The network city: a realistic planning concept?
Recent trends in daily mobility and their possible planning implications in the Netherlands (1)
Marco Bontje
Introduction
In the discussion towards the 'Fifth Report', the document that will outline the long-term strategy for physical planning in the Netherlands until 2030, one of the central questions was which new urbanisation concept should be introduced to succeed the compact city. Most of the parties involved in the discussion seemed to agree that the compact city was no longer a realistic concept, and that the new concept should refer to a region rather than a location. However, opinions differed on the scale level of the new region, the degree to which urban regions should be considered a functionally coherent entity, and which criteria should be used to determine this functional coherence. In contributions from scientists and politicians, three urbanisation concepts were frequently mentioned: the 'urban field', the 'poly-nucleated urban region', and the 'network city'. The definitions given for each of these concepts in scientific articles and policy documents so far were not clear enough to make the concepts applicable in planning practice. In the following sections, an attempt is made to clarify the differences in geographic scale and the degree of functional coherence. Also, the usefulness of mobility data for the choice of the most useful urbanisation concept and the possible implications for the leading urbanisation concept in the Fifth Report will be discussed.
The question of geographic scale: 'function follows form'?
Two concepts comparable in geographic scale are the 'urban field' and the 'poly-nucleated urban region'. The urban field was originally defined as a fusion of metropolitan and non-metropolitan spaces, with an extent of 'two hours' driving', or approximately 100 miles, from the core metropolitan area (Friedmann & Miller, 1965). Only recently the urban field concept seems to have gained some popularity in the Netherlands. In some cases, the term 'urban field' is literally used (Salet & Van Engelsdorp Gastelaars, 1996; VROM-Raad, 1998), while in other cases, the same phenomenon is dubbed 'poly-nucleated urban region' (Dieleman & Faludi, 1998). The scale level of the Dutch urban field is more modest than in its original definition, generally referring to areas with a radius of 50 to 100 km (30 to 60 miles). Examples mentioned are the Randstad and the series of medium-sized cities in the province of North-Brabant.
The other concept, that has gradually become the most dominant one in the discussion, is the 'network city'. This concept has played the most prominent role in the discussions towards the Fifth Report so far and seems to be strongly preferred by the national planners. In a document outlining the preliminary thoughts of the government towards the Fifth Report (the so-called 'Startnota', Ministry of Housing, Planning & Environment 1999) the network city concept is illustrated with examples that indicate areas with a radius of about a 20 to 30 km.
The network city so far is a rather new term that is not clearly defined yet. Confusion is caused when one looks at the scarce contributions from geographical sciences to define the network city. Lambooy (1992) and Batten (1995) seem to prefer a higher scale level, identical with that of the earlier mentioned urban field and poly-nucleated urban region. The planners themselves cause some confusion too, since in more recent discussions (unfortunately not accompanied by official publications yet), they seemed to identify the network city with a higher scale level than before. Apparently, the national planners now see the 'Delta Metropolis', a proposal of the four largest cities for a new spatial and functional design of the Randstad, as an example of the network city. However, this Delta Metropolis treats the Randstad as one functional whole and occupies an area as large as three of the 'network cities' that were proposed in the 'Startnota'. This raises the question, which scale level of urbanisation the national planners really prefer.
The urban field, the poly-nucleated urban region and the network city as well as many other urbanisation concepts seem to suffer from comparable problems of applicability. In these concepts, new patterns of urbanisation are seen as logical spatial expressions of global economic and societal tendencies. The arguments for the validity of these concepts are generally found in the changing physical appearance of cities and their surroundings. The continuous extension of the built-up areas, the disappearance of open land and the fusion of once separated urbanised areas are supposed to prove the scale enlargement of urban life. Another argument often used is the intensification of traffic networks between cities, regions and countries (a. o. Dieleman & Faludi, 1998; Hall, 1993; Besteliu & Doevendans, 2000). More specifically, many theorists point at the emergence of faster transport means like high-speed rail connections. However, does a continuous built environment automatically imply one functionally integrated urban region? And to what extent will people really use the advanced means of transportation in their daily life? Or in other words: does function follow form in the urbanisation process? These questions are addressed far too little in the debate on the geographic scale of urbanisation.
Functional integration and complementarity: daily mobility as the main criterion
In the argumentation for the most useful urbanisation concept, functional coherence should be an aspect at least as important as geographic scale. A term directly related to this is complementarity. The urban region, on whatever scale level, should include centres that together offer all functions that are relevant for the daily life of its inhabitants. Traffic mobility data are the most useful indicator for functional coherence. In the few cases that the theorists base their arguments on mobility data, they often use indicators like business contacts (firm visits, business meetings, networks of supply and demand) and volumes of goods transport (see for example Dieleman & Faludi, 1998). This generally results in functional entities at a geographic scale far above the 'daily urban systems' that were often used by Dutch researchers in the 1970s and 1980s.
It is a fact that certain segments of the population regularly travel across quite large distances, crossing the boundaries of several 'traditional' daily urban systems. However, as far as we can see from empirical evidence, this still refers only to a very small part of the population. To see an area as one functional entity just because some small specific population categories use it as such does not seem very relevant. Instead, it would be more useful to choose an urbanisation concept closer to the daily reality of the majority of the Dutch population. The geographic pattern of daily mobility, not only commuter traffic but also trips for shopping, education, recreation and basic services, should form the basis for the choice of a regional urbanisation concept.
What does this daily reality look like? To explore recent trends in daily travel patterns, a time series analysis has been undertaken with data of the 'Research of Mobility Behaviour'. This is a yearly enquiry of the National Bureau of Statistics in which respondents are asked to register all trips they make on a given day. The period under study was 1987 to 1997. In the analysis, the Netherlands was divided into 20 regions based on definitions of daily urban systems used in earlier daily mobility studies (a.o. Dingemanse, 1993; Cortie et al, 1992) and the standard statistical regions as used by the National Bureau of Statistics. In the limited space of this paper it is impossible to present the results in sufficient detail (a more detailed analysis is presented in Bontje, 2000). The most important results included:
- The number of daily trips increased considerably. This increase appeared in all distance categories, but it was much more an increase of short-distance moves (especially 0-2.5 km) than of long-distance ones.
- The share of daily trips between 0 and 20 km (a distance more or less coinciding with the average radius of 'traditional' urban regions in the Netherlands) remained very stable: it was 85.4% in 1987, and 84.5% in 1997.
- Within each of the regions, the share of daily trips staying within the regional borders decreased, but only slightly. The scores for the share of trips within regional borders in 1997 ranged between 81 and 93%.
- Those trips that went across regional borders were almost exclusively directed to directly neighbouring regions, more specifically to the central cities in these regions or to locations just across the regional border.
- The daily travel patterns within the regions show a confused picture. In some regions, the central city lost importance as a destination and sub-centres have appeared or strengthened their position. In other regions, the central city seems to have strengthened its position as a location for work, education, shopping and services, which would indicate a monocentric urban region instead of a network city.
The results seem to reconfirm patterns of daily mobility found in an earlier study for the West of the Netherlands in the 1980s (Cortie et al, 1992; Dingemanse, 1993). Another recent study produced quite comparable outcomes (Van Ham, 1999). All these studies focused on commuter traffic, but when other trip motives are added, the resulting daily travel pattern is not very different. The vast majority of daily trips still take place on the scale level of daily urban systems that many have already considered 'outdated'. The high scores on intra-regional traffic suggest that most people can find all the functions they need within the 'traditional' daily urban system. If any enlargement of the daily urban systems took place since the 1980s, it was rather a gradual extension of the existing daily urban systems than an integration of these regions into a larger functional entity.
Concepts like the urban field and poly-nucleated urban regions seem irrelevant for the current stage of Dutch urbanisation. The network city in the extent initially proposed by the national planners (Ministry of Housing, Physical Planning & Environment, 1999) seems to come much closer to the daily life of the majority of the Dutch. In this respect, a theoretical concept playing only a marginal role in the urbanisation debate so far deserves more attention. This is the concept of 'action space'. Dijst (1999) defined two types of action space: the 'potential action space', referring to the spatial entity in which a person could travel considering technological possibilities and physical constraints, and the 'actual action space', the area in which (daily) travels are made in reality. While the urban field for the Dutch case is a rather 'virtual' functional entity referring mostly to the potential action space, the network city includes the actual action spaces of a clear majority of the population.
Possible implications for the Fifth Report
When daily travel patterns are taken as a basis for future urbanisation policy, the urban field and likewise concepts should not be considered as relevant concepts. These concepts are too far from the geographic scale of daily life of most people. A further argument not discussed so far is the current Dutch mobility policy. In recent decades, the Dutch government has aimed at reducing mobility growth, most of all the growth of car mobility. When functions would be distributed across an urban field or poly-nucleated urban region on the basis of complementarity, several functions might be located outside the actual action space of many people. This could result in a dramatic increase in the distance of daily trips. Instead of adapting the spatial design of the Netherlands to the current daily travel patterns, the planners would then force people to adapt their daily travels to a new, artificially created urban region. It would be more desirable to stay close to the daily travel patterns that developed in recent years.
This makes the network city a more suitable concept for future Dutch urbanisation policy. However, for the network city concept to work, a much clearer definition is needed. This not only involves a choice of geographic scale, but also a choice of the criteria used for the functional coherence of it. Daily travel patterns seem a more useful criterion than business contacts, and the daily travels of the 'average Dutch' are more relevant than the travel patterns of very specific categories (like high executives, salesmen, shop suppliers etc.) that tend to live their daily lives in areas considerably larger than most Dutch do.
In addition, clearer statements are needed for the internal structure of the network city. The results of the time series analysis of daily mobility suggest a movement towards a more polycentric structure in some regions, but a strengthening of a monocentric structure in others. Do the planners want to facilitate a further strengthening of already emerged polycentric structures? Does this imply sticking to the already existing set of centres and sub-centres, or creating even more polycentricity? And what approach should be followed in regions that do not have a polycentric structure yet? A lot of questions still have to be answered before the network city will be an urbanisation concept that can really be applied in the Netherlands.
Discussion statements for the workshop 'Urban networks, urban nodes':
- Daily mobility patterns should be used as the basis of the future Dutch urbanisation policy. The Fifth Report should contain a strategy that facilitates the daily travels of most people on the currently valid scale level. The future urbanisation strategy should not 'artificially' enlarge the scale level of daily life by using an urbanisation concept with a scale level reaching far above the present daily mobility patterns.
- The network city as a planning concept relates directly to the recent trends in daily travel patterns of the vast majority of the Dutch population. To make the network cities to more functionally integrated entities, however, the internal infrastructure should be considerably improved. Instead of focusing on long-distance infrastructure investments like the high speed rail lines, the Dutch planners should lay most stress on short-distance infrastructure improvements: better connections between cities and suburbs and between suburbs within the network cities.
Notes
(1) Paper presented at the IFHP Congress 'Urban Networks', Workshop 'Urban Networks, Urban Nodes', Rotterdam, 10-13 September 2000. Published in: IFHP (2000): IFHP 2000 Rotterdam – Urban Networks, Towards a New Planning Perspective. Papers Report Call for Participation (p. 169-172). (back)
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