23 CFR § 490.513 - Calculation of National Highway System performance measures.

---
identifier: "/us/cfr/t23/s490.513"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "23 CFR § 490.513 - Calculation of National Highway System performance measures."
title_number: 23
title_name: "Highways"
section_number: "490.513"
section_name: "Calculation of National Highway System performance measures."
chapter_name: "FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
subchapter_number: "E"
subchapter_name: "PLANNING AND RESEARCH"
part_number: "490"
part_name: "NATIONAL PERFORMANCE MANAGEMENT MEASURES"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "23 U.S.C. 134, 135, 148(i) and 150; 49 CFR 1.85."
regulatory_source: "81 FR 13913, Mar. 15, 2016, unless otherwise noted."
cfr_part: "490"
---


# 490.513 Calculation of National Highway System performance measures.

(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”;

SL<sub>i</sub> = length, to the nearest thousandth of a mile, of Interstate System reporting segment “i”;

AV<sub>i</sub> = 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;

OF<sub>i</sub> = 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”;

SL<sub>i</sub> = length, to the nearest thousandth of a mile, of non-Interstate NHS reporting segment “i”;

AV<sub>i</sub> = 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;

OF<sub>j</sub> = 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]