bourges B., Bougnol J.,
Schmidt T., Ducroz F., Picaut J. and Mestayer P.

2. Introduction
• ANR « Sustainable City » 2008-2012
• SEA (Strategic Environmental assessment) method of UMMP
(Urban Mobility Master Plan)
• Application to Nantes UMMP 2000-2010
• A chain of models (traffic, emissions, air
quality, noise)
• Comparison of real and alternative situations
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3. 1. Needs analysis and problem’s
definition
• Toward ecomobility policies and « green »
UMMP (since a 1996 act)
• Toward systematic SEA of plans and programs
(EU Directive 2001/42/CE)
• Increasing need of tools and methods for ex
post and ex ante assessment
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4. 2. Nantes’ case study
• New infrastructures : BHLS (Bus with a High Level of Service,
here the Busway®), P+R (Park and Ride) facilities, tramline
extensions, road bridges over the Loire river…
• Many soft actions : mobility management
plans, carpooling website, car- and bike-
sharing systems, bus lanes…
• Except the Busway (biggest action), the
UMMP 2000-2010 seems a program of
transition
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5. 3. Method
A. General methodology
Two blocks:
1. Core approach : a chain of models
2. Peripheral approaches : socioeconomic
consequences (real estate values with a
hedonic price model, quality of life and travel
behaviour with dedicated social surveys,
health impacts with a basic method) and
alternative simplified approaches
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6. B. Description of the chain of the
physically-based models
a. Traffic modelling (VISEM/VISUM)
b. Atmospheric emissions modelling (CIRCUL’AIR)
c. Air pollution dispersion modelling (ADMS
Urban)
d. Noise modelling
e. Using modelling tools for evaluation purpose
f. Definition of scenarios
a, b, c : existing models are adapted and used.
d : a specific simplified model is developed
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7. a. Traffic modelling (J. Bougnol)
• 4 step Travel Demand Model (TDM)
• 11 000 links on the Loire-Atlantique area
• Multimodal model : pedestrians, private car,
public transport
• Output : Traffic flows for 4 time slots
(distinguishing peak-hours) of a typical
working day
Feeding air and noise models
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8. b. Atmospheric emissions
modelling (T. Schmidt et F. Ducroz)
• Based on COPERT IV methodology (emissions levels by
average speed and by type of vehicles considering cold
start for cars and road gradient for lorries)
• Hourly traffic and average speed
• CITEPA vehicle fleet (motorization type, power class, EURO
standard, weight class, number of axles for trucks)
• This model also calculates energy consumption
• Output : kg per km of 20 pollutant for each link of the
network and each hour of a year
• Feeding air pollution dispersion model
• Circul’air is a model developed by ASPA (regional air quality
agency Alsace)
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9. c. Air pollution dispersion
modelling (T. Schmidt et F. Ducroz)
• Chemistry/transport model
• 3000 road sources (bounded to the Nantes
Metropolis area and simplified network)
completed by other ponctual or surface sources
(residential and industrial)
• Output : concentrations of pollutants (average,
percentile) calculated in various point of an
adaptative grid
• A GIS interpolation allows to obtain a complete
visualization
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10. d. Noise modelling
(J. Picaut)
• Development of a simplified software using
Orbis GIS platform (a GPL GIS)
• Meshing between buildings with a Delaunay
triangulation (calculation points)
• Road and/or rail noise
• Direct propagation, 1st and 2nd reflexion,
horizontal diffraction
• Output: sound pressure level on each point
(Ln, Lden), then interpolated
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11. e. Using modelling tools
for evaluation purpose
• TDM were initially designed for other
purposes
• The existing literature has proven the
feasibility of using a chain of models (Chiquetto
and Mackett, 1995 ; Lee and Jo, 1995 ; Gualtieri and
Tartaglia, 1998; Ambrosino and al ., 1999; Brown and
Affum, 2002 ; Soleil and al ., 2002 ; Affum and al ., 2003 ;
Lagache and al ., 2006 ; Hatzopoulou and Miller, 2010)
• But discussions about scenarios definition and
modelling actions remained limited
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12. f. Definition of
scenarios
• 3 reference situations (2002, 2008, 2008 P+R)
• 3 integrated scenarios (without Busway,
maximal UMMP, minimal UMMP)
• sensitivity tests (individual mobility, fuel price,
public transport prices, public transport
frequency, car parking rates, limitations of
statutory speeds, evolution of the vehicle
fleet...)
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13. 4. Results
traffic (flows and speeds, evening peak hour, focus on the ring road)
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14. NO2 emissions variation with/without Busway®
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15. NO2 concentrations variation with/without Busway®
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16. Variation of the area exposed to a NO2 concentration higher than 40 µg.m-3
with/without Busway® 16

17. Road traffic noise map (including tram lines) expressed in Lden, focus on the town center
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18. 5. Encountered difficulties
• Calibration
• Input and output data uncertainties
• Presentation/visualization difficulties
• Discussion capacity
• Experience feedback
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19. 6. Conclusion
• The proposed methodology works
• Traffic modelling is a key stage
• Some policies are impossible to translate
(carpooling or bicycle promotion...)
• Eval-PDU: a tool to visualize and assess transport
policies and their main impacts (traffic, air
pollution, noise)
• Complex modelling chain requiring large amount
of data and expertise (work remains necessary on
simplification and flexibility for decision
supporting tool)
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20. Thank you for your attention
laurent.fouille@mines-nantes.fr