Calculating willingness to pay (WTP) is especially important when
carrying out profitability studies. Feasibility studies for
underground car parks are an example of the importance of the
correct evaluation of WTP. The profitability of the car park has to
be calculated as exactly as possible to provide information at the
time of tendering for its construction and franchise.
Willingness to pay is known to be very sensitive to model
specification. At first, even in small towns, paid parking places
can prove to be very unpopular with most people. Street space
is a scarce commodity belonging to everyone and should be
charged for when used individually just like other public
property.
Space is critical in areas of high commercial and demographic
concentration such as city centres. In Europe parking places are
normally regulated by using blue zones (regulation of space and
waiting time) and public car parks (regulation by fee), which can
be located either on the surface or underground. Rather than being
profit orientated, policies for regulating street parking should be
aimed at improving traffic flow, favouring the rotation of parking
spaces and freeing up areas for loading and unloading at certain
times. Therefore, when new urban projects are started, such as
shopping centres, cinemas or buildings for other leisure activities,
any public and private projects should include a study on the need
for parking places and their probable effects on traffic flow in and
around the site location.
The closest study to this work is that of Axhausen and Polak,1
which models parking choice using a stated preference survey. A
similar study can be found in the article by Hensher and King.2
Various types of parking were used in a study by Van der Goot3 in
which a logit model was applied to model the choice of parking as
a function of attributes. Other relevant studies on modelling user
behaviour when parking are those of Hunt,4 Ergu¨n5 and Gillen6 in
which no mention is made of the correct calculation of WTP nor
the problem of its variability with respect to the specification of
the utility functions during the design of the discrete choice
models. In fact none of the above-mentioned works highlight this
latter problem.
The international literature also provides many examples of
studies made on the impact of parking pricing policies,7–10
parking simulation models such as Pamela11 and the development
of parking choice models for special events such as in the article
by Sattayhatewa and Smith.12
Interesting work has also been done on car parks and
accessibility such as that of Ferguson13 who studied user
responses to changes made in the supply, location, price and
accessibility of parking.
With the exception of the study by Hess and Polak,14 no other
relevant studies are known which try to model user behaviour
when choosing between different types of parking and which also
calculate WTP to save time to final destination.
The objective of this investigation was to simulate user behaviour
when parking. A stated preference survey was used to present the
user with different situations. A trial was made at introducing
random ranges into the levels of the variables used in the design of
a stated preference survey and a study was made of their effects on
willingness to pay.
The study and modelling of user behaviour using discrete
choice models allows a calculation to be made for the user’s
willingness to pay in exchange for quicker or improved access
to final destination. Willingness to pay is a fundamental
variable which is used, or should be used, in the social and
economic assessment of construction projects and the running
of car parks because it provides a sufficiently clear idea of the
correct tariff to charge and takes into account other points of
importance to the user. There are several relevant studies on
this subject.
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