Peter Sarf
Established Member
You're working on the assumption that all 4 vehicles weigh the same. I suspect the trailers are a fair bit lighter.
Yes the trailers are lighter but not enough of a difference in weight to be insignificant as regards the power to weight ratio. It might be OK on a branch service if the existing layover times were enough to accommodate a longer end to end timing but the existence of some non-standard units would probably not fit in with the overall fleet diagramming.