ساختار بازار و نتایج بازار در بازار حمل و نقل ریلی مقررات زدایی شده

Using cross-section data on a national sample of city-pair markets for rail freight, I examine correlations between prices, quantities, and the number of single-line and interline firms serving markets. I estimate the reduced form of a structural model in which rail rates and quantities depend on the number of firms. I find that rates increase as the number of firms serving the market falls, and quantities shipped rise as the number of firms falls. The result is consistent with market power for rail freight shippers that causes markups to rise when fewer firms serve the market, and is not consistent with other explanations of the relationship between number of firms and rates and quantities. Interline shipment is much more costly than single-line, suggesting that mergers may be desirable even if they exacerbate market power problems.

Since deregulation in 1980, United States rail freight carriers have been allowed to set rates for freight shipment with only limited restrictions from regulatory agencies. The consolidation of the industry that followed deregulation may have increased welfare by allowing more single-line shipment and less interline shipment of goods; but it may also have allowed carriers to acquire market power as the number of firms, including interline combinations, available to carry goods for any given shipper declined. In this paper, I use city-pair specific and commodity-specific data covering the entire United States, which contain considerable variation in market structure, to examine issues of market conduct and performance in the rail freight industry. The first issue is whether single-line shipment of goods between two cities is more efficient than interline shipment. The second issue is whether small numbers of competitors can exercise market power to raise prices above competitive levels. If single-line shipment is more efficient than interline, then end-to-end mergers between rail firms that reduce interlining can improve welfare. But, if oligopolies with fewer firms can exploit market power, then side-by-side mergers can reduce welfare. I derive and estimate a reduced form model of supply and demand for rail freight, and measure changes in equilibrium prices and quantities as the number of firms in the market varies. Using a very flexible functional form, I find that rail rates and quantities are significantly correlated with both the number and the type of firms serving markets, after controlling for distance and other variables affecting supply and demand for shipments, and that the differences are large in economic terms. Markets without any single-line shipper have prices that are considerably higher, and quantities considerably lower, than markets with the same number of competitors but with single-line shipment; this result suggests that interline shipment has higher costs than single-line shipment. On the other hand, prices are also related to the number of shippers of either type; an additional single-line shipper in a rail freight market reduces prices by up to 10%, and increases quantities by up to 15%, compared to a market with one fewer single-line shipper. The effect of an additional indirect shipper in a market is much smaller, only 1 to 2% reductions in price and between 2 and 3% increases in quantity in most cases. I test whether simpler, linear functional forms for the number of firms are acceptable, and reject them. The results can be explained without invoking market power if rail firms have decreasing returns to scale, in which case prices would be lower when more firms share a market and each carry a smaller quantity; but past rail cost studies have usually found that rail firms have constant or increasing returns to scale within a given origin–destination market.1 The alternative explanation is that price–cost markups rise as the number of firms falls, indicating market power; this theory is consistent with both my results and previous results. The rest of the paper is organized as follows. Section 2 summarizes the existing literature on deregulation and rail market power, and describes this paper’s extensions to the literature. Section 3 describes a model of supply and demand of rail freight from which the regression equations are derived. Section 4 discusses the data and the measurement issues in describing the number of interline competitors accurately. Section 5 describes the regression results, and Section 6 discusses the implications of the results for the different theories examined. Section 7 concludes.

This paper has used cross-section data on United States rail markets to show how prices and quantities in US rail freight markets, controlling for exogenous supply and demand factors, vary with the number of firms. I find that, in general, markets that have a greater number of competitors have lower prices and higher quantities of freight shipped than do comparable markets with fewer competitors. Competitors which serve markets by interline shipment have a smaller effect on price and quantities than do competitors that ship directly. I reject the theory that prices and quantities vary due to the selection of more firms into more profitable markets. If this theory were true, then changes in the number of firms would be correlated with markets with high demand for shipment, and prices would tend to be higher in markets with more firms. This is exactly the opposite of what I find. I therefore conclude instead that the number of firms entering the market is correlated with the costs of shipping goods, or with the extent of oligopoly market power in the industry, or possibly with both. I also reject the theory that markets are competitive while returns to scale are constant or increasing. If this were so, then an increase in the number of carriers, holding market demand constant, would increase the average costs of each firm and therefore lead to higher prices and lower quantities in the markets. This too is the opposite of what I actually find.