BurlOak
Senior Member
LRTs which have parts underground or elevated do make sense. Why wouldn't they?
Boston, SF, Brussels, Edmonton, Ottawa (under construction), Newark, LA and probably many other cities have light rail running partly underground.
- A short underground section (such as most transit city lines had) at a major transfer interchange makes sense.
- When the underground section is interlined with several routes, it makes sense.
- When the underground portion is over 10km long, over 50% of the entire length, costs over $4B, and it would cost less than 10% extra to make it fully grade-separated, then it does not make sense.