turnpike

1. A frame consisting of two bars crossing each other at right angles and turning on a post or pin, to hinder the passage of animals, but admitting a person to pass between the arms.
2. A gate or bar set across a road to stop carriages, animals, and sometimes people, until a toll is paid.
3. A beam filled with spikes to obstruct passage; a cheval de frise.
4. A toll road, especially a toll expressway. In some places the clipped version, pike, is used for roads without tolls. (US)
5. A trajectory on a finite time interval that satisfies an optimality criterion which is associated with a cost function.

الجمع turnpikes