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53 Of the 44 state DOTs that responded to the survey, 38 indicated that they use an IRI-based smoothness specification for AC-surfaced pavements, with 26 state DOTs indicating that they use such a specification for both AC- and PCC-surfaced pavements. Procedures followed by the state DOTs that use an IRI-based smoothness specification regarding who collects the inertial profile data, the type of profilers allowed to collect data, certification of profilers, certification of profiler operators, height-sensor types specified for the profiler, data collection procedures, and QA procedures for the data are described in this chapter. Responsibility for Data Collection Smoothness data collection on the final paved surface for construction acceptance is either per- formed by the state DOT or by the contractor. The contractor may hire a testing company to col- lect the data. In this chapter, the term âcontractorâ is used to describe the contractor or the testing company hired by the contractor. Table 8 shows the party responsible for collecting the smooth- ness data on the final paved surface for construction acceptance in the 38 states that indicated that they use IRI-based smoothness specifications. The state DOTs that allow contractors to collect smoothness data on the final paved surface for construction acceptance perform QA testing of the collected data. As shown in Table 8, the state DOT collects the data in 16 states. The contrac- tor collects data in 20 states, and the state DOT as well as the contractor collect data in two states. It should be noted that in the states where the DOT does not accept the data collected by contractors on the final paved surface for smoothness acceptance, contractors are free to collect data for their own QC purposes. Types of Profilers Used to Collect Data Table 9 shows the type of profiler used by the state DOTs to collect profile data for computa- tion of IRI for construction acceptance on AC surfaces, PCC surfaces, and bridge decks. These are the same type of profilers allowed in the case where contractors collect data. One state DOT only allows lightweight profilers to collect IRI data for construction acceptance on both AC and PCC pavements; this state DOT does not have an IRI-based smoothness specification for bridge decks. Use of Certified Equipment for Data Collection Of the 38 state DOTs that responded to the survey indicating that they use IRI as the smooth- ness index for construction acceptance, 27 indicated that a certified profiler is used to collect the smoothness data on the final paved surface for construction acceptance. A certified profiler C H A P T E R 5 Collection of Inertial Profile for IRI Construction Acceptance
54 Inertial Profiler Certification for Evaluation of International Roughness Index is one where the IRI computed from the data collected by the profiler has satisfied a specified repeatability and an accuracy criterion. The accuracy criterion is based on comparing the IRI from the profiler with the IRI from a reference device. An accuracy criterion based on comparing IRI from one profiler with another is not considered to be a certification procedure. Several state DOTs that currently do not certify profilers indicated that their agencies do not require a profiler that is used to collect profile data for the computation of IRI for construction acceptance to be certified. Five state DOTs indicated that they are developing programs to certify state DOTâowned profilers. Two state DOTs that currently do not have IRI-based smoothness specifications but are planning to adopt IRI as the smoothness index for construction acceptance indicated that they are developing plans to certify agency-owned profilers. Contractors Collecting Data for Construction Acceptance Of the 38 state DOTs that responded to the survey indicating that they use IRI-based smooth- ness specification for construction acceptance, 22 allow contractors to collect data that is used for computation of IRI for construction acceptance on the final paved surface. Table 10 shows Party Performing Data Collection State DOTs that Responded to the Survey and have an IRI-Based Smoothness Specification Number Percentage (%) State DOT collects data 16 42 Contractor collects data and 20 53 state DOT performs QA testing State DOT collects data on some projects 2 5 and contractor collects data on some projects with state DOT performing QA testing Total 38 100 Table 8. Party responsible for collecting profile data for computation of IRI for construction acceptance. Profiler Type Number of State DOTs Responding to Survey AC Pavements PCC Pavements Bridge Decks High-speed profilers only 22 11 4 Lightweight profilers only 1 1 3 High-speed or lightweight profilers 15 14 2 Table 9. Types of profilers used to collect IRI data for construction acceptance. State DOT Requirement Number of State DOTs Certified profiler required 18 Approved profiler required 2 No certification or approval required 2 Total 22 Table 10. Requirement for contractor- owned equipment that collects data for computation of IRI for construction acceptance on the final paved surface.
Collection of Inertial Profile for IRI Construction Acceptance 55 a breakdown of the procedures used by these 22 state DOTs regarding certification or approval of the contractor-owned equipment. As shown in Table 10, 16 state DOTs allow contractors to use certified contractor-owned pro- filers to collect data, while two state DOTs allow contractors to use approved profilers to collect data. These two state DOTs use a verification procedure to approve contractor-owned equip- ment. In the verification procedure, the IRI from the state DOTâowned profiler is compared to the IRI from the contractor-owned profiler at several test sections. If the agreement is satisfac- tory based on an established criterion, the state DOT approves the profiler. This procedure is not referred to as a certification procedure, as the data from the contractor-owned profiler is com- pared to the IRI from the state DOTâowned profiler and not to the IRI from a reference device. Two state DOTs do not require contractor-owned profilers to be certified or approved. One of two indicated that it previously had a program to certify profilers. But as the site that was used for certification is currently unavailable, it has waived the certification requirement. The other state DOT indicated that calibration checks specified by the manufacturer are performed on the contractor-owned profiler before collecting data on each project, and a printout of the results from the calibration checks is obtained. Michigan DOT currently certifies contractor-owned profilers but is not included in the state DOTs shown in Table 10 because that Michigan DOT does not accept the data collected by the con- tractor. In Michigan, a DOT employee or an approved consultant can collect data for construction acceptance using a certified contractor-owned profiler. In this case, an employee of the contractor drives the profiler, while the state DOT employee or the consultant operates the profiling system. Certification of Inertial Profilers The information presented in this section is based on the responses provided by the 38 state DOTs that responded to the survey indicating that they have an IRI-based smoothness specification. Frequency of Certification A profiler is certified annually, except in two states. Both of these states do not certify contractor- owned equipment. One state indicated that they certify the profiler twice a year, in spring and fall. The other state indicated that certification is performed quarterly. The state DOTs that certify profilers indicated that a profiler is recertified if inaccuracy is suspected or after major repairs. Location and Agency Performing Profiler Certification Twenty-five states have in-state profiler certification programs. The test section(s) that are used to certify a profiler may be located on in-service roads or at a location or facility that is not subjected to public traffic. In some states, the DOT performs the certification, while in other states a univer- sity or a university-affiliated institution performs the certification. For simplicity, certification per- formed by a university-affiliated institution is referred to as a university in this synthesis. Table 11 shows the location of the test section(s) and the organization that is certifying the profilers (i.e., state DOT or university) for the 25 states that have an in-state profiler certification program. Two state DOTs take their profilers to the Minnesota DOT certification facility to get them certified. Contractor-owned profilers are certified in 19 states. Table 12 shows the location of the test section(s) and the organization (i.e., state DOT or university) that is certifying the contractor- owned profilers in these 19 states. All state DOTs that certify contractor-owned equipment also certify state DOTâowned equip- ment that is involved in smoothness data collection for construction acceptance at the same
56 Inertial Profiler Certification for Evaluation of International Roughness Index location, except for one. This state DOT has only one profiler that is under the jurisdiction of another division in the DOT. That division uses a verification siteâwhere reference measure- ments are not availableâto evaluate the consistency of the data collected by the profiler. Surface and Texture Types Used for Certification Twenty-five states have established in-state certification programs. Table 13 shows the follow- ing information for each of these states: ⢠Number of AC sections used for certification, ⢠Number of PCC sections used for certification, ⢠Whether the state has a smoothness specification for PCC, and ⢠Whether the state certifies contractor-owned profilers. The following observations can be made from the information presented in Table 13: ⢠Eleven states use only one test section to certify profilers, with this section being AC surfaced in 10 states and PCC surfaced in one state. ⢠Although 19 states have smoothness specifications for PCC pavements, only seven of these states certify profilers on at least one PCC test section. Table 14 shows the surface and texture types and the IRI levels of the test sections categorized into three IRI levels (i.e., IRI less than 70 in./mi, IRI between 70 and 120 in./mi, and IRI greater than 120 in./mi) for the test sections used for certification in the states that have an in-state certification program. Length of Section Used for Profiler Certification The length of a test section that is used for certification in the 25 states that have established in-state certification sites is shown in Figure 14. The most common length of a section used for certification is 0.1 mi, with this being the length of a test section in 17 of the 25 states. Certification Procedures for Profilers Number of State DOTs At a facility not subjected to traffic by state DOT 9 Location(s) on in-service roads by state DOT 12 At a facility not subjected to traffic by an in-state university 2 Location(s) on in-service roads by an in-state university 2 Total 25 Table 11. Profiler certification location and organization performing profiler certification for states with in-state profiler certification programs. Certification Procedures for Contractor-Owned Profilers Number of State DOTs At a facility not subjected to traffic by state DOT 7 Location(s) on in-service roads by state DOT 9 At a facility subjected to traffic by an in-state university 1 At a facility not subjected to traffic by an in-state university 2 Total 19 Table 12. Profiler certification location and organization performing profiler certification for states that certify contractor-owned profilers.
Collection of Inertial Profile for IRI Construction Acceptance 57 Device Used to Collect Reference Data for Certification In 23 of the 25 states with in-state certification programs, SurPRO is used to collect reference data. The reference data in one of the two remaining states are collected using an ARRB Walk- ing Profiler, and in the other state the data are collected using a SSI Walking Profiler. The data- recording interval of the SurPRO can be varied, but it can be set to collect data at 1-in. intervals or less. The SSI Walking Profiler can record data at 1-in. intervals, while the ARRB Walking Profiler that was being used by one state records data at 9.5-inch intervals. The data-recording interval required for a profiler that is specified in AASHTO R 56-14 (AASHTO 2017C) is 1 in. The New Mexico DOT establishes the baseline IRI of the test sections that are used for certi- fication by averaging the IRI obtained for the test section from the SurPRO and the three state DOTâowned profilers. Procedures Used to Certify Profilers The procedures used to certify profilers in the 25 states with in-state certification programs are shown in Table 15. Six state DOTs use the procedure specified in AASHTO R 56-14 for certification, while 14 state DOTs use an agency-developed procedure that includes the cross- correlation procedure specified in AASHTO R 56-14. Hence, 20 of the 25 state DOTs with an in- state certification program use the cross-correlation procedure described in AASHTO R 56-14 to certify profilers. State Number of Sections Does State Certify Number Used For Certification Have Smoothness Contractor AC PCC Specification for Profilers? Surfaced Surfaced PCC? 1 4 â Yes Yes 2 1 â No No 5 1 â Yes Yes 6 1 â Yes Yes 10 1 1 Yes No 14 2 2 Yes No 15 6 â Yes Yes 17 1 â Yes Yes 18 2 â No Yes 19 1 â Yes Yes 20 1 1 Yes Yes 21 1 â No Yes 22 â 1 Yes Yes 24 1 â Yes Yes 26 3 â Yes No 27 2 â Yes Yes 28 1 â Yes Yes 29 2 â Yes Yes 33 2 â No No 34 1 5 Yes Yes 37 1 â No No 38 3 3 Yes Yes 39 1 â Yes No 42 2 â No No 44 2 1 Yes No Note: â = no PCC sections used. Table 13. Test sections used for certification.
State Number of Sections Surface/Texture Types and IRI Levels Number Used for Certification AC PCC Surfaced Surfaced 1 4 â DAC (IRI < 70, 70 to 120, > 120 in./mi), OAC (IRI < 70 in./mi) 2 1 â DAC (IRI < 70 in./mi) 5 1 â DAC (No specific IRI) 6 1 â DAC (IRI 70 to 120 in./mi) 10 1 1 DAC (IRI < 70 in/mi), TTC (IRI 70 to 120 in./mi) 14 2 2 DAC (IRI < 70 and > 120 in./mi), TTC (IRI < 70 in./mi), DGC (IRI < 70 in./mi) 15 6 â DAC, OAC, and SMA (IRI 70 to 120 and > 120 in./mi) 17 1 â DAC (IRI 70 to 120 in./mi) 18 2 â DAC (IRI 70 to 120 and > 120 in./mi) 19 1 â DAC (IRI 70 to 120 in./mi) 20 1 1 DAC (IRI 70 to 120 in./mi), TTC (70 to 120 in./mi) 21 1 â DAC (IRI < 70 in./mi) 22 â 1 TTC (IRI 70 to 120 in./mi) 24 1 â DAC (IRI < 70 in./mi) 26 3 â DAC (IRI < 70, 70 to 120, > 120 in./mi) 27 2 â DAC (IRI < 70, 70 to 120 in./mi) 28 1 â DAC (IRI 70 to 120 in./mi) 29 2 â DAC (IRI < 70 and > 120 in./mi) 33 2 â DAC (IRI < 70 and 70 to 120 in./mi) 34 1 5 DAC and LTC (70 to 120 in./mi), TTC and DGC (< 70 and > 120 in./mi) 37 1 â DAC (IRI 70 to 100 in./mi) 38 3 3 DAC and TTC (<70 and 70 to 120 in./mi), OAC and LTC (< 70 in./mi) 39 1 â DAC (IRI < 70 in./mi) 42 2 â DAC (IRI 70 to 120 and > 120 in./mi) 44 2 1 DAC (< 70, 70 to 120 in./mi), LTC (IRI 70 to 120 in./mi) Note: â = no PCC sections used; DAC = dense-graded asphalt concrete; OAC = open-graded asphalt concrete; TTC = transversely tined concrete; DGC = diamond-ground concrete; LTC = longitudinally tined concrete. Table 14. Surface texture type and IRI level of test sections used for certification. Figure 14. Length of test section used to certify profilers. 500 ft 0 2 4 6 8 10 12 14 16 18 0.1 mi 0.2 mi Length of Test Section N um be r of S ta te D O T s
Collection of Inertial Profile for IRI Construction Acceptance 59 Written Procedures for Certification of Profilers Of the 25 states that responded to the survey indicating that they have an in-state certification program, 21 disclosed that they have a written procedure for certifying profilers. A state DOT that currently does not certify profilers because of the lack of a suitable test site also declared that they have a written procedure for certifying profilers. Several state DOTs have the procedure for certification of profilers published as a state DOT test method. An example of such a test method is California Test 387, Method of Test for Operation, Calibration, and Operator Certification of Inertial Profilers (California DOT 2017). Fee for Certifying Contractor-Owned Profilers A fee for certifying contractor-owned profilers is levied in six states: Alabama, California, Colorado, New Mexico, Pennsylvania, and Texas. The state DOT administers the profiler certification program in California, Colorado, New Mexico, and Pennsylvania. The fee charged for certifying a profiler in California is $1,000, while the fee in Colorado and New Mexico is $500. Pennsylvania charges a fee of $400 for certifying a profiler that includes the certification of an operator. The profiler certification program in Alabama and Texas are administered by NCAT and TTI, respectively. NCAT charges a fee of $1,500 for certifying a profiler. TTI offers five levels of certification: (1) HMA: Certification at a smooth and a medium-smooth dense-graded AC section and at an open-graded AC section, (2) PCC2: Certification at a smooth and a medium- smooth transversely tined PCC section, (3) PCC1: Certification at the two transversely tined PCC sections and at a longitudinally tined PCC section, (4) HMA/PCC2: Certification at the aforementioned HMA and PCC2 sections, and (5) HMA/PCC1: Certification at the previously mentioned HMA, PCC2, and PCC1 sections. The profiler owner can select the level of certification, and TTI has different charges for each level. The following are the charges assessed by TTI: (1) PCC1 or PCC 2â$2,500; (2) HMAâ$ 3,000; and (3) HMA/PCC1 or HMA/PCC2â$4,000. Documentation Provided After Certifying Contractor-Owned Profilers The following are some of the common procedures adopted by state DOTs to document that an inertial profiler has been certified: ⢠Affix a decal to the profiler, ⢠Provide a letter or a card indicating that the profiler is certified, and ⢠Post details about the profiler on the web. The responses provided by the 19 state DOTs that certify contractor-owned equipment on the procedures that are followed in their state are summarized in Table 16. One state DOT indicated that they maintain a list of the certified profilers. Procedures for Profiler Certification Number of Responding State DOTs AASHTO R 56 6 ASTM E 950 1 Agency-developed procedure (includes cross-correlation) 14 Agency-developed procedure (does not include cross-correlation) 4 Total 25 Table 15. Procedures used to certify profilers.
60 Inertial Profiler Certification for Evaluation of International Roughness Index Approval of Contractor-Owned Profilers Two state DOTs approve contractor-owned profilers for collecting data on the final paved surface for construction acceptance. The procedure for approval includes determining the accu- racy of the profiler by comparing the IRI from the profiler with the IRI from the state DOTâ owned profiler, which is treated as the reference. Based on the definition used in this synthesis, certification of a profiler involves comparing the data collected by a profiler with a reference device. Therefore, the procedure used by these two state DOTs to approve contractor-owned profilers is not considered to be certification. One state DOT uses a 0.1-mi-long broom-finished PCC section that has an IRI greater than 120 in./mi as the test section for approving contractor-owned profilers. This DOT uses an agency-developed procedure that includes the cross-correlation method as the procedure for approving profilers. The state DOT does not charge a fee for approving profilers and issues a letter indicating that the profiler is certified. The other state DOT has established a course on in-service roads to collect data that are used to approve contractor-owned profilers. This course has several surface types that are 0.2 to 0.3 mi long, and the state DOT has established test sections on each surface type that is used as test sections for approval. The surface types of the test sections and the IRI level of the test sections are: ⢠Dense-graded AC, IRI less than 70 in./mi; ⢠Transversely tined PCC, IRI greater than 120 in./mi; ⢠Diamond Ground PCC, IRI between 70 and 120 in./mi; ⢠Longitudinally grooved PCC, IRI between 70 and 120 in./mi; and ⢠Longitudinally diamond ground AC, IRI less than 70 in/mi. The reference IRI for each test section is determined using the IRI values obtained at these sections by the state DOTâowned profilers. This state DOT uses an agency-developed procedure that does not include the cross-correlation method as the procedure for approving profilers. The state DOT does not charge a fee for certifying profilers. It also issues a letter indicating that the profiler is approved and posts the details of the profiler on the web. Verification Procedures Used for State DOTâOwned Profilers As indicated previously, several state DOTs that collect profile data for computing IRI for construction acceptance using state DOTâowned profilers indicated that they do not certify the state DOTâowned profiler. These state DOTs do not certify or approve contractor-owned profilers. Several of these state DOTs indicated that they use verification procedures to verify that the Documentation Provided After Certification Number of State DOTs Decal affixed to profiler 2 Letter or card provided 8 Decal affixed to profiler and letter provided 2 Decal affixed to profiler, letter provided, and details posted to web 3 Decal affixed to profiler and details posted on web 2 Letter provided and details posted on web 2 Total 19 Table 16. Documentation provided after certification.
Collection of Inertial Profile for IRI Construction Acceptance 61 equipment is collecting consistent data. The following are some of the procedures indicated by the state DOTs for verifying the equipment: ⢠One state DOT indicated that it performs an annual verification of all profilers owned by the state DOT at a test section. Reference data at this section are collected using a SurPRO, and the data collected by the profilers are compared with the data obtained from the SurPRO. Although the data obtained from the profilers are compared with the data obtained from a reference device, the state DOT refers to this process as verification. This is because the state DOT does not have criteria developed to certify profilers. ⢠One state DOT indicated that it performs weekly verification of profilers at a test section to ensure that the profilers are collecting consistent data. ⢠One state DOT indicated that the profiler is checked at a verification section frequently to verify that the profiler is collecting consistent data. Data collected at an established verification section (i.e., control section) by a profiler at regu- lar intervals can be compared with previously collected data to evaluate whether the profiler is collecting consistent data. However, such a procedure cannot be used to verify whether the profiler is collecting accurate data. When using a control section, if a difference in data is noted when compared to the previously collected data (e.g., data collected in the previous year), it will be difficult to determine if this change occurred because of an issue with the profiler or because of a change in the profile of the verification section. Certification of Inertial Profiler Operators The inertial profiler operator must be knowledgeable of the profiler operation and be able to perform a preliminary analysis on the collected data. The profiler operator must be able to ⢠Calibrate profiler components that require calibration (e.g., DMI), ⢠Perform the manufacturerâs recommended operational checks before collecting data to ensure all components on the profiler are performing satisfactorily (e.g., block check and bounce test), ⢠Recognize any diagnostic warnings issued on the computer when there is a problem with a component in the profiler, ⢠Follow proper operational procedures when collecting data (e.g., collecting data within the specified speed range), ⢠Perform a preliminary analysis on the collected data to determine if the IRI values are reason- able, and ⢠Follow procedures identified in the state DOT specification when collecting data. Several state DOTs have a program in place to certify profiler operators and ensure that the profiler operators are competent to operate the profiler. State DOTs Requiring Profiler Operator Certification Of the 38 state DOTs that use IRI for construction acceptance, 22 allow contractors to collect the profile data on the final paved surface for computation of IRI for construction acceptance. The 16 state DOTs that do not allow contractors to collect this data do so using state DOTâ owned equipment. However, only four of the 16 state DOTs certify the DOT operators that collect the data. Of the 22 states that allow contractors to collect data on the final paved surface for construc- tion acceptance, 18 require contractor operators to be certified. In 12 of the 18 states where
62 Inertial Profiler Certification for Evaluation of International Roughness Index contractor operators are required to be certified, the state DOT operators are also required to be certified. Table 17 shows operator certification requirements in the 22 states where the DOT accepts contractor-collected data on the final paved surface for construction acceptance. One state DOT that has currently suspended its profiler certification program due to the lack of a site still requires DOT operators as well as contractorâprofiler operators to be certified. Both state DOTs that approve contractor-owned profilers, based on a verification process described previously, require contractor operators to be certified. In summary, of the 38 state DOTs that use IRI for construction acceptance, 22 have an in-state operator certification program in place. Of these 22 state DOTs, 12 require state DOT and con- tractor operators to be certified, six only require contractor operators to be certified, and four that do not allow contractors to collect smoothness-acceptance data require the state DOT oper- ators to be certified. Written Procedures for Operator Certification As described in the previous section, 22 state DOTs have an in-state profiler certification program in place. Nineteen of the 22 indicated that they have written procedures regarding pro- filer operator certification. In some cases, these procedures are included in the state DOTs test method that addresses data collection with inertial profilers. An example of such a test method is Texas Test Tex-1001-S, Test Procedure for Operating Inertial Profilers and Evaluating Pavement Profiles (Texas DOT 2017). Procedures Used to Certify Profiler Operators Some of the frequently used methods to certify profiler operators require them to do one or more of the following: ⢠Attend a class describing profiler operations, ⢠Take an online class on profiler operations, ⢠Pass a written exam administered in a classroom, ⢠Pass an online exam on profiler operations, and ⢠Pass a practical exam. Typically, the class addresses operational procedures to collect quality data, as well as the state DOT requirements regarding data collection, analysis, and submittal of data. The NHI offers the course NHI 131100 (NHI 2017) to provide training for profiler operators. One state DOT that currently requires DOT operators to be certified indicated that the DOT operators are expected to attend a training course such as NHI 131100. The practical exam usually includes the operator demonstrating the ability to perform opera- tional checks on the equipment before collecting data, the ability to calibrate the profiler com- ponents that require calibration, the ability to collect data using correct operational procedures, and the ability to analyze the collected data according to the state DOT specification. Certification Requirements for Operators Number of State DOTs State DOT and contractor operators required to be certified 12 Contractor operators not required to be certified 4 Only contractor operators required to be certified 6 Table 17. Certification requirements in states where contractor-collected data are accepted for construction.
Collection of Inertial Profile for IRI Construction Acceptance 63 The various combinations of procedures used in the 22 states that have an in-state profiler operator certification program to certify operators are shown in Table 18. Table 19 shows the number and percentage of state DOTs that require operators to satisfy each of the following criteria (based on the 22 state DOTsâout of the 44 that responded to the surveyâthat require operators to be certified): attend a class describing profiler operations, take an online class on profiler operations, pass a written exam administered in a classroom, pass an online exam, and pass a practical exam. For example, 12 of the 22 state DOTs that require opera- tors to be certified require the operator to attend a class describing profiler operations, which is 54% of the 22 state DOTs that require operators to be certified. As seen in Table 19, the most common method used for operator certification is to pass a prac- tical exam (20 of 22 state DOTs) followed by passing a written exam administered in a classroom (13 of the 22 state DOTs). The Colorado DOT has partnered with the stateâs asphalt association to certify profiler operators. The stateâs asphalt association offers technician certification courses for various categories of cer- tification, and profiler operator certification is included as a category under which a person can be certified. Profiler operator certification in Wisconsin and Missouri are also part of the statesâ technician certification programs. In Wisconsin, the operator certification is conducted by the University of Wisconsin, Platteville. In Missouri, the operator certification is conducted by the Linn State Technical College. In Texas and Alabama, the profiler certification is conducted by TTI and NCAT, respectively. In the rest of the states, the operator certification program is administered by the state DOT. Period of Validity for Operator Certification Figure 15 shows the period of validity for operator certification. Although 22 state DOTs have in-state operator certification programs, Figure 15 shows data for only 21 state DOTs. One state DOT that does not allow contractors to collect profile data for construction acceptance and only Requirements for Obtaining Operator Certification Number of State DOTs Pass a practical exam only 5 Pass a written and a practical exam 5 Attend a class, and pass a written exam 2 Attend a class, and pass a practical exam 3 Attend a class, and pass a written and a practical exam 5 Take and pass an online class, and pass a practical exam 1 Take and pass an online exam, attend a class, and pass a written exam 1 Total 22 Table 18. Combination of procedures used to certify profiler operators. Requirement State DOTs with Operator Certification Programs Requiring the Criterion Number Percentage (%) Attend a class describing profiler operations 12 55 Take an online class on profiler operations 2 9 Pass a written exam administered in a classroom 13 59 Pass an online exam 2 9 Pass a practical exam 20 91 Table 19. Requirements for operator certification.
64 Inertial Profiler Certification for Evaluation of International Roughness Index certifies DOT operators indicated that they only require a DOT operator to be certified once, and they hold quarterly verifications to ensure operators are following correct operational procedures. This state DOT is omitted from Figure 15. One state DOT that certifies operators requires them to attend a class, pass a written exam, and pass a practical exam. The practical portion of opera- tor certification is valid for 1 year, while the class and written portion of certification is valid for 5 years. The duration of validity for operator certification for this state DOT is shown as 1 year in Figure 15. As seen in Figure 15, the most common duration for validity of operator certification is 3 years followed by 1 year. Documentation Provided to Certified Operators State DOTs provide one or more of the following documentation to certified contractor operators: ⢠Letter indicating the operator is certified, ⢠Card with a photograph indicating the operator is certified, ⢠Card without a photograph indicating the operator is certified, ⢠Name of operator posted to the web, and ⢠Name of operator with a photograph posted to the web. Table 20 shows a breakdown of the various combinations of documentation provided to operators in the 18 states where contractor operators are currently certified. 1 Year 0 2 4 6 8 10 12 3 Years 4 Years 5 Years Duration of Validity of Operator Certification N um be r of S ta te D O T s Figure 15. Duration of validity for operator certification. Documentation Provided to Operator After Certification Number of State DOTs Letter provided 5 Letter and photo ID card provided 1 Letter and photo ID card provided and name posted on web 1 Letter provided and name posted on web 1 Letter provided, name posted on web, and ID card provided 1 Letter provided and name with photo posted on web 1 Photo ID card provided 1 Photo ID card provided and name posted on web 1 Name posted on web 2 Name posted on web and ID card without photo provided 1 ID card provided 3 Total 18 Table 20. Various combinations of documentation provided to operators after certification.
Collection of Inertial Profile for IRI Construction Acceptance 65 Table 21 shows the number of state DOTs adopting each of the documentation practices described previously, as well as the percentage of state DOTs adopting each of the practices. (Note: Percentages are based on eight state DOTsâout of the 44 state DOTs that responded to the surveyâthat require contractor operators to be certified. A state DOT that provides a letter and an ID card without a photograph would be included in Table 21 under âLetter provided,â as well as âCard without photographâ). The most common form of documentation provided by the state DOTs after certifying an operator is to provide a letter (10 of the 18 state DOTs) fol- lowed by posting the name of the operator on the web (seven of the 18 state DOTs). Fee for Certifying Operators A fee is required for a profiler operator to be certified in eight states. In Missouri, the cer- tification is performed through a technical college that charges a fee of $250 per operator. In Alabama, profiler certification is performed by NCAT, which charges a fee of $1,500 to certify a profiler and any number of profiler operators for that profiler. In Pennsylvania, a fee of $400 is charged for certifying a profiler and an operator, with an additional fee of $150 being charged for certifying additional operators for the profiler who are certified the same day. In Texas, operator certification is performed by TTI, which charges a fee of $400 to certify an operator. In New Mexico, the New Mexico Technician Training and Certification Program is a joint agency and industry program for certifying technicians. The profiler operator certification is performed under this program, with a fee of $100 charged for certifying an operator. The profiler operator certifica- tion program is administered by the state DOTs in California, Iowa, and Utah. The fee for certifying an operator in these states is $500, $250, and $150, respectively. Reciprocity of Certification for Inertial Profilers and Operators Inertial Profilers Of the 21 state DOTs that currently certify or approve contractor-owned profilers for collect- ing profile data for computation of IRI on the final paved surface for construction acceptance, 17 indicated that they will not accept a profiler certification issued by another state. One state DOT said they will accept a certification issued by another state, while three state DOTs indicated that they will consider accepting such a certification. The three state DOTs that indicated that they will consider accepting a certification issued by another state provided the following responses: ⢠Missouri DOT indicated that profilers certified in another state will be allowed to collect data on a case-by-case basis until the contractor is able to certify the profiler at the stateâs certification facility. Documentation Provided to Certified State DOTs that Responded to Survey Indicating that Contractor Operators Contractor Operators are Certified Number Percentage (%) Letter provided 10 56 Card with photograph provided 4 22 Card without photograph provided 5 28 Name posted to web 7 39 Name with photograph posted to web 1 6 Table 21. Number of state DOTs providing each type of documentation.
66 Inertial Profiler Certification for Evaluation of International Roughness Index ⢠Iowa DOT indicated that profilers certified in another state will be allowed to collect data, but the profiler must run specified test sections to verify the data collected by the profiler before the profiler is approved to collect data. ⢠Ohio DOT indicated that it might allow profilers certified in another state to collect data, but that will be approved on a case-by-case basis and will require a comparison of the data col- lected by the profiler with data collected by a state DOTâowned profiler. One state DOT that currently does not have its own profiler certification program in place but allows contractors to collect smoothness data for construction acceptance indicated that it is working to accept profilers certified in another state. Profiler Operators Of the 22 states that allow contractors to operate profilers and accept the data collected by the profilers, 18 require the contractor operators to be certified. Of these 18 states, 17 indicated that they do not accept a profiler operator certification provided by another state. Ohio DOT indicated that they might consider accepting operator certifications from other states on a case- by-case basis. Sensor Types Specified for Data Collection The responses received for the survey regarding the sensor type (i.e., SS, WS, and LL) specified for inertial profiler for various surface types are summarized in Table 22 for the 21 state DOTs that certify or approve contractor-owned equipment. This table also indicates whether the state has an IRI-based smoothness specification for PCC pavements. State IRI-Based Sensor Type Specified for Various Surface Number Smoothness Types Specification Used for PCC? 1 Yes Not specified 5 Yes DAC, OAC, and SMA (not specified), all PCC (LL) 6 Yes DAC, SMA (SS or LL), all PCC (LL) 12 Yes DAC (SS or LL), OAC and SMA (LL), all PCC (LL) 15 Yes Not specified 17 Yes All surfaces (LL) 18 No DAC and OAC (SS) 19 Yes Not specified 20 Yes Not specified 21 No Not specified 22 Yes Not specified 24 Yes DAC and OAC (SS, WS, LL), all PCC (LL) 27 Yes All pavements (SS or WS) 28 Yes Not specified 29 Yes Not specified 31 Yes DAC, SMA (SS, WS, LL), all concrete (LL) 33 No Not specified 34 Yes Not specified 38 Yes Not specified 38 Yes Not specified 44 Yes Not specified Note: sensor type in parentheses. Table 22. Sensor types specified for height sensors for state DOTs that certify contractor-owned equipment.
Collection of Inertial Profile for IRI Construction Acceptance 67 Out of the 21 states shown in Table 22, three states do not use an IRI-based smoothness specification for PCC pavements. Of these three states, two do not specify a height-sensor type for the profiler, and the other state specifies an SS laser for all types of AC-surfaced roads. Of the 17 states that have an IRI-based smoothness specification for PCC, 10 do not specify the sensor type for any pavement or texture type. Out of the remaining seven state DOTs, one requires LL height sensors for all surface types, one specifies either an SS or a WS laser for all surface types, and the remaining five state DOTs require LLs for PCC pavements. It is well known that height sensors with SS lasers do not collect accurate data on longitudi- nally textured surfaces (e.g., longitudinally tined PCC), and IRI computed from such data will result in an upward bias. Hence, contractors who collect data on longitudinally textured surfaces are expected to be using profilers equipped with LLs on such surfaces. The state DOTâowned equipment that is used to verify the data collected by the contractor must also use profilers equipped with LLs on such surfaces. The response to this question from the state DOTs that do not accept smoothness data col- lected by contractors appearâin several casesâto depend on the sensor type that is currently available in the state DOT profiler that collects the smoothness data, rather than on a sensor type that is specified by the state DOT. Hence, the results are not presented. Operational Procedures for Collecting Data Pre-Operational Checks Performed on State DOTâOwned Profilers The typical pre-operational checks that are performed on profilers before data collection are ⢠Verification that the distance measurement system in the profiler is accurate, ⢠Bounce test, and ⢠Block check on the laser sensors. Table 23 shows the distribution of pre-operational checks performed on the profiler before collecting data by the 38 state DOTs that responded to the survey and indicated that they have an IRI-based smoothness specification. Twenty-nine state DOTs (76% of the responding DOTs that use IRI for construction acceptance) indicated that all three tests/checks are performed on the profiler before collecting data. The following comments were provided by the state DOTs regarding pre-operational checks: ⢠Several state DOTs indicated that an accelerometer calibration, which is recommended by the manufacturer, is performed before data collection. ⢠One state DOT indicated that it often collects data at a verification site. Type of Test State DOTs Responding to Survey that Use IRI for Construction Acceptance Number Percentage (%) Verification of DMI and block check 2 5 Verification of DMI and bounce test 3 8 Bounce test and block check 4 11 Verification of DMI, block check, and bounce test 29 76 Total 38 100 Table 23. Pre-operational checks performed on state DOTâowned profiler.
68 Inertial Profiler Certification for Evaluation of International Roughness Index ⢠One state DOT indicated that it performs IRI verification of the profiler weekly on a site estab- lished on an in-service road, while another state DOT indicated that it performs verification monthly on a 0.5-mi-long road. Pre-Operational Checks Performed on Contractor-Owned Profilers When a contractor collects data for construction acceptance, a state DOT representative is expected to check whether the profiler is certified before collecting data (if the state requires a certified profiler to be used). A state DOT representative is also expected to check whether the operator is certified (if the state requires a certified operator to operate equipment). Depending on the procedures in the state, the DOT representative may observe one or more of the following pre-operational checks performed by the contractor on the profiler: ⢠Observe the contractor operator verifying the accuracy of the DMI, ⢠Observe the contractor operator performing the block check, and ⢠Observe the contractor operator performing the bounce test. Table 24 shows the various pre-operational checks the contractor is required to perform in the presence of a state DOT representative in the 22 states that allow contractors to collect data. In 11 states (50% of the states that responded to the survey indicating that they allow contractors to collect smoothness data for construction acceptance), the DOT does not require the state DOT representative to observe the contractor performing any of the procedures previously described. Two state DOTs that indicated that they do not require the state DOT representative to observe any of these procedures being performed also declared that the state DOT project personnel at the site can request the operator to perform these procedures, if needed. Quality Assurance Procedures on Contractor-Collected Data and on Disputes Quality Assurance Procedures Twenty-two of the 44 state DOTs that responded to the survey allow contractors to collect profile data on the final paved surface for construction acceptance. Some of the QA procedures that a state DOT can use to verify the contractor-collected data for construction acceptance on the final paved surface are ⢠Collect data on a portion of each project, ⢠Collect data on the entire project, and ⢠Collect data on a portion of the project or the entire project if a potential issue is flagged. Procedure State DOTs Responding to Survey that Allow Contractors to Collect Data for Construction Acceptance Observe Observe Observe Number Percentage (%) Verification Bounce Block of DMI Test Check No No No 11 50 Yes No No 2 9 No Yes No 1 5 Yes Yes Yes 8 36 Table 24. Pre-operational checks observed by the state DOT representative on contractor-owned equipment before data collection.
Collection of Inertial Profile for IRI Construction Acceptance 69 The state DOTs that allow contractors to collect data on the final paved surface for construc- tion acceptance were asked to select one of the previous responses orâif these responses were not appropriateâto indicate the procedure followed by the state DOT. Table 25 shows the responses provided by the state DOTs. The comments regarding QA procedures provided by the eight state DOTs that selected âNone of the aboveâ are ⢠The [state] DOT selects projects for QA testing based on contractor history and reasonable- ness of data. ⢠One project per contractor is selected for QA testing. The [state] DOT performs QA testing on entire project when requested by the project engineer. ⢠The [state] DOT does QA testing on 25% of the projects. ⢠The [state] DOT checks 10% of the project length. ⢠The [state] DOT collects QA data on 5% to 10% of the projects in a year. ⢠The [state] DOT collects QA data on 10% of the projects. ⢠Procedures for QA are not developed yet. ⢠The [state] DOT verifies the data collected by each contractor every year by profiling a portion of a project or the entire project. Verification testing is performed on multiple projects for contractors that have more work than others. One state DOT commented that QA is also performed randomly by selecting projects, and that all profilers used by contractors are subjected to an annual QA verification after certification. Disputes with Contractors Contractors are allowed to collect smoothness data on the final paved surface for construction acceptance in 22 of the 44 states that responded to the survey. If a contractor disputes the QA data collected by the state DOT, some of the procedures that can be followed by the state DOT are ⢠Indicate the state DOTâcollected data are accurate and ⢠Use documented procedure to address the issue. The survey requested that the state DOTs that allow contractors to collect smoothness data on the final paved surface select one of the previous procedures and/or add a comment regard- ing the procedure they use. The number of state DOTs that selected one of the two procedures are shown in Table 26. Other comments provided by the state DOTs were ⢠Several state DOTs indicated that a thorough investigation is performed if the contractor- collected data and the state DOTâcollected data are different to determine what profiler is collecting incorrect data. QA Procedure Number of State DOTs State DOT always collects data on a portion of each project 3 State DOT always collects data on entire project 4 If an issue is flagged, the state DOT collects data on a 7 portion of project or entire project None of the above 8 Table 25. QA procedures used by state DOTs for contractor-collected data.
70 Inertial Profiler Certification for Evaluation of International Roughness Index ⢠One state DOT indicated that referee testing is done by the central office, and the results obtained from the central office profiler is considered to be final. ⢠One state DOT indicated that both inertial profilers are decertified until it can be determined which device is collecting erroneous data. ⢠One state DOT indicated that if a contractor questions the accuracy of the state DOT data, the state DOT will again collect data on the project. ⢠One state DOT indicated that the project is re-profiled, and collected data are compared with the previously collected data. ⢠One state DOT indicated that discrepancies are resolved by recertification and could include third-party testing. ⢠One state DOT indicated that the data collected by the SurPRO are used as the arbiter. The SurPRO is used to collect data on the section of the project in question, and the results are then compared to the results obtained from the state DOT and contractor-collected data. The results closest to the SurPRO data (i.e., state DOT or contractor) are then determined to be correct. Although many state DOTs do not accept the contractor-collected data on the final paved surface for construction acceptance, the contractor is free to collect data on the pavement using contractor-own equipment for QC. A contractor who has collected QC data could also challenge the validity of the data collected by the state DOT if the contractor results differ from the results obtained by the state DOT. Challenges and Important Items to Consider When Setting Up a Profiler Certification Program Input was sought from a select group of states with profiler certification programs on chal- lenges that are faced and important items to consider when setting up such a program. The following are the states that were contacted with the year in which they set up the profiler certifica- tion program: Minnesota (2002), Mississippi (2007), Ohio (2007), Texas (1999), and Wisconsin (2008). All of these states currently certify contractor-owned equipment. Texas constructed a facility to certify profilers in 1999 and certified state DOT-owned equipment in 1999 and 2000. In 2001, it started to certify state DOTâowned as well as contractor-owned equipment. The Minnesota DOTs certification program was established in 2002 and certified inertial profilers and profilographs until 2009, after which only inertial profilers were certified. Challenges When Setting Up a Profiler Certification Program The following is a summary of the challenges the contacted states indicated were encountered when setting up a profiler certification program: 1. Finding a location or a facility for setting up the test sections for the profiler certification program. The test facility needed a section long enough to set up the test section, as well as a sufficient length for lead-in and lead-out. It also needed to be accessible at all times without impeding traffic. Procedure for Handling Disputes Number of State DOTs Agency-collected data are assumed to be correct 6 Documented procedures used to address disputes 9 Table 26. Procedures used by the state DOTs to address disputes.
Collection of Inertial Profile for IRI Construction Acceptance 71 2. Educating the contractors about the certification program and getting the contractors to buy into the need for certification. 3. Choosing a reliable and valid reference profiler. (Note: This state DOT indicated that at the time the certification program was established, little information was available about perfor- mance of the existing reference devices). 4. Personnel turnover of contractors result in many profiler operators not having much experience. Most new profiler operators have limited experience in operating profilers. One state DOT in- dicated that often a profiler would fail to pass operational tests/checks, such as the block check, bounce test, and the DMI check. A minor adjustment to the profiler would have resulted in the profiler passing these operational tests/checks. However, the operators were not expe- rienced enough to make these adjustments, and the profiler had to return another day for certification. 5. As the certification sites are located on in-service roads, the site must be shifted to a new location every several years once its IRI level goes above the IRI level that is required for the certification site. 6. Selecting a facility that has the different surface types required for certification at one location or selecting the various test sections required for certification that are located on in-service roads such that they are close to each other. 7. For sections located on in-service roads, selecting sections where traffic control can be pro- vided over a long window of time without causing issues with traffic backup. Important Items to Consider When Setting Up a Profiler Certification Program The following is a summary of important items to consider when setting up a profiler certification, as indicated by the states that were contacted: 1. Find a champion in the state DOT to support the smoothness specifications and the profiler certification program. 2. Establish criteria for certifying profilers consistent with the certification programs intended function. 3. Find the funds to maintain the certification facility and to cover the labor cost of the per- sons performing the certification. (Note: This input was provided by a university-associated institution that performs profiler certification). 4. Provide ample warning to contractors about the state DOTsâ decision to certify inertial profilers. It is important to explain in detail why it is necessary to certify contractor-owned profilers and to inform the contractors that the state DOTâowned equipment will also be certified using the same criteria. This was accomplished by sending letters to the contractors, making presenta- tions at workshops, and informing the contractors at industryâDOT meetings. 5. When selecting sections to serve as certification sites, avoid using sections with adverse characteristics that would complicate the analysis. 6. Keep the contractor operators informed about the certification procedureâespecially since there is personnel turnoverâto make the certification process go smoothly. 7. Have a reliable reference profiler and personnel who are proficient in operating it. 8. Develop a required class to educate profiler operators before they can be certified. This is especially important when the profiler operators are new, as they have limited knowledge and experience in operating the profiler. 9. A state DOT that does not charge a fee for certifying profiler operators indicated that some contractors send many personnel from their organization to be certified. Often, some of the operators who get certified never operate a profiler. This places a burden on the state DOT personnel who must spend time certifying all of the operators. The state DOT indicated that charging a fee may limit the number of operators each organization sends to be certified.
72 Inertial Profiler Certification for Evaluation of International Roughness Index 10. One state DOT has diamond-ground a new AC surface to evaluate the performance of the profiler on a smooth diamond-ground section. Grinding the AC surface has eliminated curling issues that are encountered when a ground PCC surface is used, where the surface of the PCC can change with variances in ambient temperature. 11. A state where construction activities occur throughout the year in most of the state indi- cated that the certification facility should be located in an area where weather conditions will not impede profiler certifications. The state DOT indicated that this is particularly im- portant when recertifying profilers that have height sensors replaced, as a delay in certifying the equipment can cause difficulties for the contractor. 12. Limit the number of persons who are involved in the profiler certification program. If dif- ferent groups of people are involved in certification (such as the group who own and control the certification site, the group who own and operate the reference profiler, the group who certify profilers and operators, and the group who provide traffic control), scheduling a date and time for profiler certifications can be problematic.
