The construction industry is one of the main sectors that plays an important role in the economic growth of a country. Many modern projects are characterized by sophistication and complexities due to the large number of parties involved during the construction process i.e. clients, users, designers, regulators, contractors, suppliers, subcontractors, and consultants. In addition to uncertainties and complexities in the physical, financial, and economic environments in which most projects are performed. Such conditions have made completing projects on schedule and on budget a difficult task to accomplish, often leading to claims on cost compensations and time extensions. This eventually leads to delay in the completion of the project. Delay could be defined as the time over run either beyond completion date specified in a contract or beyond the date that parties agree upon for delivery of a project. It is slipping over its planned schedule and is considered as common problem in construction projects.
With regard to this, this study was directed towards investigating the effectiveness of using the Gantt charts as a solution to project delays. Gantt charts are used to plan and schedule the progress of the project.
The objectives of the study were; to find out the causes of delay, evaluate the effects of delays, to know the effectiveness of using Gantt charts as a solution to project delays and the extent to which Gantt charts have been used in Kenya.
The study collected data via questionnaires that were administered to contractors whose total target population in Nairobi County is 2179, the sample size was 70 contractors. These were supplemented by secondary sources of data. Data from these sources was then statistically analyzed and presented in a graphical form.
Research findings indicated that the use of Gantt charts had a significant effect on the project completion time. The main reason behind this was that the contractors who used Gantt charts said that they noted a difference in time with those projects that they did not use Gantt charts.
The study concludes that project delays is still a rampant issue in the construction industry and a lot needs to be done on scheduling and controlling the project so as to enhance project completion on time. The study recommended more strict and intense rules and regulations on
scheduling techniques in the contract documentation of construction projects so as to try and curb the issue of project delays.

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