DANISH EMISSION INVENTORIES FOR ROAD TRANSPORT ...

period. The increase is, however, most visible from the mid-1990s and onwards.
The vehicle numbers are summed up in EU emission layers for each year
(Figure 4.2) by using the correspondence between layers and first year of
registration:
LYear(
j)
N N
(1)
j,
y
i,
y
iFYear
( j)
Where N = number of vehicles, j = layer, y = year, i = first year of registration.
Weighted annual mileages pr layer are calculated as the sum of all mileage
driven pr first registration year divided by the total number of vehicles in
the specific layer.
LYear(
j)
N
j,
y
i,
y
iFYear
( j)
LYear(
j)
M
i,
y
iFYear
( j)
i,
y
M (2)
N
Since 2006 economical incentives were targeted at private vehicle owners to
encourage them to buy Euro 5 diesel passenger cars and vans in order to
bring down the particulate emissions from diesel vehicles. The estimated
sales between 2006 and 2010 have been examined by the Danish EPA and
are included in the fleet data behind the Danish inventory (Winther, 2011).
For heavy duty trucks, there is a slight deviation from the strict correspondence
between EU emission layers and first registration year. In this case, specific
Euro class information for most of the vehicles from 2001 onwards is incorporated
into the fleet and mileage data model developed by Jensen and
Kveiborg (2011). For inventory years before 2001, and for vehicles with no
Euro information the normal correspondence between layers and first year
of registration is used.
Vehicle numbers and weighted annual mileages pr layer are shown in Annex
1 and 2 for 1990-2010. The trends in vehicle numbers pr layer are also
shown in Figure 4.2. The latter figure shows how vehicles complying with
the gradually stricter EU emission levels (EURO I, II, III etc.) have been introduced
into the Danish motor fleet.
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