Page "Toll road" Paragraph 28

Some toll roads charge a toll in only one direction.

Examples include the Severn Bridges where M4 in Great Britain crosses the River Severn, crossings between Pennsylvania and New Jersey operated by Delaware River Port Authority, and crossings between New Jersey and New York operated by Port Authority of New York and New Jersey.

This technique is practical where the detour to avoid the toll is large or the toll differences are small.