176 M.Hesse.J.-P.Rodrigue Journal of Transport Geography 12(2004)171-184 transport geography,and which are expressed in terms 3.1.Flows of flows (information,freight,transportation,vehicles), nodes and networks within the supply chain.Recent The growth of geographical areas of interaction and commentators also noted a rising interest in hubs,flows the temporal flexibilization of freight flows result in a and networks in the broader sense (Crang,2002;Cre- rising amount of freight transport.The traditional swell,2001).In the context of this paper,the system of arrangement of goods flow included the processing of physical distribution can be regarded as a material raw materials to manufacturers,with a storage function foundation for such mobility of people,goods,and usually acting as a buffer.The flow continued via information.These elements interact in space,but also wholesaler and/or shipper to retailer,ending at the final in time (Fig.4). customer.Delays were very common on all segments of Space/time convergence is a well-known concept in this chain and accumulated as inventories in ware- transport geography,where time was simply considered houses.There was a limited fow of information from as the amount of space that could be traded with a the consumer to the supply chain.This procedure is now specific amount of time,which included travel and going a different way,mainly by eliminating one or more transshipment.Logistics has expended this concept to of the costly operations in the supply chain organiza- include activities that were not previously considered tion.An important physical outcome of supply chain fully in space/time relationships.They now imply an management is the concentration of storage or ware- organization and synchronization of flows through housing in one facility,instead of several.This facility is nodes and network strategies.For instance.the con- increasingly being designed as a flow-and throughput- ventional expansion of a distribution system (Fig.4) oriented distribution center (DC),instead of a ware- involves a trade-off between marginal improvements of house holding cost intensive large inventories(Fig.5). spatial coverage (AS)and the associated marginal time Recent freight flows tend to be of lower volumes.of change (AT).Supply chain management enables a more higher frequency,often taking place over longer dis- efficient space/time convergence since the marginal dif- tances.These flows have been associated with modal ferences are larger for space (AS)than for time (AT1). adaptation.The magnitude of change can be charac- The emerging paradigm also includes in the space/time terized by the growth of geographical areas of interac. convergence the notion of time as a management con- tion,and by the temporal flexibilization of freight flows, straint of transportation.In addition of being a factor of both resulting in a rising amount of freight transport. distance/friction/impedance,time is a component of The distribution center thus becomes the core compo- flows,synchronized at nodes and the expression of a nent of such a distribution system(Fig.5). network structure.Consequently,the expansion and Truck vehicle miles have almost kept pace with GDP improvement of a distribution system from DSI to DS3 and have more than tripled between 1970 and 1999 in (Fig.4)could either imply an extended spatial coverage the US and in Europe (USDOT,2000).At the same with a similar amount of time or a similar spatial cov- time,freight by ton-miles developed more dynamically erage with a reduction of time,or ideally,a combination than by freight tons,which indicates both a demateri- of both.The distribution system is not only providing alization of the economy and rising average transport for the constant flow of commodities.but ensuring their distances.Structural change is associated with modal availability and accessibility in a synchronized-timely- shift away from rail and waterway transport,supporting fashion. road and air modes.Whereas intercity truck ton-miles DS1 Conventional ==DS2 Raw Materials Parts Manufacturing Distribution ■ 1T1 -DS3 2 Contemporary Supply Chain Managemen Supply Chain Management Flows Nodes Networks AS Space Fig.4.Geographical dimensions of logistics. Fig.5.Conventional and contemporary arrangement of freight flows.transport geography, and which are expressed in terms of flows (information, freight, transportation, vehicles), nodes and networks within the supply chain. Recent commentators also noted a rising interest in hubs, flows and networks in the broader sense (Crang, 2002; Cre￾swell, 2001). In the context of this paper, the system of physical distribution can be regarded as a material foundation for such mobility of people, goods, and information. These elements interact in space, but also in time (Fig. 4). Space/time convergence is a well-known concept in transport geography, where time was simply considered as the amount of space that could be traded with a specific amount of time, which included travel and transshipment. Logistics has expended this concept to include activities that were not previously considered fully in space/time relationships. They now imply an organization and synchronization of flows through nodes and network strategies. For instance, the con￾ventional expansion of a distribution system (Fig. 4) involves a trade-off between marginal improvements of spatial coverage (DS) and the associated marginal time change (DT ). Supply chain management enables a more efficient space/time convergence since the marginal dif￾ferences are larger for space (DS) than for time (DT 1). The emerging paradigm also includes in the space/time convergence the notion of time as a management con￾straint of transportation. In addition of being a factor of distance/friction/impedance, time is a component of flows, synchronized at nodes and the expression of a network structure. Consequently, the expansion and improvement of a distribution system from DS1 to DS3 (Fig. 4) could either imply an extended spatial coverage with a similar amount of time or a similar spatial cov￾erage with a reduction of time, or ideally, a combination of both. The distribution system is not only providing for the constant flow of commodities, but ensuring their availability and accessibility in a synchronized–timely￾fashion. 3.1. Flows The growth of geographical areas of interaction and the temporal flexibilization of freight flows result in a rising amount of freight transport. The traditional arrangement of goods flow included the processing of raw materials to manufacturers, with a storage function usually acting as a buffer. The flow continued via wholesaler and/or shipper to retailer, ending at the final customer. Delays were very common on all segments of this chain and accumulated as inventories in ware￾houses. There was a limited flow of information from the consumer to the supply chain. This procedure is now going a different way, mainly by eliminating one or more of the costly operations in the supply chain organiza￾tion. An important physical outcome of supply chain management is the concentration of storage or ware￾housing in one facility, instead of several. This facility is increasingly being designed as a flow- and throughput￾oriented distribution center (DC), instead of a ware￾house holding cost intensive large inventories (Fig. 5). Recent freight flows tend to be of lower volumes, of higher frequency, often taking place over longer dis￾tances. These flows have been associated with modal adaptation. The magnitude of change can be charac￾terized by the growth of geographical areas of interac￾tion, and by the temporal flexibilization of freight flows, both resulting in a rising amount of freight transport. The distribution center thus becomes the core compo￾nent of such a distribution system (Fig. 5). Truck vehicle miles have almost kept pace with GDP and have more than tripled between 1970 and 1999 in the US and in Europe (USDOT, 2000). At the same time, freight by ton-miles developed more dynamically than by freight tons, which indicates both a demateri￾alization of the economy and rising average transport distances. Structural change is associated with modal shift away from rail and waterway transport, supporting road and air modes. Whereas intercity truck ton-miles Space Time DS1 DS2 DS3 T1 Flows Nodes Networks S Supply Chain Management Supply Chain Management ∆ ∆T2 ∆T3 ∆ Fig. 4. Geographical dimensions of logistics. Raw Materials & Parts Manufacturing Distribution Raw Material Storage National Distribution Regional Storage Local Distribution Retailers Supply Chain Management Raw Material Distribution Center Manufacturing Retailers Customers Customers Conventional Contemporary Material flow (delivery) Information flow (order) Core component Fig. 5. Conventional and contemporary arrangement of freight flows. 176 M. Hesse, J.-P. Rodrigue / Journal of Transport Geography 12 (2004) 171–184