TECHBRIEF Construction Quality 

Assurance For Design-Build

Highway Projects

FHWA Publication No.: FHWA-HRT-12-039

FHWA Contact: Michael Rafalowski, HIPT-10, (202) 366-1571, 

michael.rafalowski@dot.gov

Introduction

A majority of State transportation agencies use the designbuild (DB) contracting method to deliver some transportation 

projects. Documented benefits of DB include faster project 

delivery, improved constructability, less cost growth, early 

cost certainty, and fewer claims. 

One area of DB contracting that requires closer examination is 

construction quality assurance (QA). DB is believed to provide 

a level of project quality equal to design-bid-build (DBB), 

as outlined in the Federal Highway Administration’s (FHWA) 

Design-Build Effectiveness Study.

(1) However, a recent examination of State agency DB procurement packages showed 

that roles and responsibilities for construction quality are 

not clearly defined in many instances. The paper “Does 

Design-Build Project Delivery Affect the Future of the Public 

Engineer?” examined 60 DB requests for proposals (RFPs) 

and found 23 cases in which assignment of responsibilities 

for verification and acceptance could not be determined.(2)

National Cooperative Highway Research Program (NCHRP) 

Synthesis 376, Quality Assurance in Design-Build Projects, 

states “With the changing quality roles found in the DB 

delivery method, it is imperative that quality responsibilities 

and the responsible parties are clearly stated in the contract 

documents.”(3) However, on DB projects, there is no change 

in the core QA functions of contractor quality control (QC) 

and agency acceptance. The design-builder still has a 

responsibility for QC, as does the contractor with DBB 

projects. The agency must retain its responsibility for the 

acceptance function, as required by Title 23, Code of Federal 

Regulations, Part 637 (23 CFR 637).(4)

One of the attributes of the DB delivery method is the single 

source of responsibility for design and construction issues.

Research, Development, and 

Technology

Turner-Fairbank Highway 

Research Center

6300 Georgetown Pike

McLean, VA 22101-2296

www.tfhrc.gov/research/
2

When preparing the RFP and contract documents, owners must clearly define the 

responsibilities of the design-builder and the 

contracting agency. The agency performs 

verification tests for compliance with RFP 

requirements and makes progress payments 

under the terms of the contract. However, 

by doing so, the agency does not assume 

responsibility for any design or construction 

issue. The design-builder remains fully responsible for the design and the construction of 

the final product.

Purpose

The purpose of this TechBrief is to help clarify 

the roles, responsibilities, and activities related 

to construction QA on DB projects. The specific 

topics discussed include QA, QC, and acceptance. Related topics such as independent 

assurance (IA), dispute resolution, personnel 

qualification, laboratory qualification, and 

warranties are also discussed. Some RFP and 

contract documents for DB projects have incorrectly assigned responsibility for acceptance to 

the design-builder, which is not in accordance 

with 23 CFR 637. Additionally, because the DB 

project delivery method is often used on large, 

complex, fast-paced projects, it presents some 

unique challenges that merit discussion. 

Quality Assurance

The American Association of State Highway 

and Transportation Officials (AASHTO) defines 

QA as “(1) All those planned and systematic 

actions necessary to provide confidence that 

a product or facility will perform satisfactorily 

in service; or (2) making sure the quality of a 

product is what it should be.”(p. 14)(5) 

Historically, agencies used the term QC/QA 

with QC referring to the contractor’s role and 

QA to the agency’s role. This term implied that 

QC and QA are separate functions; in fact, 

QA refers to the overall system for assuring 

project quality, with QC being one element of 

a comprehensive QA program. Therefore, the 

transportation industry has moved away from 

the term QC/QA and now uses QA. 

Construction QA Programs

A construction QA program consists of the 

following core elements: 

• Contractor QC.

• Agency acceptance.

• IA.

• Dispute resolution.

• Personnel qualification.

• Laboratory accreditation/qualification.

These core elements of QA apply regardless 

of the project delivery method. The agency’s 

responsibility for acceptance cannot be assigned 

to the design-builder (or to a consultant under 

contract to the design-builder) but, rather, 

remains with the agency. Each of the six core 

elements of a construction QA program for DB is 

discussed below.

Quality Control

FHWA’s Transportation Construction Quality 

Assurance Reference Manual defines QC as 

“The system used by a contractor party to 

monitor, assess, and adjust their production or placement processes to ensure that the 

final product will meet the specified level of 

quality.”(Section 2.3, p. 2–6)(6)

Use of QC Test Data in Acceptance 

Determination

While the primary purpose of QC sampling 

and testing is to provide timely information for 

the design-builder to monitor and guide each 

production or placement process, QC data for 

critical quality characteristics may also be used 

in the final acceptance determination. If QC test 

data are to be included in the agency acceptance decision, the QC data must be validated 

by agency verification test results. Lot and 

sublot sizes, sampling and testing methods, 

and sampling locations should be specified for 

each critical quality characteristic that will be 

verified by the agency. This information can be 

included directly in the DB contract documents, 
3

or reference can be made to the agency’s 

standard specifications or guide schedule of 

sampling/testing frequencies. Not all characteristics that are monitored by QC are required to 

be verified by the agency. Design-builders will 

often perform more than the minimum level 

of QC, including testing of material properties 

beyond those critical quality characteristics that 

will be used in the agency acceptance decision. 

QC Organization

There are different approaches to QC organizational structure on DB projects. Some 

agencies specify that the design-builder must 

demonstrate, through lines of authority in the 

organizational chart, that QC personnel are 

allowed to operate independently of DB construction forces to ensure that decisions made 

as part of the QC process are not influenced 

by schedule or budget. Another approach used 

by some agencies (especially on large DB projects) requires the design-builder to employ an 

independent testing firm to conduct sampling 

and testing of those critical quality characteristics that will be verified by the agency as part 

of the acceptance decision while a separate 

QC team works in close coordination with the 

construction forces, performing sampling and 

testing to monitor and guide production and 

placement processes.

Regardless of the approach, it is important that 

the DB team member in charge of construction quality report to senior management of 

the design-builder. This will convey support 

for QC and minimize potential conflicts with 

the production staff. Senior management must 

realize that superior quality will not happen 

without the seamless interaction between the 

QC teams, production/placement teams, and 

administration. The DB contract should clearly 

identify requirements for the QC organization.

Use of Consultants to Perform QC

Consultant technicians and inspectors may be 

used to conduct QC inspection and testing on 

a DB project. However, responsibility for the 

acceptance function cannot be relinquished 

to the design-builder per the requirements of 

23 CFR 637.207(b).(4) Use of a consultant firm 

hired by the design-builder for sampling, testing, and inspecting does not relieve the agency 

of its responsibility for verification testing.

QC Documentation and Records

The agency should specify the minimum level 

of QC documentation that must be provided 

by the design-builder as well as the timeframe 

and format for providing the information. This 

typically includes all QC test results intended 

for inclusion in the agency acceptance decision. 

QC test results that are used strictly for process 

control may not need to be submitted but should 

be available for review by the agency as part of 

monitoring the design-builder’s QC system.

Design-Builder Quality Management Plans

It is good practice to require the designbuilder to provide a comprehensive quality 

management plan (QMP) that outlines the 

overall quality system for both design and 

construction of the project. The construction 

QC section of the QMP should describe all 

of the QC activities that will be conducted to 

assure that the completed items of work will 

meet the specified level of quality. If a QMP is 

required, the DB contract should specify the 

format and minimum content requirements as 

well as the procedure for agency review and 

acceptance of the QMP, including any updates 

and changes submitted by the design-builder 

following initial plan acceptance. During construction, the agency and the design-builder 

should monitor adherence to and effectiveness 

of the QMP. Any weaknesses discovered in 

the QC system should be corrected, including 

revisions to the QMP. Some agencies specify 

that failure by the design-builder to follow the 

QMP will result in actions such as suspension 

of work or withholding of payment. 

Acceptance

FHWA-NHI-08-067 defines acceptance as “All 

factors used by the Agency (i.e., sampling, 

testing, and inspection) to evaluate the degree 
4

of compliance with contract requirements 

and to determine the corresponding value for 

a given product.”(Section 2.3, p. 2–9)(6)

Agency Responsibility for Acceptance

According to 23 CFR 637.207(b), the agency’s 

responsibility for acceptance does not change 

when using the DB delivery method.(4) While 

the design-builder is fully responsible for 

design, construction, and material selection, 

the agency is responsible for verifying RFP 

compliance and making progress payments 

by the acceptance of the work. As stated in 

FHWA-NHI-08-067, “All acceptance activities 

must be carried out by the agency or their 

designated agent (i.e., consultant under direct 

contract with the agency), independent of the 

contractor.”(Section 2.3, p. 2–9)(6) This does 

not preclude the inclusion of design-builder 

QC data in the acceptance decision, provided 

that the QC data are validated by the agency’s 

independently obtained verification data. It is 

important that the agency acceptance responsibilities be clearly defined in the DB contract 

documents.

Verification Sampling and Testing

23 CFR 637 defines verification sampling and 

testing as “Sampling and testing performed to 

validate the quality of the product.”(4)

The highway agency (or its designated agent) 

is responsible for conducting verification sampling and testing to provide an assessment of 

product quality that is completely independent 

of the design-builder’s QC process. As required 

in 23 CFR 637, “The verification testing shall be 

performed on samples that are taken independently of the quality control samples.”(4) Splits 

of design-builder QC samples cannot be used 

for verification.

Verification sampling and testing may be performed at a lower frequency than the designbuilder’s QC testing, particularly on DB projects 

where QC data are included in the acceptance 

determination. On some large DB projects, 

agencies have used frequencies of 1 verification test for every 10 or more QC tests. In order 

for mathematical validation procedures to be 

reliable, it is suggested that a minimum of 

7–10 agency verification results be obtained and 

used to validate the design-builder’s QC data.

It may be necessary to adjust the frequency 

of verification testing to reflect the estimated 

number of QC tests for each item of work. Rates 

of verification testing may also differ based on 

the risks involved. For example, verification 

testing may be more frequent for structural 

concrete than for embankment materials. 

On some DB projects, it may be challenging 

to conduct verification testing at the specified 

rate due to the quantities of material being 

placed and the fast-paced nature of the work. In 

addition, because DB projects are typically bid 

as a single lump sum amount or using a small 

number of lump sum pay items, agency tracking of material quantities can be more difficult 

than on DBB projects that use standard unit 

price items. This can make it more difficult to 

schedule verification activities and determine 

random sample locations. Agencies should 

take this into consideration when determining 

staffing levels for DB projects so as to provide

sufficient verification testing. The agency and 

design-builder must work cooperatively to 

find solutions to these issues because quality 

cannot be sacrificed due to large material 

quantities or fast-paced work.

Validation of QC Data

Agencies that have not included QC data in 

the acceptance decision on DBB projects may 

choose to do so on DB projects. As previously 

stated, if the design-builder’s random QC test 

data are to be included in the acceptance 

decision, the QC data must be mathematically 

“validated” against the agency verification 

test results for each lot of material. By 

including validated QC data in the acceptance 

decision, the frequency of verification testing 

by the agency (or its designated agent) can 

be reduced.

The DB contract documents should clearly 

outline the decisionmaking process that will

be used for validation of the QC data. It is 
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important to specify the validation method 

(such as F- and t-tests), as well as actions that 

will be taken in the event that the designbuilder QC test results are not validated by the 

agency verification results. There should be a 

well-defined process in place to resolve such an 

issue, including an investigation into the cause 

of the non-validation and increasing the rate 

of verification testing for the item. It is important to recognize that in some cases, even 

though the QC test data are not statistically 

validated, the material may be completely 

acceptable. In these cases, further investigation 

to determine the underlying cause of the nonvalidation is warranted. Also, it is necessary 

to specify the quality characteristics to which 

tests will be applied. Performing F- and t-tests 

on numerous quality characteristics for a 

particular material could make the analysis 

needlessly cumbersome. It is important that the 

agency identify the critical quality characteristics 

subject to the validation analysis for each 

material or work item.

Some materials, due to the small quantity 

being used, may not have a sufficient number 

of QC and verification tests to perform a statistical comparison. In these instances, use of an 

alternate method of acceptance may be necessary. To accept items requiring very few tests, 

it may be advisable to use only the agency’s 

verification testing.

Quality Measures for Acceptance

Statistical quality measures used for acceptance, such as percent-within-limits (PWL), 

are well suited to DB projects, especially projects with work items having large quantities 

of materials. Agencies currently using PWL for 

work items on their DBB projects can easily 

incorporate it as the quality measure for the 

same items on DB projects. For agencies that 

do not use PWL, it may not be appropriate to 

utilize it on DB projects without first developing 

statistical specification limits that will provide 

a fair measure of quality. Statistical specification limits are typically developed by means 

of pilot projects completed over several years. 

Employing specification limits or procedures 

developed by another agency without proper 

evaluation could lead to unnecessary disputes. 

The acceptable quality level (AQL) applied to 

each work item should be specified in the DB 

contract documents along with requirements 

for appropriate corrective action (rework or 

replacement) when the quality level is not 

met. The AQL can be set at different levels for 

different work items based on the risk associated with lower-quality material. Since most 

DB projects do not utilize unit price pay items, 

pay adjustments for material quality are often 

not applied. However, some agencies do apply 

pay adjustments either by including a typical 

unit price in the DB contract for the work item 

being evaluated or by requiring in the RFP that 

proposers submit a breakdown of work items 

with a unit price for each item subject to pay 

adjustment. When pay adjustment for quality 

is included in the DB contract, it is important 

that the agency monitor and measure material 

quantities. For work items not suited for PWL 

as the quality measure, such as items with 

small quantities, the agency’s verification test 

results should be evaluated against engineering limits to determine acceptance. 

Inspection

Just as on DBB projects, visual inspection is a 

key part of agency acceptance on DB projects. 

Acceptance inspection must be performed 

by the agency or its designated agent, not 

the design-builder. “The State’s acceptance 

program should provide a reasonable level of 

inspection to adequately assess the specific 

attributes which reflect the quality of the finished product. Acceptance inspection should 

include inspection of the component materials 

at the time of placement or installation, as well 

as the workmanship and quality of the finished 

product.”(7)

Independent Assurance

23 CFR 637 defines IA as “Activities that are an 

unbiased and independent evaluation of all the 

sampling and testing procedures used in the 

acceptance program.”(4) 
6

The purpose of the IA system is to assure 

the reliability of all data used by the agency 

in the acceptance determination. This includes 

the agency’s verification data and the designbuilder’s QC data when validated QC data are 

to be included in the final acceptance determination. IA is intended to confirm that the sampling 

and testing activities performed by the agency 

and the design-builder are conducted by qualified personnel using proper procedures and 

properly calibrated and functioning equipment. 

The results of IA testing should never be used to 

evaluate material quality. 

The responsibility for IA lies with the agency. IA 

sampling and testing is performed by agency 

personnel (or by personnel of a designated agent 

directly contracted by the agency) that are independent of the project. IA personnel, whether 

employed by the agency or a designated agent, 

cannot perform both IA and acceptance activities. For agencies that do not routinely include 

QC test results in the acceptance determination, using this approach on DB projects may 

create new challenges for the IA system. The 

design-builder may not be familiar with IA 

requirements. The need for the design-builder 

QC staff to cooperate with IA personnel should 

be clearly stated in the DB contract. Scheduling 

IA activities to obtain the required level of IA 

evaluations is often a challenge, and keeping 

track of ongoing QC and verification activities 

and personnel on large DB projects can magnify 

this problem. Using the system approach to IA 

is an effective strategy for DB projects, since IA 

frequency is based on covering all active testers 

and equipment over a period of time, independent of the number of QC and verification tests 

completed on a project.

It is important that all parties involved be 

aware of the role that IA plays in the overall 

QA program and work cooperatively to assure 

that IA staff is kept informed of project testing 

schedules and personnel. Some agencies 

include language in the DB contract requiring 

the design-builder to provide the agency’s 

project staff with updated schedules and lists of 

QC personnel for upcoming QC sampling and 

testing so that IA activities can be scheduled. 

Dispute Resolution 

If QC testing data will be included in the acceptance determination, agencies are required 

under 23 CFR 637 to have a dispute resolution 

system in place to resolve possible discrepancies between the design-builder’s QC data 

and the agency’s acceptance data.(4) While not 

required on projects where agency verification 

results will be used exclusively to determine 

acceptance, a dispute resolution system is 

highly recommended.

The dispute resolution process should be 

unbiased and timely. To address testing-related 

disputes, use of retained splits of samples used 

in the acceptance decision, alternate or third 

party laboratories, and a well-defined decision 

process to determine the outcome of the dispute are advisable. When retained splits are 

used, it is important that the dispute resolution 

split samples are properly labeled and that 

either the agency takes immediate possession 

of the dispute resolution split or proper sample 

security techniques, such as tamper-proof 

containers or security seals, are used. 

Personnel Qualification

All personnel performing sampling and testing 

for QC used in the acceptance decision, verification, or IA are required to be qualified, per 

23 CFR 637.209.(4) Agencies participate in State, 

regional, or national technician qualification 

or certification programs to ensure that technicians and inspectors are properly qualified. 

The DB contract documents should specify the 

minimum qualifications for DB personnel performing QC sampling, testing, and inspection. 

Minimum qualifications for the design-builder’s 

quality management personnel should also be 

clearly stated to ensure they have a thorough 

understanding of QA principles and experience 

working under QA specifications.

Laboratory Qualification

Any laboratory used by the agency (or its designated agent) to perform verification testing 

and all design-builder laboratories that perform QC testing included in the acceptance 
7

decision must be qualified, as outlined in 

23 CFR 637.209.(4) Laboratories that conduct 

QC testing only for process control are not 

covered by the regulation, but some agencies 

require these laboratories to meet a minimum 

standard such as approval by the agency or 

a certification organization. Laboratories 

operated by a designated agent of the agency 

that are used for IA or dispute resolution must 

be accredited by AASHTO, through a comparable program approved by FHWA, or by an 

accreditation body approved by the National 

Cooperation for Laboratory Accreditation.(8)

Non-Conforming Materials and 

Workmanship

The DB contract should describe the process 

for documentation and disposition of nonconforming work. Whether discovered by the 

design-builder or the agency, materials or workmanship that do not meet the specified level 

of quality should be properly documented, 

including the nature of the non-conformance, 

location, extent, and disposition (e.g., removed 

and replaced, reworked, accepted based on 

engineering judgment, etc.). The authority to 

approve the final disposition of non-conforming 

materials or workmanship cannot be assigned 

to the design-builder. The agency’s role in 

approving the disposition of non-conforming 

work should be clearly identified in the contract.

Warranties

Some DB contracts include warranty provisions 

for some items of work. Contract language 

should specify the warranty period and the 

enforcement process, including a detailed 

description of the measures that will be used 

to determine warranty compliance. These measures are typically maximum levels of various 

distress types that, when exceeded during 

the warranty period, require correction by the 

design-builder. Some warranty provisions also 

include specific corrective action for each distress 

type. The inspection procedure for determining 

warranty compliance should be clearly outlined 

and include provisions for notification so that 

a design-builder representative can observe 

the warranty inspections. A process for dispute 

of warranty inspection findings should also be 

included. Use of warranty provisions does not 

remove the need for an effective design-builder 

QC system; on projects where the warranty does 

not provide coverage for the anticipated life of 

the warranted product, some level of agency 

acceptance is still required. The requirements 

for warranties on DB projects are covered under 

23 CFR 635.413.(9)

Summary

The DB project delivery system offers several 

documented benefits over the traditional DBB 

method on certain projects. While DB offers 

the design-builder more control over design, 

materials, and construction methods than 

DBB, the agency still has an important role 

in assuring quality. As agencies develop DB 

procurement documents, it is important that 

roles and responsibilities for design-builder QC 

and agency acceptance be clearly defined. The 

responsibility for acceptance by the agency (or 

their designated agent) is applicable regardless 

of the project delivery method used. 

DB is often used on large, fast-paced projects, 

which can create challenges for conducting QA 

activities. Coordination and communication 

between the design-builder and the agency 

is essential for effective quality management. 

By working together within a well-defined 

QA program, the agency and design-builder 

can meet the goal of delivering a high quality 

project to the travelling public. 

Further Information

The following resources provide further information on this topic: 

• National Highway Institute Course 134064, 

“Transportation Construction Quality 

Assurance.”

• Office of Pavement Technology. (2012). 

Independent Assurance Programs, 

TechBrief, Publication No. FHWA-HIF12-001, Federal Highway Administration, 

Washington, DC. 
8

Researchers—For information related to Design-Build project delivery, contact Gerald Yakowenko 

(contract administration team leader) at gerald.yakowenko@dot.gov. Additional information related 

to the Materials Quality Assurance Program can be gained by contacting the FHWA Quality 

Assurance Team: Michael Rafalowski (Office of Pavement Technology) at michael.rafalowski@dot.gov 

and Dennis Dvorak (Pavement and Materials Technical Service Team) at dennis.dvorak@dot.gov.

Distribution—The report covered in this TechBrief is being distributed according to a standard 

distribution. Direct distribution is being made to the Resource Centers and Divisions.

Availability—The TechBrief may be obtained from FHWA Product Distribution Center by 

e-mail to report.center@dot.gov, fax to (301) 577-1421, phone to (301) 577-0818, or online at 

http://www.tfhrc.gov/research/.

Key Words—Quality assurance, Design-build, Acceptance, Quality control, Verification.

Notice—This document is disseminated under the sponsorship of the U.S. Department of 

Transportation in the interest of information exchange. The U.S. Government assumes no liability 

for the use of the information contained in this document. The U.S. Government does not endorse 

products or manufacturers. Trademarks or manufacturers’ names appear in this TechBrief only 

because they are considered essential to the objective of the document.

Quality Assurance Statement—The Federal Highway Administration provides high-quality 

information to serve Government, industry, and the public in a manner that promotes public 

understanding. Standards and policies are used to ensure and maximize the quality, objectivity, 

utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its 

programs and processes to ensure continuous quality improvement.

April 2012 FHWA-HRT-12-039

HRDI-20/04-12(500)E

References

1. SAIC, AECOM, and University of Colorado. 

(2006). Design-Build Effectiveness Study, 

Federal Highway Administration, 

Washington, DC.

2. Gransberg, D. and Molenaar, K. (2008). 

“Does Design-Build Project Delivery Affect

the Future of the Public Engineer?” Transportation Research Record 2081, Transportation Research Board, Washington, DC.

3. Gransberg, D., Datin, J., and Molenaar, 

K. (2008). NCHRP Synthesis 376: Quality 

Assurance in Design-Build Projects, 

Transportation Research Board, 

Washington, DC.

4. Quality Assurance Procedures for Construction, Code of Federal Regulations, Title 

23, Part 637, Subpart B, U.S. Government 

Printing Office, Washington, DC.

5. American Association of State Highway and 

Transportation Officials. (2006). Standard 

Recommended Practice for Definition 

of Terms Related to Quality and Statistics 

As Used in Highway Construction, 

Washington, DC.

6. Federal Highway Administration. (2008). 

Transportation Construction Quality 

Assurance Reference Manual, Report No. 

FHWA-NHI-08-067, Arlington, VA.

7. Federal Highway Administration. (2006). 

“Non-Regulatory Supplement for 23 CFR 

Part 637, Subpart B.” Accessed online: 

March 20, 2012. (http://www.fhwa.dot.gov/

pavement/0637bsup.cfm)

8. Federal Highway Administration. (2011). 

“Non-Regulatory Guidance on Approval 

of Comparable Accreditation Bodies.” 

Accessed online: March 20, 2012. (http://

www.fhwa.dot.gov/pavement/materials/

111007.cfm)

9. Construction and Maintenance, Code of 

Federal Regulations, Title 23, Part 635, 

U.S. Government Printing Office, 

Washington, DC.