Environmental Engineering Reference
In-Depth Information
Table 1
Variables needed to carry out the emission estimations and their
uncertainties
Variable Uncertainty
Actual fuel consumption L
Traffic on linear sources M
Annual average mileage for vehicle category H
Percentage of mileage travelled on each road type H
Average speed on each road type H
Average length of a single trip H
Average temperatures L
Number of vehicles in each category L
L = low uncertainty, indicating a variable obtained from continuous measure-
ments; M = medium, indicating a variable obtained from measurements in
specific periods extended to the whole year; H = high, indicating estimations
ACI (the Italian Automotive Association) provides the number of registered vehi-
cles and the fleet composition at municipality level
[5]
. The Italian Association of
Oil Companies reports the fuel sold in each province in annual oil market bulletins
[6]
. APAT (the Italian Agency for Environmental Protection) provides studies on
transportation in Italy and information about the average mileage and the average
speed of each vehicle category and on each road type
[7]
. The base year of the
emission inventory is 2006. According to the European Directive 98/70/EC fuels
must have specific properties in order to protect human health. Therefore the fuel
typology used for the emission calculation is the Fuel 2005. Data about the number
of vehicles regularly registered have been corrected through percentage reductions
(suggested by APAT) to be applied to vehicles PRE EURO, necessary to represent
vehicles actually circulating in Italy. The average length of a trip in Italy is 12 km,
as suggested by COPERT. The values of others variables, such as the average speed
on each road type and the percentage of mileage traveled on each of road type, have
been obtained from studies on transportation (APAT). The emissions due to cold
starts were calculated considering minimum and maximum temperatures for each
month in Naples municipality.
Results
As a result of the elaboration of the acquired data, the composition of circulating
vehicle fleet in Naples municipality and the average mileage estimates in terms of
kilometers covered by each vehicle category [Vehic*Km] for year 2006 are reported
in Table
2
. The estimate of the average mileages, as well as the average speeds, has
been validated at the end of the iterative procedure, when the error for the estima-
tion of fuel consumption compared with the fuel sold in Naples municipality was
been considered acceptable. In order to calculate the fuel sold in Naples municipality,
