Long Duration

The DCMA states that no more than 5% of Tasks should have a duration of 44 days (2 working months) or more.

The point of programming works is to streamline the construction process by breaking the project down into its component parts and then creating a logical sequence of events that minimises delay and ensures that the project is built in the most time and cost-efficient way.

It’s highly unusual to have a single activity that lasts for 8 weeks or more before a following trade or activity can start, hence they are an indicator of inefficient programming.  

Long duration activities should be broken down into stages that reflect when following activities can start.

For example, think of an Excavator trenching for installation of a major stormwater drainage run.  There may be 10 weeks of trench excavation and drain laying, but you would not want a trench left open for any longer than possible, due to the inherent risks of rain and collapse.

Consequently, common sense dictates that as soon as the excavator has dug a suitable length of trench, you would start laying pipe; and, as the pipe is laid, you would then progressively backfill. 

The driving factor is ensuring that the excavator digs enough trench to be able to stay ahead of the pipe laying gang.  Hence you have 3 activities, each running for a total period in excess of 44 days but broken down into a logical inter-related sequence of works that more closely reflects reality and is easier to control and monitor.

As always, there are exceptions to the 44 days duration rule, hence the allowance of 5%, but they tend to be related to resource level of use.  For example, site management would be an activity for the full duration of the project and assigned as a resource.  However, this activity is a resource loading for cost management would not be linked into the logic network affecting critical path. (see Hammock Task in Rule 4)