Title 23
SECTION 490.409
490.409 Calculation of National performance management measures for assessing bridge condition.
§ 490.409 Calculation of National performance management measures for assessing bridge condition.(a) The bridge measures in § 490.407 shall be calculated in accordance with this section and used by State DOTs and MPOs to carry out the bridge condition related requirements of this part and by FHWA to make the significant progress determination specified in § 490.109.
(b) The condition of bridges carrying the NHS, which includes on- and off-ramps connected to the NHS, shall be classified as Good, Fair, or Poor following the criteria specified in this paragraph. The assignment of a classification of Good, Fair, or Poor shall be based on the bridge's condition ratings for NBI Items 58 - Deck, 59 - Superstructure, 60 - Substructure, and 62 - Culverts. For the purposes of national performance measures under the NHPP, the method of assessment to determine the classification of a bridge will be the minimum of condition rating method (i.e., the condition ratings for lowest rating of a bridge's 3 NBI Items, 58 - Deck, 59 - Superstructure, and 60 - Substructure). For culverts, the rating of its NBI Item, 62 - Culverts, will determine its classification. The bridges carrying the NHS which includes on- and off-ramps connected to the NHS will be classified as Good, Fair, or Poor based on the following criteria:
(1) Good: When the lowest rating of the 3 NBI items for a bridge (Items 58 - Deck, 59 - Superstructure, 60 - Substructure) is 7, 8, or 9, the bridge will be classified as Good. When the rating of NBI item for a culvert (Item 62 - Culverts) is 7, 8, or 9, the culvert will be classified as Good.
(2) Fair: When the lowest rating of the 3 NBI items for a bridge is 5 or 6, the bridge will be classified as Fair. When the rating of NBI item for a culvert is 5 or 6, the culvert will be classified as Fair.
(3) Poor: When the lowest rating of the 3 NBI items for a bridge is 4, 3, 2, 1, or 0, the bridge will be classified as Poor. When the rating of NBI item for a culvert is 4, 3, 2, 1, or 0, the culvert will be classified as Poor.
(c) The bridge measures specified in § 490.407(c) shall be calculated for the applicable bridges per paragraph (a) that pertain to each target established by the State DOT or MPO in §§ 490.105(e) and 490.105(f), respectively, as follows:
(1) For § 490.407(c)(1), the measure for the percentage of bridges classified as in Good condition shall be computed and reported to the one tenth of a percent as follows:
Where:
GOOD = total number of the applicable bridges, where their
condition is Good per paragraph (b)(1) of this section; g = a
bridge determined to be in Good condition per paragraph (b)(1) of
this section; Length = corresponding value of NBI Item 49 -
Structure Length for every applicable bridge; Width = corresponding
value of NBI Item 52 - Deck Width or value of Item 32 Approach
Roadway Width for culverts where the roadway is on a fill
[i.e., traffic does not directly run on the top slab (or
wearing surface) of the culvert] and the headwalls do not affect
the flow of traffic for every applicable bridge. s = an applicable
bridge per paragraph (b) of this section; and TOTAL = total number
of the applicable bridges specified in paragraph (b) of this
section.
(2) For § 490.407(c)(2), the measure for the percentage of bridges classified as in Poor condition shall be computed and reported to the one tenth of a percent as follows:
Where:
POOR = total number of the applicable bridges, where their
condition is Poor per paragraph (b)(3) of this section; p = a
bridge determined to be in Poor condition per paragraph (b)(3) of
this section; Length = corresponding value of NBI Item 49 -
Structure Length for every applicable bridge; Width = corresponding
value of NBI Item 52 - Deck Width or value of Item 32 Approach
Roadway Width for culverts where the roadway is on a fill
[i.e., traffic does not directly run on the top slab (or
wearing surface) of the culvert] and the headwalls do not affect
the flow of traffic for every applicable bridge. s = an applicable
bridge per paragraph (b) of this section; and
TOTAL = total number of the applicable bridges specified in paragraph (b) of this section.
(d) The measures identified in § 490.407(c) shall be used to establish targets in accordance with § 490.105 and report targets and conditions described in § 490.107.
(e) The NBI Items included in this section are found in the Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation's Bridges, which is incorporated by reference (see § 490.111).