Questions and Answers on the Specification for the National Bridge Inventory
Except for any cited statutes or regulations, the contents of these Q&As do not have the force and effect of law and are not meant to bind the public in any way. These Q&As are intended only to provide information regarding existing requirements under the law or agency policies.
Topic: General (G)
QG-1 Where can I find the SNBI and in what format is the document available?
AG-1 A PDF of the SNBI can be downloaded from FHWA National Bridge Inventory website https://www.fhwa.dot.gov/bridge/nbi.cfm. Printed copies will not be supplied by FHWA.
QG-2 What is the history of National Bridge Inventory (NBI) data reporting specifications leading up to this version of the SNBI?
AG-2 The SNBI takes the place of the Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation’s Bridges (Coding Guide) published in December 1995. Earlier versions of the Coding Guide were published in 1971, 1972, 1979, and 1988. In January 2014, the SNBI Bridge Elements was published by FHWA as a supplement to the Coding Guide in response to the MAP-21 legislation requirement for States and applicable Federal agencies to report element-level data for bridges on the National Highway System.
QG-3 Why replace the Coding Guide?
AG-3 The SNBI includes data items and specifications that provide an improved ability to assess and monitor bridge safety and compliance with the National Bridge Inspection Standards. It includes clarifying item specifications and expanded examples to improve ease of use and data quality. It includes new and expanded items and codes to support the administration of risk-based data driven asset and performance management programs. These enhancements also provide the ability to report to Congress on the administration of National programs and condition and needs as well as respond to bridge-level inquiries.
QG-4 What happens with the Coding Guide?
AG-4 The Coding Guide will sunset on Dec. 31, 2025. No inventory or inspection after that date should be performed using the Coding Guide. Data collected using the Coding Guide format will be considered legacy NBI data.
QG-5 What are the most significant global changes?
AG-5 FHWA considers the following to be the most significant global changes from the Coding Guide:
- Changed from metric to U.S. customary units
- Specification and Commentary format
- Inclusion of many-to-one data relationships (both items and codes)
- Item IDs instead of Item Numbers, e.g., B.C.01 – Deck Condition Rating
- More examples including a comprehensive example that is progressed through the entire document
- Non-NBIS structures will not be processed
- Emphasis on consistency with data reported to the Highway Performance Monitoring System
QG-6 Which Coding Guide items will no longer be reported to the National Bridge Inventory?
AG-6 The following items from the Coding Guide are discontinued. Please note that information provided by some of these items can now be obtained from SNBI items. Additionally, some of these are items were calculated but not reported: FHWA Region Code (1B), Base Highway Network (12), LRS Subroute Number (13B), Structure Flared (35), Approach Guardrail (36C), Approach Guardrail Ends (36D), Reference Feature (54A), Reference Feature (55A), Structural Evaluation (67), Deck Geometry (68), Underclearances, Vertical and Horizontal (69), Work Done By (75B), Length of Structure Improvement (76), Bridge Improvement Cost (94), Roadway Improvement Cost (95), Total Project Cost (96), Year of Improvement Cost Estimate (97), Parallel Structure Designation (101), Future Average Daily Traffic (114), Year of Future Average Daily Traffic (115).
Additionally, the following calculated items that were based on certain Coding Guide items have been discontinued: Sufficiency Rating Asterisk, Sufficiency Rating, and Status (Structurally Deficient, Functionally Obsolete, Not Deficient, Not Applicable).
QG-7 What structures are subject to reporting to FHWA in accordance with the SNBI?
AG-7 Data must be reported to the NBI for all structures that meet the applicability requirements of 23 CFR 650.303 and which are defined as a bridge according to 23 CFR 650.305. Data for structures that meet the applicability requirements of 23 CFR 650.503 and which are defined as a tunnel according to 23 CFR 650.505 are reported to the National Tunnel inventory in accordance with the Specifications for the National Tunnel Inventory (incorporated by reference in 23 CFR 650.517(c)(2)).