See my other comment[0] on this. 4-rail is a viable solution, but, unsurprisingly, it costs more than a 3-rail or sometimes a two separate 2-rail lines. [0] h

See my other comment[0] on this. 4-rail is a viable solution, but, unsurprisingly, it costs more than a 3-rail or sometimes a two separate 2-rail lines. [0] https://news.ycombinator.com/item?id=31880979 https://news.ycombinator.com/item?id=31880979