M.Hesse,J.-P.Rodrigue Journal of Transport Geography 12 (2004)171-184 179 possible.Not coincidentally,most recent construction of capacity to handle large amounts of time-sensitive con- DCs and warehouses takes place in metropolitan re- signments.The logistical requirements of a hub-and- gions,at the urban fringe or beyond.Further,the spoke structure are consequently extensive as efficiency function of nodes has become more complex with sev- is dominantly derived at the hub's terminal.Routing eral distribution centers performing light manufacturing networks tend to use circular configurations where tasks such as assembly and especially packaging.The freight can be transshipped form one route to the other functions of production and distribution thus became at specific hubs.Pendulum networks characterizing blurred with logistical integration. many container shipping services are relevant examples of relatively fixed routing distribution networks. 3.3.Networks Achieving flexible routing is a complex network strategy requiring a high level of logistical integration as routes The spatial structure of contemporary transportation and hubs are shifting depending on anticipated varia- networks is the expression of the spatial structure of tions of the integrated freight transport demand. distribution.Network building leads to a shift towards larger distribution centers,often serving significant transnational catchments.However,this does not mean 4.The concept of friction in the transport geography of the demise of national or regional distribution centers. logistics with some goods still requiring a three-tier distribution system,with regional,national and international DCs. The concept of impedance,or the friction of space,is The structure of networks has also adapted to fulfill the central to many geographical considerations of eco- requirements of an integrated freight transport demand, nomic and social processes.Conventionally,this con- which can take many forms and operate at different cept was subjugated to issues concerning distance and scales (Fig.7). how to quantify it.Substantial economic research has Point-to-point distribution is common when special- focused on assessing impedance,the impacts of distance, ized and specific one-time orders have to be satisfied, time and elasticities on freight flows (Button.1993).As which often creates less-than-full-load as well as empty discussed so far,significant changes have incurred in return problems.The logistical requirements of such a freight transport nodes,flows and networks,which im- structure are minimal,but at the expense of efficiency. pacted on the concept of impedance.Logistics and Corridor structures of distribution often link high den- freight distribution,as a transport paradigm,require a sity agglomerations with services such as the landbridge review of this multidimensional concept to include four where container trains link seaboards.Traffic along the core elements,namely the traditional transport costs,but corridor can be loaded or unloaded at local/regional also the organization of the supply chain,and the trans- distribution centers.Hub-and-spoke networks have actional and physical environments in which freight dis- mainly emerged with air freight distribution and with tribution evolves.These four elements.which are high throughput distribution centers favored by parcel difficult to consider independently,jointly define the services(O'Kelly.1998:SRI International.2002).Such a concept of logistical friction and its possible improve- structure is made possible only if the hub has the ments 4.1.Transportllogistics cost Point-to-Point Fixed Routing Traditionally transports costs were considered as a distance decay function.The most significant consider- O 0 0 ations of logistics on transport costs are related to the functions of composition,transshipment and decom- Corridor Flexible Routing position.which have been transformed by logistics. More specifically,composition and decomposition costs, ◆ which involve activities such as packaging,warehousing, and assembly of goods into batches,can account to 10% Hub-and-Spoke ○Transshipment of production costs.A higher level of inventory man- ○Route node Route agement (e.g.lean management)can lead to significant ONetwork node Alter ative reduction in the logistical friction as well as terminal ○Unserviced node route improvements decreasing transshipment times and costs (Fig.8).Time is becoming as important as distance in Fig.7.Freight distribution and network strategies.Source:Adapted from Woxenius (2002)"Conceptual Modelling of an Intermodal Ex- the assessment of transportation costs and impedance. press Transport System",International Congress on Freight Transport As transport costs went down through space/time con- Automation and Multimodality,Delft,The Netherlands. vergence,the value of time went up proportionally.Forpossible. Not coincidentally, most recent construction of DCs and warehouses takes place in metropolitan re￾gions, at the urban fringe or beyond. Further, the function of nodes has become more complex with sev￾eral distribution centers performing light manufacturing tasks such as assembly and especially packaging. The functions of production and distribution thus became blurred with logistical integration. 3.3. Networks The spatial structure of contemporary transportation networks is the expression of the spatial structure of distribution. Network building leads to a shift towards larger distribution centers, often serving significant transnational catchments. However, this does not mean the demise of national or regional distribution centers, with some goods still requiring a three-tier distribution system, with regional, national and international DCs. The structure of networks has also adapted to fulfill the requirements of an integrated freight transport demand, which can take many forms and operate at different scales (Fig. 7). Point-to-point distribution is common when special￾ized and specific one-time orders have to be satisfied, which often creates less-than-full-load as well as empty return problems. The logistical requirements of such a structure are minimal, but at the expense of efficiency. Corridor structures of distribution often link high den￾sity agglomerations with services such as the landbridge where container trains link seaboards. Traffic along the corridor can be loaded or unloaded at local/regional distribution centers. Hub-and-spoke networks have mainly emerged with air freight distribution and with high throughput distribution centers favored by parcel services (O’Kelly, 1998; SRI International, 2002). Such a structure is made possible only if the hub has the capacity to handle large amounts of time-sensitive con￾signments. The logistical requirements of a hub-and￾spoke structure are consequently extensive as efficiency is dominantly derived at the hub’s terminal. Routing networks tend to use circular configurations where freight can be transshipped form one route to the other at specific hubs. Pendulum networks characterizing many container shipping services are relevant examples of relatively fixed routing distribution networks. Achieving flexible routing is a complex network strategy requiring a high level of logistical integration as routes and hubs are shifting depending on anticipated varia￾tions of the integrated freight transport demand. 4. The concept of friction in the transport geography of logistics The concept of impedance, or the friction of space, is central to many geographical considerations of eco￾nomic and social processes. Conventionally, this con￾cept was subjugated to issues concerning distance and how to quantify it. Substantial economic research has focused on assessing impedance, the impacts of distance, time and elasticities on freight flows (Button, 1993). As discussed so far, significant changes have incurred in freight transport nodes, flows and networks, which im￾pacted on the concept of impedance. Logistics and freight distribution, as a transport paradigm, require a review of this multidimensional concept to include four core elements, namely the traditional transport costs, but also the organization of the supply chain, and the trans￾actional and physical environments in which freight dis￾tribution evolves. These four elements, which are difficult to consider independently, jointly define the concept of logistical friction and its possible improve￾ments. 4.1. Transport/logistics cost Traditionally transports costs were considered as a distance decay function. The most significant consider￾ations of logistics on transport costs are related to the functions of composition, transshipment and decom￾position, which have been transformed by logistics. More specifically, composition and decomposition costs, which involve activities such as packaging, warehousing, and assembly of goods into batches, can account to 10% of production costs. A higher level of inventory man￾agement (e.g. lean management) can lead to significant reduction in the logistical friction as well as terminal improvements decreasing transshipment times and costs (Fig. 8). Time is becoming as important as distance in the assessment of transportation costs and impedance. As transport costs went down through space/time con￾vergence, the value of time went up proportionally. For A B Point-to-Point A B Corridor A B Hub-and-Spoke A B Fixed Routing A B Flexible Routing Transshipment node Route node Network node Unserviced node Route Alternative route Fig. 7. Freight distribution and network strategies. Source: Adapted from Woxenius (2002) ‘‘Conceptual Modelling of an Intermodal Ex￾press Transport System’’, International Congress on Freight Transport Automation and Multimodality, Delft, The Netherlands. M. Hesse, J.-P. Rodrigue / Journal of Transport Geography 12 (2004) 171–184 179