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Inertial Profiler Certification for Evaluation of International Roughness Index (2018)

Chapter: Chapter 6 - Collection of Inertial Profile for Network-Level IRI

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Suggested Citation:"Chapter 6 - Collection of Inertial Profile for Network-Level IRI." National Academies of Sciences, Engineering, and Medicine. 2018. Inertial Profiler Certification for Evaluation of International Roughness Index. Washington, DC: The National Academies Press. doi: 10.17226/25207.
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Suggested Citation:"Chapter 6 - Collection of Inertial Profile for Network-Level IRI." National Academies of Sciences, Engineering, and Medicine. 2018. Inertial Profiler Certification for Evaluation of International Roughness Index. Washington, DC: The National Academies Press. doi: 10.17226/25207.
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Suggested Citation:"Chapter 6 - Collection of Inertial Profile for Network-Level IRI." National Academies of Sciences, Engineering, and Medicine. 2018. Inertial Profiler Certification for Evaluation of International Roughness Index. Washington, DC: The National Academies Press. doi: 10.17226/25207.
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Suggested Citation:"Chapter 6 - Collection of Inertial Profile for Network-Level IRI." National Academies of Sciences, Engineering, and Medicine. 2018. Inertial Profiler Certification for Evaluation of International Roughness Index. Washington, DC: The National Academies Press. doi: 10.17226/25207.
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Suggested Citation:"Chapter 6 - Collection of Inertial Profile for Network-Level IRI." National Academies of Sciences, Engineering, and Medicine. 2018. Inertial Profiler Certification for Evaluation of International Roughness Index. Washington, DC: The National Academies Press. doi: 10.17226/25207.
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Suggested Citation:"Chapter 6 - Collection of Inertial Profile for Network-Level IRI." National Academies of Sciences, Engineering, and Medicine. 2018. Inertial Profiler Certification for Evaluation of International Roughness Index. Washington, DC: The National Academies Press. doi: 10.17226/25207.
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Suggested Citation:"Chapter 6 - Collection of Inertial Profile for Network-Level IRI." National Academies of Sciences, Engineering, and Medicine. 2018. Inertial Profiler Certification for Evaluation of International Roughness Index. Washington, DC: The National Academies Press. doi: 10.17226/25207.
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Suggested Citation:"Chapter 6 - Collection of Inertial Profile for Network-Level IRI." National Academies of Sciences, Engineering, and Medicine. 2018. Inertial Profiler Certification for Evaluation of International Roughness Index. Washington, DC: The National Academies Press. doi: 10.17226/25207.
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Suggested Citation:"Chapter 6 - Collection of Inertial Profile for Network-Level IRI." National Academies of Sciences, Engineering, and Medicine. 2018. Inertial Profiler Certification for Evaluation of International Roughness Index. Washington, DC: The National Academies Press. doi: 10.17226/25207.
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Suggested Citation:"Chapter 6 - Collection of Inertial Profile for Network-Level IRI." National Academies of Sciences, Engineering, and Medicine. 2018. Inertial Profiler Certification for Evaluation of International Roughness Index. Washington, DC: The National Academies Press. doi: 10.17226/25207.
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Suggested Citation:"Chapter 6 - Collection of Inertial Profile for Network-Level IRI." National Academies of Sciences, Engineering, and Medicine. 2018. Inertial Profiler Certification for Evaluation of International Roughness Index. Washington, DC: The National Academies Press. doi: 10.17226/25207.
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Suggested Citation:"Chapter 6 - Collection of Inertial Profile for Network-Level IRI." National Academies of Sciences, Engineering, and Medicine. 2018. Inertial Profiler Certification for Evaluation of International Roughness Index. Washington, DC: The National Academies Press. doi: 10.17226/25207.
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Suggested Citation:"Chapter 6 - Collection of Inertial Profile for Network-Level IRI." National Academies of Sciences, Engineering, and Medicine. 2018. Inertial Profiler Certification for Evaluation of International Roughness Index. Washington, DC: The National Academies Press. doi: 10.17226/25207.
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73 This chapter presents the results obtained from the survey regarding the procedures followed by the state DOTs to collect network-level profile data, including whether the state DOT or a vendor collects the data; certification of profilers and operators; operational procedures for col- lecting the data; and data quality management. Responses received from 44 states that responded to the survey are presented in this section. Responsibility for Data Collection State DOTs store the IRI data on the state highway system in a pavement management system. Typically, IRI computed at 0.1-mi intervals are stored. The state DOTs are required to collect profile data at specific HPMS sections located on the off-state system to compute the IRI and then submit this IRI data, along with the relevant IRI data on the state highway network, to the FHWA. The profile data for computation of IRI on the state highway network and at the HPMS sections located on the off-state network in a state may be collected by the state DOT, a vendor who collects data under a contract with the state, or both. Table 27 shows the party responsible for collecting the required data in the 44 states that responded to the survey. The following observations are noted from the information presented in Table 27: • In 18 states (41% of states that responded to the survey), the state DOT collects data on both the state highway network and at the HPMS sections located on the off-state system. • In 17 states (39% of states that responded to the survey), a vendor collects data on both the state highway network and at the HPMS sections located on the off-state system. • In one state, the state DOT collects data on the state highway network, while a vendor collects data at the HPMS sections located on the off-state highway system. In this state, the pavement management section of the state DOT handles the state highway network data collection, while the data collection at the off-state system HPMS sections is handled by the HPMS section of the state DOT. • In three states, the state DOT and the vendor both collect data on the state highway network, while only the vendor collects data at the HPMS sections located on the off-state highway sys- tem. One of these states indicated that the vendor collects data on the state highway system at the beginning of the year, and at the end of the year the state DOT collects data on pavements that were paved during the year after the vendor has collected data. • In two states, the state DOT and the vendor both collect data on the state highway system and at the HPMS sections located on the off-state system. In these states, data in one portion of the state (both state highway network and off-state network HPMS sections) are collected by the state DOT, while the vendor collects the data on the rest of the state. • In two states, the vendor collects data on the state highway system, while the state DOT col- lects data at the HPMS sections located on the off-state system. C H A P T E R 6 Collection of Inertial Profile for Network-Level IRI

74 Inertial Profiler Certification for Evaluation of International Roughness Index • In one state, the state DOT only collects data on the state highway network and does not collect data at the HPMS sections on the off-state system. • In 27 states (61% of the states that responded to the survey), the state DOT uses state DOT–owned equipment to collect data on all or a portion of the state highway network and/or at all or a portion of the HPMS sections located on the off-state system. • In 25 states (57% of the states that responded to the survey), a vendor collects data using vendor-owned equipment on all or a portion of the state highway network and/or at all or a portion of the HPMS sections located on the off-state system. Certification of Inertial Profilers Certification of State DOT–Owned Equipment As indicated in the previous section, responses received from 44 state DOTs indicated that 27 state DOTs use state DOT–owned equipment to collect network-level data. Of these state DOTs, 15 do not certify the state DOT–owned equipment that is used to collect the profile data, while 12 state DOTs certify the equipment. Table 28 shows the location and organi- zation performing the profiler certification (i.e., state DOT or university) for the 12 state DOTs that certify state DOT–owned equipment. North Dakota DOT indicated that it gets its profiler certified by another DOT facility that is not subjected to traffic. This certification is performed at the Minnesota DOT facility. Missouri DOT indicated that it gets its profilers State DOTs Responding to Survey IRI Data Collection Number Percentage (%) State Highway Network HPMS Sections on Off-State System State DOT Vendor State DOT Vendor 18 41 Yes – Yes – 17 39 – Yes – Yes 1 2 Yes – – Yes 3 7 Yes Yes – Yes 2 5 Yes Yes Yes Yes 2 5 – Yes Yes – 1 2 Yes – – – Note: — = data are not collected. Table 27. Responsibility for data collection on the state highway system and at HPMS sections on the off-state system. Organization and Location for Performing Certification Number of State DOTs By state DOT at a facility not subjected to traffic 4 By state DOT at test section(s) established on in-service roads 3 By another state DOT at a facility not subjected to traffic 1 By an in-state university at a facility not subjected to traffic 1 By an out-of-state university at a facility not subjected to traffic 1 By an in-state university at test sections 2 established on in-service roads Total 12 Table 28. Location and agency performing certification for state DOT–owned profilers.

Collection of Inertial Profile for Network-Level IRI 75 certified by an out-of-state university at a facility that is not subjected to traffic. This certifi- cation is performed at TTI. Several state DOTs that do not certify their profilers indicated that they perform some type of verification of their equipment; these verification procedures are described later in this chapter. Several state DOTs that do not certify state DOT–owned equipment indicated that their agencies do not require a profiler that is collecting network-level data to be certified. Certification of Vendor-Owned Equipment As indicated previously, responses received from 44 state DOTs declared that vendors collect network-level profile data in 25 states. Eighteen of these state DOTs indicated that they do not certify the vendor-owned equipment, with three of these state DOTs indicating that the vendor submits information to show that the profiler has been certified at NCAT. Several state DOTs indicated that their agencies do not require the vendor’s profiler to be certified. Vendor-owned equipment is certified in-state in seven states. Table 29 shows the organization performing certi- fication and the location where certification is performed in the seven states that certify vendor- owned equipment in-state. All seven states that certify vendor-owned equipment indicated that they do not accept certification for a vendor-owned equipment from another state. Within the same state DOT, the policy regarding certification of state DOT–owned and vendor- owned equipment that collect data in the state can be different. This appears to be happening because different divisions in the state DOT are in charge of the state DOT–owned profilers and data collection by the vendor. For example, in New Jersey, the DOT–owned profilers collect data on the state highway network. These profilers are certified by the state DOT at a facility within the state. The state data at HPMS sections located on the off-state network are collected by a vendor, and the equipment used by the vendor is not certified by the state DOT. In two other state DOTs, the DOT–owned equipment that collects network-level data is certified by the state DOT. However, the vendor’s equipment that collects network-level data in the state is not certified by the state DOT. Several state DOTs that certify contractor-owned profilers that collect data for construction acceptance do not certify vendor-owned equipment that collect network-level data. Frequency of Certification In the states where DOT–owned or vendor-owned equipment is certified, certification is either performed annually or before data collection. Surface Texture Types Used for Certification Fifteen states have in-state certification locations that are used to certify profilers that collect network-level data. In two of these states, the DOT as well as vendors collect network data, and Agency and Location for Performing Certification Number of State DOTsfor Contractor-Owned Equipment By state DOT at a facility not subjected to traffic 2 By state DOT at test section(s) established on in-service roads 3 By an in-state university at a facility not subjected to traffic 2 Total 7 Table 29. Location and agency performing certification for vendor-owned profilers.

76 Inertial Profiler Certification for Evaluation of International Roughness Index both the DOT and vendor-owned equipment are certified. In five of these states, only the vendor collects the network data, while in another five of these states only the DOT collects network data. In three of these states, both the vendor and DOT collect network-level data, but only the state DOT–owned equipment is certified. Table 30 shows the surface texture and the roughness level of the test sections used for profiler certification in the 15 states with in-state certification programs for certifying profilers that col- lect network-level data. The table also shows the number of AC- and PCC-surfaced test sections that are used for certification. The test sections used in these states to certify network-level profilers are the same test sections that were used to certify profilers that collect data for construction acceptance. Length of Section and Device for Reference Data Collection In the 15 states that responded to the survey and that have an in-state certification program for certifying profilers that collect network-level data, the length of a test section used for certifi- cation is 0.1 mi in 13 states and 0.2 mi in two states. In all of these states, the SurPRO is used to collect the reference data at the test sections. Procedure Used to Certify Profilers Table 31 shows the procedure that is used to certify profilers that collect network-level data in the 15 states that responded to the survey and indicated that they have an in-state certifica- tion program. Five state DOTs use the AASHTO R 56-14 procedure to perform certification, while five state DOTs use an agency-developed procedure that includes the cross-correlation method specified in AASHTO R 56-14 to certify profilers. Hence, 10 agencies use a certifica- tion procedure that includes the cross-correlation procedure specified in AASHTO R 56-14. State Number of Surface/Texture Type and Roughness Level Number Sections Used for Certification AC PCC 1 4 – DAC (IRI < 70, 70 to 120, and > 120 in./mi), OAC (IRI < 70 in./mi) 2 1 – DAC (IRI < 70 in./mi) 5 1 – DAC (IRI not specified) 14 2 2 DAC (IRI < 70, > 120 in./mi), TTC and DGC (IRI < 70 in./mi) 18 2 – DAC (IRI 70 to 120 and > 120 in./mi) 19 1 – DAC (IRI 70 to 120 in./mi) 20 1 1 DAC and TTC (IRI 70 to 120 in./mi) 21 1 – DAC (IRI < 70 in./mi) 26 3 – DAC (IRI < 70, 70 to 120, and > 120 in./mi) 29 2 – DAC (IRI < 70 and > 120 in./mi) 33 2 – DAC (IRI < 70 and 70 to 120 in./mi) 38 3 3 DAC and TTC (IRI < 70 and 70 to 120 in./mi) and OAC and LTC (IRI < 70 in./mi) 39 1 – DAC (not specified) 42 2 – DAC (IRI 70 to 120 and > 120 in./mi) 44 1 – DAC (IRI 70 to 120 in./mi) Note: — = no test sections. Table 30. Test sections used for certifying profilers that collect network-level data.

Collection of Inertial Profile for Network-Level IRI 77 Fee for Certifying Vendor-Owned Profilers Although vendors collect data in 25 of the 44 states that responded to the survey, vendor- owned profilers are certified in only seven states. A fee for certification of equipment is charged in three of these states. In California, the fee for certifying a profiler is $1,000. In the other two states (i.e., Alabama and Texas) the certification is performed by university-affiliated institutions (i.e., NCAT in Alabama and TTI in Texas). NCAT charges a fee of $1,500 to certify a profiler, which includes the certification of any number of operators for that profiler. The TTI has vary- ing fees depending on the type of certification required, and the details of fees charged by TTI to certify profilers were described in Chapter 5. Documentation Provided After Certifying Vendor-Owned Inertial Profilers Table 32 shows the type of documentation provided after certification of the profiler in the seven states where vendor-owned equipment is certified. Verification of Profilers The certification of a profiler requires the data collected by the profiler to be checked against reference data that have been collected with a reference device. Several state DOTs that do not certify DOT-owned equipment or vendor-owned equipment indicated that they perform verifica- tion of the equipment before data collection. For state DOT–owned equipment, the verification is typically performed by collecting data at an established verification site or sites where profile data have been previously collected with the profiler and evaluating the collected data with previously collected data at the site. Also, data collected by a state DOT–owned profiler at a verification site can be compared with data collected by other state DOT–owned profilers (if the state DOT has multiple profilers) to determine whether data collected by the profilers agree with each other. For vendor-owned equipment, the verification involves either (1) collecting data with the vendor’s equipment at established verification sites and then comparing the collected data with the data Procedure for Profiler Certification Number of State DOTs AASHTO R 56 5 ASTM E950 1 Agency-developed procedure (includes cross-correlation) 5 Agency-developed procedure (does not include cross-correlation) 4 Total 15 Table 31. Procedure for performing profiler certification. Documentation Provided After Certification Number of States None, DOT assumes certified profiler will collect data 2 Letter provided 1 Decal affixed to profiler and letter provided 1 Decal affixed to profiler, letter provided, and details posted on web 1 Decal affixed to profiler and details posted on web 1 Letter provided and details posted on web 1 Table 32. Documentation provided after certification of the profiler.

78 Inertial Profiler Certification for Evaluation of International Roughness Index collected by the state DOT–owned profiler at the sites, or (2) collecting data with the vendor’s equipment at established verification sites where data have been collected previously with a profiler and then comparing the collected data with historical data collected at the sites. State DOT–Owned Equipment The procedures followed by the state DOTs that provided information about the verification procedures they use are shown below. • One state DOT indicated that it performs an annual verification of all of its profilers 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 SurPRO is a reference device, the state DOT refers to this process as verification rather than certification. This is because the state DOT has not yet developed criteria to certify profilers. The profilers that collect network-level data also collect data weekly at a 5-mi-long verification section. • One state DOT indicated that the profiler collects data at an established verification site at regular intervals, and these data are checked with previously collected data at the site to ensure the profiler is collecting consistent data. • One state DOT indicated that the equipment collects data along two established routes near the office at least two times per year. • One state DOT indicated that the profiler manufacturer performs maintenance on the profilers at the start of the year; thereafter, these profilers collect data on an established verification site. • One state DOT indicated that the equipment is calibrated annually and verified monthly on a 13-mi circuit. • One state DOT indicated that the manufacturer performs an annual equipment check and calibrates system components. The state DOT indicated that the equipment can be verified at in-service locations in the state by comparing the collected data with previously collected data. • One state DOT indicated that the manufacturer performs an equipment check and calibrates system components at the start of the year. Thereafter, the equipment is run in both direc- tions at an established control site. This provides data that can check the data collected by the left and the right sensors along the same path. The profiler also collects data on a 2-mi-long verification section every week. • One state DOT has established a course on in-service roads to collect data that are used to approve contractor-owned profilers that collect data for construction acceptance. The state DOT–owned profilers that collect network-level data also collect data on this course. This course has several surface types that are 0.2- to 0.3-mi long, and the state DOT has estab- lished test sections on each surface type. The surface types located on this course are dense- graded AC (IRI less than 70 in./mi), transversely tined PCC (IRI greater than 120 in./mi), diamond-ground PCC (IRI 70 to 120 in./mi.), longitudinally ground PCC (IRI 70 to 120 in./mi), and longitudinally ground AC (IRI less than 70 in./mi). The data collected by the state DOT–owned profilers at these test sections are compared with each other to verify that the profilers are collecting satisfactory data. Vendor-Owned Equipment The procedures followed by the state DOTs that provided information about verification procedures they use before the vendor starts collecting data in the state are shown below. • One state DOT indicated that the vendor is required to collect data at about 14 verification sites. These data are compared to data collected at these sites by the state DOT–owned equip- ment and must agree within the allowable limits established by the state DOT. The established

Collection of Inertial Profile for Network-Level IRI 79 verification sites are typically 0.1-mi long, and the surface types of the verification sites include AC, surface treatment, jointed PCC, and continuously reinforced PCC. • One state DOT indicated that verification sites that are approximately 1,300-ft long are estab- lished on AC, transversely tined PCC, and longitudinally tined PCC pavements. The data collected by the vendor and the state DOT–owned profiler at these sites are compared. • One state DOT indicated that the profiler is checked against the SurPRO data collected through a 0.1-mi-long section established through a signalized intersection to verify the ven- dor’s ability to collect data in an urban environment. The state where this check is performed has a high proportion of urban roads in its highway network. • One state DOT indicated that the data collected by the vendor are compared with the data collected by the state DOT at six sites. The typical length of a site is 0.1 mi, and two sections each are established on AC pavements, composite pavements, and transversely tined PCC pavements. For each surface type, one section has an IRI less than 70 in./mi and the other has an IRI between 70 and 120 in./mi. • One state DOT indicated that the vendor collects data on a verification section established by the state DOT, and the collected data are compared with the data collected by the state DOT–owned equipment at this site. Many state DOTs that use vendors to collect network data require the vendor to collect data at control sections established throughout the state during data collection. More information about the procedures used by the state DOTs to verify the data collected by the vendor is pro- vided later in this chapter. Certification of Inertial Profiler Operators As indicated previously in this chapter, 27 of the 44 state DOTs that responded to the survey use state DOT–owned equipment to collect network-level data. Of these 27 state DOTs, only three indicated that state DOT operators are certified. One state DOT indicated that although no formal certification is performed, in-house training of operators is conducted every year. As indicated previously in this chapter, 25 of the 44 state DOTs that responded to the survey use a vendor to collect network-level data. Of these state DOTs, only two require vendors’ opera- tors to be certified through an in-state certification program. Both of these states indicated that they do not accept an operator certification provided by another state. Table 33 shows the procedures used for operator certification in the five states where operator certification is required for network-level data collection (i.e., three states that certify state DOT operators and two that certify vendor operators). One state that certifies DOT operators indi- cated that the operators must attend a training course, such as NHI course 131100 (NHI 2017). Of the five states that require profiler operators to be certified, two maintain operator certifi- cation as valid for 1 year. In two other states, the operator certification is valid for 3 years. In one state where the DOT collects the data, operators are required to be certified only once; and once certified, the certification does not expire. Procedures for Certifying Operators Number of State DOTs Attend class, pass a written exam, and pass a practical exam 2 Attend class, and pass a practical exam 2 Pass a practical exam 1 Table 33. Procedures for certification of operators who collect network-level data.

80 Inertial Profiler Certification for Evaluation of International Roughness Index In California, the fee for certifying a vendor’s operator is $500. Alabama is the other state that requires vendors’ operators to be certified. The profiler and operator certification in Alabama is performed by NCAT, which charges a fee of $1,500 for certifying a profiler and any number of operators for the profiler. Sensor Types Specified for Data Collection Twenty-five of the 44 state DOTs that responded to the survey allow vendors to collect net- work data. Table 34 shows the responses received from these state DOTs regarding the height- sensor type specified for data collection. Thirteen state DOTs indicated that they do not specify the height-sensor type for data collection. Six and four state DOTs specified an LL and SS laser, respectively. One state DOT allows either an SS laser or an LL height sensor, while one state DOT allows SS or LLs on AC surfaces but requires an LL for PCC surfaces. Twenty-seven of the 44 state DOTs that responded to the survey collect network-level data using state DOT–owned equipment. Table 35 shows the responses received from these state DOTs regarding the sensor type specified for data collection. Some of the responses received from these agencies may have depended on the sensor type that is currently on the state DOT– owned equipment, rather than the policy of the state DOT. Operational Procedures for Collecting Data It is important to ensure that accurate data are being collected during network-level data col- lection. Performing tests—such as the block check or the bounce test—according to the proce- dures and at intervals established by the agency (if the state DOT is collecting data) or according to the procedures and intervals described in the vendor’s QC plan (if the vendor is collecting data) will determine if the components in the profiler are functioning properly. The state DOT can Sensor Type Specified for Data Collection Number of State DOTs Not specified 13 LL 6 SS laser 4 SS or LL 1 SS or LL AC, LL PCC 1 Total 25 Table 34. Sensor types specified for height sensors by state DOTs that use vendors to collect network-level data. Sensor Type Specified for Data Collection Number of State DOTs Not specified 5 LL 8 SS laser 8 SS or LL 2 WS laser 2 SS or LL for AC, LL for PCC 1 SS, WS, or LL for AC, and LL for PCC 1 Total 27 Table 35. Sensor types specified for height sensors by state DOTs that use state DOT–owned equipment to collect data.

Collection of Inertial Profile for Network-Level IRI 81 also establish verification sections in different parts of the state and require the profiler to collect data at these sites. If the state DOT is collecting network-level data, data collected at the verifica- tion sections can be compared with data previously collected at these sites by the state DOT. If a vendor is collecting network-level data, the state DOT can collect data at these sites with the state DOT–owned profiler, ask the vendor to collect data at these sites, and compare the data collected by the vendor with the data collected by the state DOT. If the state DOT does not collect data at the verification sites, the data collected by the vendor at these sites can be compared with previ- ously collected data at these sites by the vendor. The state DOT can also establish a verification site near the office where the state DOT–owned profilers operate and collect data at this site at regular intervals to determine if the profiler is collecting consistent data. Data Collection by State DOT The survey asked which of the following procedures are used by the state DOT when network- level data collection is performed by the state DOT: • Collect data at verification sections established in different parts of the state during data collection; • Submit documentation at regular intervals to the office showing that the profiler has passed operational checks, such as block check and bounce test; or • None of the above. The respondent was free to select either the first or second response, select both responses, or select the third response with a comment on the procedures used. In addition, the respondent was allowed to provide additional comments. Table 36 summarized the responses provided by 27 of the 44 state DOTs that responded to the survey and indicated that they use state DOT– owned equipment to collect network-level data. The results show that 15 state DOTs collect data at verification sections during network-level data collection as a form of QC to ensure that the profiler is collecting consistent data. Data Collection by Vendor Except for three, all state DOTs that use a vendor to collect network-level data indicated that the vendor was required to submit a written data quality management procedure for network- level data collection. The responses received from these three state DOTs are: (1) one state DOT responded “Not Sure”, (2) one state DOT indicated that the vendor was required to follow the procedures in the DOTs’ data quality management plan, and (3) one state DOT indicated that Procedures Used by State DOT During Network-Level Data Collection Number of State DOTs Collect data at verification sections in different parts of state 6 Submit documentation showing profiler has passed 6 operational checks, such as block check and bounce test Collect data at verification sections in different parts of state, 7 and submit documentation showing profiler has passed operational checks such as block check and bounce test Submit documentation showing profiler has passed 2 operational checks such as block check and bounce test, and use local verification site Use local verification site 3 No required procedures 3 Total 27 Table 36. Procedures used by state DOTs when collecting network-level data.

82 Inertial Profiler Certification for Evaluation of International Roughness Index the vendor had its own data quality management plan and that it follows that plan. Typically, the procedures the vendor must follow during data collection, including the QC procedures, are part of the contract between the state DOT and the vendor for collecting the network-level data. The survey asked the state DOTs which of the following procedures are used by the vendor when collecting network-level data: • Collect data at verification sections established in different parts of the state during data collection; • Submit documentation at regular intervals to the office showing that profiler has passed oper- ational checks, such as block check and bounce test; or • None of the above. The respondent was free to select either the first or second response, select both responses, or select the third response with a comment. The respondent was also free to provide additional comments. The results from the survey are summarized in Table 37. Based on the information shown in Table 37, 20 of the 25 state DOTs that use a vendor to collect network-level data require the vendor to collect data at verification sections, while 11 state DOTs require the vendor to sub- mit documentation showing that the profiler has passed operational checks. Several state DOTs indicated that although the state DOT does not ask the vendor to submit documentation to show that the profiler has passed operational checks, the vendor is required to maintain these records, and the state DOT can request them, if desired. Several state DOTs indicated that they require the vendor to collect data at the verification sections at regular intervals (e.g., weekly, bi-weekly, or monthly). One state DOT indicated that it requires the vendor to collect data weekly at verifica- tion sites and that the state DOT maintains a spreadsheet that keeps track of when each vendor profiler performed the verification runs. One state DOT indicated that it cross-checks the vendor- collected data with the state DOT–owned profiler. Data Quality Management Information related to the development and implementation of a data quality management plan is presented by Pierce et al. (2013). Figure 16 shows responses—from the 44 state DOTs that responded to the survey—to whether the state DOT has a written data quality management plan. Only 12 state DOTs that responded to the survey (i.e., 28% of the responding DOTs) indicated that they have a written data quality management plan, with eight state DOTs (i.e., 19% of the respond- ing DOTs) indicating that they are not sure. Eighteen of the state DOTs that responded to the survey (i.e., 42% of the responding DOTs) indicated that they do not have a data quality management plan, with six state DOTs (i.e., 12% of the responding DOTs) indicating that they are developing a plan. Procedures Required by the State DOT from the Vendor During Network-Level Data Collection Number of State DOTs Collect data at verification sites located in 11 different parts of the of the state Submit documentation showing profiler has passed 2 operational checks, such as block check and bounce test Collect data at verification sections in different parts of the state, 10 and submit documentation showing profiler has passed operational checks such as block check and bounce test No required procedures 2 Total 25 Table 37. Procedures used by state DOTs when vendor collects network-level data.

Collection of Inertial Profile for Network-Level IRI 83 The items related to network-level profile data collection that can be addressed in a data quality management plan include • Equipment calibration, such as calibrating the distance measuring instrument; • Equipment operational checks, such as block check and bounce test; • Periodic testing at verification sections during data collection; • Routines for checking whether IRI computed from the data are within expected range; • Routines for checking data with previously collected data to identify inconsistencies; and • Routines for checking missing road segments. Table 38 shows a summary of the responses from the 12 state DOTs that currently have a data quality management plan in place, indicating which of the previous items are addressed in their data quality management plan. For example, eight of the 12 state DOTs indicated that equipment calibration is addressed in their plan, with seven of the 12 state DOTs indicating that equipment operational checks are addressed in their plan. Several state DOTs indicated that although they do not have a written data quality manage- ment plan, they do have procedures in place or other documents that describe the items shown in Table 38 to check the quality of the collected network-level profile data. Vendor Perspective on Profile Data Collection A survey was sent to three vendors who collect the majority of the network-level data under contract to state DOTs to obtain their perspective on several issues related to network-level data collection. Responses were received from two vendors. This section describes the vendors’ perspectives on the following issues: 1. Collection of data at verification sites in the state before collecting network-level data. 2. Requirement by the state DOTs to certify profiler at an out-of-state certification facility. Availability of Data Quality Management Plan Yes No 0 2 4 6 8 10 12 14 16 18 20 Under Development Not Sure N um be r of S ta te D O T s Figure 16. Availability of data quality management plan. Items in Data Quality Management Plan Number of State DOTs Equipment calibration (e.g., calibration of DMI) 8 Equipment operational checks (i.e., block check and bounce test) 7 Periodic testing at verification sites 8 Routines for checking whether data are within acceptable ranges 9 Routines for checking data with previously collected data 6 Table 38. Items addressed in the state data quality management plan.

84 Inertial Profiler Certification for Evaluation of International Roughness Index 3. Collection of data at verification sites during network-level data collection. 4. Submittal of a data QC plan to the state DOT before collecting data. 5. Sensor spacing specified by the state DOT. 6. Data-recording interval specified by the state DOT. 7. Height-sensor type specified by the state DOT. 8. Vendor’s fleet that is equipped with LLs. 9. Procedures adopted by the vendor when collecting data to ensure quality data are being collected. 1. Collection of data at verification sites in the state before collecting network-level data: The percentage of state DOTs that require the vendor to collect data at established verification sites before collecting data was reported as between 80% and 100% by the first vendor and 60% and 80% by the second vendor. The survey of state DOTs indicated that the vendors’ data are compared with data from a reference device only in seven states. Therefore, the benchmark that is used to compare the vendor’s data is either data collected by the state DOT–owned profiler or historical data at the site. 2. Requirement by the state DOTs to certify profiler at an out-of-state certification facility: Both vendors indicated that less than 20% of the state DOTs require the vendor to certify their profiler at an out-of-state facility, such as TTI or NCAT, before data collection. In the survey, the smallest value a respondent could select was less than 20%. In the survey of the state DOTs, only three DOTs indicated that the vendor submits documentation to show that the equipment has been certified at an out-of-state facility. 3. Collection of data at verification sites during network-level data collection: Both vendors indicated that between 80% and 100% of state DOTs require them to collect data at verification sections established in different parts of the state during data collection. 4. Submittal of a data quality plan before collecting data: Both vendors indicated that between 80% and 100% of state DOTs require them to submit a data QC plan before data collection. One vendor indicated that they submit a data QC plan to the state DOT regardless of whether such a plan is requested. 5. Sensor spacing specified by the state DOT: One vendor indicated that 80% to 100% of the state DOTs specify the sensor spacing, while the other vendor indicated that less than 20% do so. The latter vendor indicated that most states refer to the ASTM standard or the AASHTO stan- dard regarding the sensor spacing to be used. ASTM Standard E950 specifies a sensor spacing between 58 and 71 in., which is a very wide range. AASHTO Standard R 43-13 specifies a sensor spacing between 65 and 71 in. One vendor indicated that if a sensor spacing is not specified, it uses a spacing of 69 in. on average. The other vendor indicated that the spacing can depend on the data collection vehicle, but it matches the range specified in the ASTM/AASHTO standards. 6. Data-recording interval specified by the state DOT: One vendor indicated that 80% to 100% of the state DOTs specify the data-recording interval, while the other vendor indicated that less than 40% to 60% do so. The vendor who responded that 80% to 100% of the state DOTs specify the data-recording interval indicated that the state DOTs are indirectly specifying the data-recording interval by specifying an industry standard. If a data-recording interval is not specified, one vendor indicated that it uses a value of 1.5 in. The other vendor indicated that their equipment is capable of recording data over a wide range from 0.8 to 8 in. 7. Height-sensor type specified by the state DOT: Both vendors indicated that 80% to 100% of the state DOTs stipulate the height-sensor type by specifying either SS lasers or LLs. One vendor indicated that the state DOTs do not specify items such as the frequency of the LL or the method to process the data from the LL to obtain a single elevation value over the length of the line. 8. Vendor’s fleet that is equipped with LLs: One vendor indicated that 80% to 100% of its data- collection vehicles are equipped with LLs. The other vendor indicated that 60% to 80% of its equipment is equipped with LLs, and it maintains some equipment without LLs to meet customer requirements.

Collection of Inertial Profile for Network-Level IRI 85 9. Procedures adopted by the vendor when collecting data to ensure quality data are being collected: The following is a combination of the response from both vendors on the proce- dures that are used to ensure that quality data are collected: – Perform in-house testing to ensure proper calibration of the equipment. – Perform block check and bounce test daily. – Monitor the height-sensor data, accelerometer data, and profile data for each wheelpath in real time. These data are displayed graphically in real time, and all data are monitored automatically during collection. – Process the collected data each day and flag sections that have abnormal values so that they can be inspected further. The report that is generated is sent to the central office each night. – Collect data weekly at verification sites. These sites are either established by the state, or the vendor establishes verification sites as a part of the data collection contract. – Select random locations, and request that the field crew re-collect data on routes where data were collected previously to verify the IRI values. – Plot current data with historical data to verify IRI values, and verify any discrepancies to determine whether an overlay or a maintenance project is the reason for the discrepancy. – Use images from the imaging system of the vehicle to evaluate any issues noted on the data.

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TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 526: Inertial Profiler Certification for Evaluation of International Roughness Index determines the state of practice of certification of inertial profilers at the national and international levels. Inertial profilers are used to collect the repeatable and reproducible road profiles analyzed to calculate a smoothness or ride quality index, the most common of which—the International Roughness Index (IRI)—is a performance measure that state departments of transportation (DOTs) must report to the Federal Highway Administration (FHWA) as part of Highway Performance Monitoring System/Moving Ahead for Progress in the 21st Century (HPMS/MAP-21) Act and Fixing America’s Surface Transportation (FAST) Act requirements. The information in this report can help ensure that accurate data are collected both for smoothness specifications at the project level and for MAP-21 Act and FAST Act requirements that the states provide accurate and consistent IRI data.

The report is accompanied by the following appendices:

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