For the last two years, a group of researchers at the New York University Marron Institute of Urban Management has been building a big database of public transit projects around the world. Their goal: To understand what drives the costs of transit projects, what makes some places more expensive than others, and how costs can be brought down…

This month, the Transit Costs Project is planning to publish an overview of its findings. Among them: The United States is the sixth most expensive country in the world when it comes to building rapid rail projects. The reasons why range from the politicization of project management to the expanding role of consultants, the costs of labor, and efforts to limit disruption to normal traffic flow during construction.