1.A.3.b Road Transport

Last updated on 04 Dec 2014 08:38 (cf. Authors)

Short description

In category 1.A.3.b - Road Transport emissions from fuel combustion activities as well as abrasive and fugitive emissions are reported within the following categories:

NFR-Code Name of Category Method AD EF Key Source for (by1)
1.A.3.b Road Transport (RT) T1, T2, T3 NS CS see sub-categories
consisting of / including sub-categories
Emissions from Fuel Combustion
1.A.3.b i Passenger Cars T12, T3 NS CS NOx (L/T), NMVOC (L/T), CO (L/T), PM2.5 & PM10 (L/T)
1.A.3.b ii Light Duty Vehicles T3 NS CS NOx (L), PM2.5 (L/T), PM10 (T)
1.A.3.b iii Heavy Duty Vehicles T23, T3 NS CS NOx (L/T), PM2.5 (L/T), PM10 (T)
1.A.3.b iv Mopeds & Motorcycles T3 NS CS no key source
Fugitive emissions in RT
1.A.3.b v Gasoline Evaporation T3 NS CS NMVOC (T)
Emissions from wear & abrasion in RT
1.A.3.b vi Automobile Tyre and Brake Wear T3 NS CS PM2.5 (L), PM10 (L/T), TSP (L), Pb (L/T)
1.A.3.b vii Automobile Road Abrasion T3 NS CS PM2.5 & PM10 & TSP (L)

1 T = key source by Trend / L = key source by Level
2 T1: lubricants: tier1 activity data
3 T2: petroleum: tier2 activity data

Abbreviations used below as well as in the following chapters on road transport for the different types of vehicles:

  • PCs - Passenger Cars
  • LDVs - Light Duty Vehicles
  • HDVs - Heavy Duty Vehicles (if not reported separatly: including buses)
  • MCs - Motorcycles (if not reported separatly: including mopeds)

Emissions from motorised road traffic in Germany are reported under this category. It includes traffic on public roads within Germany, except for agricultural and forestry transports and military transports. Calculations are made for the vehicle categories of passenger cars, motorcycles, light duty vehicles, heavy duty vehicles and buses. For calculation purposes, the vehicle categories are broken down into so-called vehicle layers with the same emissions behaviour. To this end, vehicle categories are also broken down by type of fuel used, vehicle size (trucks and buses by weight class; automobiles and motorcycles by engine displacement) and pollution control equipment used, as defined by EU directives for emissions control ("EURO norms"), and by regional traffic distribution (outside of cities, in cities and autobahn).

Since 1990, emissions of NOx, CO, NMVOC and SO2 from road transports have decreased sharply, due to catalytic-converter use and engine improvements resulting from continual tightening of emissions laws, and due to improved fuel quality.

For buses and heavy duty vehicles (over 3.5 t total permissible vehicle weight), maximum permissible levels of hydrocarbon (HC, incl. NMVOC) emissions were lowered especially sharply (-40%) via the introduction of the EURO3 standard in 2000. Since EURO3 vehicles were very quick to reach the market as of 2000, the emission factor for hydrocarbon emissions from diesel fuel - and the relevant emissions themselves – decreased considerably after 2000.


Emissions are calculated with the aid of the TREMOD model ("Transport Emission Estimation Model" v5.4) from (ifeu, 2013) [1]. That model adopts a "bottom-up" (tier3) approach whereby mileage of the individual vehicle layers is multiplied by region-specific emission factors. For passenger cars and light duty vehicles, a “cold start surplus” is also added. The total consumption calculated on the basis of fuel type is compared with the consumption according to the Energy Balance. The emissions are then corrected with the aid of factors obtained from this comparison process. For petrol-powered vehicles, the evaporation emissions of VOC are calculated in keeping with the pollution-control technology used. From the emissions and fuel consumption for the various vehicle layers, aggregated, fuelbased emission factors (kg of emissions per TJ of fuel consumption) are derived, and then the emission factors are forwarded to the CSE via a relevant interface. In keeping with the CORINAIR report structure, these factors are differentiated only by type of fuel, type of road (autobahn, rural road, city road) and, within the vehicle categories, by "without/with emissions-control equipment". The following emissions-control categories are differentiated:

Table 1: Differentiation of emissions-control categories in road transports

Emissions-control system without with
PCs / LDVs with gasoline engines without catalytic converter with catalytic converter
PCs / LDVs with diesel engines, buses, HDVs, MCs before Euro1 standard after Euro1 standard

For calculation with TREMOD, extensive basic data from generally accessible statistics and special surveys were used, co-ordinated, and supplemented. An overview of the principal sources and key assumptions is given below. Detailed descriptions of the databases, including information on the sources used, and the calculation methods used in TREMOD, are provided in the aforementioned IFEU report.

Activity Data

The basis for CSE data collection for the road-transport sector consists of fuel consumption data provided by the Working Group on Energy Balances (AGEB). For each year, the sum of the activity rates for the various individual structural elements must correspond to the Energy Balance data, in TJ. The relevant basic Energy Balance data is shown in the table below.

Table 2: Fuel consumption in German road transport

Gasoline Diesel oil Biodiesel Bioethanol LPG CNG Petroleum
1990 1,330,479 735,920 0 0 138 0 0
1991 1,332,285 785,174 0 0 137 0 0
1992 1,344,129 853,502 0 0 229 0 0
1993 1,350,617 907,787 0 0 184 0 473
1994 1,276,637 932,060 0 0 184 0 559
1995 1,299,982 964,013 1,504 0 138 0 610
1996 1,299,879 964,580 2,046 0 115 0 638
1997 1,297,487 979,586 3,652 0 106 0 357
1998 1,300,463 1,022,794 4,081 0 106 0 637
1999 1,300,602 1,097,036 5,370 0 100 0 637
2000 1,237,055 1,108,105 12,276 0 94 0 414
2001 1,199,318 1,097,416 16,740 0 569 0 471
2002 1,166,381 1,105,842 20,460 0 607 0 472
2003 1,108,989 1,078,352 29,948 0 694 0 0
2004 1,072,720 1,110,931 38,806 1,144 1,887 0 0
2005 992,377 1,078,620 71,824 6,817 2,357 3,127 0
2006 930,834 1,082,042 130,165 13,418 4,605 4,446 0
2007 892,982 1,073,987 143,235 12,061 8,942 5,845 0
2008 854,002 1,102,623 109,393 16,328 15,652 7,144 0
2009 829,227 1,114,939 89,375 23,691 23,842 8,443 0
2010 791,416 1,168,063 88,886 30,577 21,823 8,768 0
2011 787,803 1,197,252 82,810 32,292 23,613 8,771 0
2012 739,659 1,220,797 85,485 32,778 24,591 8,934 0

Source: Evaluation tables of the Energy Balances, "Mineralölzahlen" ("Petroleum Data") of the Association of the German Petroleum Industry (MWV) and "Amtliche Mineralöldaten" ("Official Petroleum Data", BAFA).

Derivation of activity rates

Cross-check with Energy Balance

The Energy Balance is also used to model transport-quantity structures in TREMOD. For example, the German Economic Institute (DIW) carries out a fuel-consumption calculation in order to derive total mileage travelled (DIW, 2002). Some of the results of the calculation, for automobile transports, are entered into TREMOD. The DIW uses a fuel-consumption calculation in order to determine total domestic mileage; TREMOD uses some other sources and assumptions to estimate total domestic mileage – especially for goods transports (cf. the detailed description in IFEU, 2002). This estimate also takes the basic figures of the Energy Balance into account.

On the other hand, due to the many dependencies and uncertainties in the model, and to the basic data that must be taken into account, no feasible means is available for comparing mileage and energy consumption, for each year and each vehicle layer, in such a manner that the results yield the Energy Balance sum and the mileage and average energy consumption figures in the time series are plausible. For this reason, the TREMOD results for the fuel consumption are corrected, at the end of the process, in such a manner that the total for each reference year corresponds to the relevant figure in the Energy Balance.

Since TREMOD calculates fuel consumption in tonnes, the results first have to be converted into Terrajoule [TJ]. For this purpose the net calorific values of the Working Group on Energy Balances (AGEB) are used.

Table 3: Net calorific values for gasoline and diesel oil

Year Gasoline Diesel Oil
1990-1992 43.543 MJ/kg 42.704 MJ/kg
since 1993 43.543 MJ/kg 42.960 MJ/kg

Source: Working Group on Energy Balances (Arbeitsgemeinschaft Energiebilanzen)

The correction factors are derived in TREMOD separately for the various vehicle categories, as follows:

  • Firstly, a correction factor for gasoline is derived from the calculated petrol consumption for all vehicle categories and from petrol sales pursuant to the Energy Balance.
  • The correction factor for gasoline is then also used to bring fuel consumption of vehicles with diesel engines, among automobiles and other vehicles ≤ 3.5 t (light duty vehicles (LDV), and of motor homes and motorcycles (MC)), in line with the Energy Balance.
  • The difference between the corrected diesel-fuel consumption of automobiles and of other vehicles ≤ 3.5 t and the Energy Balance is then allocated to heavy duty vehicles and busses.
  • The correction factor for heavy duty vehicles and busses is then calculated from their energy consumption, as calculated in accordance with the domestic principle, and the pertinent difference, as calculated for this group, from the Energy Balance.

Table 4: Correction factors for adjustment of TREMOD estimates to the National Energy Balance

Gasoline Diesel oil
(incl. Bioethanol) (incl. Biodiesel)
Area PC, LDV, 2W PC, LDV HDV, Bus
1990 OGL 1.038 1.038 1.115
1990 NGL 1.066 1.066 1.420
1991 OGL 1.035 1.035 1.110
1991 NGL 1.061 1.061 1.015
1992 OGL 1.039 1.039 1.189
1992 NGL 0.997 0.997 1.200
1993 OGL 1.042 1.042 1.191
1993 NGL 0.976 0.976 1.301
1994 OGL 0.984 0.984 1.181
1994 NGL 0.984 0.984 1.181
1995 GER 0.996 0.996 1.205
1996 GER 0.997 0.997 1.183
1997 GER 0.993 0.993 1.186
1998 GER 0.985 0.985 1.248
1999 GER 0.986 0.986 1.308
2000 GER 0.955 0.955 1.337
2001 GER 0.941 0.941 1.240
2002 GER 0.935 0.935 1.199
2003 GER 0.921 0.921 1.140
2004 GER 0.927 0.927 1.088
2005 GER 0.916 0.916 1.083
2006 GER 0.896 0.896 1.118
2007 GER 0.889 0.889 1.061
2008 GER 0.892 0.892 1.053
2009 GER 0.887 0.887 1.093
2010 GER 0.879 0.879 1.128
2011 GER 0.891 0.891 1.096
2012 GER 0.888 0.888 1.176

Source: TREMOD 5.4 [1]

Allocation of biofuels, petroleum and LPG to the structural elements

The Energy Balance lists data for biofuels, petroleum and LPG for the transport sector. For purposes of importing into the CSE, the results for these fuels are derived as follows:

  • Biodiesel is allocated to all structural elements with diesel engines, in keeping with their percentage shares of consumption of conventional diesel fuel.
  • Bioethanol is allocated to all structural elements with gasoline engines, in keeping with their percentage shares of consumption of conventional gasoline.
  • Petroleum is allocated to busses on roads outside of municipalities – and, thus, to the structural elements SV - BUS - KOAO and SV - BUS - MTAO – in keeping with their percentage shares of consumption of conventional diesel fuel.
  • LPG is allocated to conventional automobiles, with petrol engines, on municipal roads (CSE nomenclature: SV - PKWO - KOIO).

Activity rate for evaporation

The activity data for evaporation emissions is set as total gasoline consumption, on municipal roads, pursuant to TREMOD; the corresponding figure for mopeds is the total consumption. The values corrected for the Energy Balance are used.

Motor-vehicle-fleet data

For western Germany from 1990 through 1993, and for Germany as a whole as of 1994, car ownership was calculated on the basis of the officially published ownership and new registration statistics of the Federal Motor Transport Authority (KBA). The car ownership analysis for East Germany in 1990 was based on a detailed analysis of the Adlershof caremissions-testing agency in 1992 and the time series in the statistical annuals of the GDR. For the period between 1991 and 1993, it was necessary to estimate the figures with the aid of numerous assumptions.

Fleet data for the TREMOD model, for the reference years 2001 through 2003, are obtained from the database of the Federal Motor Transport Authority (KBA). The supplied data include vehicle fleets for each reference year, broken down as required for emissions calculation, i.e. in accordance with the following characteristics: type of engine (petrol, diesel, other), size class, vehicle age and emissions standard. For each reference year, the mid-year fleet is assumed to be representative of the fleet's composition for the year. The fleet figures for the years 2004 through 2007 were calculated with the help of a fleet-shifting module in TREMOD that extrapolates past fleet-growth trends.


Mileage data were updated on the basis of the "2002 mileage survey" ("Fahrleistungserhebung 2002"; Institute of Applied Transport and Tourism Research (IVT, 2004 [3]), the "2005 road-transport census" "Straßenverkehrszählungen 2005"; Federal Highway Research Institute (BASt), 2007 [4]) and data on growth of transports on federal highways (BASt, 2008).

Shifting of fuel purchases to other countries

Because fuel prices in Germany are higher – significantly, in some cases – than in almost all of Germany's neighbours (Denmark is the only exception), for some time the fuels used in Germany have included fuels purchased in other countries and brought into the country as "grey" imports.

At present, no precise data are available on this phenomenon, which is significant for Germany's border regions and which is referred to as "refuelling tourism" ("Tanktourismus"). Although several detailed studies have been carried out, no reliable overall picture of the situation is yet available (cf. LENK et al., 2005 [5]). The sources that have documented shifting of consumers' fuel purchases to other countries (along with the resulting negative impacts on neighbouring countries' own emissions inventories) have included a study published by the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management (BMLFUW, 2005 [6]).

Emission factors

All emission factors are listed in the "Handbook Emission Factors for Road Transport 3.1" ("Handbuch für Emissionsfaktoren des Straßenverkehrs 3.1") (INFRAS, 2011 [2]), a reference work prepared via co-operation, between Germany, Switzerland, Austria and the Netherlands, in derivation of emission factors for road traffic. The emission factors in the manual originate predominantly from the measurement programmes of TÜV Rheinland (TÜV, Technical Control Association) and RWTÜV. Those programmes have included fundamental surveys for the reference years 1989/1990. In those surveys, a new method was used, for both passenger cars and heavy duty vehicles, whereby emission factors were derived according to driving habits and the traffic situation. Within the context of field monitoring data, the passenger-car emission factors were updated for cars produced up to 1994. Version 2.1 of the "Emission-factor manual for road transports", which is used for the current emissions calculations, draws on findings of the EU working group COST 346 and the ARTEMIS research programme. The emission factors are derived from the development of the various vehicle layers and from the data provided by the "Emission-factor manual for road transports". The emissions reduction achieved via the introduction of sulphur-free fuels was estimated by the Federal Environment Agency.

Derivation of emission factors

Emission factors from TREMOD

In the CSE, emission factors for the "engines" ("Antrieb") category are listed in [kg/TJ], while those for the "Evaporation" category are given in [kg/t]. For gasoline, diesel oil, LPG and CNG, these values can be derived from TREMOD for all structural elements. To this end, emissions (in tonnes) and energy consumption (in [TJ]; converted from the results "energy consumption in t", using the net calorific values) are derived from the TREMOD results and allocated to the relevant structural elements. The emission factor for each structural element then results as the quotient resulting from emissions, in tonnes per structural element, divided by the energy consumption, per structural element, in [TJ].

A similar procedure is used to obtain the emission factors for fugitive emissions, in [kg/consumption on municipal roads], in [t]). For purposes of this derivation, TREMOD results without correction to the Energy Balance are used, since such correction is already contained in the activity data for the CSE. Use of the corrected values (emissions and energy consumption) leads to the same results, however, since the correction factor cancels out in calculation of mean emission factors (emissions corrected / energy corrected = emissions uncorrected / energy uncorrected).

Emission factors for biodiesel, bioethanol, petroleum, Liquefied Petroleum Gas (LPG), and Compressed Natural Gas (CNG)

The emission factors for biodiesel and petroleum are set at the same values as those for conventional diesel fuel. The emission factors for bioethanol are set at the same values as those for conventional gasoline.


  • The SO2 emission factor for petroleum is set to 24 kg/TJ for those years in which diesel fuel has a higher value. In all other years, the lower value for diesel fuel is used.
Derivation of data for western and eastern Germany, 1994

TREMOD distinguishes between old and new German Länder only until 1993. Since the CSE also requires such differentiation for 1994, a relevant breakdown must be made using simplifying assumptions. The framework conditions include:

  • The sum total of activity rates for engines (Antrieb) must correspond to the relevant Energy Balance values (in each case, old and new German Länder).
  • In the overall result, emissions resulting from linking activity rates with emission factors must correspond to the TREMOD results for Germany.
  • With these framework conditions, the present study can carry out a relevant breakdown only under the following assumptions:
  • The emission factors for old and new German Länder are set, for all structural elements, to the relevant values for all of Germany in 1994.
  • The structural elements' percentage shares of the activity rates, for each fuel, are considered to be the same in each case for the old and new German Länder, and they are the same as the relevant values for all of Germany in 1994.

With these assumptions, the aforementioned conditions are fulfilled. A third condition is not fulfilled, however: the plausibility of emissions results in the time series, in each case, for the old/new German Länder.

Emission trends in road transport

Whereas emission trends for nitrogen oxides (NOx), NMVOC, and carbon monoxide (CO) depend on the coming into force of the diferent EURO regulations, ongoing technical developments (engines, catalysts etc.) the trend chart for sulphur dioxide (SO2) shows a totally different charcteristics: Here, the strong dependence on increasing fuel qualities (sulphur content) leads to an cascaded downward trend, influenced only slightly by increases in fuel consumption and mileage. - The ammonia emissions chart varies significantly. Here, the increasing use of catalytic converters in gasoline driven cars in the 1990s lead to a steep increase of ammonia emissions whereas both the technical development of the converters and the ongoing shift from gasoline to diesel cars result in decreasing emissions in the following years.

Emissions of particulate matter in road transport result from (i) fuel combustion and (ii) tyre and brake wear and road abrasion.
With implemetation of particle filter systems and the ongoing increase of annual mileage, today


Uncertainty estimates for activity data of mobile sources derive from research project FKZ 360 16 023: "Ermittlung der Unsicherheiten der mit den Modellen TREMOD und TREMOD-MM berechneten Luftschadstoffemissionen des landgebundenen Verkehrs in Deutschland" by (ifeu & INFRAS 2009) [8]. - For detailled information, please refer to the project's final report here (German version only!)

Uncertainty estimates for emission factors for all 1.A.3.b sub-categories were compiled during the PAREST research project. Here, the final report has not yet been published.

Planned improvements

See sub-category chapters.


Recalculations were carried out impacting all sub-categories and all pollutants due to the routine revision of the TREMOD software as well the CSE data warehouse.

The revision of the approach for LPG and CNG used in road transport was finalised resulting in recalculated CNG data for 2005 to 2009. In addition, given the emission factors provided in the EMEP/EEA guidebook 2013 (EMEAP/EEA 2013) [7], this inventory, for the first time, inlcudes heavy metal exhaust emissions besides the already considered lead fom leaded gasoline (until 1997). - For details see the sub-category chapters linked above.

For pollutant specific information on qualitative and quantitative impacts on 1990 and 2011 emission estimates see chapter 11. Recalculations and the following chapters.


See sub-category chapters.

1. ifeu, 2013: Knörr, W. et al., IFEU - Institut für Energie- und Umweltforschung Heidelberg gGmbH: Fortschreibung des Daten- und Rechenmodells: Energieverbrauch und Schadstoffemissionen des motorisierten Verkehrs in Deutschland 1960-2030, sowie TREMOD 5.4, im Auftrag des Umweltbundesamtes, Berlin.
2. INFRAS, 2011: Handbook Emission Factors for Road Transport, version 3.1 (Handbuch Emissionsfaktoren des Straßenverkehrs 3.1) URL: http://www.hbefa.net/e/index.html - Dokumentation, Bern, January 2011
3. IVT 2004: Institut für angewandte Verkehrs- und tourismusforschung e.V.: Fahrleistungserhebung 2002, Teil: Begleitung und Auswertung. Untersuchung im Auftrag der Bundesanstalt für Straßenwesen, Projektnummer FE 82.201/2001. Heilbronn/Mannheim.
4. BASt, 2007: Bundesanstalt für Straßenwesen: Unterreihe Verkehrstechnik; V 164: "Straßenverkehrszählung 2005: Ergebnisse", Thorsten Kathmann, Hartmut Ziegler, Bernd Thomas; 62 Seiten; Bergisch Gladbach, 2007
5. LENK et al., 2005: Auswirkungen des Tanktourismus auf das deutsche Steueraufkommen – eine finanzwissenschaftliche Bestandsaufnahme; Leipzig, 2005
6. BMLFUW, 2005: Abschätzung der Auswirkungen des Tanktourismus auf den Treibstoffverbrauch und die Entwicklung der CO2-Emissionen in Österreich.;Bundesministerium für Land- und Forstwirtschaft, Umwelt und Wasserwirtschaft; Wien; 2005
7. EMEP/EEA 2013: EMEP/EEA air pollutant emission inventory guidebook – 2013
8. ifeu & INFRAS, 2009: IFEU – Institut für Energie- und Umweltforschung Heidelberg gGmbH und INFRAS Zürich: Ermittlung der Unsicherheiten der mit den Modellen TREMOD und TREMOD-MM berechneten Luftschadstoffemissionen des landgebundenen Verkehrs in Deutschland, FKZ 360 16 023, Heidelberg & Zürich.
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