PART B: In a total of 150-300 words for Part B, describe under what circumstance
ID: 1839052 • Letter: P
Question
PART B:
In a total of 150-300 words for Part B, describe under what circumstances an engineer would want to specify a performance specification. Also, under what circumstances would an engineer want to specify a design specification? In your own words, provide 3 examples of a portion of work that is specified using the performance specification criteria (see chapter 32.12 in your book for examples. DO NOT MERELY COPY THESE EXAMPLES).
Performance specifications set forth an objective or general standard that is supposed to be achieved, and the contractor is expected to exercise his ingenuity in achieving that objective or standard of performance, selecting the means and assuming a corresponding responsibility for the selection. Performance specifications specify the results to be obtained and leave it to the contractor to determine the best way to achieve the desired results. Therefore, the contractor not only warrants that the system will be constructed as planned but also that it will perform as intended.
Design specifications, on the other hand, precisely state how the work is to be performed. Design specifications describe in detail the materials to be used and the manner in which the work is to be executed. There is no flexibility allowed to a contractor’s approach, and the contractor is required to follow design specifications as one would a road map. Here, the contractor does not warrant that the system will perform in any certain way.
Explanation / Answer
PERFORMANCE SPECIFICATION :
Used on circumstances where the design team doesn't know the requirements but wish the contractor’s to select suitable materials and methods to meet the criteria.
It doesn’t confirm what will be provided, only what has to be achieved.
It is something like “Give me something that works”.
Good relationships between Owner and Contractor/ Reputed contractors gets Performance.
Outputs are aimed at satisfying a functional need in terms of quality, quantity, and reliability.
The technical specifications define the desired result, which outputs will be measured, and how they will be measured and the frequency of measurements.
The bidding documents do not normally prescribe the inputs or a work method for the contractor, thus leaving the contractor free to propose the most appropriate solution, based on mature and well proven experience.
As the supplier can use their own tried and tested approach / methodology/ it creates the opportunity for shorter implementation times.
More responsibility ,risk and assets are transferred to the contractor.
DESIGN SPECIFICATION :
The design specification is a detailed description and expresses the requirement in detail.
The design specification of work specifies all the qualities and quantities of material, workmanship and the execution of work.
It is prepared to express the requirements clearly in a concise form avoiding repetition and ambiguity.
The specifications are arranged as far as possible in the same sequence of order as the work is carried out.
The design specification form an important part of Contract document and the contractor should obey to the given specifications.
Design specifications should state the desired outcome.
These specifications carry a high degree of risk for the contractor as he will be held responsible for design omissions and related errors in the specifications.
A good design specification should be clear, consistent and exact.
Reasonable tolerances should be included and should be non-restrictive to encourage competition.
EXAMPLES OF PERFORMANCE SPECIFICATIONS :
1. The specification would provide a required pumping rate, say 500 gallons per minute, a required pressure 20 psi and the difference in height between the pump and the final destination 40 feet.
2. The concrete’s chloride & sulfate resistance based on the severity of the soil salinity will be performance criteriacontrary to the specified strength of 40MPa above.
3. Warehouse whose abrasion resistance and flatness will be a better specification for the concrete slab rather than its strength.
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