 U.S. Department of Transportation Federal Highway Administration |
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 |
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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 |
|---|---|
| 0 | Field evaluation and documented engineering judgment |
| 1 | Load Factor (LF) |
| 2 | Allowable Stress (AS) |
| 3 | Load and Resistance Factor (LRFR) |
| 4 | Load Testing |
| 5 | No rating analysis or evaluation performed |
| 6 | Load Factor (LF) rating reported by rating factor (RF) method using MS18 loading. |
| 7 | Allowable Stress (AS) rating reported by rating factor (RF) method using MS18 loading. |
| 8 | Load and Resistance Factor Rating (LRFR) rating reported by rating factor (RF) method using HL-93 loadings. |
| 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 |
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.