Cities and supplies: does “logistical loosening” enhance pollution?

Over the last 30 years, cities have experienced growth, one of the consequences of which is the distance from logistics facilities (sorting platforms and warehouses). from the hearts of cities. This phenomenon, called logistical loosening, was first demonstrated in the Paris metropolitan area.

This would result in increased distances travelled – and therefore increased emissions – to deliver parcels in the city. However, the consequences of distance remain a subject of debate today: when the situation is considered as a whole, the city and its peripheries, a relaxation appears then as an optimal solution.

How is demand distributed across space?

If we consider only the city center, the relaxation of logistics results in increased distances traveled. Logistics facilities are located further from the city center and a greater distance is required for operations (deliveries and shipments). This results in an enhance in greenhouse gas emissions caused by the transportation of goods.

Following this logic, it would be intriguing to encourage the return of logistics facilities to city centers in order to reduce the negative externalities generated (pollution, congestion, etc.). However, this reasoning only applies if the huge majority of demand is concentrated in the city center.

If we take into account the latter and the surrounding region, the balance of power changes. In the case of Île-de-France, if the city of Paris has a population density (20,544.8 inhabitants per km²) significantly higher than in the rest of the region (1010.9 inhabitants per km²), only the population of Paris is represented 18% of the total population of Île-de-France.

If residents are the determinant of the size of flows, let us not forget about enterprises, and in particular industrialists, who are the main emitters of goods. This industrial structure is located mainly on the outskirts of cities, which is illustrated by a learn on the carrier.

“Polycentric” logistics.

Another element to take into account is that carriers do not operate in gigantic regions (such as Île-de-France) from a single point, but have several platforms, each managing its own territory.

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By adopting a polycentric approach, the territory is divided into sub-areas according to the logic of transport optimization (i.e. minimizing the distance covered by trucks). Taking into account the demand dispersed throughout the territory and not concentrated in its center and the choice of a polycentric organization, the decision to locate platforms on the periphery seems obvious.

At first glance, it is true that this choice may not be an optimal situation for the functioning of city centers. However, the impact on the entire territory (here Île-de-France), and not only the subterritory that is the urban center (here Paris), must be assessed, so as not to improve the local situation to the detriment of the global situation.

Access to land and minimizing costs

The polycentric approach has other advantages. In a situation where access to land is becoming increasingly complicated (especially in the case of gigantic plots in densely populated areas), such an organization allows the utilize of several platforms of smaller size than if the operator worked only from “one platform” (flows are divided between different centers). Additionally, it allows moving away from urban centers access to cheaper plots.

Until then, only city logistics were considered, without taking into account the city outskirts and intercity routes. However, platforms are the link between long distances and the first or last kilometers.

Moving the platform to the heart of the city centre also means moving those long-distance flows that currently stop on the outskirts of the city. As a result, the location and number of platforms correspond to the optimisation of both the first and last kilometre, as well as the long haul, in order to minimise overall costs.

The End of Logistics Facilities in the City?

The strategy of polycentric location on the outskirts is not incompatible with the installation of microplatforms (or microhubs) in the heart of cities. The latter then act as satellites of the peripheral platforms in order to configure local deliveries.

They are also necessary for deliveries by cargo bikes, vehicles with a much shorter range than trucks. They are therefore only connected to edge platforms and not directly to all network platforms (national or international).

Finally, giving a single answer to the question of the consequences of relaxing logistics in terms of pollution and efficiency is complicated. On the one hand, there is demand in the periphery, which is significant in terms of resources but less dense (industry and some private individuals), and on the other hand, demand for resources is smaller but much denser (urban centers). To achieve this, carriers have implemented strategies such as polycentrism to be able to meet such a diverse demand.

It is also necessary to maintain logistics spaces in the heart of cities, especially for the implementation of cyclology. The latter mode of transport also represents a sustainable solution for the decarbonization of freight transport, a key challenge for the coming decades.

The authors do not work for, consult, own, or receive funding from any organization that might benefit from this article, and have declared no relevant affiliations outside their research organization.