{"data":{"id":"us/23-cfr-490.513","jurisdiction":"us","citation":"23 CFR 490.513","heading":"Calculation of National Highway System performance measures.","body":"(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.\n(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:\nWhere:\nR = 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);\nI = Interstate System reporting segment “i”;\nSLi = length, to the nearest thousandth of a mile, of Interstate System reporting segment “i”;\nAVi = total annual traffic volume to the nearest single vehicle, of the Interstate System reporting segment “i”;\nJ = geographic area in which the reporting segment “i” is located where a unique occupancy factor has been determined;\nOFi = occupancy factor for vehicles on the NHS within a specified geographic area within the State/Metropolitan planning area; and\nT = total number of Interstate System reporting segments.\n(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:\nWhere:\nR = 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);\ni = non-Interstate NHS reporting segment “i”;\nSLi = length, to the nearest thousandth of a mile, of non-Interstate NHS reporting segment “i”;\nAVi = total annual traffic volume to the nearest 1 vehicle, of the Interstate System reporting segment “i”;\nj = geographic area in which the reporting segment “i” is located where a unique occupancy factor has been determined;\nOFj = occupancy factor for vehicles on the NHS within a specified geographic area within the State/Metropolitan planning area; and\nT = total number of non-Interstate NHS reporting segments.","path":["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"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-23.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:24:50Z","sha256":"6f8b271a43ca58397ff80b2e1db57e3849e5683c029a8cb00de2e2aa8497d1fc","source_id":"us-cfr","stale":true,"prev":"us/23-cfr-490.511","next":"us/23-cfr-490.515"},"notice":"GroundRules: Original legal text. Not legal advice."}