Civil: Construction PE

Remember that ES for any activity equals the maximum EF of all its predecessors. The forward pass calculates ES first, then EF. This is fundamental to finding the critical path and total project duration.

Free Float is always less than or equal to Total Float. For activities with multiple successors, use the minimum Early Start. Zero Free Float means any delay immediately affects successor activities. Remember: FF ≥ 0 always.

Late Start is calculated during the backward pass of CPM analysis. Remember that activities with LS = ES are on the critical path (zero total float). Always verify your backward pass calculations by checking that predecessor LS + Duration = successor LF.

Total Float = 0 identifies critical path activities. Remember TF can also be calculated as LF - EF. Critical path activities must start and finish on time to avoid project delays. Activities with positive float provide scheduling flexibility.

Remember this formula applies only when R ≤ 7 ft/hr and column dimensions ≤ 6.5 ft. Always check the coefficient values - Cc = 1.2 for retarders and Type III cement significantly increases pressure. Maximum pressure is also limited to unit weight × height (γh).