Federal regulations · Through 2026-08-25 · Newer source version available

23 CFR 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”;
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.

Where this section sits in the code

Title 23—Highways
CHAPTER I—FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
SUBCHAPTER E—PLANNING AND RESEARCH
PART 490—NATIONAL PERFORMANCE MANAGEMENT MEASURES
Subpart E—National Performance Management Measures To Assess Performance of the National Highway System

(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.

Collected 2026-08-27T02:24:50Z. Source file · JSON

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