The purpose of this subpart is to implement the requirements of 23 U.S.C. 150(c)(6) to establish performance measures for State Departments of Transportation (State DOTs) and the Metropolitan Planning Organizations (MPOs) to use to assess the national freight movement on the Interstate System.

The performance measures to assess the national freight movement are applicable to the Interstate System.

The definitions in § 490.101 apply to this subpart.

The performance measure to assess freight movement on the Interstate System is the: Truck Travel Time Reliability (TTTR) Index (referred to as the Freight Reliability measure).

(a) Travel time data needed to calculate the Freight Reliability measure in § 490.607 shall come from the travel time data set, as specified in § 490.103(e).

(b) 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 directional mainline highways of the Interstate in the State.

(c) When truck travel times are not available in the travel time data set (data not reported, or reported as “0” or null) as specified in § 490.611(a)(1)(ii) for a given 15 minute interval, State DOTs shall replace the missing travel time with an observed travel time that represents all traffic on the roadway during the same 15 minute interval (“all vehicles” in NPMRDS nomenclature).

(d) 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 Freight Reliability metric/measure.

(a) The State DOT shall calculate the TTTR Index metric (referred to as the TTTR metric) for each Interstate System reporting segment in accordance with the following:

(1) A truck travel time data set shall be created from the travel time data set to be used to calculate the TTTR metric. This data set shall include, for each reporting segment, a ranked list of average truck travel times, to the nearest second, for 15 minute periods of a 24-hour period for an entire calendar year that:

(i) Includes “AM Peak” 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 “Mid Day” 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 “PM Peak” 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;

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

(v) Includes “Weekend” 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 Truck Travel Time (50th percentile) shall be determined from each of the truck travel time data sets defined under paragraph (a)(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 95th percentile truck travel time shall be determined from each of the truck travel time data sets defined under paragraph (a)(1) of this section as the time in which 95 percent of the times in the data set are shorter in duration. Both the Normal and 95th percentile truck 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) Five TTTR metrics shall be calculated for each reporting segment; one for each data set defined under paragraph (a)(1) of this section as the 95th percentile travel time divided by the Normal Truck Travel Time and rounded to the nearest hundredth.

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

(1) All metrics shall be reported to HPMS by reporting segments. When the NPMRDS is used metrics 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).

(2) The TTTR metric shall be reported to HPMS for each reporting segment (to the nearest hundredths) for each of the five time periods identified in paragraphs (a)(1)(i) through (v) of this section; the corresponding 95th percentile travel times (to the nearest second) and the corresponding normal (50th percentile) travel times (to the nearest second).

(a) The performance for freight movement on the Interstate in § 490.607 (the Freight Reliability measure) shall be calculated in accordance with this section by State DOTs and MPOs to carry out the freight movement on the Interstate System related requirements of this part, and by FHWA to make the significant progress determinations specified in § 490.109 and to report on freight performance of the Interstate System.

(b) The Freight Reliability measure shall be computed to the nearest hundredth as follows: