1.A.3.b vi - Road Transport: Automobile Tyre and Brake Wear

Last updated on 09 Mar 2017 09:41 (cf. Authors)

Short description

In sub-categories 1.A.3.b vi - Road transport: Automobile tyre and brake wear emissions from automobile tyre and brake wear in RT are reported. Therefore, these sub-category is an important source for a) particle emissions and b) emissions of heavy metals, POPs etc. included in these particles.

NFR-Code Name of Category Method AD EF Key Category for (by1)
1.A.3.b vi Automobile tyre and brake wear T1, T3 NS, M CS PM2.5 (L/T), PM10 (L/T), TSP (L), Pb (L)

Method

Activity Data

For detailed mileage data, please see superordinate chapter.

Emission factors

The tier1 emission factors used here have been derived within a literature study in 2006. During this study, average amounts of particulate wear per km and for different types of brakes or tyres ( = EFPM - specific) were derived from which annual amounts of PM emissions can be estimated as follows:

(1)
\begin{gather} EM(PM)_\text{ annual, type of vehicle} = EF(PM)_\text{ specific, per km} \cdot Mileage_\text{ annual, type of vehicle} \end{gather}
Table 1: Average wear rates [mg TSP / vehicle km] for different types of road vehicles
Ø Wear rate for…
Vehicle type …tyres …brakes
Passenger Cars 90 14
Motorcycles 45 7
Mopeds 23 3.5
Light Duty Vehicles 150 29
Heavy Duty Vehicles 600 67
thereof: Trucks 800 67
thereof: Buses 500 67

Based on average contents of heavy metals in tyres and brakes per gram of emitted particulate matter (also derived during the literature study), emission factors for HM and PAHs were estimated as follows:

(2)
\begin{gather} EF(HM)_\text{ per km, type of vehicle} = EM(PM)_\text{ per km, type of vehicle} \cdot ØHM-content_\text{ type of brake or tyre} \end{gather}
Table 2: Average heavy metal contents [mg HM / kg TSP] in particulate matter from tyre and brake wear
Ø HM content in particulate matter from…
…tyre wear …brake wear
HM all vehicles PC & LDV HDV: Truck HDV: BUS MTW
Cd 2 11 0 0 11
Pb 14.5 8,580 180 180 8,580
Hg 0.02 0 25 25.00 0
As 1.6 9 42 42.00 9
Cr 1.8 130 5,400 5,400 130
Cu 2.8 113,400 231,000 231,000 681,000
Ni 1.8 240 335 335 240
Se 20 20 20 20 20
Zn 11,5001 36,600 9,250 9,250 36,600
Zn 19,5002

1 for PCs, LDVs and MTWs
2 for all HDVs

From these PM-based emission factors, emission estimates for HM and PAHs are estimated as follows:

(3)
\begin{gather} EM(HM)_\text{ annual, type of vehicle} = EF(HM)_\text{ per km, type of vehicle} \cdot Mileage_\text{ annual, type of vehicle} \end{gather}

In contrast to passenger cars, LDVs and HDVs, as there are no aggregate HM or PAH contents available for motorized two-wheelers as a whole but for mopeds and motorcycels separately, and as estimates have to be provided as sum for all motorized two-wheelers (MTWs) within the NFR tables, the emission factors applied here represent annual implied values.
These IEFs display weighted values calculated from the named specific tier1 EFs for mopeds and motorcycles and the annual mileages for both kind of motorized two-wheelers.

(4)
\begin{gather} IEF_\text{ annual, MTWs} = (EF_\text{ mopeds} \cdot Mileage_\text{ annual, mopeds} + EF_\text{ motorcycles} \cdot Mileage_\text{ annual, motorcycles}) / Mileage_\text{ annual, mopeds + motorcycles} \end{gather}

Here, as the mopeds : motorcycles mileage ratio changes annually, the IEFs change on an annual basis, too. (As these changes occur in the fourth decimal place or later, they are not diplsayed in the overview tables below.)

Table 3: Overview of the emission factors applied
Material Tyre Wear Brake Wear
Vehicle type PCs LDVs HDVs Buses MTWs1 PCs LDVs HDVs Buses MTWs1
Particulate Matter [mg/km]
PM2.5 4.49 7.10 18.90 18.90 1.93 2.93 4.56 12.74 12.74 1.44
PM10 6.40 10.10 27.00 24.30 2.80 7.35 11.47 32.00 28.80 3.63
TSP 10.70 16.90 45.00 45.00 4.60 7.50 11.70 32.65 32.65 3.70
Heavy Metals [µg/km]
Priority HM
Pb 1.31 2.18 8.70 7.25 0.56 120.00 249.00 12.00 12.00 51.11
Hg 0.002 0.003 0.012 0.010 0.001 0.00 0.00 1.68 1.68 0.00
Cd 0.18 0.30 1.20 1.00 0.08 0.15 0.32 0.00 0.00 0.07
Other HM
As 0.14 0.24 0.96 0.80 0.06 0.13 0.26 2.81 2.81 0.05
Cr 0.16 0.27 1.08 0.90 0.07 1.82 3.77 361.80 361.80 0.77
Cu 0.25 0.42 1.68 1.40 0.11 1,588 3,289 15,477 15,477 4,056
Ni 0.16 0.27 1.08 0.90 0.07 3.36 6.96 22.45 22.45 1.43
Se 1.80 3.00 12.00 10.00 0.80 0.28 0.58 1.34 1.34 0.12
Zn 1,035.00 1,725 11,700 9,750 442 512 1,061 620 620 218
POPs [µg/km]
PCDD/F NA NA NA NA NA NA NA NA NA NA
PAH
B[a]P 0.03 0.05 0.13 0.12 0.01 NA NA NA NA NA
B[b]F 0.04 0.06 0.16 0.14 0.02 NA NA NA NA NA
B[k]F IE IE IE IE IE NA NA NA NA NA
I[..]P 0.02 0.02 0.08 0.07 0.01 NA NA NA NA NA
∑ PAHs 1-4 0.09 0.14 0.38 0.34 0.04 NA NA NA NA NA

1 motorized two-wheelers: annual implied EF as used for 2015 estimates

Discussion of emission trends

(emissions from wear/abrasion only; no fuel combustion included)

NFR 1.A.3.b vi - Emissions from Tyre and Brake Wear is key source for emissions of PM2.5, PM10, TSP and Lead (Pb).

All reported emissons from tyre and brake wear are connected directly to the mileage driven by the road vehicles covered.

Particulate Matter - PM2.5, PM10,TSP and BC

Selected heavy metals - Chromium, Nickel and Zinc

The emissions of heavy metals are as well linked directly to the trend of mileage.

Recalculations

All non-annual tier1 EFs applied remain unchanged. In contrast, some insignificant changes occured to the annual IEFs applied to motorized two-wheelers.
Overall, recalculations were carried out almost exclusively due to the regular the revision of the mileage data modelled in TREMOD. (see superordinate chapter for recalculated mileage data).

For information on the impacts on 1990 and 2014 emission estimates, please see the pollutant specific recalculation tables following chapter 8.1 - Recalculations.

Uncertainties

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". For detailled information, please refer to the project's final report here (German version only!)

Uncertainty estimates for emission factors were compiled during the PAREST research project. Here, the final report has not yet been published.

Planned improvements

At the moment, no category specific improvements are planned.

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