Germà Bel
email: gbel@ub.edu

Preventing competition because of "solidarity": Rhetoric and reality of airport investments in Spain

Keywords: Public Enterprise, Legal monopolies, Air Transportation, Models Public Enterprise, Legal monopolies, Air Transportation, Models with Panel Data Jel Codes: L32, L43, L93, C23 Public Enterprise, Legal monopolies, Air Transportation, Models with Panel Data Jel Codes: L32, L43, L93, C23 Public Enterprise, Legal monopolies, Air Transportation, Models with Panel Data Jel Codes: L32, L43, L93, C23 Public Enterprise, Legal monopolies, Air Transportation, Models with Panel Data Jel Codes: L32, L43, L93, C23:

From a public interest perspective, there could be a justification for constraining market mechanisms with the aim of progressive redistribution. However, some policies might be based on selfish motivations of government agents. In this paper, we empirically contrast if the infrastructure policy is based only on public interest motivations or if it is also based on the private motivations of policy makers. In this way, Spain infrastructure policy provides a useful policymaking field to test hypothesis about the behavior of policy makers. We find some evidence regarding the strength of political motivations in explaining such behavior. In fact, results from our analysis show that political motivations can eventually play a more relevant role than social welfare maximization.

Introduction

Traditionally, airports have been seen as monopolistic infrastructures that hold tight control over flights with origins and destinations in their hinterlands. Consequently, neither economic analysis nor infrastructure policy used to consider competition as one of the relevant features of airports. Nowadays there exists a clear trend towards corporatization of airports. Like privatization, corporatization has been seen as a way to reform airports whose ownership and management have remained public. Within this context, competition has been seen as a powerful tool to stimulate efficiency.

Competition among airports at the international level is now a standard feature in all developed countries. Moreover, within each country airports compete to grow and win an increasing part of the business. Spain, alone among developed countries with more than one large airport, defies this pattern. Despite having a large population and several large airports, Spain air travel remains organized as a totally integrated network: airports are exclusively owned and managed by the central government. Thus, competition among airports does not exist. The market has no role in issues such as pricing or resource Why is the Spanish system such an exception? No matter the political affiliation of the ruling party, politicians in charge and bureaucrats have regularly claimed that interterritorial solidarity is the main rationale for their choice. Their story goes as follows: less developed areas in Spain must have airports for regional development. However, such areas cannot sustain airports costs. In this way, it is said that centralized management and allocation of funds would allow the surplus from the largest and most profitable airports to pay for the deficits incurred by the smallest and least profitable airports. In short, rich airports would be paying for keeping poor airports working. Is this what is actually happening?

As far as social welfare maximization is concerned, there could be a potential justification for constraining market mechanisms with the aim of progressive redistribution. 1 This brings us to a traditional conundrum of public policy; the trade-off between efficiency and equity. However, if we accept that the behavior of public agents is aimed to their own interest, some policies designed to prevent competition might actually be based on selfish motivations, while justified on the grounds of progressive redistribution.

Through our analysis we will empirically contrast two competing explanations for the persistence of the unusual model in Spain. On the one hand, there does exist the public interest explanation. From the point of view of the 'general interest', market mechanisms would generate a less than socially desirable level of airport operating facilities, and public intervention is needed to correct this 'market failure'. This would be consistent with the standard explanation by politicians and bureaucrats we have summarized above. However, On the other hand, we explore a public choice approach. Within that framework, the agents of governments are rational utility maximizers: politicians trying to maximize success in elections, while officials seek to maximize their own budget. As long as each group pursues its own-interests they will tend to resist institutional arrangements that might constrain their behavior and enhance opportunities for efficient performance.

Within our specific framework, introducing market mechanisms in the provision of public services would limit increases in the discretionary budgets in the control of officials (Niskanen, 1971). Our results provide evidence that governments distribute investment in airports so that they can increase their electoral support.

The idea of this work is related with the recent literature on regional allocation of public investments. Some recent works in this literature focus the attention on the traditional trade-off between equity and efficiency in public policies (Yamano and Ohkawara, 2000;de la Fuente, 2005). Our paper is more closely related to the literature that analyzes not just the efficiency-equity issue but also the role of political factors in explaining the regional allocation of public investment in infrastructure. 2 Kemmerling and Stephan (2002) show that, along with the equity objective, political support from citizens for the incumbent party in the central government is crucial in explaining the distribution of investment grants across cities. Castells and Solé (2005) find that political considerations promote differences in the attractiveness of regions to the central government in such a way that a deviation from the efficiency-equity rule can arise.

Certainly, the efficiency-equity trade-off relationship in infrastructure policies is a basic and relevant story. But it is not the sole story to be found in the regional allocation of 2 Another similar strand of literature but less related to our work is that focused on the political motivations with regard to grant allocations between different government levels. Empirical applications of this issue can be found, for example, in Worthington and Dollery (1998), Case (2001), Costa et al. (2003) and Johansson (2003). Indeed, airport management in Spain is embodied with specific features that allow us to test a hypothesis about the behavior of government agents. Since one of the main consequences of integrated airport management is that decisions about investment are centralized in the national government, we want to disentangle the following questions: Is the allocation of investments in Spanish airports effectively based on redistributive purposes? Which factors explain actual allocations? Is airport policy in Spain consistent with publicly announced objectives?

To advance our research we organize the paper as follows. First, we briefly review the main features of the Spanish system of airport management and finance and analyze it within the framework of international models. Then we proceed with our empirical analysis. Initially, we focus on economic factors, and subsequently, political factors.

Finally, we summarize our main results and draw out their main implications.

Airport management in Spain: the exception to the rule

High quality airport facilities foster intercity agglomeration economies and influence the location decision of firms, especially those in knowledge intensive sectors (Button et al., 1999;Brueckner, 2003). Hence, the link between the quality of airport facilities and urban economic growth could provide a rationale for guaranteeing airport facilities in less developed regions. In a similar way, scale economies could provide a motivation to support small airports. Indeed, high fixed costs associated with airport operations may help explaining the existence of a positive relationship (although no necessarily a linear one) between air traffic and airport profitability -and so the amount of self-finance available for investments (European Commission, 2002). Thus, airports that generate a low volume of traffic may not be profitable Managing airports as an integrated national network arises as a, though by no means the only, possible strategy of regional policy. In fact, as shown in airports that belong to large national airport networks are usually managed on an autonomous basis. This is the case for Germany, France, Italy and the United Kingdom (and other large Anglo-Saxon countries such as the USA, Canada and Australia).

Autonomy is also the case for the Netherlands, Ireland, Denmark, Belgium and Austria.

Indeed, in all these countries grants and subsidies to small airports and/or airports located in poor regions are often available from more than one government level.

Where a national network is run in a centralized way, it has just one large airport. Such a situation exists in Sweden, Portugal, Finland and most of the new accession countries.

Spanish is unique, because it is the only European country with several large cities and airports in which all airports are managed by a single national agency.

Insert table 1 about here

Indeed, the Spanish Airports and Air Navigation Agency (AENA) owns and manages more than 40 commercial airports in Spain. AENA is a public entity belonging to the Ministry in charge of transportation issues, and it enjoys an autonomous legal and economic status. Investment decisions are centralized and are financed through the surplus of the entire airport system. 3 In this way, there is a system of non-transparent, cross-subsidization across Spanish airports. Importantly, politicians have justified centralized management on the grounds that it supports territorial cohesion. The possibility of competition between airports or the benefits of a differentiated commercial policy is not recognized.

Where airports are managed on market criteria, the amount of investment in each airport should be strongly associated with the revenues obtained from local operations.

Such revenues are fundamentally determined by the amount of traffic at the airport. On the contrary, when a territorial cohesion criterion is in place less developed regions should 3. Investment decisions are taken as follows: The Budget proposed by the Spanish Government to the Parliament displays in an annex the investments that AENA intends to implement during the fiscal year. The Spanish Parliament can either approve or reject this proposal, which cannot be modified. It is worth mentioning that there is no allocation of funds from the budget, since all AENA investment is financed with aeronautical fees and commercial revenues. Furthermore, scale economies should justify an investment allocation outcome in which large (profitable) airports cross-subsidize small (unprofitable) airports. Some facts about the investment behavior of AENA cast doubts about political claims concerning the integrated airport network as a guarantee of the territorial cohesion criterion.

The first year of activity of AENA was 1992 (in the previous period, the Ministry in charge of transportation issues was the unique responsible of airport management). Table 2 shows the relationship between investment and passenger traffic for the Spanish airport network in period 1992-2004, and the corresponding relative position of each region in terms of economic development. We present the results aggregated on a regional basis because the regional level is the one for which most of the variables needed for further analysis are available (individual information for each airport is available upon request).

Column (3) shows the relationship for every Spanish region between share of total investment and share of total passengers.

Insert table 2 about here

In the period 1992-2004, the richest Spanish region with the largest airport, Madrid, accumulated about 60 per cent of total investment but only 22 per cent of total traffic. The ratio (investment share)/(traffic share) is certainly high: 2.60. Overall, airports in the less developed Spanish regions (Extremadura, Andalusia, Galicia, Murcia and Asturias) received a share of investment lower than their share of air traffic generated. Thus, the allocation of airport investments in Spain does not seem to follow the territorial cohesion criterion regularly used by politicians to justify centralized management. Furthermore, several lightly populated regions with low levels of air traffic have an investment/traffic ratio smaller than one. In short, we must go look further to determine whether airport investments decisions have been effectively aimed to other objectives. In order to obtain an equation that explains the allocation of airport investments across regions, we consider that policy makers of the central government maximize an objective function. Such objective function could be aimed to social purposes and/or political interests since both aspects could affect the utility of those agents.

To this regard, we follow the approach of Bernham and Craig (1987). The objective function of the central government is defined over infrastructure outcomes in region i (i =1,.....I) from a given country at period t (t = 1,….T) and can be expressed through the following form:

W t = i O it , ( 1
)
where O it is a vector of infrastructure outcomes. This expression implies that the central government maximizes infrastructure outcomes. The first derivative with respect to O it is assumed to be positive (QW t /QO it > 0).

The central government's maximization problem is subject to two constraints. First, there is a resource constraint. This implies that total investments can not be higher than the total resources available for that purpose:

i INV it R t , (2)
where R t are total resources available at period t, which are assumed to be fixed and constant across regions, and INV it are airport investments across regions.

The second constraint specifies that infrastructure outcomes across regions depend on investments made on them weighted by a vector of regional characteristics at period t, Z it .

Additionally, each element of the vector of regional characteristics is weighted by a parameter, Z , such that unequal concern of the central government about different regions can arise: First order conditions of the central government's maximization problem yield

O it = C it ( Z Z it )h(INV it ), (3)
h'(INV it ) C it ( Z Z i ) = m, for all i (4)
Here, m is the multiplier associated to the resource constraint, which necessarily binds.

This provides us with a general specification of the investment equation that is going to be tested in our empirical analysis:

INV it /R t = g[C it ( Z Z it )]
(5)

Our empirical model will consider g as a linear function, which could be justified as a first order Taylor approximation:

INV it /R t = i Z Z it , ( 6
)
where

Z it = GDP it , PAX it , NAC it , INCUM it , CORRE it (See definitions below).
Given the value of R t , Z > 0 implies that QINV it /QZ it > 0, while Z' < 0 implies that QINV it /QZ' it < 0. In this context, we must consider the elements of the vector of regional characteristics.

Gross Domestic Product per capita (GDP) and air traffic (PAX) are included in this vector. Indeed, where territorial cohesion criteria influence the airport investment decisions of the central government, regions with low product per capita should receive more investment than regions with high product per capita. Furthermore, where airport investments are aimed to support small airports those investments in a region should increase less than proportionally to the traffic generated for the airports of that region.

In addition to this, the central government could try to maximize the surpluses of domestic rather than international passengers, since the latter are not incorporated in its objective function. Thus, the proportion of national traffic with respect to the total traffic (NAC) should be included in the vector of regional characteristics.

Finally, the political clout of each region, due to the popularity of the central government's incumbent party in the corresponding region (INCUM) or due to the correspondence between the incumbent party in the central and regional governments 7) should take a value lower than 0.

Hypothesis II: If investments are aimed to support small airports, those investments in a region should increase less than proportionally to the traffic generated for the airports of that region. According to this hypothesis, PAX in equation ( 7) should take a value lower than 1.

Hypothesis III: Government looks after cross-subsidies from international passengers to national travelers. Consistently with this, investments should be higher in regions with higher ratios domestic traffic/total traffic. According to this hypothesis, NAC in equation ( 7) should take a value greater than 0.

Hypothesis IV: Investment allocations are used to enhance political support.

Consistently with this, investments should be higher in regions where the ruling party has strong electoral support and/or the regional government is held by the same party holding national government. According to this hypothesis, INCUM and CORRE in equation ( 7) should take a value greater than 0.

Hypothesis I, II are consistent with an objective funcion of policymakers of the central government that fits a social welfare function, while hypothesis IV is consistent with a welfare funcion of policymakers that fits with a political rent-seeking behaviour.

Hypothesis III is consistent with an objective funcion of policymakers that fits both with a social welfare function and a political rent-seeking behaviour.

Economic factors

It is of central interest in our empirical analysis to examine any type of crosssubsidization that can take place between the regional networks of the Spanish airport system. Hence equation ( 6) can be expressed for the empirical analysis in the following way:

INV it = µ + GDP GDP it + PAX PAX it + NAC NAC it + it , (8)
where INV it refers to the percentage of investment made in airports from region i with respect to the total investment in the national airport network. GDP it refers to Gross Domestic Product per capita, PAX it refers to the percentage of annual passengers carried in the airports from region i with respect to the total annual traffic in the national airport network and NAC it refers to the percentage of national passengers carried in the airports from region i with respect to the total annual traffic in the regional airport network. The error term ( it ) is assumed to be independent and identically distributed over regions and time, with mean 0 and variance 2 . However, we test (and correct if pertinent) these assumptions in the empirical analysis.

In order to estimate this model, we have constructed a panel data for the period 1992-2004 for the 15 Spanish regions with airports. This period captures the first year of activity of the current airport management system and it is long enough to smooth out distortions from single projects in a particular period. To this regard, as figure 1 shows, the huge amount of investments made in the last six years in comparison to the previous years allows claiming that initial conditions should not play a relevant role.

Insert figure 1 Table 3 shows the results of our estimates of the investment equation, while table 4 indicates the elasticities than can be inferred from them. Column 1 presents the results of the estimates when using the Feasible Generalized Least Squares estimator (FGLS). The tests about the validity of the error term assumptions indicate the existence of heteroskedasticity and cross-sectional correlation. A problem of serial autocorrelation does not seem to take place. Column 2 displays the results of the estimates when using the FGLS estimator with the error term corrected for heteroskedasticity and cross-sectional correlation. In this setting, Betz and Katz (1995) show that FGLS estimator involves an underestimation of standard errors. In column 3, we present the results of the estimates when using the Ordinary Least Squares Estimator with Panel Corrected Standard Errors (PCSE). This latter estimator corrects both for heteroskedasticity and cross-sectional correlation in the error-term and for underestimation of standard errors.

As could be expected, the three estimators provide similar values of the estimated coefficients but different standard errors. Correction for heteroskedasticity and crosssectional correlation using the FGLS estimator reduces the standard errors (see columns 1 and 2 of table 3). The estimation with the PCSE estimator is more efficient than that using FGLS without correcting for heteroskedasticity and cross-sectional correlation (see columns 1 and 3 of table 3) but tends to increase the standard errors obtained with the FGLS estimator with robust standard errors (see columns 2 and 3 of table 3). In any case, 4. There is a possible simultaneity bias for the GDP variable as long as airport investment can be a determinant of economic growth. However, our units of measurement are flows rather than stocks so that annual investments in airports have a very low weight on the total stock of infrastructure, which must be one of the main determinants of economic growth. In addition, it is worth taking into account that airport effects on economic growth are particularly strong at a microeconomic level (greater market access, travel time reductions, attraction of high-tech firms and so on). Additionally, we argue that the PAX variable should not be endogenous either. Indeed, air traffic in a year can be dependent on airport capacity as a stock but not on the contemporaneous annual investments in the airport, which influences only partially that stock for the following years. statistical significance of all explanatory variables is not affected for the calculation of the standard errors.

Insert table 3 about here

Insert table 4 about here

All variables are significant and the overall explanatory power of the equation estimated is reasonably high, regardless of the econometric technique used. Our results show clear evidence that progressive redistribution is not relevant to the airport investment choice of the central government. Indeed, the percentage of total investments in a region seems to increase when product per capita of that region also increases, which is not consistent with hypothesis I above.

In addition to this, we do not find evidence that airport investments are motivated by a scale economies argument (in order to support regions with the smallest airports) because the percentage of total investments increases more than proportionally to the output generated for each regional airport network. Indeed, a 10 per cent increase in the share of the total traffic of the airport network implies about a 13 per cent increase in the share of the total investments made in the airport network. Holding the other factors constant, the percentage of total investments is higher in regional airport networks with a higher proportion of national traffic. These results are consistent with our hypothesis III above but not with our hypothesis II. 1997 and 1998. 5 From the data, it can be observed that cross-subsidization across Spanish airports does not take place from high-profitability to low-profitability regional networks, as expected if scale economies were controlled. Actually, the most profitable airport has the highest traffic-5. Since the late nineties AENA and the Spanish Government have been extremely reluctant to provide financial information on individual airports. Indeed, one of the consequences of an integrated management is that it makes possible for governments to be less transparent and, thus, less subject to democratic control. investment ratio, while many of the non-profitable airports have traffic-investment rates lower than one. In fact, data from this table, along with the results of the investment equation estimates, allows us to infer a type of redistribution not mentioned by Spanish airport authorities. All profitable regional networks with low investment-traffic ratios (Balearic Islands, Canary Islands, Andalusia and C. Valenciana) have a common feature.

They all have, at least, one large airport focused on tourist traffic. This fact seems to confirm that cross-subsidization from international to domestic passengers is taken place in the Spanish airport system.

Political factors

Since neither progressive redistribution nor scale economies seem to be the real objective of the centralization of the Spanish airport network, further analysis is needed to understand the objectives of Spanish airport authorities. Several studies (Cadot et al., 1999;Kemmerling and Stephan, 2002;Castells and Solé, 2005) show that political motivations based on the self-interest of the public decision-makers can play a crucial role in the allocation of the stock of infrastructure across regions.

Where election systems are based on proportional rules, as is the case in Spain, politicians are motivated to maximize the number of votes their party obtains in highly populated electoral districts. 6 Following Grossman (1994), the incumbent party in the central government may allocate public resources in order to buy the support of voters and political agents across regions. Ceteris paribus, more resources will be invested in those regions that have the most -and most valuable -political capital to offer. Such political capital will be greater where the support for the incumbent party in the central government is also greater, and it will be even more valuable where a correspondence exists between the incumbent party in the central government and the incumbent party in the regional government. Alternatively, some studies argue that the central government could invest more in the regions where the closeness in elections between the two main parties is higher (Dalhberg and Johansson, 2002;Johansson, 2003). Under this hypothesis, the incumbent party tries to obtain higher rates of returns -in terms of votes-from its investments.

In order to capture these political factors, we add to equation ( 8) the following political variables:

INCUM: Percentage of votes in the last general elections for the incumbent party in the central government in the corresponding regions of the sample.

SWING: The difference in the percentage of votes between the two main parties in the general elections across regions.

CORRE: Dummy variable that takes value 1 when there is a correspondence between the incumbent party in the central government and the incumbent party in the regional government.

Data for the political variables have been obtained from the web site of the Ministry of Domestic Affairs (Ministerio del Interior). It is expected a positive sign in the coefficient of variables INCUM and CORRE, as especified in our hypothesis IV above, while it is expected a negative sign in the coefficient of the variable SWING.

The political variables are estimated separately in order to avoid multicollineality.

Tables 5 and6 show the results of our estimates of equation ( 8 Least Squares Estimator (FGLS).

Insert table 5 about here

Insert table 6 about here

Results for the economic variables do not change substantially in relation to those obtained in the specification without political variables. The variable capturing the influence of partisan support, INCUM, is statistically and economically significant. Thus, we find some evidence that partisan support could play an important role in the investment allocation choices of the central government. Indeed, the incumbent party in the central government seems to compensate regions for partisan support in order to assure votes.

Results for the variable that captures the difference in the percentage of votes between the two main parties in the general elections across regions, SWING, show that such effect is, in our context, not relevant. We believe this is not surprising in our analysis, since swing voters are of paramount importance within the framework of one-seat elections systems, where one vote gives the majority. This is not the case in Spain, where jurisdictions are multi-seat and seats are assigned by means of a proportional system (with d'Hont correction). Because of this, maximization of absolute number of votes fits better than marginal changes due to swing voters.

The coefficient of the dummy variable capturing the correspondence between the incumbent party in the central government and the incumbent party in the regional government, CORRE, is also economically and statistically significant. Thus, political affiliation seems to favor better coordination between decision-makers at different territorial levels of government.

Overall, our results suggest that politics mater in the allocation of airport investments across regions. Divergence between the policy announced and the policy effectively implemented could be explained, at least to some extent, by a desire to maximize the contribution of that policy to the re-election chances of the incumbent party.

Concluding remarks

The Spanish model of airport management and finance is singular among comparable developed countries. Spain is unique among countries with several large cities and important airports in that its system is strictly centralized and publicly owned. This peculiar institutional setting prevents competition among Spanish airports, and policy makers and bureaucrats in charge of the system rhetorically justify it on grounds of inter-territorial solidarity.

Through our empirical analysis of the determinants of airport investments in Spain across regions, we find that the choices of the central government have been motivated by neither a progressive redistribution criterion nor the demands of supporting smaller airports. Indeed, ceteris paribus high-income regions receive relatively more public resources than low-income regions. In addition to this, we find evidence that investment increases more than proportionally to the output generated by the regional airport networks, while our data shows that cross-subsidization from high-profitability airports to low-profitability regional networks does not seem to take place. On the contrary, we find that cross-subsidization arises from international to domestic passengers.

Given that economic factors do not explain the allocation of investments across regions, we pay attention to the influence of political motivations. We find some evidence that the incumbent party in the central government could try to maximize support from regional citizens. Indeed, more public resources seem to be invested in those regions where the support for the party in central government is greater. In addition to this, more public resources are invested in those regions where the incumbent party in the central government and the incumbent party in the regional government are the same. Rich and big airports do not pay to keep poor and small airports working. According to our results, solidarity seems to be merely a rhetorical excuse to prevent competition among Spanish airports. In fact, competition would constrain discretionary power of policy makers and bureaucrats over management and budgets. We are aware that the public choice paradigm for explaining policymaking is too simple and naïve, and policy processes are much more complex than can be explained by the self-interested policy maker alone. Nevertheless, when analyzing why the system of airport management and finance in Spain is different from any other comparable country, we do not find much more than rhetoric about solidarity to prevent competition in order to maximize power and budget. Why is the Spanish system such an exception? No matter the political affiliation of the ruling party, politicians in charge and bureaucrats have regularly claimed that interterritorial solidarity is the main rationale for their choice. Their story goes as follows: less developed areas in Spain must have airports for regional development. However, such areas cannot sustain airports costs. In this way, it is said that centralized management and allocation of funds would allow the surplus from the largest and most profitable airports to pay for the deficits incurred by the smallest and least profitable airports. In short, rich airports would be paying for keeping poor airports working. Is this what is actually happening?

F

As far as social welfare maximization is concerned, there could be a potential justification for constraining market mechanisms with the aim of progressive redistribution.2 This brings us to a traditional conundrum of public policy; the trade-off between efficiency and equity. However, if we accept that the behavior of public agents is aimed to their own interest, some policies designed to prevent competition might actually be based on selfish motivations, while justified on the grounds of progressive redistribution.

Through our analysis we will empirically contrast two competing explanations for the persistence of the unusual model in Spain. On the one hand, there does exist the public interest explanation. From the point of view of the 'general interest', market mechanisms would generate a less than socially desirable level of airport operating facilities, and public intervention is needed to correct this 'market failure'. This would be consistent with the On the other hand, we explore a public choice approach. Within that framework, the agents of governments are rational utility maximizers: politicians trying to maximize success in elections while bureaucrats, in this case 'AENA' top managers, seek to maximize their own budget. As long as each group pursues its own-interests they will tend to resist institutional arrangements that might constrain their behavior and enhance opportunities for efficient performance. Within our specific framework, introducing market mechanisms in the provision of public services would limit increases in the discretionary budgets in the control of bureaucrats (Niskanen, 1971). Our results provide evidence that governments distribute investment in airports so that they can increase their electoral support.

The idea of this work is related with the recent literature on regional allocation of public investments. Some recent works in this literature focus the attention on the traditional trade-off between equity and efficiency in public policies (Yamano and Ohkawara, 2000;de la Fuente, 2005). Our paper is more closely related to the literature that analyzes not just the efficiency-equity issue but also the role of political factors in explaining the regional allocation of public investment in infrastructure. 3 Kemmerling and Stephan (2002) show that, along with the equity objective, political support from citizens for the incumbent party in the central government is crucial in explaining the distribution of investment grants across cities. Castells and Solé (2005) find that political considerations promote differences in the attractiveness of regions to the central government in such a way that a deviation from the efficiency-equity rule can arise.

3 Another similar strand of literature but less related to our work is that focused on the political motivations with regard to grant allocations between different government levels. Empirical applications of this issue can be found, for example, in Worthington and Dollery (1998), Case (2001), Costa et al. (2003) and Johansson (2003). Certainly, the efficiency-equity trade-off relationship in infrastructure policies is a basic and relevant story. But it is not the sole story to be found in the regional allocation of public investments in infrastructure. This paper adds to the literature by analyzing a scenario where infrastructure policy may pursue neither efficiency nor equity.

Indeed, airport management in Spain is embodied with specific features that allow us to test a hypothesis about the behavior of government agents. Since one of the main consequences of integrated airport management is that decisions about investment are centralized in the national government, we want to disentangle the following questions: Is the allocation of investments in Spanish airports effectively based on redistributive purposes? Which factors explain actual allocations? Is airport policy in Spain consistent with publicly announced objectives?

To advance our research we organize the paper as follows. First, we briefly review the main features of the Spanish system of airport management and finance and analyze it within the framework of international models. Then we proceed with our empirical analysis. Initially, we focus on economic factors, and subsequently, political factors.

Finally, we summarize our main results and draw out their main implications.

Airport management in Spain: the exception to the rule

High quality airport facilities foster intercity agglomeration economies and influence the location decision of firms, especially those in knowledge intensive sectors (Button et al., 1999;Brueckner, 2003). 4 Hence, the link between the quality of airport facilities and urban economic growth could provide a rationale for guaranteeing airport facilities in less developed regions. In a similar way, scale economies could provide a motivation to support small airports. Indeed, high fixed costs associated with airport operations may help explaining the existence of a positive relationship (although no necessarily a linear one) between air traffic and airport profitability -and so the amount of self-finance available for investments (European Commission, 2002). Thus, airports that generate a low volume of traffic may not be profitable

Managing airports as an integrated national network arises as a, though by no means the only, possible strategy of regional policy. In fact, as shown in table 1, European airports that belong to large national airport networks are usually managed on individual basis. This is the case for Germany, France, Italy and the United Kingdom (and other large Anglo-Saxon countries such as the USA, Canada and Australia). Autonomy is also the case for the Netherlands, Ireland, Denmark, Belgium and Austria. Indeed, in all these countries grants and subsidies to small airports and/or airports located in poor regions are often available from more than one government level.

Where a national network is run in a centralized way, it has just one large airport. Such a situation exists in Sweden, Portugal, Finland and most of the new accession countries.

Spanish is unique, because it is the only European country with several large cities and airports in which all airports are managed by a single national agency.

Insert table 1 about here

Indeed, the Spanish Airports and Air Navigation Agency (AENA) owns and manages more than 40 commercial airports in Spain. AENA is a public entity belonging to the Ministry in charge of transportation issues, and it enjoys an autonomous legal and economic status. Investment decisions are centralized and are financed through the surplus of the entire airport system. 5 In this way, there is a system of non-transparent, cross-subsidization across Spanish airports. Importantly, politicians have justified centralized management on the grounds that it supports territorial cohesion. The possibility of competition between airports or the benefits of a differentiated commercial policy is not recognized.

Where airports are managed on market criteria, the amount of investment in each airport should be strongly associated with the revenues obtained from local operations.

Such revenues are fundamentally determined by the amount of traffic at the airport. On the contrary, when a territorial cohesion criterion is in place less developed regions should receive more resources for investment than their share of traffic would justify.

Furthermore, scale economies should justify an investment allocation outcome in which large (profitable) airports cross-subsidize small (unprofitable) airports.

Some facts about the investment behavior of AENA cast doubts about political claims concerning the integrated airport network as a guarantee of the territorial cohesion criterion.

The first year of activity of AENA was 1992 (in the previous period, the Ministry in charge of transportation issues was the unique responsible of airport management). Table 2 shows the relationship between investment and passenger traffic for the Spanish airport network in period 1992-2004, and the corresponding relative position of each region in terms of economic development. We present the results aggregated on a regional basis because the regional level is the one for which most of the variables needed for further analysis are available (individual information for each airport is available upon request).

Column (3) shows the relationship for every Spanish region between share of total investment and share of total passengers.

Insert table 2 about here

In the period 1992-2004, the richest Spanish region with the largest airport, Madrid, accumulated almost 60 per cent of total investment but only 22 per cent of total traffic.

The ratio (investment share)/(traffic share) is certainly high: 2.60. Overall, airports in the less developed Spanish regions (Extremadura, Andalusia, Galicia, Murcia and Asturias) received a share of investment lower than their share of air traffic generated. Thus, the allocation of airport investments in Spain does not seem to follow the territorial cohesion criterion regularly used by politicians to justify centralized management. Furthermore, several lightly populated regions with low levels of air traffic have an investment/traffic ratio smaller than one. In short, we must go look further to determine whether airport investments decisions have been effectively aimed to other objectives.

Empirical analysis: Determinants of the regional allocation of airport investments

In order to obtain an equation that explains the allocation of airport investments across regions, we consider that policy makers of the central government maximize an objective function. Such objective function could be aimed to social purposes and/or political interests since both aspects could affect the utility of those agents.

To this regard, we follow the approach of Bernham and Craig (1987). The objective function of the central government is defined over infrastructure outcomes in region i (i =1,.....I) from a given country at period t (t = 1,….T) and can be expressed through the following form:

W t = i O it , (1)
where O it is a vector of infrastructure outcomes. 6 This expression implies that the central government maximizes infrastructure outcomes. The first derivative with respect to O it is assumed to be positive (QW t /QO it > 0).

The central government's maximization problem is subject to a resource constraint.

This implies that total investments can not be higher than the total resources available for that purpose:

i INV it R t , (2)
where R t are total resources available at period t and INV it are airport investments across regions.

6 For simplicity, henceforth the vector of infrastructure outcomes is defined as a variable. Infrastructure outcomes across regions depend on investments made on them, as well as on specific factors such as the intensity of use. Additionally, infrastructure outcomes will also depend on the objectives of the central government since it is needed to consider not only the aggregate effect of infrastructure policies but also its impact on different regions, for example on regions with different income levels.

In this way, the allocation of investments in infrastructures across regions should depend on a vector of regional characteristics at period t, Z it . Additionally, each element of the vector of regional characteristics may be weighted by a parameter, Z , such that unequal concern of the central government about different variables (Z), which values may be different -or not-from one region to another, can arise.

Hence we can derive a general specification of the investment equation that is going to be tested in our empirical analysis:

INV it /R t = i Z Z it , (3)
where

Z it = GDP it , PAX it , NAC it , INCUM it , CORRE it (See definitions below).
Given the value of R t , Z > 0 implies that QINV it /QZ it > 0, while Z' < 0 implies that QINV it /QZ' it < 0. In this context, we must consider the elements of the vector of regional characteristics.

Gross Domestic Product per capita (GDP) and air traffic (PAX), which in the empirical analysis refers to the percentage of passengers carried in the airports from a region with respect to the total traffic in the national network, are included in this vector.

Indeed, where territorial cohesion criteria influence the airport investment decisions of the central government, regions with low product per capita should receive more investment than regions with high product per capita. Furthermore, where airport investments are aimed to support small airports those investments in a region should increase less than proportionally to the traffic generated for the airports of that region. In addition to this, the central government could try to maximize the surpluses of domestic rather than international passengers, since the latter are not incorporated in its objective function. Thus, the proportion of national traffic with respect to the total traffic (NAC) should be included in the vector of regional characteristics.

Finally, the political clout of each region, due to the popularity of the central government's incumbent party in the corresponding region (INCUM) or due to the correspondence between the incumbent party in the central and regional governments (CORRE), may play a central role in the allocation choice of public resources of the central government as we will see below. It is worth noting that in the empirical analysis INCUM refers to the percentage of votes in the last general elections for the incumbent party in the central government in the corresponding regions of the sample, while CORRE is a dummy variable that takes value 1 when there is a correspondence between the incumbent party in the central government and the incumbent party in the regional government.

Hence equation ( 3) can be expressed as follows:

INV it /R t = µ + GDP GDP + PAX PAX + NAC NAC + INCUM INCUM + CORRE CORRE + it , (4)
where it is a random error term. From our analysis the following hypotheses can be established, which we test in further sections:

Hypothesis I: Consistently with claims of progressive redistribution, regions with low product per capita should receive more investment than regions with high product per capita. According to this hypothesis, GDP in equation ( 4) should take a value lower than 0.

Hypothesis II: If investments are aimed to support small airports, those investments in a region should increase less than proportionally to the traffic generated for the airports of that region. According to this hypothesis, PAX in equation ( 4) should take a value lower than 1. Hypothesis III: Government looks after cross-subsidies from international passengers to national travelers. Consistently with this, investments should be higher in regions with higher ratios domestic traffic/total traffic. According to this hypothesis, NAC in equation ( 4) should take a value greater than 0.

Hypothesis IV: Investment allocations are used to enhance political support.

Consistently with this, investments should be higher in regions where the ruling party has strong electoral support and/or the regional government is held by the same party holding national government. According to this hypothesis, INCUM and CORRE in equation ( 4) should take a value greater than 0.

Hypothesis I, II are consistent with an objective function of policymakers of the central government that fits a social welfare function, while hypothesis IV is consistent with a welfare function of policymakers that fits with a political rent-seeking behaviour.

Hypothesis III is consistent with an objective function of policymakers that fits both with a social welfare function and a political rent-seeking behaviour.

Economic factors

It is of central interest in our empirical analysis to examine any type of crosssubsidization that can take place between the regional networks of the Spanish airport system. Hence equation (3) can be expressed for the empirical analysis in the following way:

INV it /R t = µ + GDP GDP it + PAX PAX it + NAC NAC it + it , (5)
where INV it /R t refers to the percentage of investment made in airports from region i with respect to the total investment in the national airport network. The explanatory variables are defined as follows:

1. GDP it : Gross Domestic Product per capita of region i.

2. PAX it : Percentage of annual passengers carried in the airports from region i with respect to the total annual traffic in the national airport network. 3. NAC it : Percentage of national passengers carried in the airports from region i with respect to the total annual traffic in the regional airport network.

The error term ( it ) is assumed to be independent and identically distributed over regions and time, with mean 0 and variance 2 . However, we test (and correct if pertinent) these assumptions in the empirical analysis.

In order to estimate this model, we have constructed a panel data for the period 1992-2004 for the 15 Spanish regions with airports. This period captures the first year of activity of the current airport management system and it is long enough to smooth out distortions from single projects in a particular period. To this regard, as figure 1 shows, the huge amount of investments made in the last six years in comparison to the previous years allows claiming that initial conditions should not play a relevant role.7

Insert figure 1 about here Data on the territorial allocation of investment have been obtained from the Ministry of Transport; data for Gross Domestic Product per capita have been obtained from the Spanish Statistics Institute. Finally, data of airport traffic have been obtained from AENA.

Table A-1 in Appendix shows the description and summary statistics of the variables used for estimating our investment equation.8

Table 3 shows the results of our estimates of the investment equation, while table 4 indicates the elasticities than can be inferred from them. Column 1 presents the results of the estimates when using the Feasible Generalized Least Squares estimator (FGLS). The not seem to take place. Column 2 displays the results of the estimates when using the FGLS estimator with the error term corrected for heteroskedasticity and cross-sectional correlation. In this setting, Betz and Katz (1995) show that FGLS estimator involves an underestimation of standard errors. In column 3, we present the results of the estimates when using the Ordinary Least Squares Estimator with Panel Corrected Standard Errors (PCSE). This latter estimator corrects both for heteroskedasticity and cross-sectional correlation in the error-term and for underestimation of standard errors.

As could be expected, the three estimators provide similar values of the estimated coefficients but different standard errors. Correction for heteroskedasticity and crosssectional correlation using the FGLS estimator reduces the standard errors (see columns 1 and 2 of table 3). The estimation with the PCSE estimator is more efficient than that using FGLS without correcting for heteroskedasticity and cross-sectional correlation (see columns 1 and 3 of table 3) but tends to increase the standard errors obtained with the FGLS estimator with robust standard errors (see columns 2 and 3 of table 3). In any case, statistical significance of all explanatory variables is not affected for the calculation of the standard errors.

Insert table 3 about here

Insert table 4 about here

All variables are significant and the overall explanatory power of the equation estimated is reasonably high, regardless of the econometric technique used. Our results show clear evidence that progressive redistribution is not relevant to the airport investment choice of the central government. Indeed, the percentage of total investments in a region seems to increase when product per capita of that region also increases, which is not consistent with hypothesis I above. In addition to this, we do not find evidence that airport investments are motivated by a scale economies argument (in order to support regions with the smallest airports) because the percentage of total investments increases more than proportionally to the output generated for each regional airport network. Indeed, 10 percentage points increase in the share of the total traffic of the airport network implies about 13 percentage points increase in the share of the total investments made in the airport network. Holding the other factors constant, the percentage of total investments is higher in regional airport networks with a higher proportion of national traffic. These results are consistent with our hypothesis III above but not with our hypothesis II. 1997 and 1998. 9 From the data, it can be observed that cross-subsidization across Spanish airports does not take place from high-profitability to low-profitability regional networks, as expected if scale economies were controlled. Actually, the most profitable airport has the highest trafficinvestment ratio, while many of the non-profitable airports have traffic-investment rates lower than one. In fact, data from this table, along with the results of the investment equation estimates, allows us to infer a type of redistribution not mentioned by Spanish airport authorities. All profitable regional networks with low investment-traffic ratios (Balearic Islands, Canary Islands, Andalusia and C. Valenciana) have a common feature.

They all have, at least, one large airport focused on tourist traffic. This fact seems to confirm that cross-subsidization from international to domestic passengers is taken place in the Spanish airport system.

9 Since the late nineties AENA and the Spanish Government have been extremely reluctant to provide financial information on individual airports. Indeed, one of the consequences of an integrated management is that it makes possible for governments to be less transparent and, thus, less subject to democratic control.

Political factors

Since neither progressive redistribution nor scale economies seem to be the real objective of the centralization of the Spanish airport network, further analysis is needed to understand the objectives of Spanish airport authorities. Several studies (Cadot et al., 1999;Kemmerling and Stephan, 2002;Castells and Solé, 2005) show that political motivations based on the self-interest of the public decision-makers can play a crucial role in the allocation of the stock of infrastructure across regions.

Where election systems are based on proportional rules, as is the case in Spain, politicians are motivated to maximize the number of votes their party obtains in highly populated electoral districts.10 Following Grossman (1994), the incumbent party in the central government may allocate public resources in order to buy the support of voters and political agents across regions. Ceteris paribus, more resources will be invested in those regions that have the most -and most valuable -political capital to offer. Such political capital will be greater where the support for the incumbent party in the central government is also greater, and it will be even more valuable where a correspondence exists between the incumbent party in the central government and the incumbent party in the regional government.

Alternatively, some studies argue that the central government could invest more in the regions where the closeness in elections between the two main parties is higher (Dalhberg and Johansson, 2002;Johansson, 2003). Under this hypothesis, the incumbent party tries to obtain higher rates of returns -in terms of votes-from its investments.

In order to capture these political factors, we add to equation ( 5 3. CORRE: Dummy variable that takes value 1 when there is a correspondence between the incumbent party in the central government and the incumbent party in the regional government.

Data for the political variables have been obtained from the web site of the Ministry of Domestic Affairs (Ministerio del Interior). It is expected a positive sign in the coefficient of variables INCUM and CORRE, as specified in our hypothesis IV above, while it is expected a negative sign in the coefficient of the variable SWING.

The political variables are estimated separately in order to avoid multicollineality.

Tables 5 and6 show the results of our estimates of equation ( 5) with the addition of the political variables. In columns 1 and 2, we show the results when the political variables added are INCUM and SWING, respectively. In column 3, we show results when the political variable added is CORRE. Regarding the econometric techniques used, we follow the same procedure to section 3.1. As in the previous estimation without political variables, the tests about the validity of the error term assumptions indicate the existence of heteroskedasticity and cross-sectional correlation but not a problem of serial autocorrelation. In order to clarify the exposition, we just present the results when using the Ordinary Least Squares Estimator with Panel Corrected Standard Errors (PCSE). As in the previous estimation without political variables, the values of the coefficients and its statistical significance are similar to those obtained when using the Feasible Generalized Least Squares Estimator (FGLS).

Insert table 5 about here

Insert 10 percentage points increase in the percentage of votes of the incumbent party in a region implies about 8 percentage points increase in the share of the total investments made in the airport network. Thus, we find some evidence that partisan support could play an important role in the investment allocation choices of the central government. Indeed, the incumbent party in the central government seems to compensate regions for partisan support in order to assure votes.

Results for the variable that captures the difference in the percentage of votes between the two main parties in the general elections across regions, SWING, show that such effect is, in our context, not relevant. We believe this is not surprising in our analysis, since swing voters are of paramount importance within the framework of one-seat elections systems, where one vote gives the majority. This is not the case in Spain, where jurisdictions are multi-seat and seats are assigned by means of a proportional system (with d'Hont correction). Because of this, maximization of absolute number of votes fits better than marginal changes due to swing voters.

The coefficient of the dummy variable capturing the correspondence between the incumbent party in the central government and the incumbent party in the regional government, CORRE, is also economically and statistically significant. Indeed, such correspondence implies almost 4 percentage points increase in the share of the total investments made in the airport network. Thus, political affiliation seems to favor better coordination between decision-makers at different territorial levels of government.

Overall, our results suggest that politics mater in the allocation of airport investments across regions. Divergence between the policy announced and the policy effectively implemented could be explained, at least to some extent, by a desire to maximize the contribution of that policy to the re-election chances of the incumbent party.

Concluding remarks

The Spanish model of airport management and finance is singular among comparable developed countries. Spain is unique among countries with several large cities and important airports in that its system is strictly centralized and publicly owned. This peculiar institutional setting prevents competition among Spanish airports, and policy makers and bureaucrats in charge of the system rhetorically justify it on grounds of inter-territorial solidarity.

Through our empirical analysis of the determinants of airport investments in Spain across regions, we find that the choices of the central government have been motivated by neither a progressive redistribution criterion nor the demands of supporting smaller airports. Indeed, ceteris paribus high-income regions receive relatively more public resources than low-income regions. In addition to this, we find evidence that investment increases more than proportionally to the output generated by the regional airport networks, while our data shows that cross-subsidization from high-profitability airports to low-profitability regional networks does not seem to take place. On the contrary, we find that cross-subsidization arises from international to domestic passengers.

Given that economic factors do not explain the allocation of investments across regions, we pay attention to the influence of political motivations. We find some evidence that the incumbent party in the central government could try to maximize support from regional citizens. Indeed, more public resources seem to be invested in those regions where the support for the party in central government is greater. In addition to this, more public resources are invested in those regions where the incumbent party in the central government and the incumbent party in the regional government are the same.

Rich and big airports do not pay to keep poor and small airports working. According to our results, solidarity seems to be merely a rhetorical excuse to prevent competition among Spanish airports. In fact, competition would constrain discretionary power of 18 policy makers and bureaucrats over management and budgets. We are aware that the public choice paradigm for explaining policymaking is too simple and naïve, and policy processes are much more complex than can be explained by the self-interested policy maker alone. Nevertheless, when analyzing why the system of airport management and finance in Spain is different from any other comparable country, we do not find much more than rhetoric about solidarity to prevent competition in order to maximize power and budget. Bel, 2002 andRvyT, 1999).

F

  most relevant features of airport management are decided on bureaucratic basis and approved within the Spanish Government budgetary process.

  that choices of governments have been motivated by neither a progressive redistribution criterion nor the claim of supporting smaller airports.

  infrastructure. This paper adds to the literature by analyzing a scenario where infrastructure policy may pursue neither efficiency nor equity.

  for investment than their share of traffic would justify.

  ) with the addition of the political variables. In columns 1 and 2, we show the results when the political variables added are INCUM and SWING, respectively. In column 3, we show results when the political variable added is CORRE. Regarding the econometric techniques used, we follow the same procedure to section 3.1. As in the previous estimation without political variables, the tests about the validity of the error term assumptions indicate the existence of heteroskedasticity and cross-sectional correlation but not a problem of serial autocorrelation. In order to clarify the exposition, we just present the results when using the Ordinary Least Squares Estimator with Panel Corrected Standard Errors (PCSE). As in without political variables, the values of the coefficients and its statistical significance are similar to those obtained when using the Feasible Generalized

  robust to heterocedasticity and contemporaneous correlation. 2 OLS with panel corrected standard errors (Standard errors robust to heterocedasticity and contemporaneous correlation).3 Standard errors in parenthesis 4 Significance at 1% (***), 5% (**), 10% (*)

  panel corrected standard errors (Standard errors robust to heterocedasticity and contemporaneous correlation).2 Standard errors in parenthesis 3 Significance at 1% (***), 5% (**), 10% (*) have been seen as monopolistic infrastructures that hold tight control over flights with origins and destinations in their hinterlands. Consequently, neither economic analysis nor infrastructure policy used to consider competition as one of the relevant features of airports. Nowadays there exists a clear trend towards corporatization of airports. Like privatization, corporatization has been seen as a way to reform airports whose ownership and management have remained public. Within this context, competition has been seen as a powerful tool to stimulate efficiency.Competition among airports at the international level is now a standard feature in all developed countries. Moreover, within each country airports compete to grow and win an increasing part of the business. Spain, alone among developed countries with more than one large airport, defies this pattern. Despite having a large population and several large airports, Spain air travel remains organized as a totally integrated network: airports are exclusively owned and managed by a State Owned Enterprise, 'AENA'. Thus, competition among airports does not exist. The market has no role in issues such as pricing or resource allocation. Some of the more relevant features of airport management, such as investment policy, are decided on bureaucratic basis and approved by the Spanish Parliament together with the National Budget. 1

  politicians and bureaucrats we have summarized above. However, our results show that choices of governments have been motivated by neither a progressive redistribution criterion nor the claim of supporting smaller airports.

  validity of the error term assumptions indicate the existence of heteroskedasticity and cross-sectional correlation. A problem of serial autocorrelation does

  Percentage of votes in the last general elections for the incumbent party in the central government in the corresponding regions of the sample.

  : The difference in the percentage of votes between the two main parties in the general elections across regions.

table 1

 1

	, European

about here

	Table A-1 in Appendix shows the description and summary statistics of the variables used
	for estimating our investment equation. 4
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	Data on the territorial allocation of investment have been obtained from the Ministry
	of Transport; data for Gross Domestic Product per capita have been obtained from the
	Spanish Statistics Institute. Finally, data of airport traffic have been obtained from AENA.

Table A

 A

-2 in Appendix provides additional evidence of the results obtained in our estimates of the investment equation. In this way, table A-2 presents airport financial data for the last two years in which this information is available,

Table A -1. Description of the variables and summary statistics (Number of observations: 195)

 A

	Page 21 of 56	Submitted Manuscript
		Appendix
	Variable	Description	Mean	Standard	Minimum	Maximum
				deviation	value	value
	INV INV	Total investment in airports of the region (10 3 euros) The share of investment of each region over	54,181.31 0.07	184,457.3 0.130	10.22 0	1,552,165 0.707
	GDP	total investment Gross Domestic Product per capita in each region (euros)	13,368	4,054	6,408	23,889
	PAX	Total output (number of annual passengers carried in airports of the region)	8,001,865	1.05e+07	15,547	3.81e+07
	PAX NAC	The share of output of each region over total traffic Percentage of national passengers over total	0.07 0.66	0.08 0.27	0 0.08	0.26 1
	INCUM SWING CORRE	o r P F o r P traffic in airports of each region Percentage of votes in the general elections for the incumbent party in each region The difference in the percentage of votes between the two main parties in the general elections across regions Correspondence between incumbent party F o r in the central and regional government in each region P	0.41 0.08 0.52	0.10 0.12 0.50	0.18 -0.21 0	0.58 0.32 1
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Editorial Office, Dept of Economics, Warwick University, Coventry CV4 7AL, UK

Table A -2. Spanish airports operating profits. Millions of euros

 A

	Region Madrid (1)	Operating results (Yearly average 1997-98) 89.7	Share of the total surplus generated by regions with surplus 39.3%	Share of the net surplus of the network 45.7%	Ratio Investment-traffic 2.60
	Canary Islands (8) Catalonia (3)	40.7 40.2	17.8% 17.6%	20.8% 20.5%	0.41 0.99
	Balears Islands (3)	41.8	18.3%	21.3%	0.35
	Valencian C. (2)	10.8	4.7%	5.5%	0.35
	Andalusia (6)	5.1	2.2%	2.6%	0.39
	Surplus in system	228.3	100.0%
	Extremadura (1) Castile & Leon (3) Murcia (1) Navarra (1) Asturias (1) Cantabria (1) Aragon (1) F o r F o r Galicia (1) Basque C.(1) Losses in system P -0.6 -1.8 -2.0 -2.1 -2.6 -2.8 -2.9 -6.9 -7.6 -32.2 P		-0.3% -0.9% -1.0% -1,1% -1.3% -1.4% -1.5% -3.5% -3.9%	0.54 1.82 0.80 0.69 0.98 1.04 1.82 0.70 1.18
	Network surplus	196.1 e e		100.0%
		e r e r
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Note: 1998 is the last year for which financial data on operating results for individual airports has been made available by AENA. See footnote 11 above. Source: Own elaboration on AENA information (published in

Bel, 2002 and RvyT, 1999)

.

Tables and figures Figure 1. Total investments in the Spanish airport network, 1985-2004. Mean annual values over the period (milions of euros 2004)

  Source: Own elaboration on information obtained from Ministerio de Fomento. Data in the period 1985-1993 is available at the web page of IVIE-FBBVA, while data in the period 1994-2004 is available at the web page of Ministerio de Fomento.

				1470.97
	1600.00
	1400.00
	1200.00
	1000.00
	800.00		409.55
	600.00	300.74
	400.00
	0.00 200.00 F o 1985-1991 r	1992-1998	1999-2004
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Table 1 . Major airports and air traffic of passengers in EU-25 countries.

 1

	Source: Eurostat

Table 2 . Spanish airport and regional data, 1992-2004. Mean annual values over the period

 2 In parenthesis, we indicate the number of airports of the region that provide commercial traffic. Source: Own elaboration on information obtained from the web page of the Ministerio de Fomento (Spanish ministry of transports), the Spanish statistics Institut (INE) and the web page of IVIE-FBBVA.

	Region*	(1) Share of total	(2) Share of total	(3) Ratio	(4) Share of total	(5) Share of total GDP	(6) Relative
		investment (Spain = 817,114 10 3 constant euros)	traffic (Spain = 120,291,150 passengers)	Investment-traffic (1/2)	population (Spain = 38,617,092 inhabitants)	(Spain = 557,063,815 10 3 constant euros)	wealth index (5/4)
	Madrid (1)	57.81%	22.36%	2.60	13.61%	17.72%	1.30
	Catalonia (3)	14.60%	14.78%	0.99	16.31%	19.54%	1.20
	Canary islands (8)	9.06%	22.31%	0.41	4.38%	4.12%	0.94
	Balears islands (3)	6.62%	18.98%	0.35	2.14%	2.56%	1.20
	Andalusia (6)	3.79%	9.81%	0.39	18.97%	14.10%	0.74
	Basque C. (3)	2.44%	2.07%	1.18	5.46%	6.61%	1.21
	Valencian C. (2)	2.15%	6.08%	0.35	10.69%	10.12%	0.95
	Galicia (3)	1.33%	1.90%	0.70	7.13%	5.69%	0.80
	Asturias (1)	0.54%	0.55%	0.98	2.82%	2.42%	0.86
	Castille & Leon (3)	0.38%	0.21%	1.82	6.51%	6.05%	0.93
	Aragon (1)	0.36%	0.20%	1.82	3.11%	3.34%	1.07
	Cantabria (1)	0.20%	0.19%	1.04	1.39%	1.33%	0.95
	Navarra (1)	0.15%	0.22%	0.69	1.41%	1.76%	1.25
	Murcia (1)	0.15%	0.19%	0.80	2.51%	2.97%	0.85
	Extremadura (1)	0.01%	0.03%	0.54	2.79%	1.84%	0.66
	*

Table 3 . Investment equation estimates. N = 195 1

 3 Standard errors robust to heterocedasticity and contemporaneous correlation. 2 OLS with panel corrected standard errors (Standard errors robust to heterocedasticity and contemporaneous correlation). 3 Standard errors in parenthesis 4 Significance at 1% (***), 5% (**), 10% (*) 5 Wald1 = Wald Test ( 2 ) of joint significance; BP = Breusch-Pagan LM test of cross-sectional correlation; Wald2 = Wald test for groupwise heteroskedasticity; Dp= Bhargava et al. test for serial autocorrelation (modified Durbin-Watson test)

Table 4 . Estimated elasticities (evaluated at sample means)

 4

Table 5 . Investment equation estimates. N = 195

 5

	1 OLS with panel corrected standard errors (Standard errors robust to heterocedasticity and contemporaneous correlation). 2 Standard errors in parenthesis
	3 Significance at 1% (***), 5% (**), 10% (*)

Table 6 . Estimated elasticities (evaluated at sample means)

 6

	Dependent variable: INV
	PCSE 1 (1)	PCSE 1 (2)	PCSE 1 (3)
	GDP

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Table A -

 A 2 in Appendix provides additional evidence of the results obtained in our estimates of the investment equation. In this way, table A-2 presents airport financial data for the last two years in which this information is available,

table 6 about here

  Results for the economic variables do not change substantially in relation to those obtained in the specification without political variables. The variable capturing the influence of partisan support, INCUM, is statistically and economically significant. Indeed,

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Tables and figures Figure 1. Total investments in the Spanish airport network, 1985-2004. Mean annual values over the period (milions of euros 2004)

	APPENDIX
	(Insert Table A-1)
	(Insert Table A-2)
	o r F o r F o r F o r F o r F o r
	P P P P P P
	e e e e e e
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	21

Table 1 . Major airports and air traffic of passengers in EU-25 countries.

 1

	Country	Number of	Total	National	International	Airport	Airport
		Top 50 EU	passengers	passengers	passengers	management	Ownership
		airports. 2002	(10 3 ). 2003	(10 3 ).2003	(10 3 ).2003
	United	8	177,946	24,416	153,530	Individual	private, regional
	Kingdom						gov.
	Germany	8	121,136	21,193	99,943	Individual	private, regional gov. and national
							gov.
	Spain	9	120,248	31,324	88,925	Centralized	national
							government
	France	6	96,296	26,712	69,584	Individual	national gov. (Paris), chambers of
							commerce (rest)
	Italy	6	73,912	24,477	49,436	Individual	private, regional
							gov.
	Netherlands	1	41,168	154	41,014	Individual	private, national government
	Greece	1	28,237	5,030	23,207	Individual	private (Athens),
							national go. (others)
	Sweden	1	20,441	6,875	13,567	Centralized	national
							government
	Ireland	1	20,010	812	19,197	Individual	national government
	Denmark	1	19,575	1,606	17,969	Individual	private, national
							government
	Portugal	2	17,739	2,853	14,886	Centralized	national
							government
	Austria	1	15,799	548	15,251	Individual	private, national gov.
	Belgium	1	15,087	2	15,085	Individual	private, regional
							gov.
	Finland	1	10,516	2,701	7,816	Centralized	national
							government
	Czech Republic	1	7,761	161	7,600	Individual	national gov. (Prague) / regional
							gov. (others)
	Poland	-	7,067	Na	Na	Centralized	national
							government
	Cyprus	1	6,077	1	6,076	Centralized	national
							government
	Hungary	1	5,010	0	5,010	Individual	private
	Malta	-	2,648	44	2,604	Individual	private
	Luxembourg	-	1,449	0	1,449	Centralized	national
							government
	Slovenia	-	920	Na	Na	Individual	private, national
							gov.
	Lithuania	-	722	1	721	Centralized	national government
	Latvia	-	712	0	712	Centralized	national
							government
	Estonia	-	710	15	695	Centralized	national
							government
	Slovakia	-	626	32	594	Centralized	national government

Source: Eurostat, European

Commission (2002Commission ( , 2006) )

and airports web pages.

Table A -1. Description of the variables and summary statistics (Number of observations: 195)

 A

	Variable	Description	Mean	Standard	Minimum	Maximum
				deviation	value	value
	INV INV	Total investment in airports of the region (10 3 euros) The share of investment of each region over	54,181.31 0.07	184,457.3 0.130	10.22 0	1,552,165 0.707
	GDP	total investment Gross Domestic Product per capita in each	13,368	4,054	6,408	23,889
	PAX	region (euros) Total output (number of annual passengers carried in airports of the region)	8,001,865	1.05e+07	15,547	3.81e+07
	PAX NAC	The share of output of each region over total traffic Percentage of national passengers over total	0.07 0.66	0.08 0.27	0 0.08	0.26 1
	INCUM	traffic in airports of each region Percentage of votes in the general elections	0.41	0.10	0.18	0.58
		for the incumbent party in each region
	SWING	The difference in the percentage of votes	0.08	0.12	-0.21	0.32
		between the two main parties in the general elections across regions
	CORRE	Correspondence between incumbent party in the central and regional government in	0.52	0.50	0	1
		each region

Table A -2. Spanish airports operating profits. Millions of euros

 A Note 1: 1998 is the last year for which financial data on operating results for individual airports has been made available by AENA. See footnote 11 above. Note 2: Numbers in parenthesis indicate the number of commercial airports in each region.

	Region Madrid (1)	Operating results (Yearly average 1997-98) 89.7	Share of the total surplus generated by regions with surplus 39.3%	Share of the net surplus of the network 45.7%	Ratio Investment-traffic 2.60
	Canary Islands (8) Catalonia (3)	40.7 40.2	17.8% 17.6%	20.8% 20.5%	0.41 0.99
	Balears Islands (3)	41.8	18.3%	21.3%	0.35
	Valencian C. (2)	10.8	4.7%	5.5%	0.35
	Andalusia (6)	5.1	2.2%	2.6%	0.39
	Surplus in system	228.3	100.0%
	Extremadura (1) Castile & Leon (3) Murcia (1) Navarra (1) Asturias (1) Cantabria (1) Aragon (1) Galicia (3) Basque C.(3) Losses in system	-0.6 -1.8 -2.0 -2.1 -2.6 -2.8 -2.9 -6.9 -7.6 -32.2		-0.3% -0.9% -1.0% -1,1% -1.3% -1.4% -1.5% -3.5% -3.9%	0.54 1.82 0.80 0.69 0.98 1.04 1.82 0.70 1.18
	Network surplus	196.1		100.0%

Source: Own elaboration on AENA information (published in

One could ask whether alternative systems of grants and subsidies could work better to make up the deficits of the non-profitable airports. In every other country, no matter its system of management and funding, these kinds of tools are used so that unprofitable airports can operate. We do not go with detail into this, since this departs from the central questions in our paper.

Editorial Office, Dept of Economics, Warwick University, Coventry CV4 7AL, UK Submitted Manuscript

Where election systems are based on majority rule, as it happens in the USA and UK, for instance, politicians try to maximize the probability of winning seats in a unipersonal electoral district.

Another relevant feature of airport management, slots' assignment to airlines, is decided by a commission made of 'AENA' top managers and direct representatives of the Ministry of Transport (Ministerio de Fomento).

One could ask whether alternative systems of grants and subsidies could work better to make up the deficits of the non-profitable airports. In every other country, no matter its system of management and funding, these kinds of tools are used so that unprofitable airports can operate. We do not go with detail into this, since this departs from the central questions in our paper.

In a more general context, a great number of studies have analyzed the impact of public capital stock on private sector productivity [e.g.[START_REF] Aschauer | Is Public Expenditure Productive?[END_REF],Duffy-Deno and Ebberts (1991),Garcia-Milà and McGuire (1992), Holtz-Eakin (1994), Flores de Frutos et al. (1998),[START_REF] Miller | On the optimality of public capital for long run economic growth: Evidence from panel data[END_REF],[START_REF] Milbourne | Public investment and economic growth[END_REF]]. In general terms, such impact is considered to be relevant although there is no agreement on the precise elasticities estimated.

Investment decisions are taken as follows: The Budget proposed by the Spanish Government to the Parliament displays in an annex the investments that AENA intends to implement during the fiscal year. The Spanish Parliament can either approve or reject this proposal, which cannot be modified. It is worth mentioning that there is no allocation of funds from the budget, since all AENA investment is financed with aeronautical fees and commercial revenues.

The allocation of investments across regions in period 1985-2004 is similar to that obtained in period 1992-2004. Data for traffic is not available before 1992 so that the empirical analysis is restricted to period 1992-2004.

 8 There is a possible simultaneity bias for the GDP variable as long as airport investment can be a determinant of economic growth. However, our units of measurement are flows rather than stocks so that annual investments in airports have a very low weight on the total stock of infrastructure, which must be one of the main determinants of economic growth. In addition, it is worth taking into account that airport effects on economic growth are particularly strong at a microeconomic level (greater market access, travel time reductions, attraction of high-tech firms and so on). Additionally, we argue that the PAX variable should not be endogenous either. Indeed, air traffic in a year can be dependent on airport capacity as a stock but not on the contemporaneous annual investments in the airport, which influences only partially that stock for the following years.

Where election systems are based on majority rule, as it happens in the USA and UK, for instance, politicians try to maximize the probability of winning seats in a unipersonal electoral district.

Acknowledgements

Our research on infrastructure and competition has received financial support from the Spanish Commission of Science and Technology (CICYT, BEC2003-01679) and from the Fundación Rafael del Pino. Preliminary versions of this paper have been presented at Cornell University and Harvard University. We are thankful to comments and suggestions from Joan Calzada, John Foote, José A. Gómez-Ibáñez, John Meyer, Antonio Miralles, Albert Solé, and Wu Xun. Usual disclaimer applies.

Acknowledgements

Our research on infrastructure and competition has received financial support from the Spanish Commission of Science and Technology (CICYT, BEC2003-01679) and from the Fundación Rafael del Pino. Preliminary versions of this paper have been presented at Cornell University, Harvard University and the 26 th annual meeting of the European Public Choice Society. We are thankful to comments and suggestions from Joan Calzada, John Foote, José A. Gómez-Ibáñez, John Meyer, Antonio Miralles, Albert Solé, and Wu Xun. Usual disclaimer applies.

Editorial Office, Dept of Economics, Warwick University, Coventry CV4 7AL, UK Submitted Manuscript