A continuous model of optimal-cost routes in a circular city

This paper deals with the determination of optimal-cost routes in a circular city where the routes are not confined to a discrete network, but may vary continuously. The Euler-Lagrange equation is derived for the general radially-symmetric case for position-dependent cost. This equation is solved by quadratures. In a special case, the integral representation is evaluated explicitly. A model of a circular city is then assumed, consisting of a circular central business district surrounded by a transition zone. A detailed analysis is then carried out which permits the determination of optimal-cost routes. The results may be employed to improve decision-making in regard to whether to build bypasses around, or direct routes through, a city.