Regional corridor model: Towards a regional corridor model

Abstract

One of the key concepts underlying the science of spatial planning refers to the role of development corridors as a planning instrument to potentially restructure economic space. Although strong evidence exists that corridors are regarded as important spatial development instruments that channel economic development, counter-arguments indicate the need for more diversified strategies at regional and national levels, as well as a greater awareness of agglomeration economies to allow for the integration of corridors as strategic and supporting networks. Drawing on fundamental literature, a regional corridor model was developed with the aim to establish a spatial framework through which corridor development can be integrated as strategic and supporting networks to support the notion of ‘sustainable spatial- and settlement planning’, i.e. the appropriate compilation and administration of policies affecting spatial organisation at local, regional and national levels. Based on the empirical research, regional and national governments could, through the RCM, develop a realistic spatial perspective on long-term settlement patterns and investment opportunities which could transform economic space development and seek to connect the potential of urban systems in economic development.

Keywords

Corridors regional corridor model economic space development planning region regional and urban systems regional economic zones

Introduction

Regional and urban systems represent the most dynamic structural component of economic space (Surd, 2009). They form part of a network of systems all linked together creating synergies of interactive growth (Bourne and Simmons, 1978). This linkage of systems initiate connections between economic nodes and is referred to by Hohenberg and Lees (1985) as functional relationships creating interregional spillovers which is an important determinant of a settlements’ place and economic performance. To simplify, Bosker (2007) articulated that regions, considering proximity, with a high level of economic agglomeration are beneficial to the economic growth of regions with a low level of economic agglomeration i.e. a region that expands economically will allow nearby regions to also benefit.

These interregional spillovers support the notion of network linkages, also referred to in the contemporary as development corridors that still plays a key role in economic space development (Brand, 2017). In support of corridors, numerous approaches and concepts as to the delineation of regions for various purposes have been dealt with since the Second World War. Settlement- and development theories reflect on the ‘region’ and ‘regional approaches’ to growth and development, and the interpretations thereof vary mostly in terms of levels of development of a region (Scott, 2000). The concepts of urban systems and the relevance of urban hierarchies have similarly been developed and integrated into ‘regionalisation’ the past four decades. The conceptualisation and delineation of regional trading blocs have received much attention since the amalgamation of Western Europe, but still the conceptualisation of a ‘region’ remains somewhat intangible when not demarcated for a specific, usually, sectoral, objective.

The approach followed in this paper is based on what the influence sphere of a region entails, and how it can potentially, via a proposed corridor model, be modelled. It follows on extensive theoretical viewpoints of regional planning and the interaction within and between regions. The paper also focuses on the degree to which economic activities are concentrated on a specific locality. Furthermore, the paper illustrates that the influence of corridors to advance economic space development stretched beyond their boundaries. Corridors need to be dealt with in an integrated and sustainable manner and should never be considered in isolation. Evident from the paper is that corridors do not generate significant economic benefits in isolation, but rather have to be analysed as part of integrated global or regional economic networks.

Modelling economic spaces

Economic spaces are subjectively constructed and the variety and interpretation thereof is dependent on a theoretical approach. A theoretical approach involves a conservative connotation to relations and functions that link distant localities (cities and regions) in such a way that economic space development is shaped by events and interactions (Gildenhuys, 1994; Mallick, 2005; Watts, 1993). Drewes (2015) put forward the argument that economic space development is built on the basis of opportunities and comparative advantages, resulting in a spatially selective approach where certain cities or regions are selected as preferred locations of development. This section deals with the rationale behind economic spaces and consideration is given to different theoretical orientations.

The central place orientation is best understood against the publications of (1) the geographer Walter Christaller, who published ‘The central place theory’ in 1933 (Baskin, 1966); (2) the economist August Lösch, who published ‘The economics of location which deals with the location of profitability’ in 1954 and (3) Perroux (1955) who introduced the theory on growth poles. Christaller noticed that towns of a certain size were roughly equidistant. By examining, and defining the functions of the settlement structure and the size of the hinterland, he found it possible to model the pattern of settlement locations using geometric shapes. Christaller referred to the geometric shapes as market areas or spheres of influence and considered them complementary because of the relationship that existed between the central place and its hinterland. Lösch, on the other hand, focused on how to maximise consumer welfare and create an ideal consumer landscape, where the need to travel for any goods or service was minimised and profits were constant. Perroux on the other hand concluded that economic development or growth was not uniform over an entire region, but, instead, took place around a specific pole or node. According to him, the node is often characterised by a key industry around which linked industries develop, mainly through direct and indirect effects. The one common principle emerging from their theories is the consideration that the optimum location is where profit is the greatest, i.e. finding a zone of profitability.

Notwithstanding the importance of the central place orientation, its static nature does not allow, or respond easily to economic changes. This, as reflected on by Otterstrom (2007), resulted in the understanding of natural settlement establishment as opposed to planned settlement establishment which was largely determined by human motivation in the progression of development forces that create economic spaces. The alternative as envisaged by the Taaffe et al. (1963) and Vance (1970) models was to establish an underlying spatial diffusion process of development patterns and related settlement hierarchies. Taaffe et al. (1963) envisaged six stages, namely, (1) few dispersed seaports with limited hinterlands (scattered ports); (2) the discovery of new inland raw materials with access roads being built from selected ports to new inland localities (penetration lines and port connections); (3) the progressive deepening of settlement hierarchies influenced by the layout of transport roads (development of feeders); (4) the direct reciprocal connection among the originally isolated inland centres is created (beginnings of interconnection); (5) the completion of the settlement hierarchy, whereas the most important centres are reciprocally very well connected (complete interconnection) and (6) the existence of hierarchically more important priority connections among the most important centres (high priority main roads). Vance (1970) on the other hand envisaged five stages, namely (1) the search for economic possibilities (exploration); (2) the periodic harvesting of products in limited settlements; (3) increased settlements exporting commodities to the mother country; (4) settlements penetrating inland to serve as collection points and (5) the emergence of a central place where the collection points took on a service function and developed as regional centres.

Despite the pedagogic value of central place orientation and settlement diffusion, it is still difficult to avoid the conclusion that a general theory to explain economic geography based on location, size and spacing, is unattainable. Much of literature has ignored the specifics behind market forces, and instead, has been obsessed with geometry – the shape of the market areas. In re-establishing the concept of economic space development, Krugman (1991) considered three key questions: What is the impact of trade on the geographical distribution of industries? How does economic integration shape spatial disparities? And why do firms agglomerate in certain places as integration deepens? The outcome resulted in the emergence of the New Economic Geography (NEG), which, according to Krugman, is the study of the location, distribution and spatial organisation of economic activities across space, i.e. it is based on the fundamental elements of why self-reinforcing centripetal forces pull economic activities into a location that persists over time. The innovative contribution of the NEG is composed of concepts which allow for the dynamics of spatial clustering (and dispersing) of economic activities when trade barriers are progressively removed. In essence, the NEG represents the renewed interest in the ‘general theory of location and space economy’. The NEG explains the geographical unevenness of the economic landscape as a situation of equilibrium when considering the following conditions: (1) the benefits derived from lower production costs which coerces firms to geographically concentrate their productive activities rather than dispersing them; (2) increasing returns which allows for the creation of larger production units that are, in turn, more efficient than smaller ones, since, when a firm decides to concentrate production in one single location, the benefits of scale economies give it an advantage over spatially dispersed firms; (3) the interaction between transport costs and increasing returns which constitutes a crucial force towards agglomeration (or dispersion) in location behaviour and (4) access to external sources such as workforces pooling, specialised goods and services and technological spillovers that give rise to the localisation of individual industries or localisation of manufacturing as a whole.

With the urban evolution orientation, Pumain (2000) maintained that no evidence to adequately explain urban systems could be derived from the principles of static theories such as central places and economic equilibrium. In his view, activities cluster in certain localities according to their individual interests without there being any necessary relations with other localities. According to him, the spatial configuration of urban centres, their size and spacing, are the product of more or less constant processes whereby towns and cities are adapted to modifications and adjustments. The dynamic characteristic appears to be the competition between urban centres for the attraction and creation of wealth, by means of exchange and the adoption of innovations. This is made possible by a high degree of interconnectivity, which enables information to circulate i.e. a change that occurs in one town or city will quickly be copied and adopted in other towns or cities. Pumain (2000) surmise that urban systems is not the consequence of the optimal organisation of settlements at a given moment in time, but rather of gradual and historical adaptation of settlements originally established for a particular function, which has subsequently been transformed for the exercise of various specialist functions. Therefore, the current form of settlements and subsequently economic spaces is the result of a long evolution and not the optimisation of various factors at a particular point in time.

The core-periphery on the other hand, is based on the notion that, as one urban or regional centre expands in economic prosperity, it engulfs other urban or regional centres nearby, creating a continuous evolution of economic development and growth, whether negative or positive (Baldwin, 2001). The one key element standing out from what the core-periphery differentiates is the creation of a spread and backwash effect. Perroux (1955) referred to it as forward and backward linkages while the Swedish economist Myrdal (1957) referred to it as the economic development effect. The backwash takes place when the adverse effects dominate and the level of economic activity in the peripheral community’s decline, i.e. if one particular area starts growing or developing, it causes people, human capital as well as physical capital, from other parts to gravitate towards this growing centre. This essentially leaves the other areas worse off than before because their best brains and capital left to go to the growing centre (Chen and Partridge, 2013). In brief, backwash means that growth in one area adversely affects the growth in another.

Counter to the backwash effect is the spread effect. Spread refers to the situation where the positive impacts on nearby localities and labour markets exceed the adverse impacts, i.e. when one particular area starts to grow or develop, it positively effects the growth in adjoining areas (Chen and Partridge, 2013). In brief, development in one place spreads to areas located in its proximity, leaving the adjoining areas better off than before. Chen and Partridge (2013) suggested that backwash effects and spread effects could explain the longer or more changeable processes of economic space development.

One can conclude that the aforementioned theories interact dynamically to create patterns of urban and regional development centres or nodes i.e. creating a hierarchy of higher- and lower-order settlements. Furthermore, settlements and, ultimately, economic spaces do not develop at the same rate. This notion is contributed to the fact that, due to the uneven distribution of factors such as natural resources or political considerations, certain urban systems grow faster over time than others. The result is that settlements fulfil a specific role in the context of their regional and urban environment. Therefore, settlements are classified into various functional types which are normally referred to as ‘central functions’. The characteristics of central functions ultimately determine the settlement's position within the hierarchy of settlements, which also determines the settlement’s place of performance overall in the economic spaces. The outcome is a regional and urban system comprising lower-order settlements (large in number) and higher-order settlements (few in number), each having different impacts on and contributions towards economic space development (Zipf, 1949).

Development corridors

Although the previous section focused on the basic dynamics behind economic space development, this section focuses on how the concept of development corridors can create opportunities to strengthen partnerships and increase the spatial attractiveness of regions and cities to business and industrial sectors, resulting in economic growth and development.

As seen from the previous section, economic growth tends to occur in the matrix or hierarchy of urban and regions nodes and it is through this hierarchy that the evolving space economy is organised. In the view of Brunner (2013), applying the development corridor concept as an integrated spatial framework allows for the economic landscape to be mapped in a more dynamic way which allows for the distribution of benefits between cities and regions; i.e. when potential corridors are modelled along economic spaces, large cumulative benefits can become apparent promoting investment opportunities. Brunner also suggested that corridors do not stand alone and their role in economic space development can only be comprehended in terms of the network effects that they induce, whereby new opportunities are created to foster market integration. He points out that the dynamic interaction between corridors creates patterns of economic development based on combined elements as described in the previous section. Furthermore, according to him, what corridors can achieve for economic development and integration depends, firstly, on the characteristics that the specific existing economic networks in which the corridors are embedded personify, and, secondly, on the characteristics that the corridor development intends to introduce or strengthen.

The concept of what a development corridor entails is by no means regarded as simplistic. Although most definitions and descriptions put forward different perceptions, development corridors are generally referred to as promoting urban reconstruction and the enhancement of urban growth. However, development corridors also bring forward other important alternatives such as the channelling of economic growth, the reconstruction of fragmented spatial disparities and the mapping of economic spaces (Yeates, 1984).

Although scholars such as Friedmann (1972), Tuppen (1977), Geyer (1988), Andersen and Burnett (1998), Arvis (2011), Buiter and Rahbari (2011), Henning and Saggau (2012), Srivastava (2012), Brunner (2013) and Brand (2017) put forward various ideas and considerations of what constitute as a development corridor, evidence from their works revealed two prominent characteristics: (1) there is a link between nodes which provides access to different levels of economic opportunities and (2) the intensity of economic development at nodes varies in size and dominance. Although scholars such as Geyer (1988) and Druce (1997) distinguished the fundamental attributes and properties relating to development corridors, Gottmann (1961) and Whebell (1969) initially hypostasised the term corridor. Gottmann (1961) made the argument that a corridor is basically a confirmation of the complex process of interaction, be it social, economic, or administrative, between two primary development centres, which tend to augment the development process in each centre, as well as in secondary centres on the axis in between. Whebell (1969) on the other hand maintained that a corridor denotes a linear pattern of major towns joined by highly developed ‘bundles’ of transport routes. He elaborated that the development of a corridor, may itself, lead to the establishment of secondary urban centres.

Yeates (1984), Geyer (1988) and Druce (1997), allocated the following conditions as fundamental attributes and properties to development corridors, namely (1) corridors must have a vibrant development centre or node at both ends, with an axis linking the two centres; and (2) the centres or nodes must be mutually dependent, in order to support the flow of economic activities along the axis. Besides Geyer (1988) and Druce (1997) observations, Brand (2017) alluded to the notion that corridors are also dependent on a highly developed centre or node that extends the flow of economic activities along multiple axes, i.e. highly developed node interacting with a multiple of less developed nodes creating the potential for further development and growth. Figures 1 and 2 show the fundamental attributes and properties connecting different development centres.

Figure 1.

Economic agent extending its benefits along a defined geography.

Figure 2.

Economic footprint.

Henning and Saggau (2012), Felipe (2012) and Brunner (2013) emphasised that networks displaying high economic cohesiveness normally resulted in the impact of development corridors tending to be more distributed and, conversely, networks displaying low economic cohesiveness resulted in the effects of development corridors tending to cluster. Therefore, according to them, the impact of development corridors is not limited to specific regions. They emphasised that it was important to measure the creation of potential corridors against the economic cohesion of high and low networks in which potential corridors are embedded. This measurement establishes three key conditions: (1) the degree of development; (2) the geographical scale – local, regional, national and continental and (3) the status of integration, ranging from local to continental. Figure 3 shows the different network effects.

Figure 3.

Network effects.

It is important to understand the existence of an ever-changing world, which is often linked to the rate at which transportation systems are developing. Dynamic societies and the development of regions and cities are leading to an ever-changing demand for transport, not only the availability of transport, but also faster and more efficient means of transportation systems. The ability to guarantee smooth and efficient transportation of people and goods is a fundamental requirement for a successful, modern economy. Needham (1977) commented that movement does not take place for its own mysterious reasons; movement takes place because of connections between activities. Therefore, it is fundamental to understand that movement is a function of connecting activities. A well-integrated transportation system opens up larger markets, ensuring greater opportunities and competition, which are essential for economic development and growth. The type of connectivity systems which augment the growth of economic development are categorised as road, rail, sea and air. These modes of connectivity are categorised as either general systems or key gateways. Road and rail in the view of Eddington (2006) are considered general systems because they provide the basic connectivity needed to drive economic growth, while, sea and air according to the World Bank (WB) (2012), are considered key gateways because they provide an advancement in transportation technology whereby trade barriers are lowered, allowing for deeper integration of market access across the globe.

It is evident that development corridors represent axes which express forces of development, i.e. it is an outcome of the flow of activities (goods, services and information) between urban centres, which leads to the manifestation of economic growth. The functional relationships between nodes play an important and decisive role in the creation of corridors. Linking cities not only improves the operational and economic efficiency of a region or country, but it also creates a myriad of new economic opportunities, more specifically, it creates integrated networks of systems supporting the flow of goods; improved infrastructure; increased and more efficient interactions; and expanded business involvement.

Regional corridor model

As far back as the 1930s, Wright (1934) maintained that there are diverse approaches to specifying a model of interest. He was the first to suggest that the most intuitive way to specify a model is to describe one’s model by means of a path diagram. In this regard, based on the literature reviewed for this article, a detailed illustration of what regional corridor model (RCM) entails is shown in Figure 4. A diagram provides a useful guide to clarify ideas about the relationships that exist among variables and entities. In essence, models refer to the imitation of real-world processes or systems and are generally used to not only illustrate the eventual outcome of specific conditions, but also what courses of actions are required, i.e. the creation of a model represents the key characteristics, behaviours and functions of the selected system or process (Wang and Wang, 2012).

Figure 4.

Regional corridor model.

The aim of the RCM is to construct a theoretical regional spatial framework through which development corridors can be integrated as strategic and supporting networks to support the notion of what constitute ‘sustainable spatial and settlement planning’. The application thereof would be linked to the relevant census periods of a region, i.e. usually every 5 to 10 years.

The creation of the RCM as a theoretical framework considers the following key outputs, namely: (1) to establish the spatial distribution of settlements according to central functionality which represents the economic dominance of settlements relative to one another i.e. creating a network of regional development centres; (2) to establish the relative advantage of the network of regional centres when considering distance friction and degree of benefits, i.e. creating potential development corridor zones and (3) to establish the integrated and supporting networks of development corridors upon which a regional spatial framework to guide economic space development can be fashioned. The RCM takes into account two important conditions: (1) what constitute as economic space development when focussing on cities and regions as economic forces and (2) the concept and importance of development corridors as supporting networks to guide economic space development. Both conditions are discussed in detail in the Sections ‘Modelling economic spaces’ and ‘Development corridors’ of the paper.

Creation of a network of regional centres (output level one) revolves around four key steps:

To establish a general functional network of cities – The first step mainly focuses on an Urban Function Index (UFI) to establish a general network of cities. The purpose of an UFI is twofold: (1) to determine the economic weight of settlements relative to one another; and (2) to distinguish between the sizes of the commercial, service and industrial components of urban and regional economies. In essence, it determines the relative economic dominance of cities in relation to one another. The outcome measures the relative strength of commercial and industrial clustering as a means of determining the potential strength of economic spaces.

To convert the sphere of synergy(i.e. cities’ proximity to one another that elevates performance) that exist in the general network of cities into broader regional nodes – The second step considers a daily and weekly urban system to convert the general network of cities into broader networks of regional centres. Settlements have recently been linked to the daily and weekly urban system concept advanced by Geyer Jr. and Geyer (2015). According to them, travelling distances between urban centres are used to quantify the relationships and flows (synergy) that exist between settlements within a network. The daily urban system includes all settlements located within one hour’s travel time which, according to Newman (2004), remains a fairly constant commuting distance. Closely associated with the daily urban system is the concept of the weekly urban system (Hall and Hay, 1980), which includes all settlements (higher and lower order), located within two hours' commuting distance. The outcome elevates cities, lower as well as higher order, into broader regional nodes when consideration is given to the concept of synergy i.e. proximity – commuting distance between cities – when establishing functionality of central places.

To establish the degree of economic attraction or economic output levels exerted by each regional node, in relation to one another – The third step is to establish the degree of economic attraction or economic output levels exerted by each regional node based on the economic weight, which is referred to as Economic Impact Factor (EIF). According to Brand et al. (2015), the economic output exerted refers to the total population, in relation to economically active populations, as well as the value of all goods and services produced in an economy based on Gross Value Added (GVA), and is primarily used to compare the relative economic output that exists between urban centres. Furthermore, strong emphasis is also placed on sea and air movement (key gateways) as a means to lower trade barriers to allow for deeper integration of market accessibility. Sea and airports according to Geyer (1988) represents a nodal locality which is an important consideration in the ranking of urban centres. The inclusion of sea and airports requires establishing the degree of trade output (total value of volume and movement of goods and people passing through) by sea and air movement, relative to one another. Therefore, the overall outcome establishes the economic output levels (economic weight) of the functional networks of regional nodes relative to one another and are calculated using the following algorithm

EIFi = ((\frac{PEi}{PTi}) / (\frac{\sum_{PEi \dots n}}{\sum_{PTi \dots n}})) + (MmPIFi + MmAIFi) x (\frac{GVAi}{\sum_{GVAi \dots n}})

where $EIFi$ is the EIF for city i (i = 1 … n); $PEi$ is the economically active population of city i; $PTi$ is the total population of city i; $\sum_{PEi \dots n}$ is the sum of the economically active population of all the cities; $\sum_{PTi \dots n}$ is the sum of the total population of all the cities; $MmPIFi$ is the Multi-modal Port Index Factor of city i; $MmAIFi$ is the Multi-modal Air Index Factor of city i; $GVAi$ is the GVA of city i; and $\sum_{GVAi \dots n}$ is the sum of the GVA of all the cities. The outcome elevates the status of the most dominant economic spaces based on the degree of economic attraction exerted by each regional node.

To categorise the network of regional nodes into a functional regional index – The last step is to categorise the distribution of the most dominant economic spaces into a functional regional index. The economic weight from the EIF provides for a natural break which translates into a ranking score thereby allowing the opportunity to categorise each regional node as either (1) mega; (2) primary; (3) secondary or (4) intermediate. The regional index in essence identifies a city’s ‘place’ of functionality (performance) within a network.

Creation of potential development corridor zones (output level two) revolves around two key steps:

To convert the degree of economic attraction exerted by each regional node into prominent growth poles – The first step is to establish the relative advantage that exists between each regional node. The relative advantage is derived from calculating the Link Demand Value (LDV) between each regional node as a simple gravity model, using the following algorithm

LDVi / i i = \frac{(P i x Pii)}{D i / i i^{2}} x \frac{(EIFi x EIFii)}{D i / i i^{2}}

where $LDVi / i i$ is the LDV between cities i and ii; $P i x Pii$ is the total population of city i and total population of city ii; $D i / i i^{2}$ is the square of the distance between cities i and ii; $EIFi x EIFii$ is the EIF of city i and EIF of city ii; and $D i / i i^{2}$ is the square of the distance between cities i and ii. According to Janelle (1969), the relative advantage or LDV of a given place attracts the centralisation and specialisation of economic activities, i.e. larger urban areas attract people, ideas and commodities more than smaller urban areas. This is also emphasised by Johnston (1976), indicating that gravity correlates positively with the size of the economy, but negatively with distance, thereby providing a good fit in determining prominent growth poles. Considering that distance friction ultimately defines the attraction levels between two places, i.e. if the distance increases, the attraction levels decrease and vice versa, an LDV value above 1 is considered the best fit (strongest attraction level) in determining which of the regional nodes are considered the most prominent growth poles.

To convert the prominent growth poles into a Cumulative Corridor Impact Factor (CCIF) to create potential development corridor zones – Having established the most prominent growth poles allows the opportunity to convert the linkages between these poles into potential development corridor zones. Therefore, the second step is to convert the outcome from the LDVs into a CCIF. To achieve this, the linkages between mega, primary, secondary and intermediate nodes are segmented into sections and cumulative adding of each adjacent section (increasing by one addition after another) within the potential link determines the vitality (forcefulness) of a corridor zone. The reason for selecting cumulative addition is that it allows quantifying the degree or the force each mega, primary, secondary and intermediate node exerts as benefits through successive additions, which determine the overall strength of a corridor zone. The CCIF is calculated using the following algorithm

P C = (S C 1 + S C 2 + \dots SCn)

where $P C$ is the potential corridor (1 … n); $S C 1$ is the section corridor 1 of the potential corridor; $S C 2$ is the section corridor 2 of the potential corridor and $SCn$ is the section corridor n of the potential corridor.

Having established the potential development corridor zones does not constitute development corridors. Therefore, to determine the potential of the most noteworthy development corridors (output level three) the CCIF is converted into Economic Space Development Axes (ESDA). Although the CCIF establishes potential development corridor zones based on the linkage between the different regional nodes, the ESDA determines, with the use of a ranking score, the ultimate, integrated and supporting networks of development axes upon which a regional spatial framework to guide economic space development can be built. The ESDA considers the weight from the CCIF to translate the different strengths of potential development corridor zones into an ESDA ranking index. Applying the ranking index denotes (1) the regional nodes size as an intersection point and (2) the strength (force) of interaction that exists between regional nodes. This allows the ranking of development corridors as either:

Predominant if it has a high degree of development and interaction, i.e. notable potential

Prominent if it has a medium to high degree of development and interaction, i.e. notable potential

Significant if it has a medium degree of development and interaction, i.e. constricted potential or

Less significant if it has a low degree of development and interaction, i.e. minimal potential.

It is important to highlight that the modelling of spatial interactions depicted by the RCM is not a new concept. A considerable body of literature conceptualising the modelling of spatial interaction exists. Isard (1951) as far back as the 1950s maintained that the analysis of interregional linkages and flows can be approached from several directions. He, for example, outlined an input–output model concluding that the impact of regional change is transmitted to other regions which affects the flow between regions. The key question is what strategic options do the RCM as a potential spatial framework offer to promote ‘sustainable spatial and settlement planning’? Although strong evidence exist that corridors are regarded as important spatial development instruments which channel economic development, arguments that emerged from the assessments and critiques of corridors indicate the need for broader supporting strategies at a regional level, as well as a greater awareness of agglomeration economies to allow for the integration of corridors as strategic and supporting networks (Lamont, 1999; Oranje, 1995). Therefore, the RCM as a potential integrated spatial framework offers distinct attributes, namely:

It recognises the economic position of regional nodes, relative to one another

It provides a framework for the establishment of potential regional economic zones

It promotes explicit, focused areas (nodes) guiding economic space development

It promotes economic advantages for nodes located in close proximity to connecting linkages

It creates economic conditions stimulating intra-regional and cross-border trade opportunities

It supports policy initiatives to promote economic spatial transformation

It provides a frame for infrastructure and resource implementation.

The participation in the development of corridors on a regional scale is a desirable option not to be dismissed. One can anticipate that the evolution of development corridors will result in, on the one hand, the strengthening of nodes linked to the benefits exerted by corridors and, on the other hand, strong intra-national and inter-regional economic integration. Therefore, development corridors do not contain, as such, the resolution of the challenges presented by different development agendas; development corridors are created to seek development and investment opportunities supported by policy interventions.

Regional application: South Africa

The concept of development corridors is the result of decentralised thinking i.e. distribution of economic development as a network concerning the interactive linking of cities.

The economic growth and prosperity of a country is, to a large extent, dependent on the efficient functioning of cities and regions. The national economic growth of a country is becoming more and more dependent on the ability of cities and regions to perform crucial functions within the macro and micro economic environment. The key question here is how to present the RCM as a strategic planning framework that could promote and enhance economic space development? The answer starts with the notion that the RCM should be introduced as an integrated policy framework whereby preferred locations for investment opportunities are quantified.

The evolutionary development of national development policies in South Africa provided two perspectives; pre-1990 focusing on economic growth and separate development and post-1990 focusing on social and political issues (Drewes and Van Aswegen, 2013). Post-1990, South Africa adopted various development policies in an effort to rebuild and transform the economy of the country after years of economic isolation. Policies that played a major role were the Reconstruction and Development Programme adopted in 1995 which was considered the cornerstone of government development; the Growth, Employment and Redistribution strategy adopted in 1996 to stimulate faster economic growth; Spatial Development Initiatives (SDI) adopted in 1996 to address fragmented development patterns; the Accelerated and Shared Growth Initiative for South Africa adopted in 2005 as a further development on the first two developmental strategies; the New Growth Path adopted in 2010 to accelerate economic growth to rapidly reduce poverty, unemployment and inequality; the Spatial Planning and Land Use Management introduced in 2013 bringing together through the development of Spatial Development Frameworks (SDFs) promoted at national, provincial, local and district levels, the collective vision of government, businesses and civil society to promote social and economic inclusion; the National Development Plan (NDP)-2030 introduced in 2013 as South Africa's long-term socio-economic development roadmap i.e. emphasises the beginning of a new focus on strategic planning for South Africa; and the Integrated Urban Development Framework introduced in 2014 unlocking development synergies that emanate from coordinated investments in cities, thereby ensuring a new approach for South African cities and towns (Brand and Drewes, 2019).

To accentuate the notion of a shift in thinking, Brand and Drewes (2019) recently measured the RCM as a potential integrated spatial framework against regional development programmes supported by the NDP. The regional development programmes they took under consideration were the (1) National Infrastructure Plan introduced in 2012 envisioning a long-term planning framework for investment in major strategic infrastructure projects – 19 projects of which 3 directly relate to development corridors; (2) the Industrial Policy Action Plan introduced in the beginning of 2000 launching 5 Industrial Development Zones (IDZs) as well as 11 state-owned industrial parks as tools to assist in the economic development of regions; and (3) the Southern Africa regional development corridor initiatives of which three (the North–South development corridor being diverted at Johannesburg with the one axis directed to Mmabatho and the other axis directed to Polokwane) are directly linked to South Africa.

Empirical evidence suggested that several of the regional development programmes do not align with viable development axes or centre that can advance economic development effectively at a regional level. For example as illustrated in Table 1, measuring the IDZs and the state-owned industrial parks against the RCM, only 2 from the 5 IDZs and 7 from the 11 state-owned industrial parks matched up to either a prominent or predominant development axis or centre. From the South African development corridor initiatives, only one from the three initiated matched up to a prominent or predominant development axis. Also, considering the Southern Africa development corridor initiatives, two and one of the North-South axes matched up to a prominent or predominant axis. Therefore it seems that a certain degree of the initiated regional development programmes do not conform to a supporting regional network to promote economic development.

Table 1.

Regional development initiatives supported by the NDP.

Industrial parks		Place	Province	RCM
1	Seshego	Polokwane	Limpopo	Constricted potential
2	Nkowankowa	Tzaneen	Limpopo	Minimal potential
3	Queenstown	Queenstown	Eastern Cape	Minimal potential
4	Vulindlela	Mthatha	Eastern Cape	Minimal potential
5	Isithebe	Durban/Richards Bay	KwaZulu-Natal	Notable potential
6	Botshabelo	Thaba Nchu/Bloemfontein	Free State	Notable potential
7	Phuthaditjhaba	Harrismith	Free State	Notable potential
8	Bodirelo	Mogwase	North West	Notable potential
9	Babelegi	Hammanskraal	North West	Notable potential
10	Garankuwa	Pretoria	Gauteng	Notable potential
11	Ekandustria	Bronkhorstspruit	Gauteng	Notable potential
Industrial Development Zones		Place	Province	RCM
1	Coega	Port Elizabeth	Eastern Cape	Constricted potential
2	Richards Bay	Richards Bay	KwaZulu-Natal	Notable potential
3	Saldanha Bay	Saldanha Bay	Western Cape	Constricted potential
4	East London	East London	Eastern Cape	Constricted potential
5	Atlantis	Cape Town	Western Cape	Notable potential
South African corridors		Corridor axes		RCM
1	Durban-Free State-Gauteng	Johannesburg-eThekwini		Notable potential
2	South-East	Northern Cape-Nelson Mandela Bay-eThekwini		na – no result
3	Saldanha-Northern Cape	Saldanha Bay-Northern Cape		Constricted potential
Southern African corridors		Corridor axes	Nodal cross-border link	RCM
1	Walvis Bay	Walvis Bay-Mmabatho-Johannesburg	Mmabatho	Notable potential
2	Maputo	Johannesburg-Nelpruit-Maputo	Nelspruit	Notable potential
3	North-South	eThekwini-Johannesburg-Mmabatho	Mmabatho	Notable potential
4	North-South	eThekwini-Johannesburg-Polokwane	Polokwane	Constricted potential

RCM: regional corridor model.

Source: Brand, 2017.

Furthermore, considering that the first regional development programmes (IDZs and state-owned industrial parks) were introduced around 2000, their regions when combined, between 2001 and 2018 exhibited a general economic growth of 31.3% (an average growth of 1.7% per annum) which is below the National average. Furthermore, it seems that the regions located on the most predominant and prominent axes when combined, presented a general growth of 37.7% (an average growth of 2.1% per annum) which surpasses the National average. Lastly, predominant regions when combined, presented an overall growth of 39.5% (an average growth of 2.2% per annum) which also outperforms the National average. The National economy for the same period, presented a general growth of 35.1% (an average growth of 1.9% per annum). One can only assume that predominant economic hubs are still preferred as ideal locations for economic integration. It seems that predominant regions are beyond major impacts by development corridors i.e. predominant regions reduce distance friction allowing corridors to emerge as potential investment opportunities. This is evident considering that the regions located on the most predominant and prominent axes presented a better average per annum growth than the regions associated with development programmes. This supports the notion that regions with a high level of economic agglomeration allow nearby regions to also benefit. Instead, these kinds of powerhouses have amassed production, transformation and access to market functions comparable to other regions. Moreover, this kind of urban conglomeration is considered the wealth of the country, thereby further concentrating resources and functions away from other regions. This means the economic growth of regions outside predominant regions is not advancing to a point of attractiveness and competiveness. What is found to be lacking is an integrated regional approach towards spatial policies or frameworks, combined with an explicit spatial focus; in this case development corridors as strategic and supporting networks that can model economic space development at a regional level.

Conclusion

When potential corridors are modelled along economic spaces, large cumulative benefits can become apparent promoting investment opportunities. The RCM provides a potential solution, whereby preferred locations for investment opportunities are identified to guide economic development.

Two important considerations emerge, i.e. (1) predominant regions normally have a monopolistic stranglehold on economic growth, which must be softened i.e. concentrate economic activities away from these regions and (2) the implication that factors to increase preferred locations appeal as destinations for investment to promote inclusive growth lies with cities and regions. For the first consideration the RCM could provide central governments with the opportunity to develop a realistic spatial perspective on long-term settlement patterns and investment opportunities i.e. define policies and strategic action alternatives to promote sustainable economic development away from predominant regions. For the second consideration the RCM could present cities and regions with the opportunity to align themselves with their unique circumstances, i.e. cities and regions would respond pro-actively and innovatively; they would realise their economic potential as a consumer, producer, landowner or investor to promote economy development and growth.

The implementation of the RCM as a spatial framework would not only recognise the economic position of cities and regions, it would also distinguish the economic strength and impacts of cities and regions in relation to one another. In principle, the RCM would transform policy-thinking by integrating the traditional top-down with a bottom-up strategy, meaning to promote cities and regions’ potential by virtue of local knowledge, diversification and innovation with the support of central government. Cities and regions are ideally placed to identify opportunities whereas central governments are ideally placed to offer policy and strategic support to realise these opportunities. In essence, the RCM provides a framework for marshalling cities and regions to identify relevant priorities at the right level of granularity so that implementation of an appropriate action plan with the support of central government becomes realistic and meaningful.

Note: The economic figures are based on GVA at basic prices provided by Quantec (2019). GVA is defined as output valued at basic prices less intermediate consumption valued at purchaser’s price. The GVA is known by the price at which the output is valued and is a useful way of comparing regions of different sizes of economies.

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

J Ernst Drewes

Biographical notes

Ernst Drewes is a professional, registered Urban and Regional Planner with 28 years of experience in the industry and holds a PhD in Urban and Regional Planning. He is a member of the South African Council for Planners (SACPLAN) and the International Society for Urban and Regional Planners (ISOCARP). He holds the position of Associate Professor in the Department of Urban and Regional Planning at North-West University. As a rated researcher with the National Research Foundation (NRF), his research is focused on strategic spatial planning, regional resilience and planning legislation. He is the Chairman of the Editorial Board of the Town and Regional Planning Journal.

Andre Brand is a Director at Statistics South Africa. He is also an Extra-Ordinary Senior Lecturer in the Research Unit for Environmental Sciences and Management at the North West University. Andre completed his PhD at the North West University. His research interests lie in the area of urban and regional planning, ranging from theory to design. He specialises in regional planning with a specific focus on corridor development. Andre is married to Delveen, and has a son, Johnathan. He enjoys playing golf, non-fiction books, good food, and wine. He, occasionally put pen to paper creating comical short stories.

References

Andersen

Burnett

(1998) Activity Corridors, Spines, Streets and Nodes and Access Management. Johannesburg, Gautrans..

Arvis

(2011) Connecting Landlocked Developing Countries to Markets – Trade Corridors in the 21st Century. Washington: World Bank.

Baldwin

(2001) Core-periphery model with forward-looking expectations. Regional Science and Urban Economics 31(1): 21–49.

Baskin

(1966) Central Places in Southern Germany. Englewood Cliffs: Prentice-Hall.

Batten

(1995) Network cities: Creative urban agglomerations for the 21st century. Urban Studies 32(2): 313–327.

Bosker

(2007) Growth, agglomeration and convergence: A space-time analysis for European regions. Spatial Economic Analysis 2(1): 91–100.

Bourne

Simmons

(1978) Systems of cities. Definitions, concepts and approaches: Introduction. In: Bourne LS and Simmons JW (eds) Systems of Cities: Readings on Structure, Growth and Policy. New York: Oxford University Press, pp.18‒27.

Brand

(2017) The use of corridor development as a strategic and supporting instrument towards the development of national space economies. PhD Thesis, North-West University, South Africa.

Brand

Drewes

(2019) Identification of network cities in South Africa. GeoJournal. DOI: 10.1007/s10708-019-10097-z.

10.

Brand

Geyer

Jr. , et al. (2015) Corridor development in Gauteng. South Africa: GeoJournal 82: 311–327.

11.

Brunner

(2013) What is economic corridor development and what can it achieve in Asia’s sub regions? Asian Development Bank (ADB) working paper on regional economic integration, 117, Asian Development Bank (ADB), Manila. Available at: http://hdl.handle.net/11540/2308 (accessed October 2016).

12.

Buiter

Rahbari

(2011) Trade Transformed – The Emerging New Corridors of Trade Power. Citi GPS: Global Perspectives & Solutions.

13.

Chen

Partridge

(2013) When are cities engines of growth in China? Spread and backwash effects across urban hierarchy. Regional Studies 47: 1313–1331.

14.

Drewes

(2015) More explicit regional policy for South Africa, please Mr President. Journal of Town and Regional Planning 67: 58–67.

15.

Drewes

Van Aswegen

(2013) National planning in South Africa: A critical review. WIT Transactions on Ecology and the Environment 173: 193–204.

16.

Druce

(1997) Corridor development. Unpublished.

17.

Eddington

(2006) The Eddington Transport Study. Main report: Transports role in sustaining the UK's productivity and competitiveness. London: HM Treasury.

18.

Felipe

(2012) Product complexity and economic development. Structural Change and Economic Dynamics 23: 36–68.

19.

Friedmann

(1972) A General Theory of Polarized Development. London: Collier-McMillan.

20.

Geyer

(1988) The Terminology, Definition and Classification of Development Axes. Potchefstroom: University of Potchefstroom.

21.

Geyer Jr.

Geyer

(2015) Disaggregated population migration trends in South Africa between 1996 and 2011: A differential urbanisation approach. Urban Forum 26: 1–13.

22.

Gildenhuys

(1994) Urban reconstruction and development: The petrification of the Apartheid city. Paper presented at the International Conference on Growth Management for Cities in Crisis of the South African Institute of Town and Regional Planners, Cape Town. September, 1994.

23.

Gottmann

(1961) Megalopolis: The Urbanized North-Eastern Seaboard of the United States. Cambridge: MIT-Press.

24.

Hall

Hay

(1980) Growth Centres in the European Urban System. Los Angeles: University of California Press.

25.

Henning

Saggau

(2012) Networks, spatial diffusion of technological knowledge, and regional economic growth: An agent-based modelling approach. International Journal of Innovation and Regional Development 4: 204–231.

26.

Hohenberg

Lees

(1985) The Making of Urban Europe: 1000‒1950. Cambridge: Harvard University Press.

27.

Isard

(1951) Interregional and regional input-output analysis: A model of a space-economy. The Review of Economics and Statistics 33: 318–328.

28.

Janelle

(1969) Spatial reorganization: A model and concept. Annals of the Association of American Geographers 59: 348–364.

29.

Johnston

(1976) The World Trade System: Some Enquiries into Its Spatial Structure. London: G. Bell.

30.

Krugman

(1991) Increasing returns and economic geography. Journal of Political Economy 99: 483–499.

31.

Lamont

(1999) Mdantsane—East London development corridor progresses in East London.

32.

Lösch

(1954) The Economies of Location. New Haven: Yale University Press.

33.

Mallick

(2005) Development Theory, Rostow’s Five-Stage Model of Development and Its Relevance in Globalization. Newcastle: University of Newcastle.

34.

Myrdal

(1957) Economic Theory and Underdeveloped Regions. New York: Harper & Row.

35.

Needham

(1977) How Cities Work: An Introduction. New York: Pergamon Press.

36.

Newman

(2004) Why we’re reaching our limits as a one-hour city. Sydney Morning Herald, 26 April, p.24.

37.

Oranje

(1995) The need for an appropriate system of urban development control: Arguments and characteristics. Town and Regional Planning 39: 22–33.

38.

Otterstrom

(2007) Rapid settlement diffusion: The development of the semi-peripheral region North of San Francisco, California, 1850‒1880. Historical Geography 35: 241–268.

39.

Perroux

(1955) Note sur la notion de pole de croissance. Economie Appliqué 7: 307–320.

40.

Pumain

(2000) Settlement systems in the evolution. Geografiska Annaler. Series B, Human Geography 82: 73–87.

41.

Quantec (2019) GVA–Income & Production–Regional Output and GVA at basic prices by industry and 2011 local municipal/ward-based metro region level.

42.

Scott

(2000) Economic geography: The great half-century. Cambridge Journal of Economics 24: 483–504.

43.

Srivastava

(2012) Regional Corridors Development: A Framework. ADB Economics Working Paper No. 258. Manila: ADB.

44.

Surd

(2009) Geography of Settlements. Cluj: Cluj University Press.

45.

Taaffe

Morrill

Gould

(1963) Transport expansion in underdeveloped countries: A comparative analysis. Geographical Review 53: 503–529.

46.

Tuppen

(1977) Axial Regions: An Appraisal of Their Formation, Evolution and Definition. Discussion Paper in Geography No. 4. Salford: University of Salford.

47.

Vance

Jr (1970) The Merchant’s World: The Geography of Wholesaling. Englewood Cliffs: Prentice-Hall.

48.

Wang

(2012) Structural Equation Modelling. Applications Using Mplus. New York: John Wiley.

49.

Watts

(1993) The geography of postcolonial Africa: Space, place and development in Sub-Saharan Africa (1960‒93). Singapore Journal of Tropical Geography 14: 173–190.

50.

Whebell

CFJ

(1969) Corridors: A theory of urban systems. Annals of the Association of American Geographers 59: 1–26.

51.

World Bank (2012) Handshake. International Finance Corporation quarterly journal on public-private partnerships, air and sea PPPs, 6 (July 2012).

52.

Wright

(1934) The method of path coefficients. The Annals of Mathematical Statistics 5: 161–215.

53.

Yeates

(1984) The Windsor-Quebec city axis: Basic characteristics. Journal of Geography 83: 240–249.

54.

Zipf

(1949) Human Behaviour and the Principle of Least Effort. Cambridge: Addison-Wesley.