Abstract: Through the study of the changes of the retail sales value of social consumption in the two cities of Ningbo and Jiaxing on both sides of Hangzhou Bay Cross-Sea Bridge before and after its opening, this paper makes an analysis of the impact of transportation infrastructure on the consumption of cities along the route. By employing the synthetic control method, the cities in the controlled group are given the power to simulate the retail sales value of social consumer goods in the two cities under the counter factual conditions that the bridge is assumed not opened to traffic. The findings show that since the bridge was opened to traffic the actual retail sales value of social consumer goods in Ningbo and Jiaxing has failed to reach the level that should have been reached when it was not opened to traffic in theory, namely, there is an issue of consumption outflow. The bridge opening to traffic has resulted in the loss of retail sales value of social consumer goods in Ningbo by 4.1%, and in Jiaxing by 7.7%. This proves that there exists a “siphon effect” in the improvement of transport facilities.

Key words: cross-sea bridge; siphon effect; consumption loss; synthetic control method