John Dunnicliff puts forward his recommendations as to who should be responsible for instrumentation and monitoring during construction
When it comes to instrumentation and monitoring, the golden rule is: tasks should only be assigned to the people who have the greatest motivation to achieve high-quality data.
Those tasks include:
- buying instruments
- installing instruments
- collecting data
- interpreting data, and
implementing actions resulting from the data.
How can we ensure that these tasks are assigned to the people who are most likely to maximise quality?
Clearly, data interpretation should be the responsibility of the people who initiated the monitoring programme, and implementation should be by construction personnel.
But what about the first three tasks?
Let’s call these “field instrumentation services”.
If principal contractors, temporary works contractors, specialist geotechnical subcontractors or design/build contractors have initiated the monitoring programme, they will have the greatest motivation, and all’s well.
But if the programme has been initiated by the designer of the project, here are four reasons for not assigning field instrumentation services to the principal contractor:
- Principal contractors may not have enough motivation to ensure quality. Use of the conventional low-bid procedure, whereby field instrumentation services are included as items in the principal contactor’s contract, has often led to poor-quality data.
- Monitoring cannot start until after the principal contract has been awarded, hence adequate pre-construction (baseline) data is usually unavailable.
- It costs the project owner more. Potential monitoring subcontractors give prices to principal contractors prior to tendering. In my own experience as a subcontractor, after contract award there is normally a bargaining process, and the project owner pays £1 for work that costs the principal contractor 85p or 90p.
- For multi-principal contract projects, there would be one monitoring subcontractor for each principal contract.
For field instrumentation services I would recommend that, for pre-construction baseline data or during construction, outside the principal contractor’s work area, a specialist firm under contract with the project owner be appointed.
During construction, within principal contractor’s work area, I would recommend appointing either a specialist firm, as nominated subcontractor, or the principal contractor, with partnering and rigorous specifications.
You can download more details from www.bitech.ca/news.htm (scroll down to the only entry for 2001).
This article includes many comments from the technical literature in support of a qualifications-based selection procedure, which can be useful when trying to convince decision-makers to accept this approach.
I know very well that it isn’t easy to convince owners - and project managers in design firms, who supposedly have the owner’s interests at heart - that it’s in their interest to adopt a qualifications-based selection procedure for field instrumentation services, but it is.
I urge you to join the campaign to maximise quality of monitoring data.
- John Dunnicliff is a self-employed geotechnical instrumentation consultant.