
Source: adapted from Woxenius, J. (2006) "Temporal Elements in
the Spatial Extension of Production Networks", Growth and Change, Vol.
37, No. 4, pp. 526-549.
Different Components of Transport Time
Transport time is also an important dimension in the evaluation of
transport costs, particularly since logistics concomitantly involves
cost and time management. The major time related elements are:
- Transport time. Concerns the real duration of a transport,
which tend to be easily understood since commonly a proportional
function of distance. Geographical constraints such as weather or
technical limitations such as operational speed have a direct impact
on transport time. Transport time on road is technically limited
to legal speed limits. For maritime and air, the limitation mainly
concerns fuel economy and design speed. Although rail can accommodate
a variety of speeds, tight schedules impose limited variations in
operational speeds.
- Order time (not shown). Almost all transport requires
a form of advance preparation, mainly to secure a capacity, an itinerary
and a rate. In some cases, the order time is short and a matter
of queuing on a first come first served basis, while in others orders
have to be secured months in advance.
- Timing. Involves the usage of a specific departure time,
which depending on the mode can have a level of flexibility. While
for air and rail travel timing is commonly tight due to fixed schedules
and access to intermodal capacity (such as a gate and a takeoff
time) commuters and trucking have more flexibility. If there is
congestion either at the origin, destination or in between, trucking
companies may elect to modify their schedule accordingly (earlier
or later delivery).
- Punctuality. The ability to keep a specified schedule,
which can be represented as an average deviation from a scheduled
arrival time. The longer the distance, the more likely are potential
disruptions that may affect schedule integrity. Some movements may
have a level of tolerance to disruptions in punctuality while others,
such as heading to a business meeting or flows in a just-in-time
supply chain, have limited tolerance.
- Frequency. The number of departures for a specific time
range. The higher the frequency, the better the level of service.
However, a high frequency ties up a larger quantity of vehicles.
Distance is also a factor for lower frequency since transport demand
tends to decline accordingly. Combining long distance travel and
high frequency is an expensive undertaking for transport providers
as a greater number of vehicles must be assigned to a specific route,
as in the case of maritime container shipping.