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.
Transport time is also an important dimension in evaluating transport costs, particularly since logistics concomitantly involves cost and time management. The major time-related elements are:
- Transport time. Concerns the real duration of transport, which tends to be easily understood since commonly a proportional function of distance. Geographical constraints such as weather or technical limitations (e.g. operational speed) have a direct impact on the transport time. Transport time on roadways 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, schedules impose limited variations.
- 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. In other cases, particularly large shipments, orders must be secured months in advance so that capacity can be made available. This is the case for maritime shipping where capacity usually needs to be booked (reserved) weeks in advance. There is also the presence of a spot market where capacity can be booked with limited advance notice, but subject to higher rates and the likelihood that there will be no capacity available.
- Timing. Involves the usage of a specific departure time, which depending on the mode, can have a level of flexibility. While air and rail travel timing is commonly tight due to fixed schedules and access to a terminal 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. Represents 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 deliveries 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 and the risk of lower asset utilization. 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.