Time Constraints: The Cost of Sustainability - Sustainable Urban Logistics: Concepts, Methods and Information Systems - page 162

and the lack of national or regional bodies dealing with city logistics, as there exist
for urban passenger traffic, is significant.
Still, the distribution of goods in urban environments is an everlasting problem
for most municipalities (Dablanc 2007 ), and many different tools or solutions are
available for them to improve the efficiency of the system (Muñuzuri et al. 2005 ).
The use of these solutions to deal with urban logistics issues does not necessarily
mean bigger benefits for logistic companies, but rather and attempt to better
regulate and manage freight deliveries in urban areas. The ultimate objective is the
reduction of the clash between the interests of logistic companies and those of
other stakeholder groups (residents, workers, retailers, etc.) involved in urban
mobility. And the usual outcome of this scenario in municipal regulations is a
series of restrictions imposed on delivery vehicles, in order to reduce their effect
on the overall urban congestion levels and parking problems.
In order to reduce urban freight traffic movements in towns, municipalities have
a powerful policy measure in accessibility regulations, which establish when and
how delivery vehicles may access the innermost areas of the city, which are
usually the most congested ones but also the ones concentrating (at least in Eur-
ope) higher levels of commercial and business activities, and thus requiring higher
amounts of goods and higher numbers of deliveries. For many years, access time
window regulations have been seen as the most popular answer to avoid urban
freight transport traffic inside the city centre.
Access time windows as a policy measure implies that a specific group of urban
road users is only allowed to enter the city center, a specific area or a given street
during a specified time interval. Outside that access time window, entering the
specified area is not allowed.
These access time windows represent only additional accessibility regulations,
and do not require any infrastructure or technology provision. Therefore, they
constitute a very simple and cheap measure to implement. The objective of the
time windows is assumed to be the avoidance of the collision of interests between
different groups of stakeholders, namely freight carriers and the owners of cars
who drive them to work or go shopping in the restricted areas. However, there are
usually some negative side effects which are often not assessed previously to
implementing this solution. The fact is that very often, due to access time win-
dows, freight delivery vehicles are forced to enter congested areas during peak
hours, thus worsening congestion and pollution problems. Therefore, when
attempting to implement this solution, careful analyses and evaluation processes
are required beforehand, to ensure that the negative effects do not outweigh the
positive ones.
1.2 Different Policy Configurations
In Europe many municipalities have established the beginning o their access time
windows to the city center at 6 o'clock in the morning, and its ending (and thus the