Traffic monitoring can efficiently promote urban planning and encourage better use of public transport. Efficient traffic information collection is one important part of traffic monitoring systems. Based on a technique using wireless sensor networks (WSNs), this paper provides a flexible framework for regional traffic information collection in accordance with user request. This framework serves as a basis for future research in designing and implementing traffic monitoring applications. A two-layer network architecture is established for traffic information acquisition in the context of a WSN environment. In addition, a user-customizable data-centric routing scheme is proposed for traffic information delivery, in which multiple routing-related information is considered for decision-making to meet different user requirements. Simulations have shown good performance of the proposed routing scheme compared with other traditional routing schemes on a real-world urban traffic network.