Highways officials are examining ways of extending the country's first congestion charge in Durham City.
A £2 toll was introduced in October 2002 to limit traffic along Saddler Street, which leads to the Market Place and the Cathedral.
Durham County Council has applied for government funding to carry out preliminary work on extending it.
The new charges would apply to either a widened cordon in the city centre or to the A690 linking Durham with the A1.
Highway chiefs believe an extension of the scheme as part of a package of transport improvements in the city could be essential to prevent traffic eventually grinding to a halt.
They have applied to the Government's new Traffic Innovation Fund for cash to test the viability of the move and the level of public support.
Council Leader Ken Manton said: "If our bid is successful, it will help us to review whether a viable and practical scheme can be developed and explain which of the two options would bring the greatest benefits to the people of Durham."