Delay of construction projects, particularly highway construction, is a severe issue in the developing economies. So, this study aims at determining the stationary cause of construction delay in the highway projects by utilizing prior validated data from the Egyptian developing construction market. The data represent the responses of 56 engineers working in the Egyptian highway construction companies on the effectiveness degrees of 38 causes of construction delay. By adopting Fuzzy Trapezoidal Membership Function, “insufficiency and ineligibility of the technical staff of the main contractor to accomplish the scope of the project", “mistakes in design", “delay in inspecting the project activities by the technical staff of the consultant", “poor efficiency of construction equipment", and “difficulties in funding the project by the main contractor" have been rated to be the top-five causes of delay. Also, Ginni's Mean Difference Measure of Dispersion indicated that the stationary cause of construction delay is “low productivity of labors". Additionally, in a comparison with twenty-one developing nations, it has been concluded that the top-five and stationary causes of delay are frequent in the developing economies. Nonetheless, “mistakes in design" is the most recurrent cause, influencing eighteen of the explored countries. These findings equip the practitioners in the developing construction markets with the top-critical causes of delay in their highway projects. This leads to directing their attempts toward managing these causes. Consequently, the high percentages of delay in their highway construction projects can be radically minimized.