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: Transitioning Data (T)
QT-1 What is transitioned NBI data?
AT-1 Transitioned NBI data is data collected in accordance with the Coding Guide that has been transitioned to SNBI-based data using the logic contained in the FHWA Data Crosswalk and Detailed Code Mapping tables. The FHWA intends to provide an online Transition Tool that may be used to transition a Coding Guide-based NBI file to an SNBI-based file. The Transition Tool will be available on the FHWA website from April 2023 until June 2026.
Agencies can use the Data Crosswalk and Detailed Code Mapping tables, or the Transition Tool, to initially populate their data collection systems or tools in preparation for further collection and validation of SNBI-based NBI data. The FHWA will use the same to transition its legacy data so that it can be used concurrently with SNBI data. This will allow for data comparison and trend analyses over a period of coverage that includes data collected in accordance with the Coding Guide, transition period data, and data collected in accordance with the SNBI. Legacy data will also continue to be available from the NBI in original Coding Guide format.
QT-2 Which Coding Guide items and codes/values will be transitioned to SNBI-based data?
AT-2 As shown in the Data Crosswalk tables, not all Coding Guide data can be transitioned to the SNBI, and not all SNBI fields can be populated by transitioned data. The FHWA transition logic applies only to items and codes/values, which are defined similarly in the Coding Guide and SNBI and for which a relationship can be described by rules that transition the data format, codes/values, and units of measure. The FHWA Data Crosswalk identifies if a data item transitions cleanly, partially, or not at all. An item which all Coding Guide codes/values map to SNBI codes/values is categorized as a clean transition. An item which some Coding Guide codes/values map to SNBI codes/values is categorized as a partial transition.
- "Yes" indicates a clean transition for that data item, meaning that all Coding Guide data codes/values transition to SNBI codes/values for that item. Items that transition cleanly should be verified, and corrected if necessary, before the March 15, 2028, data submittal.
- "No" indicates that Coding Guide data cannot transition to SNBI codes/values for that item. These fields transition to a null value, and should be populated before the March 15, 2028, data submittal.
- "Partial" indicates one or more of the following, for which in all cases the transitioned data should be verified, and corrected if necessary, before the March 15, 2028, data submittal.
- Some code/values transition cleanly, and some do not.
- Some or all codes/values transition into temporary codes that must be resolved into permanent codes by the March 15, 2028, data submittal.
- Codes are transitioned based on a logical assumption that is explained in the "Transition Notes for Developer" or "Additional Notes" column.
- "Calculate" indicates that the value is calculated from Coding Guide items and then transitioned. This field will be calculated for each data submittal and need not be verified.
QT-3 How long will data exist in transitioned form?
AT-3 The FHWA will accept transitioned data only for the 2026 and 2027 data submittals, as SNBI-based data is being collected or verified. These two datasets will contain a combination of transitioned SNBI data and collected or verified SNBI data. Verified data refers to transitioned data that has been validated by inspection or review. Transitioned data will not be accepted for the March 15, 2028, data submittal, as at that time FHWA will have implemented business processes and program oversight that no longer uses transitioned data and are based on a complete SNBI-based NBI dataset.
QT-4 When FHWA uses the term "legacy data," what does that mean?
AT-4 Legacy data is data that was reported to FHWA using the Coding Guide. Legacy data will continue to be available from the NBI in its original form.