The purpose of this subpart is to implement the requirements of 23 U.S.C. 150(c)(3)(A)(ii)(IV) and (V) to establish performance measures for State Departments of Transportation (State DOTs) and Metropolitan Planning Organizations (MPOs) to use to assess:

(a) Performance of the Interstate System; and

(b) Performance of the non-Interstate National Highway System (NHS).

(a) The performance measures are applicable to those portions of the mainline highways on the NHS as provided in paragraphs (a)(1) and (2) of this section (and in more detail in § 490.507):

(1) The Travel Time Reliability measures in § 490.507(a) are applicable to all directional mainline highways on the Interstate System and non-Interstate NHS.

(2) [Reserved]

(b) [Reserved]

[82 FR 6031, Jan. 18, 2017, as amended at 83 FR 24936, May 31, 2018; 88 FR 85392, Dec. 7, 2023; 90 FR 16466, Apr. 18, 2025]

All definitions in § 490.101 apply to this subpart. Unless otherwise specified in this subpart, the following definitions apply to this subpart:

Level of Travel Time Reliability is a comparison, expressed as a ratio, of the 80th percentile travel time of a reporting segment to the “normal” (50th percentile) travel time of a reporting segment occurring throughout a full calendar year.

Normal Travel Time (or 50th percentile travel time) is the time of travel to traverse the full extent of a reporting segment which is greater than the time for 50 percent of the travel in a calendar year to traverse the same reporting segment.

Travel time cumulative probability distribution means a representation of all the travel times for a road segment during a defined reporting period (such as annually) presented in a percentile ranked order as provided in the travel time data set. The normal (50th percentile) and 80th percentile travel times used to compute the Travel Time Reliability measures may be identified by the travel time cumulative probability distribution.

[82 FR 6031, Jan. 18, 2017, as amended at 83 FR 24936, May 31, 2018; 88 FR 85392, Dec. 7, 2023; 90 FR 16466, Apr. 18, 2025]

There are two performance measures to assess the performance of the Interstate System and the performance of the non-Interstate NHS for the purpose of carrying out the National Highway Performance Program (referred to collectively as the NHS Performance measures).

(a) Two measures are used to assess reliability (referred to collectively as the Travel Time Reliability measures). They are:

(1) Percent of the person-miles traveled on the Interstate that are reliable (referred to as the Interstate Travel Time Reliability measure); and

(2) Percent of person-miles traveled on the non-Interstate NHS that are reliable (referred to as the Non-Interstate Travel Time Reliability measure).

(b) [Reserved]

[82 FR 6031, Jan. 18, 2017, as amended at 83 FR 24936, May 31, 2018; 88 FR 85392, Dec. 7, 2023; 90 FR 16466, Apr. 18, 2025]

(a) Travel time data needed to calculate the Travel Time Reliability measures in § 490.507(a) shall come from the travel time data set, as specified in § 490.103(e).

(1) State DOTs, in coordination with MPOs, shall define reporting segments in accordance with § 490.103(f). Reporting segments must be contiguous so that they cover the full extent of the mainline highways of the NHS in the State.

(2) [Reserved]

(b) State DOTs shall not replace missing travel times when data are not available in the travel time data set (data not reported, or reported as “0” or null) as specified in § 490.511(b)(1)(v).

(c) AADT needed to calculate the Travel Time Reliability measures will be used, as reported to HPMS in June of the reporting year, to assign an annual volume to each reporting segment. Annual volume will be calculated as:

Annual Volume = AADT × 365 days

(d) The average occupancy factors for the State and/or metropolitan area (as applicable) needed to calculate Travel Time Reliability measures shall come from the most recently available data tables published by FHWA unless using other allowed data source(s).

(e) If an NHS roadway is closed, the State DOT is not required to include those time periods for those segments of road in the calculations required for the Level of Travel Time Reliability (LOTTR) metric (see § 490.511(a)(1)).

[82 FR 6031, Jan. 18, 2017, as amended at 83 FR 24936, May 31, 2018; 88 FR 85392, Dec. 7, 2023; 90 FR 16466, Apr. 18, 2025]

(a) Two performance metrics are required for the NHS Performance measures specified in § 490.507. These are:

(1) Level of Travel Time Reliability (LOTTR) for the Travel Time Reliability measures in § 490.507(a) (referred to as the LOTTR metric).

(2) [Reserved]

(b) The State DOT shall calculate the LOTTR metrics for each NHS reporting segment in accordance with the following:

(1) Data sets shall be created from the travel time data set to be used to calculate the LOTTR metrics. This data set shall include, for each reporting segment, a ranked list of average travel times for all traffic (“all vehicles” in NPMRDS nomenclature), to the nearest second, for 15 minute periods of a population that:

(i) Includes travel times occurring between the hours of 6 a.m. and 10 a.m. for every weekday (Monday-Friday) from January 1st through December 31st of the same year;

(ii) Includes travel times occurring between the hours of 10 a.m. and 4 p.m. for every weekday (Monday-Friday) from January 1st through December 31st of the same year;

(iii) Includes travel times occurring between the hours of 4 p.m. and 8 p.m. for every weekday (Monday-Friday) from January 1st through December 31st of the same year; and

(iv) Includes travel times occurring between the hours of 6: a.m. and 8: p.m. for every weekend day (Saturday-Sunday) from January 1st through December 31st of the same year.

(2) The Normal Travel Time (50th percentile) shall be determined from each data set defined under paragraph (b)(1) of this section as the time in which 50 percent of the times in the data set are shorter in duration and 50 percent are longer in duration. The 80th percentile travel time shall be determined for each data set defined under paragraph (b)(1) of this section as the time in which 80 percent of the times in the data set are shorter in duration and 20 percent are longer in duration. Both the Normal and 80th percentile travel times can be determined by plotting the data on a travel time cumulative probability distribution graph or using the percentile functions available in spreadsheet and other analytical tools.

(3) Four LOTTR metrics shall be calculated for each reporting segment; one for each data set defined under paragraph (b)(1) of this section as the 80th percentile travel time divided by the 50th percentile travel time and rounded to the nearest hundredth.

(c)-(d) [Reserved]

(e) Starting in 2018 and annually thereafter, State DOTs shall report the LOTTR metrics, defined in paragraph (b) of this section, in accordance with HPMS Field Manual by June 15th of each year for the previous year's measures.

(1) Metrics are reported to HPMS by reporting segment. All reporting segments where the NPMRDS is used shall be referenced by NPMRDS TMC(s) or HPMS section(s). If a State DOT elects to use, in part or in whole, the equivalent data set, all reporting segment shall be referenced by HPMS section(s); and

(2) The LOTTR metric (to the nearest hundredths) for each of the four time periods identified in paragraphs (b)(1)(i) through (iv) of this section: the corresponding 80th percentile travel times (to the nearest second), the corresponding Normal (50th percentile) Travel Times (to the nearest second), and directional AADTs. If a State DOT does not elect to use FHWA supplied occupancy factor, as provided in § 490.507(d), that State DOT shall report vehicle occupancy factor (to the nearest tenth) to HPMS.

(f) [Reserved]

[82 FR 6031, Jan. 18, 2017, as amended at 83 FR 24936, May 31, 2018; 88 FR 85393, Dec. 7, 2023; 90 FR 16466, Apr. 18, 2025]

(a) The NHS Performance measures in § 490.507 shall be calculated in accordance with this section by State DOTs and MPOs to carry out the Interstate System and non-Interstate NHS performance-related requirements of this part, and by FHWA to make the significant progress determinations specified in § 490.109 and to report on system performance.

(b) The Interstate Travel Time Reliability measure specified in § 490.507(a)(1) shall be computed to the nearest tenth of a percent as follows:

Where: R = total number of Interstate System reporting segments that are exhibiting an LOTTR below 1.50 during all of the time periods identified in § 490.511(b)(1)(i) through (iv); I = Interstate System reporting segment “i”; SLi = length, to the nearest thousandth of a mile, of Interstate System reporting segment “i”; AVi = total annual traffic volume to the nearest single vehicle, of the Interstate System reporting segment “i”; J = geographic area in which the reporting segment “i” is located where a unique occupancy factor has been determined; OFi = occupancy factor for vehicles on the NHS within a specified geographic area within the State/Metropolitan planning area; and T = total number of Interstate System reporting segments. (c) The Non-Interstate Travel Time Reliability measure specified in § 490.507(a)(2) shall be computed to the nearest tenth of a percent as follows: Where: R = total number of non-Interstate NHS reporting segments that are exhibiting an LOTTR below 1.50 during all of the time periods identified in § 490.511(b)(1)(i) through (iv); i = non-Interstate NHS reporting segment “i”; SLi = length, to the nearest thousandth of a mile, of non-Interstate NHS reporting segment “i”; AVi = total annual traffic volume to the nearest 1 vehicle, of the Interstate System reporting segment “i”; j = geographic area in which the reporting segment “i” is located where a unique occupancy factor has been determined; OFj = occupancy factor for vehicles on the NHS within a specified geographic area within the State/Metropolitan planning area; and T = total number of non-Interstate NHS reporting segments. [82 FR 6031, Jan. 18, 2017, as amended at 83 FR 24936, May 31, 2018; 88 FR 85393, Dec. 7, 2023; 90 FR 16466, Apr. 18, 2025]