Building Bridges?

The Forth Bridge, The Tay Bridge, The Skye Bridge and The Humber Bridge.

Which is the odd one out?

Clearly the last of these is in England but that is only a fraction of the reasoning. Nonetheless, it remains the answer when all logic is applied.

 Being non-Scottish IT STILL HAS TOLLS.

 PS. I built The Humber Bridge. (Okay - there were a number of others who also helped.)