Time Constraints: The Cost of Sustainability - Sustainable Urban Logistics: Concepts, Methods and Information Systems - page 163

Fig. 1 A representative example of percentage of Dutch cities that allow access to their
downtown areas at each time of the day (PSD 2002)
re-opening of accessibility) at 11 o'clock is more and more prevalent. Some cities
have time windows associated to the use of load zones. In cities with access time
windows, these limitations are also shown on load zone signals, but in some other
cities the time windows in load zones are used instead of having access time
windows to the city centre. Figure 1 shows graphically an example of a repre-
sentative distribution of time window regulations among Dutch cities.
On the other hand, in most South European cities, deliveries are also allowed
until 11 o'clock, although it is very common for shops to open around 10 o'clock
(see Table 1 ). A change in the time windows is a long-time request of carriers, but
no modifications have been introduced for years. The result is that carriers often
have to disregard time window restrictions, caught between the need to make
the delivery and the risk of getting a ticket. This is especially being the case in the
afternoon, when access time windows usually remain closed until 5 o'clock, the
time when shops normally open. Time windows are not habitual in small towns,
but they are one of the most widespread policy measures in medium and large
cities.
The importance assigned to the subject of urban freight distribution varies
widely between municipalities. Basically they can be roughly divided into three
categories:
• Municipalities with active policy attitude in the field of urban freight distribu-
tion, understanding that a well organized system of urban freight distribution
can be a solution to other specific problems (e.g. accessibility, environmental
zoning, descending town visits).