The time and cost optimizations are very important to be understood in a construction project planning. By knowing these, the time and cost in a project can be measured to obtain maximum profit. The aim of this study is to obtain the result of velocity duration to find out the change in project cost with additional working hours (overtime) and additional workforce, then conduct a comparison in order to get effective result. This study employed the time cost trade off method and used Microsoft Project 2010 program. The findings of the study showed that in normal condition with the project duration of 147 days has a normal total project cost of Rp 3.672.736.653,00. Meanwhile, in 1 hour overtime with the project duration of 103,73 days has a total project cost of Rp 3.487.750.911,17. In 2 hours overtime with the project duration of 71,37 days has a total project cost of Rp 3.350.013.645,22. Additionally, in 3 hours overtime with the project duration of 46,79 days has a total project cost of Rp 3.245.993.154,92. As for the workforce addition of 1 hour overtime has a duration of 103,73 days and costs around Rp 3.485.565.135,38. The workforce addition of 2 hours overtime has a duration of 71,37 days and costs around Rp 3.345.096.104,11. Meanwhile, the workforce addition of 3 hours overtime has a duration of 46,79 days and costs around Rp 3.238.026.956,81. Therefore, the cheapest cost with the fastest duration found in the 3 hours overtime workforce addition with duration of 46,79 days and cost of Rp 3.238.026.956,81.