Engineering, project finance, rail construction, and transit operation firms in the U.S. and four countries have expressed interest in helping the District of Columbia develop a planned 22-mile streetcar system, district Department of Transportation officials announced this week. DDOT received 20 responses from firms in China, Spain, Great Britain and Japan, as well as the U.S., to its June 26 request for information, agency spokesman Dara Ward said in a release. The submissions are not formal proposals to operate the DC Streetcar project and the local Circulator bus system, as a public-private partnership, Ward said, though a DDOT release indicated that the agency solicited the responses “in an effort to explore the potential of entering into a public-private partnership.” The project would represent a streetcar revival in the district, which phased them out in favor of buses 50 years ago. Other cities have gone back to streetcars in recent years, with bond-financed networks now operating in Portland, Ore. and Tampa, Fla., among other places. New or expanded streetcar networks, including P3s, also have been discussed in cities like San Antonio, Tex. and Los Angeles, Calif.