This paper uses system dynamics (SD) approach to predict and measure construction projects strategies and decisions success. SD model captures construction projects design phase processes using VENSIM software to simulate policies used. The model is validated by comparing results for the base case of Love, Edwards et al. 2008 model. Two scenarios are proposed to overcome owner changes. These changes are minimizing project schedule from 45 to 25 weeks. Polices used to overcome these changes are: 1- assign overtime to the available designers to increase the work output (one designer work more than one shift); 2- assign more experienced designers to work without assigning overtime to these designers (increase the available designers but the designer work only one shift). The SI model is developed to compare between these two scenarios. Two-round Delphi questionnaire are used for data gathering to build structure index (SI) model that represent measure of project success. Four success parameters; time, cost, quality, and Client's Satisfaction; are used to formulate a success measure index for construction projects. This helps in indexing the success of finished projects in order to compare with each other. Also, using the proposed SI model with SD helps in measuring organization strategy success. And, help decision makers to assess their decisions. The results show that more designers assigned to finish the work in time (i.e. scenario two) is better than scenario one (i.e. better than working overtime that leads to more rework and increases the cost).