*3.3. Resource Supply*

After the project scheduling scheme is determined, the resource supplier seeks to minimize the total operational cost and transportation time by optimizing the transportation volume between the supply and demand points. The transportation model can be expressed as follows.

#### 3.3.1. Operating Cost Target

The resource supplier transports the corresponding amount of resources to the demand point of the project. The total operating cost (i.e., *Zc*) of the resource transport model is the transportation cost from the supply point to the demand point. Therefore, the total operational cost of this model can be expressed by Equation (14):

$$Z\_c = \sum\_{i=1}^{I} \sum\_{s=1}^{S} \sum\_{t=1}^{T} \sum\_{k=1}^{K} c\_{isk} v\_{isk}(t) \tag{14}$$

#### 3.3.2. Transport Time Target

Minimizing transportation time is an important goal. The transportation time on the transportation path (*i*,*s*) in the time period *<sup>t</sup>* can be expressed as *Tis*(*t*) = <sup>∑</sup>*<sup>K</sup> <sup>k</sup>*=<sup>1</sup> *t iskvisk*(*t*). Therefore, the total transportation time in this model can be expressed by Equation (15):

$$Z\_t = \sum\_{t=1}^{T} \max\_{\bar{i}\_s \mathbf{s}} T\_{is}(t) \tag{15}$$
