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So you are letting a contract for a construction project…
How do you make sure you communicate your expectations?
How do you set the requirements for the work to be performed?
That’s where specifications come into play.
Specifications establish the requirements, under which a contractor must deliver the project,
enabling all parties to evaluate the degree of conformance.
Specifications fall along a spectrum ranging from prescriptive to performance.
On one end of this spectrum, are prescriptive specifications,
also known as materials and methods specifications,
or recipe specifications.
The contracting agency can prescribe a list of materials and methods that the contractor must use,
provide definite proportions, require specific types of equipment and methods to place the material
the cookbook recipe approach.
As long as the contractor follows the list and directions, the agency accepts the completed
work and bears the complete burden of responsibility for the quality and performance.
On the other end of this spectrum…
long-term performance warranty specifications that rely on a warranty and maintenance agreement
to guarantee the quality for a certain length of time.
Contractors are taking on all the risk for quality and performance until that time.
Repairs and maintenance are completed at the contractor’s expense.
However, keep in mind, we are talking about highways, bridges, and other infrastructure products
that should last twenty years or more.
A lot can happen over twenty years.
Businesses change hands, close, or relocate.
Agency personnel may retire or move on to other responsibilities.
Performance warranties should only be used when contractor has control over the performance,
and not in situations where factors unrelated to construction; such as site conditions,
traffic and environmental factors, can impact performance.
5 to 10 year performance warranties and shorter 2 to 4 year materials and workmanship warranties
address some of these concerns, but warranty specifications have other shortcomings.
They require long-term monitoring with associated administrative needs.
They require distinguishing between design- and construction-related problems.
Reduced bonding capacity is also a concern.
Because of risks associated with future uncertainties, bonding companies are typically not willing
to provide warranties to contractors beyond five years, unless they can increase their margin.
This increases the overall cost of the project to an agency.
Maybe there is a better way…
What if the contractor is paid based on results and outcomes?
If the construction exceeds expectations in terms of quality or schedule, then everyone benefits,
and the agency can provide an associated incentive to the contractor.
If the quality or schedule doesn’t meet the specifications, there’s a price or disincentive to pay.
The agency sets the incentives and disincentives for the job based on agency targets and expectations.
It’s up to the contractor to determine the best and most profitable way to get the job done.
These types of specifications are termed end-result specifications.
The contractor takes the entire responsibility for delivering the infrastructure product.
The agency either accepts or rejects the final product or applies a pay adjustment as specified.
End results specifications may be combined with prescriptive specifications to give some
level of comfort that reasonable processes and procedures are followed by the contractor.
These types of specifications are termed quality assurance specifications.
The contractor is responsible for quality control and the agency is responsible for acceptance.
End result specifications and quality assurance specifications use methods such as random sampling,
lot-by-lot testing, and statistical analysis to evaluate and accept the product.
Another way of paying the contractor based on construction quality is through
performance specifications.
Performance specifications are a type of quality assurance specifications that consider how
the finished product should perform over time.
After all, when the rubber meets the road…
It all comes down to performance!
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Under the umbrella of performance specifications, there are performance warranties, as described earlier,
and there are also Performance-Related and Performance-Based specifications.
Both measure quality of the end result, but in different ways.
Performance-Related and Performance-Based Specifications and Performance Warranties
are two sides of the same coin.
In essence, "pay me now" for Performance-Related and Performance-Based Specifications.
At the end of construction, the contractor is paid based on predicted future performance
with no further obligations.
or, "pay me later" for Performance Warranties, whereas the contractor is not fully absolved
of responsibilities until the completion of the warranty period.
Performance-based specifications are quality assurance specifications that describe and
directly evaluate for acceptance those fundamental engineering properties that relate to performance.
If the contractor provides a product with the specified fundamental engineering properties,
then an expected performance level can be predicted.
Because it can be time consuming and expensive to test fundamental engineering properties,
performance-based specifications may be difficult to fully implement for highway construction,
with current technology.
There’s also performance related specifications.
How is that different?
These are also quality assurance specifications similar to performance-based specifications,
but with one crucial difference that addresses some of the shortcomings of the other types
of specifications.
Instead of using fundamental engineering properties directly, these use quality characteristics
related to fundamental engineering properties that predict performance.
For example: asphalt binder content and its effect on rutting and fatigue cracking in
asphalt pavements, and compressive strength and its effect on transverse
cracking and spalling in concrete pavements.
This makes them less time consuming and more cost effective to use for acceptance,
without the need for monitoring or other drawbacks of warranty specifications.
Prior to letting a project, the agency establishes targets for quality and performance for the project
which are then incorporated in the specifications for that project.
The specifications include pay tables, established based on the modeled performance difference
between quality of construction or “as-constructed” and the target established by the agency or “as-designed”.
Once the work is complete, sample data collected, based on the specified statistical sampling
and testing plan are analyzed. The contractor is awarded incentives or assessed disincentives as specified.
There are several types of specifications to choose from.
Appreciating the differences, risks, and benefits of each, can help you to choose the best path
for your construction project.
For more information about the different types of specifications, visit
www.fhwa.dot.gov/research/
Help with writing and implementing specifications is available through the FHWA Resource Centers
and through NHI course 134001: Principles and Applications of Highway Construction Specifications.
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