Time-cost model for building projects in Nigeria

The concept of project duration is important in assessing the success or viability of a construction project. A time-cost relationship for construction projects in Nigeria has been developed based on Bromilow's time-cost model. Cost data on 87 completed building projects executed within the period 1991-2000 were obtained. The data were subjected to regression analyses using double log and later the piecewise model with breakpoint. For the Nigerian situation, the Bromilow's time-cost model was found to be T = 63C0.262 with poor predictive abilities (R = 0.453, R2 = 0.205). An improved model using piecewise model with good predictive abilities (R = 0.875, R2 = 0.765) was found to be T = 118.563-0.401C (C ≤ 408) or 603.427 + 0.610C (C>408). The model is shown to be useful in predicting construction project durations.