http://www.hrpub.org Civil Engineering and Architecture 9(2): 347-356, 2021 DOI: 10.13189/cea.2021.090208 Infrastructure Projects for Green Cities between Implementation Challenges and Efficiency Indicators Ahmed M. Selim 1,* , Doha M. Saeed 2 1 Department of Architecture, Modern Academy for Engineering and Technology, Cairo, Egypt 2 Department of Architecture, Badr University, Cairo, Egypt Received December 7, 2020; Revised January 28, 2021; Accepted February 24, 2021 Cite This Paper in the following Citation Styles (a): [1] Ahmed M. Selim, Doha M. Saeed , "Infrastructure Projects for Green Cities between Implementation Challenges and Efficiency Indicators," Civil Engineering and Architecture, Vol. 9, No. 2, pp. 347 - 356, 2021. DOI: 10.13189/cea.2021.090208. (b): Ahmed M. Selim, Doha M. Saeed (2021). Infrastructure Projects for Green Cities between Implementation Challenges and Efficiency Indicators. Civil Engineering and Architecture, 9(2), 347 - 356. DOI: 10.13189/cea.2021.090208. Copyright©2021 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Abstract The world's population will be 9.2 billion in 2050, which is 2.2 billion more than today, with most of the increase in Africa, the Middle East, and South Asia. That will negatively affect the availability of arable land, infrastructure, and environmental performance of cities, furthermore, achieving sustainability pillars (environmental, economic, social) becomes mandatory for all countries after signing in the recommendation of the 2015 UN Summit, many initiatives and concepts were adopted to face these challenges and accomplish sustainable development. The green cities concept (GCC) and its strategies are considered an optimum approach to achieve sustainable development objectives and overcome these challenges, by enhancing performance for the existing infrastructure, reducing natural resource consumption, decreasing CO 2 emission, and engaging citizens in decision-making. On another hand, infrastructure projects are vital for achieving (GCC) concept because it reflects the progress and economic performance of countries. This study discusses the green cities, conventional and green infrastructure challenges, then presents Public-Private Partnership (PPPs) as a tool for implementing and overcoming its challenges from the green economy and green contracts perspectives. In addition, concluding an Operational Framework for implementing infrastructure projects by (PPPs) which determines the main phases in (PPPs), allocates the most important strategies for each phase, and indicates the main internal stockholders who share in decision-making. Finally, the study assigns (53) efficiency indicators and obtains a weight for each indicator by identifying the Relative Importance Index through an online questionnaire evaluated by (15) experts to track the achievement of the operational framework. Keywords Infrastructure Projects, Green Cities, Implementation Challenges, Efficiency Indictors 1. Introduction Regarding the 2015 UN summit under title (Transforming our world: Sustainable Development plan 2030) recommendations, which adapted 17 goals [1], the newly agenda concentrates on issues related to sustainable urbanization within specific a goal as: (Goal 11) “make cities and human settlements safe, inclusive, resilient and sustainable and strengthen implementation of the international partnership (Goal 17). As well, a number of other goals are related to this issue, those on clean water and sanitation (Goal 6), and affordable and clean energy (goal 7). In fact, most of the countries adopted different initiatives to achieve this agenda. Green Cities Concept (GCC) and its strategies are considered an optimum approach to achieve sustainable development objectives and overcome these challenges, where, The (GCC) not only affects the urban development growth but also the economic and social growth of the cities as by its aspects which aim to achieve a reduction in natural resources and