Last edited 01 May 2020

Time certainty


Construction projects are often seen to be a balance between three related performance indicators; time, cost and quality. Generally, an increace in quality will result in an increase in cost and time, a reduction in time will result in an increase in cost and so on.

For clients and contractors in the construction industry, time certainty is one of the most important performance criteria.

Time certainty is the likelihood that even before a project starts, but also during the project, it will be completed within the required time. Time certainty is also affected by cost certainty which is the likelihood that a project will be completed within the budgetary requirements.

Construction clients often hold these two concepts as their top priorities as delays and cost overruns can lead to higher costs for the client and a possible diminished relationship between client, contractor, occupants, customers and so on. For contractors, an excessive time extension to the project programme may mean lower than expected profits and a diminution of reputation and competitiveness.

Construction projects tend to be high-risk undertakings which very frequently generate time and cost overruns. Typical factors that can delay a project include:

A 1996 study by the Construction Industry Board (CIB) revealed that time certainty (and also cost certainty) is more often than not likely to be under the contractor’s control. This is mainly because time overruns are frequently seen to be:

If delays occur on a project, contractors are impacted almost immediately by additional costs resulting from:

In their paper ‘Cost Certainty and Time Certainty: An International Investigation’ (Hong Xiao and David G Proverbs), time certainty was found to be largely dependent on first, cost certainty and second, the importance contractors allocate to cost, comparing them to the two sides of the same coin; neglecting one will have an adverse effect on the other. Also, the authors maintain that projects completed on time are those where the contractor realises there is no other option and so does as much as possible to bring this about.

Greater planning input by the contractor is also known to have a positive effect on improving project performance (Faniran et al., 2001) and is why faster projects are usually found to be cheaper at the tender stage, punctual to deadlines and completed to customers’ satisfaction (NEDO, 1988).

A possible indicator of a contractor’s time certainty is that delays on previous similar projects are likely to reoccur on future projects. A good reputation is therefore critical for time certainty performance.

Generally time certainty improves as a project progresses, as there are fewer remaining risks that could affect project completion.

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