Define and tabulate the logical relationships $($i$.$e$.,$ list of predecessors$)$ among the activities.A small project comprises the construction of two identical houses on a single parcel. Project includes a site leveling activity and each house consists of excavation, reinforcement installation, formwork placement, and casting concrete activities. The activities and the associated direct cost $($DC$)$ of each activity are given in the following table.

$\backslash$table$[[,$Activity,Description,Cost $($S$)],[,$A$,$Site leveling,$8,500],[$House $1,$B$1,$Excavation,$2,000],[$C$1,$Reinforcement installation,$6,000],[$D$1,$Formwork placement,$5,500],[$E$1,$Casting concrete,$6,000],[$House $2,$B$2,$Excavation,$2,000],[$C$2,$Reinforcement installation,$6,000],[$D$2,$Formwork placement,$5,500],[$E$2,$Casting concrete,$6,000]]$

The quantity of earth works for "Site leveling" activity needs to be estimated with respect to the grid view shown in Fig. $1$ and by using the "Grid Method". Fig. $1$ displays a $15m$ grid survey of levels taken on the construction site which is required to be brought to a level of $57m.$ Quantity of earth works for "Excavation" activity should be determined by using the dimensions of the trench shown in Fig. $2$ with a width and a depth of $1\mathrm{.}50m$ and $2\mathrm{.}00m,$ respectively. Quantities for "Reinforcement installation", "Formwork placement", and "Casting concrete" activities are already estimated as $420$ tons, $850m^2,$ and $1,650m^3,$ respectively. The crew assigned for "Site leveling" activity is formed of $2$ Trucks and $3$ Graders which can work with an output rate of $69$

$\frac{m^3}{h}r.$ Productivity for "Excavation" activity is estimated to be $4$ man$-$hours $\frac{?}{m^3}$ and a crew formed of $8$ Labors and $2$ General Foremen is assigned for this activity. Crew assigned for "Reinforcement installation" activity is formed of $2$ Steel Workers and $2$ Labors which can work with an output rate of $21$ ton$/$day$.$ Productivity for "Formwork placement" activity is estimated to be $0\mathrm{.}64$ manhours $\frac{?}{m^2}$ and a crew formed of $3$ Carpenters and $1$ General Foreman is assigned for this activity. Productivity for "Casting concrete" activity is estimated to be $0\mathrm{.}16$ man$-$hours $\frac{?}{m^3}$ and a crew formed of $3$ Concrete Workers is assigned for performing it$.$

Figure $1-$ Grid view of the construction site