Environmental Engineering Reference
In-Depth Information
Fig. 7 Different types of
shopping trip chains
(Gonzalez-Feliu et al.
2012a
)
Other
3
Household
Household
Household
2
Retailers
1
The model proposed focuses on trip attraction rates, i.e. the number of trips that
arrive at a zone for shopping purposes. This is done by assuming that all trips
arriving at a retailing activity for shopping purposes are connected to a second trip,
i.e., a purchasing activity is never the final point of a trip chain (see Fig.
7
):
Figure
7
illustrates different trip chains focusing only on shopping trips that are
related inside a given zone. As stated in Gonzalez-Feliu et al. (
2010a
), a shopping
trip is related to a succession of trips with different purposes, and we feel that bit is
important to see them as a part of a more complex trip structure that can be called
the trip chain. From these considerations, we propose to generate shopping trip
attraction according to the general methodology discussed in Cubukcu (
2001
); the
number of private car shopping trips T
j
attracted by a zone j can be formulated as
follows: T
j
¼
f Ret
j
;
X
j
; where: T
j
is the total number of shopping trips attracted
to zone j; Ret
j
the set of retailing activity characteristics vector in section j and X
j
the set of socioeconomic characteristics of the people and households belonging to
section j.
The trip attraction function can be defined in different ways. We propose a
multi-linear function that depends on the category of urban space (Gonzalez-Feliu
et al.
2012a
). The model can be formulated as follows:
T
CUA
j
¼
a
CUA
1
:
POP
j
þ
a
CUA
2
:
NrSMC
j
þ
a
CUA
3
:
Emp
BS
j
þ
a
CUA
4
:
CC
j
T
NP
j
¼
a
NP
1
:
POP
j
þ
a
NP
2
:
Emp
BS
j
þ
a
NP
3
:
CC
j
þ
a
NP
4
Dens
j
T
FP
j
¼
a
FP
1
:
POP
j
þ
a
FP
:
Emp
BS
j
þ
a
FP
:
CC
j
2
3
Where NrSMC is the number of small and medium stores; Emp-BS the number
of employees in the supermarkets and big commercial stores of the zone; CC is a
binary variable that indicates the presence of a shopping centre (Ségalou
1999
).
This variable takes the value 1 if at least one extra-urban shopping centre is located
inside the zone and 0 otherwise. These variables give the retailing activity char-
acteristics of the zone. Moreover, POP is the population of the given zone and
Dens the Population density of the attraction zone.
We observe from the equations that each model has a different set of variables
from the others. This has been done to provide the strongest combination related to
Search WWH ::
Custom Search