§ 490.311 Calculation of pavement metrics. ( a ) The condition metrics and inventory data elements needed to calculate the pavement performance measures shall be calculated in accordance with the HPMS Field Manual (incorporated by reference, see § 490.111), except as noted below.
( b ) State DOTs shall calculate metrics in accordance with the following relevant HPMS requirements. ( 1 ) For all pavements, the IRI metric: ( i ) Shall be computed from pavement profile data in accordance with AASHTO Standard R43-13, Standard Specification for Transportation Materials and Methods of Sampling and Testing, Standard Practice for Quantifying Roughness of Pavement, 2014, 34th/2014 Edition, AASHTO, 1-56051-606-4 (incorporated by reference, see § 490.111);
( ii ) Shall be reported for all pavements as the average value in inches per mile for each section; and
( iii ) Shall not be estimated from a PSR or other observation-based method except where permitted in § 490.309(b)(3)(iii).
( 2 ) For asphalt pavements— ( i ) The Cracking__Percent metric shall be computed as the percentage of the total area containing visible cracks to the nearest whole percent in each section; and
( ii ) The rutting metric shall be computed as the average depth of rutting, in inches to the nearest 0.01 inches, for the section.
( 3 ) For CRCP, the Cracking__Percent metric shall be computed as the percentage of the area of the section to the nearest whole percent exhibiting longitudinal cracking, punchouts, spalling, or other visible defects. Transverse cracking shall not be considered in the Cracking__Percent metric.
( 4 ) For jointed concrete pavements— ( i ) The Cracking__Percent metric shall be computed as the percentage of slabs to the nearest whole percent within the section that exhibit cracking;
( ii ) Partial slabs shall contribute to the section that contains the majority of the slab length; and
( iii ) The faulting metric shall be computed as the average height, in inches to the nearest 0.01 inch, of faulting between pavement slabs for the section.
( 5 ) For the mainline highways on the non-Interstate NHS with posted speed limits of less than 40 MPH— ( i ) The present serviceability rating (PSR) may be used as an alternative to the IRI, Cracking__Percent, rutting, and faulting pavement condition metrics.
( ii ) The PSR shall be determined as a 0 to 5 value per the procedures prescribed in the HPMS Field Manual.
( iii ) Alternative pavement condition methods may be allowed to estimate a PSR with prior approval from FHWA of the method of correlation between their condition determination and PSR as required in the HPMS Field Manual.
( c ) State DOTs shall report the four pavement metrics listed in § 490.309(a) as calculated following the requirements in paragraphs (a) and (b) of this section in accordance with the following relevant HPMS requirements: ( 1 ) Pavement condition metrics shall be reported to the HPMS in uniform section lengths of 0.1 mile (528 feet); shorter sections are permitted only at the beginning of a route, the end of a route, at bridges, or other locations where a section length of 0.1 mile is not achievable; and the maximum length of sections shall not exceed 0.11 mile (580.8 feet)
( 2 ) Each measured section shall have a single value for each of the relevant condition metrics. Sections where condition is estimated from PSR will have one value for the overall condition.
( 3 ) The time and location reference shall be reported for each section as follows: ( i ) The State__Code, Route__ID, Begin__Point, and End__Point shall be reported as specified in the HPMS field manual (incorporated by reference, see § 490.111) for each of the four condition metrics.
( ii ) The Year__Record shall be reported as the four digit year for which the data represents for each of the four condition metrics; and
( iii ) The Value__Date shall be reported as the month and year of data collection for each of the four condition metrics.
( 4 ) Sections for the four condition metrics shall be reported to the HPMS for the Interstate System by April 15 of each year for the data collected during the previous calendar year.
( 5 ) Sections for the four condition metrics shall be reported to the HPMS for the non-Interstate NHS by June 15 of each year for the data collected during the previous calendar year(s).
( d ) The three inventory data elements, Through__Lanes, Surface__Type, and Structure Type shall be reported to the HPMS as directed in Chapter 4 of the HPMS Field Manual for the entire extent of the NHS. ( 1 ) Section Lengths for the three inventory data items are not required to meet the 0.1 mile nominal length but may be any logical length as defined in the HPMS Field Manual.
( 2 ) The three inventory data elements shall be reported to the HPMS for the Interstate System by April 15 of each year.
( 3 ) The three inventory data elements shall be reported to the HPMS for the non-Interstate NHS by June 15 of the each year that data reporting is required.