Marzieh Samadi-Foroushani - Department of Industrial Engineering, Eyvanekey University, Eyvanekey,Iran. Tehran Disaster Mitigation and Management Organization, Tehran, Iran.
Amir Shahrabi Farahani - Islamic Azad University, Central Tehran Branch, Tehran, Iran. Program and Budget of Tehran Municipality, Tehran, Iran.
Soheil Kousari - Department of Environmental Engineering, University of Science and Research, Tehran, Iran. Program and Budget of Tehran Municipality, Tehran, Iran.
Mohammad Javad Keyhanpour - Department of Civil Engineering, Islamic Azad University, Tehran, Iran.
Ali Nasiri - Faculty of Health and Health Management Research Center, Baghiyatallah University of edical Sciences, Tehran, Iran. Tehran Disaster Mitigation and Management Organization, Tehran, Iran.

The urban development planning process in Tehran municipality has been implemented for about two decades in the form of compiling four medium-term urban development plans of Tehran. Despite the efforts made, there are challenges to achieving the goals. This research has analyzed the barriers and identified solutions to improve the system of the development plan of Tehran by formulating the mess and using soft systems methodology during a systemic intervention by planning the learning process in practice. The innovative research method is the embedding of mess formulation in soft systems methodology. Formulating the mess analyses the barriers to identifying inefficiencies about aspects of how power, wealth, knowledge, value, and aesthetics are produced and distributed in a social system. Soft systems methodology is an action-research approach for learning human systems in complex problem situations. After a thematic review by referring to the key actors involved in formulating Tehran's urban development plan, first, the problem situation was analyzed, and a rich picture of the problem was drawn. According to formulating the mess, the obstacles were presented and discussed through some sessions in five subsystems of generation and distribution of power, wealth, knowledge, value, and aesthetics. Later, a conceptual model of the ideal system of urban development planning was designed. Then, desirable and executable system changes were identified based on a comparison of the ideal system and the current system, and they were proposed in the form of purposeful activities toward system improvement. Tehran's urban development planning requires a major change in the approach toward planning and solving complex urban problems. This study is an application of systems thinking approaches in learning in practice and managing the complexity of the diversity of views of urban planners in the experience of urban development planning in Tehran.

Urban development planning, Soft systems methodology, Formulating the mess, Tehran Municipality