Over half of the delays recorded were due to
traffic congestion. Some companies already allow
for known congestion in their planning and
scheduling routines, so the real impact is
partially hidden.
Effective monitoring to determine trends as to
where and when congestion regularly occurs can
enable operators to reroute and reschedule
movements accordingly.
It is interesting to note that although congestion
was deemed responsible for 57% of all delayed
legs, the average resulting time delay (25.5
minutes) was less than half that of any other
type of delay.
Booking times were used by a total of 19 fleets and
the range of recorded arrival time indicated the
possible impact of the deviations from schedule.
The length of the time windows used varied from
0.5 to 8 hours with an average of 0.74 hours, or
just 45 minutes. The prevalence of delivery
windows throughout the industry is illustrated by
the fact that only 17.8% (1,139 legs) did not have
such a window.
Being too early for a delivery can be as disruptive
as arriving too late, due to limited access or a lack
of waiting areas. Although 18.6% (1,189) of all
legs were affected by delays, late arrivals actually
accounted for only 7.7% (496) of legs. This
indicates that companies may be building in extra
time in their delivery schedules to accommodate
potential delays. This would be logical since
although having a vehicle waiting at a delivery
point is undesirable, an early arrival is still
preferable to a load refusal due to a missed
delivery window.
Failed legs, either wholly or partially, cause
unnecessary activity and result in wasted
resources.
If delivery failure is due to non-loading then
vehicle utilisation is affected and the energy
consumed is less effective (this only occurred in
0.4% of all legs)