Presentation by Dr James Tate at www.aimsun.com/2016-aimsun-users-meeting-athens

1. 14th Annual Aimsun Users’ Meeting
MESO and MICRO
Real Driving Emission models for AIMSUN
Dr James Tate
Institute for Transport Studies,
University of Leeds, UK
Email: j.e.tate@its.leeds.ac.uk
Twitter: drjamestate
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Speed (km.h
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NOX(grams.km
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)

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#DIESELGATE
NOX common marques & models
October 2015
Euro Standard
NOX(grams.km
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)
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AUDI
Euro 3 Euro 4 Euro 5
BMW FORD
Euro 3 Euro 4 Euro 5
LANDROVER MERCEDES
Euro 3 Euro 4 Euro 5
PEUGEOT SKODA
Euro 3 Euro 4 Euro 5
VAUXHALL VOLKSWAGEN
Euro 3 Euro 4 Euro 5
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VOLVO

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12thMay2016

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EMISSION MODELLING WITH AIMSUN
▶ Calibrated & Validated Network
▶ Set ‘realistic’ UK vehicle dynamics
▶ Harvest ALL trajectories
▶ Manipulate into emission model format (1Hz)
▶ Instantaneous Emission Modelling e.g. PHEM
BEST PRACTICE

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CHALLENGES
• AVERAGE SPEED (MESO) EMISSION MODELS LIMITATIONS
– Most commonly applied emission model e.g. COPERT, HBEFA, EFT (UK)
– Under-predict emissions at low-speeds
– As ‘average’ uncertainties increase for shorter links
• EMISSION MODELS IN TRAFFIC SIMUATION SOFTWARE OFTEN DATED
• EXTERNAL INSTANTANEOUS EMISSION MODELS (IEM) CUMBERSOME
SOLUTIONS
• NEW TYPE OF AVERAGE SPEED EMISSION MODEL FOR THE EU FLEET
• NEW SIMPLE (FAST) IEM IMPLEMENTED WITHIN AIMSUN (API)
– 1hz time step
– Limited range of vehicle types & categories e.g. Euro 5 diésel car, LGV, HGV

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UNDER-PINNING DATA
Taking the road into the Laboratory
The London Drive Cycle & Emission Testing (TfL)
Time (seconds)
Speed(km/h)
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motorway
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suburban
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https://www.london.gov.uk/sites/default/files/In-
service%20emissions%20performance%20of%20Euro%206VI%20vehicles%20WEBSITE%20COPY.pdf

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TfL EURO 6 / VI LABORATORY TESTING
12 PASSENGER CARS: tested over the entire LDC (140 kms)
▶ Powertrains | petrol (2), diesel (9) and petrol-HEV (1);
▶ Exhaust after-treatments | 3 way Cat, LNT and SCR;
▶ Market segments | Compact, Supermini, Small family, Family/MPV, SUV/4x4,
Prestige/sports and Hybrid; and
▶ Marques | BMW, Fiat, Lexus, Mercedes, Peugeot, Volvo and Volkswagen.
3 HEAVY-GOODS VEHICLES: tested over the suburban sub-cycles only
▶ Rigid HGV N2 7500kg
▶ Rigid HGV N3 18000kg
▶ Artic HGV N3 40000kg
▶ LADEN and UN-LADEN
7
1 Millbrook Vehicle Emission testing laboratories that meet the
requirements of Directive 2007/46 EC Article 41, Section 3
and have been designated as a Category A Technical Service
for Individual Vehicle Approvals (IVA).

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LIMITATIONS
Average speed Emission Models
▶ Analysis of Laboratory Testing data
▶ Uncertainties greater on short links

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TfL EURO 6 PASSENGER CAR RESULTS
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1.2
Average CO2 (as % of type-approval [g/km])
AverageNOX[g/km]
Euro 5b/b+ diesel limit
Euro 6b/c diesel limit
Petrol-Hybrid
CompactPrestige/sports
Small family
Small family
Family/MPV
Family/MPV
Small familySUV/4x4
Supermini
Prestige/sports
Family/MPV
Moody, A., Tate, J. 2016. In service CO2 and NOX emissions of Euro 6/VI cars, light- and heavy-duty goods vehicles in real London driving:
Taking the road into the Laboratory. The 21st International Transport and Air Pollution (TAP) Conference, Lyon, France, May 24-26, 2016.

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* Zallinger, M., Tate, J., and Hausberger, S. 2008. An instantaneous emission model for the passenger car fleet.
Transport and Air Pollution conference, Graz 2008
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CO2(g.sec
1
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Time (seconds)
NOX(g.sec
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Modelled_CO2
Observed_CO2
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UNDER-PINNING MODEL
Instantaneous Emission Model PHEM*
Passenger car and Heavy-duty Emission Model
 Verification & Validation

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NEW TYPE OF AVERAGE SPEED
EMISSION MODEL
• Basis ‘MICRO-trips’: Stationary  Speed > 5 km.h-1  Stationary
• Regression relationships (in ‘R’) fitted to each ‘MICRO-trip’
average-speed & Emission Rate
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Time (seconds)
Speed(km.h
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NEW TYPE OF AVERAGE SPEED
EMISSION MODEL
• Example Euro 5 diesel car | 401 London Drive Cycle ‘Micro-trips’
CO2 NOX
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Speed (km.h
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NOX(grams.km
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CO2(grams.km
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PASSENGER CARS

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NEW TYPE OF AVERAGE SPEED
EMISSION MODEL (EM)
Coloured line : TfL EM
Grey : COPERT
Dotted : Standard

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NEW TYPE OF AVERAGE
SPEED EMISSION MODEL
London Real Driving Trajectory data
i.e. configured for local driving conditions FOR EACH vehicle type

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The ‘London Taxi’ (LTI)
Also: Van, Truck, Bus, Coach

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NEW TYPE OF AVERAGE SPEED
EMISSION MODEL
• Process

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WORK IN PROGRESS
STEP 1. Emission Functions being applied to London fleet + traffic movement data
▶ Observed and Modelled link flows & speeds
▶ Hourly resolution
STEP 2. Input for London air pollution dispersión simulations (Autumn 2016)
EXPECTED OUTCOMES
• Higher emissions predicted across Central London, accounting for:
▶ Traffic congestion especially in peak periods
▶ Fleet mix (high proportion of Taxis, Buses and Trucks)
• Closer agreement between MEASURED and MODELLED levels of air pollution
NEW AVERAGE SPEED LONDON EMISSION MODEL

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• NEW generation of IEMs derived from PEMS (Portable Emission Measurement
Systems) and Remote Sensing data i.e. semi-empirical
• Formulation Vehicle Specific Power (VSP)
– Accounts for power demands: Acceleration (a), Road gradient (⍬), Rolling resistance and
Aerodynamic drag (from speed v). Units kW.ton-1
• E.g. Basis of the US ‘MOVES’ IEM
• European Model* developed from TNO’s growing database of PEMS testing
data (now 1,000s passenger cars)
• Currently implemented in AIMSUN API (FP7 ecoDriver Project)
Fast, Simple Instantaneous Emission Models
* Ligterink, N., Tate, J. Heijne, V. 2016. Vehicle emission model for traffic simulations. The 21st International Transport and Air Pollution (TAP)
Conference, Lyon, France, May 24-26, 2016.

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Fast, Simple Instantaneous Emission Model
e.g. Verification of Euro 5 diesel car OBSERVED vs. MODELLED (blue CO2
& red NOX) with TfL London Drive Cycle data (extract)
Ligterink, N., Tate, J. Heijne, V. 1 2016. Vehicle emission model for traffic simulations. The 21st International Transport and Air Pollution (TAP)
Conference, Lyon, France, May 24-26, 2016.

21. 14th Annual Aimsun Users’ Meeting
Fast, Simple Instantaneous Emission Models
e.g. Verification of Euro 5 diesel truck (18t Rigid HGV) OBSERVED vs. MODELLED
(blue CO2 & red NOX) with TfL London Drive Cycle data (extract)
Ligterink, N., Tate, J. Heijne, V. 1 2016. Vehicle emission model for traffic simulations. The 21st International Transport and Air Pollution (TAP)
Conference, Lyon, France, May 24-26, 2016.

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SUMMARY
• New MESO emission model (Average Speed)
+ Reliable predictions for short links
+ Reliable predictions for low driving speeds
+ Simple, consistent function form
+ Whole European fleet old & new, petrol & diésel
+ Up-to-date (includes the very latest Euro 6c diésel cars)
• New MICRO (instantaneous) emission model
+ Reliable predictions for Euro 5 / V vehicles
+ Expect up-dates for Euro 6 / VI
+ Fast computation
+ Evaluation of traffic management policies (relative change)

23. 14th Annual Aimsun Users’ Meeting
MESO and MICRO
Real Driving Emission models for AIMSUN
Dr James Tate
Institute for Transport Studies,
University of Leeds, UK
Email: j.e.tate@its.leeds.ac.uk
Twitter: drjamestate
0 20 40 60 80
012345
Speed (km.h
1
)
NOX(grams.km
1
)