要旨：This paper examines a conventional assumption of transport costs; any bilateral transport costs are symmetric. Using a comprehensive dataset on transport transactions in Japan, we first describe a directional imbalance of transport costs by transport mode and examine its potential sources such as density economies, long-haul economies, and a directional imbalance of transport flow. Based on the method of instrumental variables, we find that the density economies drive a deviation from symmetric transport costs between prefectures. We then develop a theoretical model of economic geography in which asymmetric transport costs occur in a transport sector for the density economies. Compared with the model without density economies, we show that agglomeration of economic activities is likely to emerge under any ranges of cost parameters. Thus, the economies of density in transport flows act as an agglomeration force.

要旨：In a closed monocentric city with three distinct land use patterns consisting of firms, condominiums and housing lots, we determine simultaneous optimization of regulations on building size, lot size and zonal boundaries under the existence of agglomeration externality in the business district and of traffic congestion externality in the residential zones. Results show that the optimal regulations are at most second best, and require not only downward adjustment to the market size of buildings at outer locations using maximum FAR regulation but also upward adjustment at more central locations using minimum FAR regulation within the business district, and similar regulations in the condominium zone, followed by a cap on the minimum lot size in the suburb. Moreover, the optimal city size is more compact than a market city, but whether the business district size should be compact or greater, depends on the relative level of agglomeration externality and the congestion. In addition, the boundary between condominium zone and housing lot zone does not need to be controlled.

要旨：我が国のタクシー産業は1993年から段階的に規制緩和が実施されており特に2002年の規制緩和は需給調整機能の廃止を目的とした参入規制や運賃制度の緩和が実施された。本研究の目的は我が国のタクシー産業における需要関数の推計を行い、2002年の規制緩和が消費者の動向へ与えた効果を計測することである。推定結果によれば需要の価格弾力性は負であり、運賃と2002年規制緩和ダミーの交差項は正に有意であるので、価格弾力性は0へ近づいた。つまり、規制緩和によって需要の価格弾力性が小さくなり、消費者にとってタクシーが必需品に近づいたと言える。これは規制緩和に伴って発生した各種新サービスが有効に機能した結果と考えられる。