In the company of ducks

A restorative solitary walk recce and risk assessment from Milngavie back to the city centre. A pair of mallards kept me company along the Allander Water for a couple of miles or more. Nothing except a fox, a heron, a field of geese, two dog walkers and a jogger until I arrived at Maryhill. 
I do wonder why ScotRail uses the expression formed of  3 coaches when which has 3 coaches would do just as well.