I doubt that any equipment could operate on 11 foot track centers since a switch engine is 10'-4" over the handrails. Two of them passing on adjacent tracks would consume 10'-4" of space and in a curve probably wouldn't clear.

Sidings on the Portland Traction in Portland from the streetcar days are 13' 0" centers...a trainman walking between a cut doesn't have much safety room.

Current track centers are a MINIMUM of 14'-0"

Believe new construction on Class I's is minimum 20 feet. This is probably dictated that any track closer than 20' centers has to be Class I or better. At 20'-1" it can be considered "excepted" and maintained to the lowest (nonexistant) standard.

I may be wrong but believe 14' is MINIMUM.

Sammie