After the huge debate between whether to use a double or single bore subway systems for BART's expansion to Downtown San Jose, it appears there is still some controversy with the design. It was decided that the expansion would use a single bore, which would make it the first system of it's kind in the United States. The key benefit of the design is that we would not have to dig up all of Santa Clara Street and disrupt businesses and residents for years. It would actually be less expensive to build. The downside is that this segment of the BART system would be completely different than the rest of the network, and that would require extensive retraining of staff.
Now it appears that there is a compromise solution, and that is to increase the size of the tunnel from 45 feet to a massive 55 feet. By volume, that is about a 50% increase in size. This would allow the trains to run side by side like the rest of the network, but would increase cost and complexity.
It is actually an interesting proposal for me because the extra space above and below the trains could perhaps be utilized for another mode of transportation. It looks large enough for electric buses or even Light Rail. Perhaps, we could see a next generation Loop or Hyperloop system utilize those spaces. While it is clear San Jose needs to be fully connect to BART, we should also think about how we can leverage this project to support the future generation of mobility.
Source:
SVBJ
