A note on postman problems with zigzag service

This note presents a generalization of postman problems with more flexibility of servicing street segments. Street segments requiring a service on both sides of the street can be covered either by two separate services or a single zigzag service. A mixed integer formulation and a transformation of these postman problems into a symmetric traveling salesman problem are presented. Even if the cost for zigzag service is not smaller than the cost of two separate services, there is still a potential of improving solutions of the corresponding arc routing problem.