The debate between rail rapid transit and light rail was conducted without reference to any specific right-of-way or railroad tracks. The CPO's 1975 Regional Comprehensive Plan described a $1.5 billion rail-rapid transit system in San Diego featuring a system of and 11 lines. However, by this time, it was widely acknowledged by public officials that a BART-like rapid transit system would be much more expensive than light rail. Rail rapid plans were stalled due to high costs. Proponents of the rail rapid system were concerned about the low speed of at-grade streetcar systems. Operating deficits were also a concern. A 1974 CPO study concluded that a streetcar system would incur operating deficits of $1.9 million annually. It was also understood that any BART-like system would incur substantial deficits.