Energy Efficiency of Passenger Transport in Poznan Agglomeration in the Face of Peak Oil - Technology Management for Sustainable Production and Logistics - page 162

the consumption level considerably. The author's research from 2008 indicates
that average yearly congestion level in Poznan during morning rush hours between
7 and 9 a.m., calculated by means of travel time index (TTI) was 2.36 (Igli´ski
2008 ). It means that each journey during morning rush hours in Poznan was
almost 2.5 times longer than in free flow traffic conditions. At that time, further
research was carried out on the relationship between fuel consumption and travel
time (traffic congestion level).
At free flow traffic conditions and warmed up engine and without any load
(apart from the driver), a test vehicle (1,599 cm 3 capacity, 83 kW max power out-
put) used ca. 6 l of petrol per 100 km. 8 However, in normal conditions the con-
sumption rose to 9 l/100 km and in very high level of traffic congestion, which
was also the case, the consumption rose to as much as 12-14 l/100 km. The rela-
tion between fuel consumption and travel time is described by a linear function:
y = 0.0066x + 4.1043 at coefficient of determination R 2 = 0.87, in which y—
consumption volume (l/100 km) and x—travel time(s) (Igli´ski 2008 ).
There are no detailed data on traffic congestion in Poznan district, where the
congestion level is lower than in Poznan itself. Similarly, there are no data on the
traffic on roads connecting Poznan with Poznan district, especially main roads,
where the traffic congestion level is very high. Most transportation is carried out in
Poznan and between Poznan and Poznan district. Because of the ca. 25 % growth
in number of cars registered in Poznan agglomeration since the 2008 study, the
author assumes that during traffic rush hours, when the highest number of obliga-
tory journeys takes place, the mean TTI in Poznan agglomeration is 2.0. At this
level of traffic congestion, the mean consumption of fuel rises by around 35 % in
comparison to free flow traffic conditions (Table 4 ).
So the values of weighted arithmetic mean (taking into consideration the num-
ber of vehicles in a given group (Table 4 )) for fuel consumption in passenger cars
in Poznan agglomeration are: 9.3 l/100 km for petrol-fuelled cars and 7.8 l/100 km
for diesel-fuelled cars. 9 Within one day and for a distance of 15.8 km the total con-
sumption of fuel is 521.5 thousand l of petrol and 205 thousand l of diesel. The
heating value of one l of petrol is 9.7 kWh and of diesel fuel—10.7 kWh so the
energy expenditure necessary for transport performance of 100 pkm in a passenger
car in Poznan agglomeration is 62.9 kWh.
This means that passenger car transport (62.9 kWh/100 pkm) is two times less
effective than by bus (29.2 kWh/100 pkm) and four times less effective than by
8 The section of 5 km in length, on which the research was conducted is a dual carriageway with
two or three lanes and a speed limit of between 50 and 80 km/h, with long distances between
crossings (a few of them being elevated road intersections). So driving along this section corre-
sponds to a combined driving rather than just city driving mode.
9 It must be added that an average car in Poland is 16 years old. In Pozna´ agglomeration, it is a
bit lower due to high economic activity and many new, company cars. Still, an average car is over
ten years old. Not all the cars are roadworthy, either, and more and more cars have air condition-
ing, which influences the fuel consumption level, so as a result, the actual consumption may be
even higher.