Anexos

Bearing in mind the dimensions of space just dealt with, what meanings can be attributed to the evolution of metropolitan areas in a polycentric sense?

If attention is concentrated on the absolute space dimension alone, the phe-nomenon that emerges in the foreground is that of an increase in the number of polarities and, above all, the collapse of an organisation grounded on a simple hierarchy enabling polarities to be classified at levels based solely on the rarity of the functions present in them. As is known, according to interpretative models of Christallerian derivation, a single polarity tends to exist at a higher level, fully equipped with a complete range of service facilities, from the rarest (equipped also with a wide gravitational basin) to the most commonplace, passing through a se-ries of intermediate degrees of rarity. This kind of polarity possesses the maximum degree of centrality and is also geographically located in the centre of the metropoli-tan system. The polarities at the level immediately below are more numerous and characterised by the absence of extremely rare functions, though otherwise fully equipped; as we gradually come down the hierarchical scale, the number of polari-ties corresponding to each level increases and their equipment in terms of functions is poorer.

The processes that can actually be observed in the transformation of postfordist metropolitan areas subvert, at least partially, this pattern. For the principal phe-nomenon we see – on a parallel with the transition towards an economy dominated by the central role of services and activities with a high rate of knowledge – is the multiplication of specialised poles, marked by the presence of rare activities but not equipped with all functions. These poles, often located in highly accessi-ble spatial ambits (especially as concerns accessibility by car or with respect to long-haul transport systems) but far from the traditional central areas of the city, are greatly differentiated, but cannot be classified in a simple hierarchical order, in that they address in each case a widened potential user basin, of metropolitan, and sometimes inter-metropolitan importance. This does not mean that, as we will see in the next paragraph, beside this type of polarity, concentrations of functions at a lower level destined to support the users of specific residential areas are not also recognisable.

However, the tendency that can be acknowledged is that of an increase in inde-pendence among these two types of polarity and the different relationship that each sets up with the city; while the circuit of highly specialised poles takes shape as a network of nodes fundamentally detached from residential spheres, the sub-poles that are smaller in size maintain close ties with the characteristics of the quarters where they have become established and, in fact, tend to reproduce the differential features of them; for example, in the presence of population concentrations belong-ing to particular ethnic groups, the respective polarities of services are also ‘ethni-cised’. Thus, while in many ways polarities of a larger size tend to be characterised by a logic dominated by globalisation and model standardisation, polarities of a more reduced scale may also be differentiated on the grounds of local influence;

if, on the one hand, this phenomenon shows the capacity of this type of pole for

adapting to the context, on the other it underlines the detachment between global and local logics, favouring socio-cultural fragmentation of metropolitan spaces.

The processes described synthetically above may, moreover, be understood better if, apart from considering absolute space, the relative and relational space dimen-sions are also examined.

In particular, if the accent is placed on flow analysis – following the approach Harvey refers to for relative space – the fact emerges more clearly that this new organisation of polarities is simultaneously dependent on the existing structure of flows of various kinds and generator of multi-directional flows, possessing much lower predictability than the traditional hierarchical structures had.⁴ Dependence clearly emerges if we observe the localisation of many types of pole that have de-veloped in recent times, such as, for example, the great commercial concentrations that have arisen in periurban areas, or those that have arisen from the radical ‘re-functionalisation’ that interchange nodes in long-haul transport systems have under-gone, like airports, railway stations (especially those on high-speed train circuits), the port zones of tourist importance; a transformation that has turned these, too, into concentrations of commercial activities and leisure, as well as service facilities for the international economy. This localisation, instead of depending essentially on the spatial organisation of the homes of potential users (as established by the Christallerian model), seems basically aimed at intercepting flows of subjects who are moving around for the most varied reasons, as well as explicitly directed at using the services offered by single polarities. And it is often a question of subjects making long journeys, be it by car, train, plane or ship. Moreover, in localising these polarities, factors tied to different types of flow also count substantially, such as the system of supplying goods or the distribution of images and information; the latter aspect is fundamental, for example, for polarities for which visibility in the media is decisive, as is the case of structures attracting international tourism.

On the other hand, whatever the preponderant factors be in localisation choices, the great concentrations of functions, in their turn, are generators of movement;

they thus produce a mix between ‘intercepted’ and ‘generated’ flows, which con-tributes to giving transfers their chaotic, ‘zigzagging’ character that has been high-lighted many times in recent literature.⁵There is, however, a limit to the fluidity of transfers (at least as regards flows of material entities like people and goods): they need to be carried out by specific means of transport and communication, requiring unusual infrastructures that enable transfers to be implemented only by particular channels.⁶ This limit is particularly evident for concentrations of activities located outside metropolitan areas: thus, for example, a large shopping mall making use of a motorway network attracts and mixes a great variety of flows, provided, however, that transfers are carried out by car, for the centre is almost unreachable on foot or by bicycle, or by public transport. This means that, as already hinted earlier, specialised polarities of a higher level tend to establish reciprocal relations, rather than establish relationships with the surrounding space or with the polarities serving residents. For many aspects, in fact, it could be said that the network of polarities of this type, though constituting a distinctive function of the metropolitan nature of an area, is to some extent set apart from the reality of each particular metropolis.

Interconnection between poles of a higher level does not, in effect, respect any type of administrative boundary and sometimes creates complementarity, even at a great distance: think of what was said before about transport system nodes. Thus, in describing the structure of these interconnections, authors often have recourse nowadays to metaphors less of an areal nature and more of an axial one; instead of speaking – as in the past – of ‘urban armature’ of a given territory (referring to the image of urban polarities as an element of structure fit to solidify a territory understood as a continuous, delimited entity), we speak of ‘arteries’ or ‘corridors’, etc. (Florida 2007). Terms like this suggest a connection that surpasses single urban areas, to directly define an inter-metropolitan level, open to global flows; at the same time they refer to a structure which, though not respecting hierarchical scales, does not have an ubiquitous nature; a ‘corridor’, of course, links a plurality of territo-rial ambits but, inevitably, leaves aside others, touching them at a tangent without involving them and, so doing, increasing their marginality.

This last aspect may, on the other hand, be further interpreted by bringing into play the third dimension: that of relational space. This places particular interest on the relationship between polarities and their environment, in all the complex-ity and stratifications it presents. As has just been highlighted, it is undeniable that nowadays a strong tendency exists to form polarities that take shape as enti-ties alienated from their immediate territorial context: to specify their nature the

‘capsule’ metaphor (Mela 2005) has sometimes been used, in that it is a case of complexes with an architectural and urbanistic configuration that pay tribute to narrow-mindedness and introversion.

In effect, these poles are often made up of a set of closed containers with spe-cialised functions and are complementary to each other, separated from external space by technical infrastructures (road arteries, parking areas, spaces occupied by warehouses, thermal plant, etc.) and equipped with strong internal controls for safety purposes (private police, closed-circuit TV, devices for channelling and regulating visitor flows). Looking closer, however, this alienation of the environment is only one aspect of reality; actually, these polarities do not by any means have a neu-tral role, either with regard to built-up environment or with reference to the more general ecosystem balance. On the contrary, by maximising internal functionality and economic profitability, they often produce negative effects on the surrounding environment in many ways, e.g. by radically changing landscape features, increas-ing pollution by causincreas-ing intensification of road traffic, contributincreas-ing to rarefyincreas-ing the commercial and services network in surrounding quarters or favouring further effects of residential sprawl. In these cases, then, rather than indifference of the capsules towards the environment, we could speak of parasitism with respect to it, since they take from the context only the elements directly useful for their activities (the benefits), while they discard elements that are not of interest, constituting costs for the collectivity in environmental, social and economic terms.

In this largely problematic picture, however, some tendencies in a positive direc-tion exist as regards reladirec-tions between polarity and environment, or which at least present ambivalence, departing from which interesting possibilities open up for ter-ritorial planning intervention. Examples of these tendencies can be found above all

in the transformation of spatial organisation of central functions tied in the past to urban centres, like those linked with higher education, research, cultural and leisure activities, tourism, etc. Concerning these activities, too, a process is underway which is leading to the formation of specialised polarities, equipped with the essential tech-nological support and linked with the international flows. This process is leading to a phenomenon of reorganisation of central areas of large cities (think, in particular, of the historic centres of European cities) into thematic ‘districts’; for example, with the formation of university, museum, tourist/commercial poles, situated next to the already consolidated financial/economic and public administration poles.

A tendency of this kind certainly presents ambivalent aspects. For on the one hand, it entails that each polarity, with the purpose also of equipping itself to sustain competition with other similar centres in other urban areas, be able to mobilise in its favour not only the environmental resources but also human and symbolic ones, stratified over time in its context: unusual past aspects, sedimented images, compe-tences and attitudes linked with the aura of the city. On the other hand, however, as these centres belong to a global network of flows, this appeal for environmental rooting may co-exist with processes of standardisation of the supply, which in some way bring this type of polarity near to those previously considered ‘capsular’. A paradoxical effect may therefore arise: the method by which a museum district or a tourist one emphasises the uniqueness that binds it to the symbolic stratification of the context, follows scenario logics and languages that are global, risking trans-formation of the district into a format, in which ‘typicalness’ is enacted in impover-ished, though universally comprehensible, forms.

In spite of these risks, the development of rooted urban polarities in the context opens up the opposite perspective from that of capsularisation for them; these poles actually benefit from an opening towards the city and are led to establish comple-mentarity between different levels of fruition; thus, for example, even a museum pole at an international level may gain advantage from being frequented by resi-dents, or a highly qualified research pole may be interested in opening up to the local economy. Moreover, environmental quality is a factor of definite importance for these urban districts: this may lead the way to research on sustainable planning and management models in all senses of the term: capable of limiting the use of energy, ready to increment means of transport with less impact, careful about con-serving historic/cultural specificity, etc.