Over some years, many public projects in Jordan have experienced delays due to inappropriate initial work management plan. This case has led to cost and time overruns in most of the public projects in Jordan. This study focuses on the key factors affecting the efficiency and achievement of labor productivity in public projects and ranks these factors according to their relative importance index (RII). This study aims to analyze the factors affecting labor productivity in public projects in Jordan, labors achievements and motivation, and give suggestions to improve labors productivity and performance. To achieve the purpose of the study a questionnaire was developed to observe the impact of critical factors on labor productivity and the traffic intersections in Amman: Al-Ersal /Al-Hurryah intersection and Marj Al-Hamam intersection project was selected to be the study sample. The data from the questionnaire were statistically analyzed using the Statistical Package for the Social Science (SPSS) program ,to analyze the data collected from the survey, this study used the method of Relative Importance Index (RII) to measure the impact of the critical factors affecting labor productivity and analyze the factors in the questionnaire are significant or non-significant. From the analysis of 32 Factors that were identified from literature review affecting the labor productivity, it is concluded that the top ten factors affecting labor productivity in the traffic intersections in Amman: Al-Ersal /Al-Hurryah intersection and Marj Al-Hamam intersection project are as follow: (1) Payments delay to labor, (2) Material Shortage, (3) Tools and equipment shortage, and Low wages in the same rank , (4) Allocate tasks to labors fairly and according to specialization, (5) Job Security, (6) Deficiency of motivation, (7) Labor absenteeism, (8) Incompetence of site supervisor, (9) Poor communication of supervisor with labors, (10) Lack of labor skills and experience.