Behavioral Modeling of Urban Freight Transport - Sustainable Urban Logistics: Concepts, Methods and Information Systems - page 227

Table 1 Attribute levels and ranges used in the SRE

Attribute Number

of levels

Level and range of attribute
(Status Quo underscored)

Loading/unloading bays (LUB): 3 400, 800, 1200

Probability of free l/u bays (PLUBF): 3 10 %,20%,30%

Entrance fee (EF): 5 200€, 400€, 600€, 800€, 1000€

the stakeholders contacted (Stathopoulos et al. 2011 ). The attributes were also
validated via a pilot test with real operators. The final list included: LUB, PLUBF,
and EF. All attributes are considered as possible levers of intervention by local
decision-makers and perceived as appropriate measures for possible policy mixes
by stakeholders (Marcucci et al. 2012 ). Attributes, number of levels, and ranges
are reported in Table 1 . Attributes are all characterized by, at least, three levels
thus allowing the test of non-linear effects that represent the core of this paper and
play a special role in the evaluation of policy reactions to policy changes where
different effects can be originated by varying specific levels. Joint stakeholder as
well as local policy-makers meetings were an important source of information
concerning the attribute distribution and range. Based on the ranges provided by
the stakeholders and the comments from local planning changes the minimum and
maximum points of the attribute ranges were defined to achieve realism and
properly mirror plausible policy changes. For LUB and PLUBF the minimum
coincides with the current situation, implying that the policy scenarios only pro-
posed an increase in the levels. EF was defined having a wide range of variation in
both directions with respect to the status quo level since past policy changes have
been quite abrupt.
A SRE is adopted to test currently unavailable options. The alternatives pre-
sented to respondents, who had to rank them, include two policy options plus the
SQ alternative. Table 2 reports an example of a SRE task.
In total, 252 interviews were finalized and 229 used after removing pilot
interviews that were utilized to preliminary test the design. The sample of retailers
used for estimation consists of 90 units whose distribution is scattered in nine main
macro-freight sectors, namely: (1) food (fresh, canned, drinks, tobacco, bars, hotels
and restaurants); (2) personal and house hygiene (detergents, pharmaceuticals,
cosmetics, perfumes, watches, barbers, etc.); (3) stationery (e.g. paper, newspa-
pers, toys, books, CDs etc.); (4) house accessories (e.g. dish washers, computers,
telephones, metal products etc.); (5) car accessories (e.g. vehicle components,

Table 2 Example of a ranking task

Policy 1 Policy 2 Status Quo

Loading/unloading bays (LUB): 400 800 400

Probability of free l/u bays (PLUBF): 20 % 10 % 10 %

Entrance fee (EF): 1000€ 200€ 600€

Policy ranking h h h