An idea for a new piece, though it may only be interesting on a larger board.

Engineer - Automatically builds a 'road' when it moves.  Any piece on a 'road' may move to any other square lying on the road in one turn.

Not sure if each army should have their own roads and/or be able to destroy roads. Having recons (spies?scouts?, whatever they are called here) positioned on a road revealing enemy pieces that cross the road is also a possibility.

There seems to be both some potential for speeding things up as
well as introducing a new level of complexity with this.  I think larger boards / piece counts would also be possible.

Thoughts?