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Bridges & Structures

MEMORANDUM
Subject: ACTION-Revisions to the Recording and Coding Guide for the Structure, Inventory and Appraisal of the Nation's Bridges (Coding Guide) Items 63 and 65, Method Used to Determine Operating and Inventory Ratings Date: November 15, 2011
From: /s/ Original Signed by
M. Myint Lwin, P.E., S.E. Director,
Office of Bridge Technology
Refer To: HIBT-30
To: Federal Lands Highway Division Engineers
Division Administrators

The purpose of this memorandum is to notify your offices that we are revising the National Bridge Inventory (NBI) Item 63 - Method Used to Determine Operating Rating, and Item 65 - Method Used to Determine Inventory Rating in the Coding Guide report number, FHWA-PD-96-001. Following are the six new codes for the items. These codes are being added to properly identify Assigned Load Ratings.

Code Description
A Assigned rating based on Load Factor Design (LFD) reported in metric tons
B Assigned ratings based on Allowable Stress Design (ASD) reported in metric tons
C Assigned ratings based on Load and Resistance Factor Design (LRFD) reported in metric tons
D Assigned rating based on Load Factor Design (LFD) reported by rating factor (RF) using MS18 loading
E Assigned ratings based on Allowable Stress Design (ASD) reported by rating factor (RF) using MS18 loadings
F Assigned ratings based on Load and Resistance Factor Design (LRFD) reported by rating factor (RF) using HL93 loadings

All new bridges entered into the NBI inventory are expected to use these new codes if an assigned load rating method was used. Past bridges that used and meet the requirements for assigned load ratings are to be re-coded indicating the correct method by the April 2014 NBI submittal.

If there are any questions regarding these codes please direct them to Ann.Shemaka@dot.gov, 202-366-1575, or Gary.Moss@dot.gov, 202-366-4654.

Attached are the revised coding guide pages that contain the complete list of codes that are available for these 2 items.


Attachment

Item 63 - Method Used to Determine Operating Rating
1 digit

Item 63 - Method Used to Determine Inventory Rating
1 digit

Use one of the codes below to indicate which load rating method was used to determine the Operating Rating/Inventory Rating in Item 64/Item 66 for this structure.

Code Description
0Field evaluation and documented engineering judgment
1Load Factor (LF)
2Allowable Stress (AS)
3Load and Resistance Factor (LRFR)
4Load Testing
5No rating analysis or evaluation performed
6Load Factor (LF) rating reported by rating factor (RF) method using MS18 loading.
7Allowable Stress (AS) rating reported by rating factor (RF) method using MS18 loading.
8Load and Resistance Factor Rating (LRFR) rating reported by rating factor (RF) method using HL-93 loadings.
AAssigned rating based on Load Factor Design (LFD) reported in metric tons
BAssigned ratings based on Allowable Stress Design (ASD) reported in metric tons
CAssigned ratings based on Load and Resistance Factor Design (LRFD) reported in metric tons
DAssigned rating based on Load Factor Design (LFD) reported by rating factor (RF) using MS18 loading
EAssigned ratings based on Allowable Stress Design (ASD) reported by rating factor (RF) using MS18 loadings
FAssigned ratings based on Load and Resistance Factor Design (LRFD) reported by rating factor (RF) using HL93 loadings

Code 0 is to be used when the load rating is determined by field evaluation and documented engineering judgment, typically done when plans are not available or in cases of severe deterioration. Field evaluation and engineering judgment ratings must be documented.

Code 5 is to be used when the bridge has not been load rated or load rating documentation does not exist.

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Updated: 09/04/2013
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000