Time Constraints: The Cost of Sustainability - Sustainable Urban Logistics: Concepts, Methods and Information Systems - page 171

Fig. 7 Readjustment of the arrival time to customer i ? 1 in order to ensure that the vehicle is
not inside the restricted zone while the time window is closed
Fig. 8 Readjustment of the arrival time to customer i as close as possible to the new arrival time
to customer i ? 1
Next, and seeking to reduce the overall route duration, the arrival time to the
previous customer i also needs to be revised, moving it forward as close as pos-
sible to the new arrival time to customer i ? 1. This mechanism is represented in
Fig. 8 .
This readjustment can in turn result in different scenarios in case the customers
visited before customer i ? 1 are also located inside the restricted zone. In that
case, the route planning procedure needs to do the following:
Revise backwards until the first customer located outside the restricted zone.
This is the reference customer (P ref ), where the vehicle is able to wait until the time
window is open again.
Move back the group of customers located inside the restricted zone (P RZ ), to
visit them after the time window opens (see Fig. 9 ).